Vascular endothelial generating factor pathway in ovarian cancer

Abstract

Ovarian cancer remains the most lethal malignancy of the female reproductive tract. Because early-stage disease is almost silent, roughly 70% of patients present with advanced, disseminated tumors. The current standard—maximal cytoreductive surgery followed by platinum-based chemotherapy—achieves only transient control: recurrence is the rule rather than the exception, and acquired resistance steadily erodes therapeutic benefit.

A growing body of evidence now positions vascular endothelial growth factor (VEGF) at the epicenter of this therapeutic impasse. Beyond driving neo-angiogenesis, VEGF fuels invasion, metastatic spread, and chemoresistance and independently predicts malignant ascites formation. Exploiting this insight, VEGF-directed molecular therapeutics and immunotherapies are emerging as a rational strategy to break past the plateau of conventional treatment. By dissecting and re-engineering the tumor vasculature, these approaches offer the prospect of precision regimens that restore drug sensitivity and prolong survival.

Here we synthesize current knowledge on VEGF signaling in ovarian cancer. We catalogue upstream regulators of VEGF expression within the tumor microenvironment, delineate the downstream pathways that orchestrate malignant behavior, and critically review VEGF-targeted agents that have entered—or are poised to enter—the clinic.

Background

Ovarian cancer is one of the deadliest cancers in the female reproductive system and one of the leading causes of cancer deaths worldwide [1]. Since ovarian cancer usually has no obvious clinical symptoms in the early stage, it is often detected in the late stage, which makes the early diagnosis and treatment of ovarian cancer very difficult [2]. At the same time, the incidence and mortality of ovarian cancer vary in different regions. In China, the incidence and mortality are higher than the world standard, so ovarian cancer can also be regarded as one of the most challenging diseases in the female reproductive system [3]. At the present stage, the treatment of ovarian cancer mainly relies on the combination of surgery and chemotherapy. Still, due to the high recurrence rate of the postoperative period, and the change in the body’s resistance to the drugs used for a long period, especially to the platinum drugs, it suggests that ovarian cancer needs a new therapeutic strategy [4, 5].

In recent years, studies have shown that the treatment of ovarian cancer has gradually evolved in the direction of molecular targeted therapy and immunotherapy [6]. Among these therapeutic strategies, targeted therapy against vascular endothelial growth factor (VEGF) is particularly important [7, 8]. VEGF is an important pro-angiogenic factor that promotes angiogenesis by binding to a variety of receptors. Cancer cells initiate the “angiogenic mechanism” by triggering the production of a series of angiogenic factors, the most critical of which is VEGF, which acts through the paracrine pathway to trigger a dramatic increase in angiogenesis within the tumor. VEGF is an important inducer of many steps of angiogenesis and plays an important role in many physiological and pathological processes of angiogenesis, such as diabetic retinopathy [9].

This was demonstrated in a number of studies that VEGF expression is strongly correlated with invasiveness, metastasis, and response to chemotherapy in ovarian cancer. VEGF expression correlates with tumor invasiveness and response to chemotherapy [10]. Studies have shown that high expression of VEGF is associated with advanced disease and poorer survival [11]. Meanwhile, the expression level of VEGF in patients with ovarian cancer was proved to be an independent predictor for the prediction of post-treatment ascites formation, with an HR value of 0.27, P < 0.004 [12]. Up to now, surgery has been one of the most important means of treatment of ovarian cancer, which usually involves the removal of Surgery is usually the treatment of choice for patients with early-stage ovarian cancer, and is often used in combination with chemotherapy in advanced-stage patients [13]. Although in some cases, treatment of ovarian cancer by surgery can significantly improve the survival rate of patients with advanced-stage ovarian cancer, the effect varies depending on the specific conditions of the patient. For example, complete cytoreduction surgery (R0 resection) is associated with a higher survival rate, but not all patients can achieve this standard due to individual differences [14]. In addition, even if complete cytoreduction is successfully achieved, patients with advanced ovarian cancer are still at a high risk of recurrence [15]. Recent experiments in this area suggested that the risk of recurrence of ovarian cancer 6 months after surgery is 53% [16]. Given the close correlation between the expression level of VEGF and the development and prognosis of ovarian cancer, this paper reviews various strategies for regulating VEGF in the treatment of ovarian cancer in recent years, with special attention paid to the vascular angiogenesis factor pathway in ovarian cancer. Finally, we present the prospect of vascular angiogenesis factor and its pathway in ovarian cancer.

VEGF and its signaling pathways

The full name of VEGF is Vascular Endothelial Growth Factor, which is a homodimeric glycoprotein with a molecular weight of approximately 45 kDa [17]. The chemical composition of VEGF consists of two identical polypeptide chains that form a dimeric structure and are linked by disulfide bonds. Each polypeptide chain contains 750 amino acid residues, of which eight cysteine residues form a ring structure, and these cysteine residues form a structural domain called a cysteine knot [18]. Folkman first proposed the hypothesis that tumor growth is dependent on angiogenesis in 1971 and introduced the concept that tumor dormancy is caused by the blockage of angiogenesis for the first time [19]. After Folkman’s theory, it took about ten years to discover the key protein, VEGF, which is considered to be a key factor in promoting angiogenesis. VEGF was originally discovered by Senger and Dvorak in 1983 and named ‘vascular permeability factor’ (VPF) [20]. In 1989, Ferrara and Henzel found that it was identical to a factor in pituitary follicular cells, and they purified, cloned, and named this factor as ‘VEGF’ [21].

The VEGF family consists of several isoforms, such as VEGF-A, VEGF-B, VEGF-C, and VEGF-D, which act through different receptors [22]. VEGFR-1 is a VEGF receptor belonging to the tyrosine kinase family of receptors. It is mainly expressed by vascular endothelial cells and placental trophoblast cells and has a high affinity for binding VEGF-A and VEGF-B [23]. VEGF-A is the main angiogenic mediator, and VEGFR-1 negatively regulates angiogenesis by capturing VEGF-A and reducing the binding of VEGF-A to VEGFR-2 [24]. VEGFR-2, also known as KDR/Flk-1, is the main signaling receptor of the VEGF family and is responsible for mediating angiogenesis, endothelial cell proliferation, and permeability regulation of angiogenic endothelial cells [25], this receptor has two ligands, VEGF-A and VEGF-C, of which VEGF-C has a particularly prominent role in cancer, and its high expression in gastric and colorectal cancers correlates with lymph node metastasis [26]. VEGFR-3, a tyrosine kinase receptor, is mainly activated through its ligands, VEGF-C and VEGF-D, it plays an important role in embryonic development and adult tissues, especially in lymphangiogenesis and the development of the lymphatic system [27], and is mainly involved in lymphangiogenesis [7]. VEGF-D, a secreted glycoprotein belonging to the VEGF family, is strongly expressed in the SKOV3 cell line and has been associated with the rapid proliferation of tumor cells through the lymphatic vessels and the increase in the diameter and number of lymphatic vessels [28]. Overexpression of VEGF-D upregulates CA125 expression in metastatic lymph nodes and promotes tumor cell invasion, thereby exacerbating lymph node metastasis [29]. VEGF plays a central role in angiogenesis and vasculogenesis, and its expression has been validated in a wide range of tissues. The function of this growth factor is mediated through receptors on cell membranes, in particular the VEGFR-1 and VEGFR-2 receptors. These receptor structures include seven extracellular domains and one intracellular domain containing tyrosine kinase activity. The extracellular domain is responsible for binding ligands and promoting receptor dimerization, a process that in turn activates tyrosine kinases, leading to phosphorylation of the receptor itself. Subsequently, this series of events triggers signal transmission downstream through the PCγ/IP3-DAG/PKC pathway, ultimately activating a series of diverse signal cascades [30]. These pathways ultimately converge on the nucleus, leading to DNA replication, cell proliferation, cell survival, and cell migration. Although VEGFR-2 is the major mediator of VEGF activity, its affinity for VEGF is 10-fold lower than that of VEGFR-1.In contrast, VEGFR-1 is weakly phosphorylated after binding to VEGF and is thought to act as a regulator of VEGFR-2 signaling [31]. In addition, the interaction between VEGFR-1 and VEGFR-2 may be competitive in some cases, for example, in some tumor cells, VEGFR-1 may exert a negative regulatory effect by inhibiting VEGFR-2 signaling [32].

Among VEGF receptors, there are also soluble VEGF receptors, namely sVEGFR-1 and sVEGFR-2, whose role is to capture VEGF and thereby prevent VEGF molecules from acting biologically [33]. These soluble receptors reduce the biological effects of VEGF by binding to VEGF and preventing its interaction with receptors on the cell surface [32].sVEGFR-1 can also form negative complexes with surface VEGFRs to further inhibit VEGF signaling. This negative complex can reduce the affinity of VEGF to its receptor, thereby inhibiting angiogenesis mediated by VEGF [34].sVEGFR-2 functions as an endogenous inhibitor of VEGF activity and inhibits angiogenesis by competitively binding to VEGF to reduce the binding efficiency of VEGF and its receptor [35]. In the tumor microenvironment, VEGFR-3 regulates tyrosine phosphorylation sites by forming a heterodimer with VEGFR-2, thereby affecting tumor angiogenesis and lymphangiogenesis [36].

In addition to VEGFR, VEGF interacts with a group of co-receptors, neurophospholipids (NRPs). Neurofilament Protein 1 (NRP1) and Neurofilament Protein 2 (NRP2) are also involved in VEGF signaling as co-receptors.NRP1 and NRP2 act as co-receptors for VEGF, they bind to the VEGFRs (such as VEGFR-1 and VEGFR-2) and thus participate in VEGF signaling [37]. NRP1 and NRP2 enhance the binding capacity of VEGF to its receptor and promote downstream signaling through the formation of complexes with VEGFRs.NRP1, as a specific receptor for VEGFA165, enhances the binding of VEGFA165 to the NRP1, as a specific receptor for VEGFA165, can enhance the binding of VEGFA165 to the endothelial cell surface, thereby promoting angiogenesis and tumor progression [38]. Meanwhile, it has also been shown that NRP1 not only acts independently of VEGFR-2 but also regulates signaling through the formation of a complex with VEGFA165 [39], which further supports the strong binding ability between VEGFA165 and NRP1. Furthermore, NRP1 can bind to VEGFR-2 to form the NRP1 receptor and promote downstream signaling [40]. VEGFR-2 to form the NRP1-NRP1-VEGFR complex, which enhances VEGF signaling [41]. It has also been demonstrated that NRP1 increases the binding of VEGFA165 to VEGFR-2 and enhances the chemotaxis and mitogenic activity of endothelial cells [42].

The binding of VEGF and its isoforms to their corresponding receptors induces receptor dimerization, activates intracellular tyrosine kinase domains, triggers autophosphorylation, and initiates downstream signals. VEGF initiates multiple signaling pathways (e.g., the PI3K/AKT/mTOR, ERK signaling pathways, etc.) through this mechanism of action, which collectively contributes to tumor angiogenesis, invasiveness, and chemotherapy resistance, providing a potential target for ovarian cancer treatment. Resistance, providing potential targets for the treatment of ovarian cancer. The PI3K/AKT/mTOR pathway is an intracellular signaling pathway involving phosphatidylinositol 3-kinase (PI3K), protein kinase B (AKT), and mammalian target of rapamycin (mTOR), which are among the most frequently mutated gene elements in cancers of the uterus, endometrioid carcinoma and ovarian cancer. The activation of the PI3K/AKT/mTOR signaling pathway is mainly achieved through various mechanisms, including gene mutation, amplification or dysregulation of expression, which can delay tumor growth and prolong survival [43]. VEGF activates the PI3K/AKT signaling pathway by binding to its receptor (e.g., VEGF-A binds to VEGFR-1 and VEGFR-2) [44]. VEGFR-2 activates PI3K through tyrosine sites, especially tyrosine 1173, which recruits the p85 subunit of PI3K, and thus participates in endothelial cell proliferation and survival [45]. After activation of PI3K, it phosphorylates and activates AKT, which in turn promotes cell proliferation, migration, and angiogenesis [46].

The extracellular signal-regulated kinase (ERK) signaling pathway is continuously activated in ovarian cancer, which is closely related to the proliferation and survival of cancer cells [47]. VEGF binds to VEGFR-2 at specific sites and phosphorylates VEGFR-2, and after VEGFR-2 phosphorylation, PLCγ binds to the receptor’s phosphorylation sites through the SH2 structural domains, especially the Y1175 site. After VEGFR-2 phosphorylation, PLCγ binds to the phosphorylation sites of the receptor through the SH2 structural domain, especially Y1175, and the activated PLCγ hydrolyzes PIP2 to generate IP3 and DAG, which activates PKC and then the ERK pathway [48] and promotes cell proliferation. Cisplatin-based chemotherapy has also shown a tendency to activate the ERK signaling pathway to up-regulate the expression of VEGF in ovarian cancers, which further supports the association between ERK and VEGF [49].

Factors affecting the expression of VEGF and pathways in ovarian cancer cells

The expression of VEGF is regulated by many factors, including hypoxia, inflammatory factors (such as TNF-α and IL-1β), ROS, carcinogenic factors, growth factors (such as PDGF BB and TGF-β), and miRNA (Figs 1, 2, 3, 4, 5 and 6).

Fig. 1.

Summary table of VEGF families and receptors

Fig. 2.

Example figure of VEGF and its signaling pathway

Fig. 3.

Table of factors affecting the expression of VEGF and pathways in ovarian cancer cells

Fig. 4.

Schematic representation of the excitation conditions and some cascades of the VEGF signaling pathway using VEGFR-2 as an example

Fig. 5.

Thinking map of VEGF signalling pathway-based medication for ovarian cancer treatment

Fig. 6.

VEGF-based and VEGF signalling pathway future prospects

Hypoxia-induced factors

In ovarian cancer cells, hypoxia regulates the expression of VEGF through a variety of mechanisms. Hypoxia-inducible factor HIF-1α (HIF-1α) is a transcriptional regulator that responds to and regulates the hypoxic environment, and the expression of many genes in organisms is closely related to the biological behaviors of malignant tumors [50]. In ovarian cancer, the high expression of HIF-1α is closely related to the degree of malignancy, invasiveness, and poor prognosis of the tumor [51]. Under hypoxic conditions, HIF-1α is released enters the nucleus of the cell, and combines with SP1 to form a complex, which promotes the transcription of the VEGF gene [52]^, at the same time, HIF-1α binds to hypoxic response elements to activate the expression of several hypoxic response genes, including VEGF, and enhances tumor invasion and metastatic ability [53]. Studies have shown that VEGF secretion in OVCAR-3 cells can be significantly inhibited by down-regulating the expression of HIF-1α [54]. In addition, hypoxia also stabilizes VEGF mRNA expression by prolonging its half-life [55]. The stability of VEGF mRNA is enhanced under hypoxic conditions, which may be due to apoptosis and degradation of cyclins caused by hypoxia [56].

Inflammatory factors

In ovarian cancer cells, inflammatory factors such as TNF-α (TNF-α) and IL-1β regulate the expression and function of VEGF through a variety of mechanisms. Tumour necrosis factor α is a potent pro-inflammatory cytokine secreted by a variety of cell types in the immune system, such as tumour cells [57]. TNF-α firstly binds to the TNFR1 on the cell surface TNF-α first binds to tumour necrosis factor receptor 1 on the cell surface and activates the TNFR1 ligand-induced death domain, which is followed by the involvement of TNFR1-associated junction proteins (TRAF2/5) and the activation of receptor-kinase-associated proteins, whose interactions result in the activation of the mitogen-activated protein kinase (TAK1), and then the activation of the NF-kB bait molecule, which leads to the secretion of I κB kinase α/β (IKKα/β) complex, which is responsible for phosphorylating and degrading IκBα and releasing NF-κB into the nucleus [58]. After entering the nucleus, NF-κB can regulate the expression of a variety of genes including VEGF [59] The activation of NF-κB signaling pathway is related to the invasion and proliferation of ovarian cancer cells (involving OVCAR-3 cells and SK-OV-3 cells), and inhibition of this pathway can effectively reduce the invasion and migration ability of ovarian cancer cells [60]. Interleukin-1β (IL-1β), one of the IL-1 cytokine family, is a cytokine that primarily promotes the release of inflammation and plays a dominant role in the control of cell proliferation, differentiation, and apoptosis [61]. IL-1β is expressed through its receptor interleukin-1 receptor 1 (IL-1R1), which activates myeloid differentiation primary response 88 protein, thereby initiating the NF-κB signalling pathway [62].That was demonstrated in a number of studiers that TNF-α and IL-1β can interact and activate each other’s signaling pathways at high concentrations, which may further enhance NF-κB activation and VEGF expression [63] affecting ovarian cancer cell proliferation, migration, and angiogenesis.

ROS

Oxidative stress plays an important role in the occurrence, development, and treatment resistance of ovarian cancer. Oxidative stress regulates the expression and function of VEGF through various mechanisms in ovarian cancer cells [64]. Oxidative stress interferes with normal cellular functions by increasing the level of reactive oxygen species (ROS), including inhibition of apoptotic mechanisms and promotion of cell proliferation [65]. Studies have demonstrated that ROS promotes VEGF expression by activating HIF-1α in ovarian cancer cells, thereby promoting angiogenesis and tumor formation [66]. Specifically, ovarian cancer cells (such as OVCAR-3 and A2780/CP70 cells) produce higher levels of ROS than normal ovarian epithelial cells (IOSE cells), and these ROS are able to stimulate VEGF expression [67]. In ovarian cancer, ROS specifically activates HIF-1α to promote VEGF expression through multiple mechanisms. ROS can increase ROS levels by inhibiting the p47phox subunit of NADPH oxidase 4(NOX4), thereby promoting the expression of HIF-1α and VEGF [68].

Carcinogenic factors

Genetic alterations of oncogenes and tumor suppressors associated with oncogenic transformation also induce VEGF expression. c-Myc is an important oncogene, and its expression in ovarian cancer is significantly higher than that in normal ovarian tissues, and the overexpression of c-Myc is closely related to tumor invasiveness and metastatic ability [69]. c-Myc can regulate VEGF production in B cells by stimulating the initiation of VEGF mRNA translation, resulting in a 10-fold increase in VEGF production through its overexpression [70], which in turn enhances tumor angiogenesis and invasion. Studies have shown that there are genetic alterations of several oncogenes and tumor suppressors in ovarian cancer, such as TP53, BRCA1, KRAS, etc. The mutation or aberrant expression of these genes can regulate VEGF expression through different signaling pathways. For example, activation of the KRAS gene usually promotes VEGF expression through the Ras-MAPK pathway, while inactivation of BRCA1, a tumor suppressor, may lead to upregulation of VEGF expression [71].

Growth factors

In ovarian cancer, growth factors such as PDGF BB and TGF-β can affect the expression and function of VEGF through a variety of mechanisms. It has been shown that PDGF BB induces VEGF secretion from ovarian cancer cells through the activation of platelet-derived growth factor receptor (PDGFR) and that the levels of PDGF BB and VEGF are strongly correlated in malignant ascites of ovarian cancer patients [72]. It was shown that PDGF BB induced VEGF secretion in ovarian cancer and inhibition of PDGFR receptor β activity significantly reduced serum VEGF levels in ovarian cancer [73].

Meanwhile, PDGF-BB not only induced VEGF expression in ovarian cancer cells but also promoted VEGF expression and cell proliferation in ovarian cancer-derived microvascular endothelial cells [72]. After TGF-β1 was treated, the expression of SMAD4 was significantly inhibited, while the level of VEGF was significantly increased, especially in the si-SMAD4 group, where the increase in VEGF was the greatest [74], suggesting that TGF-β1 may promote the production of VEGF by inhibiting SMAD4, thus inhibiting the proliferation of tumor cells.

MiRNA

Recent studies have shown that VEGF expression is also regulated by microRNAs (miRNAs). miRNA expression profiling in ovarian cancer has revealed their key roles in tumourigenesis, invasion, and metastasis. miR-145, for example, inhibits angiogenesis in ovarian cancer by targeting VEGFA and VEGFR-2, miR-146a and miR-155 regulate angiogenesis and chemoresistance in ovarian cancer by targeting VEGFA and VEGFR-2 [75]. In addition, miR-199a and miR-125b are downregulated in ovarian cancer tissues, and their overexpression inhibits tumor-induced angiogenesis, which is associated with their negative regulation of VEGF expression [76]. miR-217 was found to downregulate both VEGF and VEGFR-2 expression, thereby inhibiting angiogenesis in ovarian cancer [77]. Overall, these data suggest that miRNAs play an important role in regulating VEGF and its biological significance in ovarian cancer cells.

Role of VEGF and its pathway in ovarian cancer cells

VEGF and its pathway play an important role in ovarian cancer cells, and the expression level of VEGF is closely related to the Federation of International Gynaecological and Obstetrics Organisations (FIGO) stage of ovarian cancer, and the overexpression of VEGF is directly related to poor survival rate. At the same time, factors such as the FOXA1 protein regulate the expression of VEGF and other proteins, and the expression level of VEGF and its receptor is closely related to clinicopathological characteristics of ovarian cancer, including disease recurrence, disease-free survival (DFS), and prognosis. Several studies have also found that the expression levels of VEGF and its receptor are closely related to the clinicopathological characteristics of ovarian cancer, including disease recurrence, DFS prognosis and so on. Therefore, VEGF can be used as an independent and important indicator to assess the prognosis of patients with ovarian cancer, which provides a valuable scientific basis for the diagnosis, treatment, and prognostic evaluation of ovarian cancer.

Several in-depth studies have shown a strong correlation between the expression level of VEGF and the FIGO stage of ovarian cancer, especially in advanced ovarian cancer (stage III-IV) cases, the expression of VEGF is significantly increased compared with early stage (stage I-II), which has been confirmed by a wide range of studies. The direct link between VEGF overexpression in ovarian cancer and poor survival has been demonstrated, and it has been shown that the expression level of VEGF in metastatic ovarian cancer is higher than that in primary tumors [78]. FOXA1 protein, a transcription factor, exhibits significant heterogeneity of expression in ovarian cancer. Its high expression was significantly correlated with the high pathological grade and FIGO stages III and IV of ovarian cancer. Studies have shown that FOXA1 may play a key role in carcinogenesis during the growth and metastasis of ovarian cancer by regulating the expression of various proteins, including VEGF [79]. The angiogenesis regulators VEGF-A, VEGFR-1, and VEGR-2 have a complex relationship with the p53 status and prognostic factors. Studies have shown that positive staining for VEGF-A, VEGF-R2, and p53 is clinically significant in FIGO stage I-II epithelial ovarian cancer patients [80]. Specifically, positive expression of VEGF-A and VEGF-R2 was significantly associated with disease recurrence and disease-free survival (DFS), whereas positive expression of p53 predicted poorer In ovarian cancer tissues, the expression levels of VEGF and its receptors (such as KDR and flk-1) were significantly elevated and closely correlated with the clinicopathological features of the disease, and patients with higher VEGF expression generally had a poor prognosis and shorter survival time; moreover, the expression levels of VEGF showed a significant correlation with the key clinicopathological parameters, such as the tumor stage, the degree of differentiation, and the metastasis [81]. These findings provide a valuable scientific basis for understanding the pathogenesis and prognosis of ovarian cancer.

Several authoritative studies have consistently demonstrated that high levels of VEGF expression in various cancers are associated with poor prognosis; for example, in cervical cancer, high VEGF expression was negatively correlated with overall and disease-free survival [82], and in endometrial cancer, VEGF expression was also strongly correlated with tumor invasiveness, metastatic potential, and poor prognosis [83]. In addition, serum VEGF levels have been widely used as a biomarker for the assessment of cancer prognosis, e.g., in patients with esophageal squamous cell carcinoma (ESCC), changes in serum VEGF levels reflect the overall survival (OS) and progression-free survival(PFS) of the patients [84], and in the prognostic assessment of hepatocellular carcinoma (HCC), serum VEGF levels have also demonstrated a high degree of sensitivity and specificity [85]. The VEGF gene is regarded as one of the key genes for the poor prognosis of patients with advanced epithelial ovarian cancer [86]. The expression of VEGF in ovarian cancer is closely associated with the OS, DFS, and disease progression status of patients, and the serum VEGF level can be used as an independent prognostic factor for ovarian plasmacytoid carcinoma, and its predictive efficacy is even better than that of traditional prognostic variables such as the stage and the size of the residual tumor [87]. Several studies have highlighted the significant association between high VEGF expression and poor prognosis of ovarian cancer, and it was found that strong VEGF expression was observed in up to 86% of ovarian cancer cases [88], and the expression rate of VEGF in plasma adenocarcinoma or endometrioid adenocarcinoma was close to 90% [89]. The prognostic parameter in patients with ovarian cancer, as its level decreased significantly after tumor resection and increased again at recurrence, suggests that it may serve as an effective biomarker for predicting the recurrence of ovarian cancer [90].In addition, the concentration of VEGF-C in ascites and serum was an independent predictor of shorter OS in patients with ovarian cancer [91].

In conclusion, VEGF, as a key pro-angiogenic factor, plays a crucial role in the occurrence, development, metastasis, and prognosis of ovarian cancer. High expression of VEGF is usually indicative of poor prognosis of ovarian cancer patients, and therefore, it can be used as an independent and important indicator to assess the prognosis of ovarian cancer patients.

The main mechanisms by which the VEGF signaling pathway interferes with ovarian cancer include (1) from ligand-receptor binding, hypoxia-induced HIF-1α pathway, affecting the tumor microenvironment to promote tumor angiogenesis. (2) from ligand-receptor binding, induction of inflammatory factor release, and protein-protein interactions to enhance vascular permeability. (3) from ligand-receptor binding, synergism of other factors, and ascites in ovarian cancer to promote lymphangiogenesis.

Promoting tumor angiogenesis

Overexpression of VEGF in ovarian cancer cells is closely related to tumor growth and angiogenesis, and studies have shown that the expression of VEGF is significantly increased in ovarian cancer, and this increase is closely related to tumor invasiveness and metastasis. For instance, high concentrations of VEGF can induce the proliferation and migration of vascular endothelial cells and the formation of new vascular networks [92]. VEGF activates signaling pathways mainly by binding to its receptor VEGFR (especially VEGFR-2) and triggering the autophosphorylation of the receptor [93].VEGFR, as a tyrosine kinase receptor, recruits a variety of adaptor proteins, such as Shc, Grb2, Gab1, and Gab2, to activate the downstream signaling pathways after binding to the autophosphorylation of VEGFR-2 [94, 95]. These signaling pathways include the PI3K/AKT and MAPK/ERK pathways, which together enhance tumor angiogenesis [96]. For example, binding of VEGF to its receptor VEGFR-2 triggers the autophosphorylation of the receptor, which activates PI3K, which in turn activates AKT. The PI3K/AKT signaling pathway plays a role in a variety of cellular functions, including cell proliferation, migration, and survival [97]. AKT promotes the activity of eNOS by phosphorylating it, and the activation of eNOS generates nitric oxide, NO, which is important in vasodilation and angiogenesis [98]. Lysophosphatidylcholine (LPA) is a small molecule of phospholipids, which is widely present in living organisms [99]. The intracellular action of LPA involves various signaling pathways, such as RhoA, PI3K, Rac/Rho, etc. These pathways regulate cell migration, proliferation, inhibition of apoptosis, and other biological functions [100], and in oncology, LPA and its receptor have been found to be closely related to cancer progression [101]. VEGFR-2, after binding to the receptor, can activate Ras, which in turn activates Raf kinase, initiating the MAPK cascade, and ultimately activating ERK, which promotes cell proliferation and migration [102]. The activation of ERK can promote cell proliferation and migration [103].

HIF-1α binds to the promoter region of VEGF gene and directly activates its transcription. Hypoxia-induced HIF-1α pathway can promote angiogenesis in coordination with PI3K/Akt/mTOR pathway and regulating miRNA [104]. HER2 and other growth factors, miR-21 can also enhance VEGF expression through different pathways [105], and VEGF and HIF-1α form a self-reinforcing cycle, through which hypoxia activates VEGF transcription and amplifies the effect, and the two synergistically drive angiogenesis. It plays a key role in many physiological and pathological processes such as tumors [106, 107].

VEGF not only plays a direct role in ovarian cancer cells but also influences the surrounding microenvironment through paracrine secretion to further promote tumor angiogenesis, such as VEGF secreted by ovarian cancer cells can act on the adjacent normal vascular endothelial cells, inducing them to proliferate and migrate, thus forming a new vascular network [108]. In addition, VEGF also plays a key role in the immune microenvironment of ovarian cancer, inhibiting the anti-tumor immune response by binding to VEGFR-2 and suppressing the function of effector T cells and regulatory T cells [78].

Enhancement of vascular permeability

In the process of ovarian cancer, VEGF enhances vascular permeability in a variety of ways, thereby promoting tumor growth and metastasis. VEGF can stimulate the proliferation and migration of endothelial cells, which directly promotes the formation of blood vessels and the increase of vascular permeability. As a key regulator of angiogenesis, VEGF activates multiple signal transduction pathways including PI3K and FAK through the interaction with the VEGF receptor, which not only promotes the proliferation of endothelial cells and inhibits their apoptosis, but also leads to the enhancement of vascular permeability [109]. This enhanced vascular permeability allows plasma proteins and water to leak out of the tumor microenvironment, which provides a favorable environment for the migration and proliferation of tumor cells. VEGF activates FAK via VEGFR-2, which in turn regulates vascular permeability by phosphorylating downstream targets (such as paxillin and ERK) [110]. Studies have shown that FAK inhibitors, such as PF-572,218, can reduce VEGF-induced vascular permeability increase, suggesting that FAK plays a key role in this process [111].

VEGF indirectly enhances permeability by inducing the release of inflammatory mediators. VEGF activates VEGFR-1 and promotes macrophages to secrete IL-6 and IL-8, which further recruits inflammatory cells and amplifies vascular leakage [112]. VEGF can also stimulate endothelial cells to release von Willebrand factor (vWF) through VEGFR2-Tyr1175-dependent PLCγ1 and PKA pathways, promoting platelet adhesion and inflammatory response [113]. Vegf-induced inflammatory mediators (such as TNF-α and IL-6) can further stimulate endothelial cells to secrete more VEGF, forming a positive feedback loop [114].

In addition, VEGF further increases vascular permeability by weakening adhesion between endothelial cells through down-regulation of the expression of adhesion proteins (such as VE-calmodulin and Claudin 5) [115]. p38 MAP kinase (p38 MAPK) has been found to be a key molecular switch in the VEGF—induced increase in vascular permeability [116]. p38 MAPK plays an important role in the immunosuppressive microenvironment of ovarian cancer, especially in regulating the function of indoleamine 2,3-dioxygenase. p38 MAP kinase inhibition reduces CD14 + cell-mediated recruitment of immune Tregs and promotes the Th17 response, which may potentiate the immune response in patients with ovarian cancer [117]. Thus VEGF not only promotes angiogenesis but also increases the permeability of existing blood vessels, making it easier for tumor cells and their metabolites to enter the blood circulation or lymphatic system through blood vessels, thus promoting tumor spread and metastasis.

Promotion of lymphangiogenesis

In ovarian cancer, VEGF-C and VEGF-D promote lymphangiogenesis by binding to specific receptors and activating downstream signaling pathways; specifically, VEGF-C and VEGF-D bind to VEGFR-3, inducing downstream signaling and regulating cell survival and lymphangiogenesis [118]. VEGF-D, as one of the VEGF family members, is strongly expressed in ovarian cancer cells, especially in a mouse model of the SKOV3 cell line, and its overexpression is closely related to the rapid proliferation of tumor cells through lymphatic vessels and the increase in the diameter and number of lymphatic vessels. Highly expressed VEGF-D accelerated tumor growth and lymphatic metastasis, whereas low-expressed VEGF-D suppressed lymphangiogenesis and lymph node metastasis [28].VEGF-D regulates cell survival and lymphangiogenesis by promoting tumor lymphangiogenesis and draining lymphatic vessel vasculature [29], therefore VEGF-D is also known as an important component of the VEGF family [28]. In a xenograft model, VEGF-D overexpressed mice showed significantly increased lymph node metastasis and tumor volume [29]. Studies have shown that VEGF-D is highly expressed in ovarian cancer, and its overexpression is closely associated with the rapid proliferation of tumor cells, expansion of lymphatic vessels, and metastasis. For example, in a mouse model of the SKOV3 cell line, the high expression of VEGF-D not only promoted lymphangiogenesis but also enhanced the invasive and migratory ability of tumor cells, thus accelerating lymph node metastasis [28, 29]. In addition, inhibition of the expression or function of VEGF-D significantly reduced lymphangiogenesis and lymph node metastasis, which provides a new target for ovarian cancer treatment [118, 119]. VEGF can promote lymphangiogenesis, which is mainly associated with the overexpression of VEGF-D in ovarian cancer and a significant increase in lymph node metastasis, suggesting that VEGF-D plays an important role in lymph node metastasis by promoting the generation of tumor lymphangiogenic vessels and enhancing tumor invasiveness [29].

VEGF also synergizes with other factors to promote lymphangiogenesis, and the interaction between VEGF and CCBE1 in lymphangiogenesis is mainly reflected in the fact that CCBE1 enhances lymphangiogenesis by promoting the activation of proteolytic cleavage of VEGF-C. Collagen- and calcium-binding EGF-like structural domain protein 1 (CCBE1), a secreted protein that plays a key role in lymphangiogenesis, interacts with ADAMTS3 protein to promote cleavage of VEGF-C from its inactive 29/31 kDa form to a more active 21/23 kDa form. CCBE1 promotes the cleavage of VEGF-C from its inactive 29/31 kDa form to a more active 21/23 kDa form through interaction with ADAMTS3 protein, thereby enhancing the signaling of VEGF-C [120], and promoting lymphangiogenesis.ADAMTS3 is a metalloproteinase containing a thrombospondin-like structural domain, which plays an important role in lymphangiogenesis.ADAMTS3 is involved in lymphangiogenesis by hydrolyzing VEGF-C and promoting its activation [29].ADAMTS3 also binds to CCBE1 and enhances the activity of VEGF-C [121]. Therefore, ADAMTS3 promotes the activation of VEGF-C and lymphangiogenesis by hydrolyzing VEGF-C and interacting with its complex CCBE1 [122]. Therefore, ADAMTS3 promotes VEGF-C activation and lymphangiogenesis by hydrolyzing VEGF-C and interacting with its complex CCBE1 in lymphangiogenesis.

In addition, the formation of ascites in ovarian cancer is closely related to lymphangiogenesis, and ascites, an accumulation of fluid in the abdominal cavity caused by tumor cell infiltration and abnormal angiogenesis in patients with ovarian cancer, constitutes a pathological state that contains a rich variety of components, including cancer cells, non-cancerous cells, free DNA, a variety of signaling molecules, extracellular matrix proteins, and proteases, which create a complex fluid-tumor microenvironment [122]. It is worth noting that ascites may also metastasize via the lymphatic route, which affects lymphangiogenesis and patient survival [123]. The accumulation of peritoneal fluid is affected by elevated levels of VEGF, which enhances vascular permeability and facilitates the passage of large quantities of fluid, accelerating the process of transmembrane metastasis. This mechanism involves epithelial-mesenchymal transition (EMT), which encourages the shedding of ovarian cancer cells from the primary site into the peritoneal fluid and their eventual migration to the lymph nodes through the lymphatic system.

Treatment

Anti-vascular endothelial growth factor therapy

Bevacizumab

In the treatment of ovarian cancer, anti-VEGF therapy is an important targeted therapeutic strategy, because VEGF, by binding to VEGF receptors, activates a series of signaling pathways and regulates the activation, proliferation, and migration of vascular endothelial cells to promote tumor growth, invasion, and metastasis [124]. Bevacizumab, the first anti-angiogenic targeted drug, is a humanized IgG1-type monoclonal antibody targeting VEGF, inhibiting the formation of tumor neovascularization by binding VEGF and preventing its binding to the receptors on the endothelial cell surface [125]. It inhibits tumor neovascularisation by binding to VEGF and preventing it from binding to receptors on the surface of endothelial cells [126]. Several clinical trials have demonstrated that the combination of bevacizumab with chemotherapy significantly prolongs PFS in patients with ovarian cancer. For example, in patients with platinum-sensitive recurrent ovarian cancer, the OCEANS study showed that the combination of bevacizumab and chemotherapy prolonged PFS to 12.4 months, compared with 8.4 months with chemotherapy alone [127]. In addition, the ICON7 study showed that bevacizumab in combination with chemotherapy in newly diagnosed patients with ovarian cancer significantly increased PFS [128], and the GOG clinical trial demonstrated that the combination of chemotherapy with bevacizumab prolonged PFS by 3 months [129]. In the GOG-0213 study, the median OS was 42.2 months in the bevacizumab group and 37.3 months in the chemotherapy-only group, and the median PFS was significantly better in the bevacizumab group than in the chemotherapy-only group [130]. The trial showed that bevacizumab combined with chemotherapy in patients with recurrent platinum-resistant ovarian cancer extended the median PFS from 3.4 months to 6.7 months, and the HR of bevacizumab in patients with recurrent ovarian cancer was about 0.53, indicating that it significantly reduced the risk of death in patients with recurrent ovarian cancer, indicating that bevacizumab significantly improved PFS in patients with recurrent ovarian cancer [131]. The primary mechanism by which bevacizumab slows down tumor growth and proliferation by inhibiting angiogenesis has been demonstrated in the treatment of ovarian cancer [132]. On the whole, bevacizumab has demonstrated significant efficacy in the treatment of ovarian cancer, and its effectiveness in prolonging PFS is widely recognized, although the improvement in OS is limited.

Pazopanib

Tyrosine kinase inhibitors (TKIs) are a class of drugs used in the treatment of many cancers and other diseases, which inhibit the proliferation, migration, and invasion of tumor cells by blocking cellular signaling pathways by inhibiting the activity of tyrosine kinases. Tyrosine kinases play an important role in the development of cancer, and their dysregulation can occur through overexpression, fusion-site mutations, or aberrant activation of signaling pathways. These may increase the oncogenic capacity of tyrosine kinases [132]. Pazopanib is a multi-target TKI that inhibits VEGFR-1, VEGFR-2, and VEGFR-3, as well as other receptors, such as PDGFR and c-Kit. In the AGO-OVAR16 phase III trial, pazopanib was used as a maintenance therapy for patients with stage II-IV ovarian cancer who had progressed without surgery, and who had received at least five cycles of prior platinum-paclitaxel first-line chemotherapy. The results showed that the median PFS was 17.9 months in the pazopanib group compared to 12.3 months in the placebo group, and pazopanib significantly prolonged the PFS of the patients (HR = 0.77, P = 0.0021), that is, pazopanib significantly prolonged PFS in patients with ovarian cancer in maintenance therapy [133]. Therefore, pazopanib as maintenance therapy significantly prolonged PFS in patients with stage II-IV ovarian cancer that had progressed without surgery, and has been widely used in the treatment of various cancers, such as renal cell carcinoma and soft-tissue sarcoma, and demonstrated an important clinical value, despite the individual differences in its efficacy.

Sorafenib

Sorafenib is also a multi-targeted TKI that inhibits tumor growth primarily through inhibition of the VEGF receptor and PDGF signaling pathways and has shown anti-proliferative effects in other cancer types [134]. Sorafenib has been used in clinical trials in combination with bevacizumab in the treatment of ovarian cancer and showed partial remission [135]. In addition, a clinical study reported the results of a phase II trial of the combination of bevacizumab and sorafenib in patients with recurrent ovarian cancer, which further validated the potential efficacy of sorafenib in recurrent ovarian cancer [136], and experimentally demonstrated that the IL6-STAT3-HIF signaling pathway is associated with the therapeutic response to angiogenesis inhibitor Sorafenib is associated with the therapeutic response of angiogenesis inhibitor, and it enhances the antitumor effect by inhibiting Stat3-induced apoptosis of tumor cells and reducing immunosuppressive cells [137].In conclusion, sorafenib, as a multi-targeted TKI, is not only effective in the treatment of ovarian cancer when used alone but also demonstrates good antiproliferative effect and potential efficacy when combined with bevacizumab.

VEGF trap protein (VEGF trap)

VEGF trap protein is a protein used to block VEGF and inhibit its activity by binding to VEGF.VEGF Trap has an important role in antitumor therapy because it prevents VEGF from binding to its receptor, thereby inhibiting tumor angiogenesis and growth [138]. Aflibercept, as a ‘VEGF Trap’ protein, inhibits angiogenesis by inhibiting VEGF-A, VEGF-B, and PlGF signaling, and has shown some effect in controlling malignant ascites, but subsequent clinical studies are lacking [139]. VEGF Trap not only inhibits tumor growth but also induces tumor vascular degeneration. For example, in some cases, VEGF Trap can lead to the degradation of tumor vasculature, which accelerates tumor degradation by depriving the tumor of its original vascular support [140]. This mechanism of action may be related to the apoptotic induction of endothelial cells and peripheral vascular cells by VEGF Trap [141]. Thus, the VEGF Trap still has great potential in under-explored clinical areas, and by effectively blocking the VEGF signaling pathway, they not only provide a new strategy for anti-tumor therapy but may also open up more new avenues for the treatment of malignant ascites and other angiogenesis-related diseases in the future.

Cediranib (AZD2171)

Cediranib (AZD2171) is an oral VEGFR inhibitor targeting VEGFR-1, VEGFR-2, VEGFR-3, PDGFRB, and c-kit, and has shown some antitumor activity [144]. In clinical studies, Cediranib has been used to treat recurrent epithelial ovarian, fallopian tube, and peritoneal cancers. A phase 2 study showed a clinical benefit rate of 30% for Cediranib in these cancers, with 17% of patients achieving a partial response (PR) and 13% achieving stable disease (SD) for more than 16 weeks [142]. Cediranib has also shown some efficacy in combination with Olaparib in platinum-resistant ovarian cancer [143]. Further studies have shown that the combination of Cediranib with Olaparib has positive anti-tumor effects in high-risk plasmacytoid ovarian cancer and significantly improves survival in patients with recurrent platinum-sensitive ovarian cancer compared with Olaparib alone [144]. This suggests that Cediranib may provide additional therapeutic benefits to ovarian cancer patients in combination therapy.

Aptamer aptamer

Aptamers are high-affinity and specific nucleic acid sequences that can recognize and bind to specific molecules or proteins and thus play an important role in cancer therapy. Aptamers are valuable in the early diagnosis of ovarian cancer. For example, by using the systematic evolutionary selection (SELEX) technique, researchers have developed aptamers that can specifically recognize ovarian cancer cells, such as TOV-21G and CAOV-3. These aptamers can distinguish ovarian cancer cells from other types of cells, such as cervical cancer cells, thus improving diagnostic specificity [145]. These aptamers can differentiate ovarian cancer cells from other types of cells, such as cervical cancer cells, thus improving diagnostic specificity [146]. In addition, aptamers can also be used to detect biomarkers associated with ovarian cancer, such as binding to specific membrane proteins for early detection of tumors [147]. Despite the potential of aptamers in the diagnosis and treatment of ovarian cancer, there are still some challenges in their clinical application, such as the reusability of aptamers and the cost of manufacturing [148].

Combination of VEGF inhibitors

The combination of VEGF inhibitors and other targeted agents has great potential in clinical treatment. Several studies have shown that the combination of VEGF inhibitors with platinum agents such as carboplatin, cisplatin or paclitaxel can significantly prolong PFS and OS in patients with ovarian cancer. In terms of the use of VEGF inhibitors in combination with platinum agents, the median PFS and response rate among patients with platinum-resistant ovarian cancer (PROC) varied according to treatment regimen: the median PFS was 2.3 months and the response rate was 10% with bevacizumab alone; The median PFS was 4.1 months and the response rate was 19% in patients treated with bevacizumab combined with apatinib. With bevacizumab plus aspirin, the median PFS was 4.0 months and the response rate was 15%. Thus, the combination of bevacizumab plus Atezolizumab provided a significant improvement with respect to PFS, as compared with bevacizumab alone [149]. Statistical analysis showed that the PFS hazard ratio of bevacizumab combination therapy group was 1.56, indicating that its efficacy was better than monotherapy [150]. A systematic review in 2024 also pointed out that combination therapy with VEGF/VEGFR inhibitors plus chemotherapy significantly prolonged OS and PFS and improved objective response rate compared with single-agent chemotherapy [151].In addition, VEGF inhibitors such as Aflibercept and Nintedanib have also been shown to prolong PFS when used in combination with other agents. For example, Nintedanib, in combination with carboplatin and paclitaxel, significantly prolonged PFS. Similarly, the combination of Trebananib with paclitaxel also significantly improved PFS [152].

The synergistic effect of VEGF inhibitors and immunotherapy has recently attracted much attention. Combination therapy of VEGF inhibitors with immune checkpoint inhibitors, such as PD-1/PD-L1 and CTLA-4, is thought to potentially improve anti-tumor efficacy by ‘normalizing’ the tumor microenvironment and enhancing antigen presentation and T-cell activity [153]. In ovarian cancer, several clinical trials have shown that the combination of VEGF inhibitors and immune checkpoint inhibitors has shown good efficacy in ovarian cancer. A phase I study showed that the combination of anti-PD-L1 drug Durvalumab and Cediranib in 14 patients with recurrent or metastatic ovarian cancer resulted in a disease control rate of 75% and a response rate of 50% [154]. Another phase II trial showed that Nivolumab combined with bevacizumab was used in 38 patients with recurrent ovarian cancer, and the response rate was 28.9%, 40% in platinum-sensitive patients and 16.7% in platinum-resistant patients [155]. These results demonstrate the great potential of the combination strategy of VEGF inhibitors and immunotherapy in the treatment of ovarian cancer, and bring new hope for further exploration of better treatment options and improvement of prognosis of ovarian cancer patients.

As a new inhibitor, PARP inhibitor (PARPi) has been used in the clinical treatment of ovarian cancer. The principle of PARPi is to induce the accumulation of DNA double-strand breaks by inhibiting the repair of DNA single-strand breaks, thereby producing a “synthetic lethal” effect in tumors that are deficient in homologous recombination repair. Clinical trials have shown that the combination of PARPi and bevacizumab significantly prolongs PFS in ovarian cancer patients with BRCA mutations [156]. Studies have shown that the combination of VEGF inhibitors and PARPi exerts a synergistic effect not only by directly acting on tumor cells, but also by affecting the TME. For example, VEGF inhibitors can reduce tumor vascular density and improve the immunosuppressive state of the tumor microenvironment, thereby enhancing the activity of immune cells and antitumor effect. A study using a patient-derived xenograft model of ovarian cancer (OC-PDX) found that the combination of Olaparib and cediranib showed broad antitumor activity in all OC-PDX models. Moreover, it has stronger synergistic effect in platinum-resistant or olaparib insensitive tumors [157]. Furthermore, these data suggest that the combination of VEGF inhibitors with PARPi has significant clinical value in ovarian cancer.

Innovative antiangiogenic combinations: beyond VEGF blockade

Although VEGF-directed therapies (bevacizumab, TKIs) plus chemotherapy extend progression-free survival in ovarian cancer, their integration with non-cytotoxic, precision agents remains largely untapped. Recent mechanistic work shows that VEGF signaling intersects with DNA-repair networks, immune checkpoints, and metabolic circuits, opening rational avenues for multi-target regimens [158, 159]. VEGF inhibition triggers acute hypoxia, transcriptionally silencing BRCA1/2 and homologous-recombination genes. This phenocopies a “BRCAness” state even in genomically stable tumors, priming them for PARP inhibition. Marques et al. [160] demonstrated that olaparib + cediranib improved overall survival in non-BRCA-mutated patients through hypoxia-mediated RAD51 suppression and heightened genomic instability. Pre-clinical data suggest TKIs inhibit ABCB1 efflux pumps, restoring intracellular PARPi levels, indicating that VEGF-TKIs re-sensitize BRCA1/2-revertant, PARPi-resistant tumors [161]. Transient VEGF suppression alone cannot sustain T-cell infiltration [162]. Dual blockade with immune-checkpoint inhibitors (ICIs) converts immunologically “cold” lesions into inflamed tumors, suggesting immuno-oncology synergy could remodeling the tumor microenvironment [163, 164]. VEGF blockade depletes Tregs and MDSCs while normalizing aberrant vasculature. PD-1/PD-L1 inhibition prevents T-cell exhaustion within the newly permissive TME. KN048 (2024) achieved a near half objective response rate in platinum-resistant ovarian cancer with atezolizumab + bevacizumab + liposomal doxorubicin versus bevacizumab/doxorubicin alone [149]. Spatial transcriptomics data linking VEGF-C expression to tertiary lymphoid structure (TLS) presence suggests that anti-VEGF-C therapy, which inhibits lymphangiogenesis, might hinder the development or function of these immune structures. This is significant because TLS are often associated with improved responses to immunotherapy, meaning that antagonizing VEGF-C could potentially reduce the effectiveness of immune checkpoint inhibitors (ICIs). In essence, the spatial transcriptomics data highlights a potential trade-off: while anti-angiogenesis therapies (like anti-VEGF) can improve blood vessel normalization and T cell infiltration, they might also negatively impact TLS formation and thus reduce the effectiveness of immunotherapies that rely on these structures [165]. Biomarker-guided selection is mandatory. In addition, metabolic reprogramming, e.g., HIF-1α and VEGF jointly up-regulate FASN and SCD1, driving lipid-droplet accumulation—a chemoresistance scaffold accentuates the importance of the HIF-VEGF-Lipid axis [166]. VEGF-TKIs (e.g., pazopanib) plus FASN inhibitors (TVB-2640) deplete energy reserves and trigger ferroptosis [167]. Moreover, epigenetic modulators could also influence angiogenesis by silencing angiogenic transcripts, for instance VEGF transcription is epigenetically maintained by BRD4-dependent H3K27 acetylation [168]. Accordingly, BET inhibitors (JQ1) suppress VEGF-A/VEGF-C while down-regulating c-MYC, preventing compensatory angiogenesis. Early-phase trials (NCT04840589) are evaluating BETi + bevacizumab in BRCA-wildtype disease [169]. All in all, shift from vertical VEGF pathway suppression to horizontal multi-pathway blockade spanning angiogenesis, DNA repair, metabolism, and immunity. Investment in functional biomarkers—HIF-1α activity assays, lipid-droplet imaging—will be indispensable for dose-finding and patient selection in these complex regimens.

Discussion

Through the comprehensive analysis and systematic investigation, VEGF provides conditions for cancer cell growth and metastasis by promoting tumor angiogenesis, vascular permeability, and lymphangiogenesis in ovarian cancer, and in view of its significance, anti-angiogenic targeted therapies have become a new strategy for the treatment of ovarian cancer, and at present, targeted drugs such as bevacizumab, pazopanib, sorafenib and apciparib have demonstrated remarkable efficacy in the treatment of ovarian cancer, by specifically binding to VEGF or inhibiting its receptor and blocking the signaling pathway related to tumor neovascularization. Currently, targeted drugs such as bevacizumab, pazopanib, sorafenib, and apocynin, by specifically binding to VEGF or inhibiting its receptor and blocking the signaling pathway related to tumor neovascularization, have demonstrated remarkable efficacy in the treatment of ovarian cancer, providing new therapeutic choices and hope for ovarian cancer patients.

Although some progress has been made in the application of the VEGF signaling pathway in gynecological oncology, many problems and challenges remain. Firstly, there is still a lack of uniform treatment protocols for the clinical application of VEGF inhibitors. For example, the single-agent response rate of bevacizumab in recurrent ovarian cancer is only 8%−15%, and the dosage and duration of treatment have not been standardized [170]. Although the combination of anti-VEGF drugs with other drugs can improve the response rate, such as the combination of aflibercept and docetaxel for the treatment of ovarian cancer, it can improve the response rate, and the combination of anti-VEGF drugs with other drugs can improve the response rate. Although the combination of anti-VEGF drugs with other drugs can improve the response rate of ovarian cancer, for example, the combination of Aflibercept and docetaxel in the treatment of PROC increased to 54% [171], when VEGF inhibitors are combined with other drugs in chemotherapy, the effect of the order of administration of multiple drugs on the therapeutic efficacy of VEGF inhibitors needs to be verified by large-scale studies [172]. Bevacizumab has shown significant effects in reducing ascites and improving PFS, but its high cost and drug resistance have limited its widespread use [173].

Resistance of ovarian cancer to VEGF-targeted therapy is also a major challenge in current treatment. Its mechanism involves changes in tumor microenvironment, intrinsic drug resistance of tumor cells, regulation of immune microenvironment, and metabolic reprogramming. For example, anti-VEGF therapy may lead to hypoxia in the tumor microenvironment, and then induce tumor cells to secrete a variety of immunosuppressive factors (such as GM-CSF, IL-6, IL-10,), thereby inhibiting the activity of immune cells. For example, anti-VEGF therapy can induce the expression of GM-CSF, which then recruits and maintains myeloid-derived suppressor cells in the tumor microenvironment and inhibits the proliferation and function of CD8 + T cells [10]. At the metabolic level, it was found that the dependence of ovarian cancer cells on glutamine was enhanced after anti-VEGF treatment, and the expression of glutaminase, a key enzyme in glutamine metabolism, was also increased. Thus, enhanced glutamine metabolism may provide ovarian cancer cells with greater survival and proliferation, leading to resistance to treatment [174]. At the same time, the treatment strategy of ovarian cancer is constantly being optimized. Recent studies have shown that the use of lipid nanoparticles to deliver FST mRNA has successfully achieved tumor suppression and improved chemotherapy resistance in a mouse model of ovarian cancer [175]. In addition, another study has proposed mirNA-based therapeutic strategies, such as the use of mirNA-oligonucleotide therapy, by analyzing the expression patterns of miRNA and mRNA [175]. So in terms of drug resistance, in the future, you might want to think about multi-targeted angiogenesis inhibitors, anti-VEGF combined with immune checkpoint inhibitors, Targeting cancer stem cells or metabolic pathways, optimizing drug delivery regimens, developing new drugs such as nano-delivery systems and CAR-T cell therapy, and biomark-based precision medicine such as genetic testing or liquid biopsy to screen the dominant population, while combining cutting-edge technologies such as single-cell sequencing and organoid models to further analyze drug resistance mechanisms. To provide multi-dimensional solutions for breaking through the bottleneck of ovarian cancer treatment.

Secondly, the molecular heterogeneity of ovarian cancer is remarkable, and it is classified into five histological subtypes: high-grade plasma carcinoma (HGSC), endometrioid carcinoma, clear cell carcinoma (CCC), mucinous carcinoma, and low-grade plasma carcinoma (LGSC), which are fundamentally different in terms of their origins, molecular alterations, and clinical behaviors [176]. The sensitivity of ovarian cancer to VEGF-targeted therapies varies significantly between molecular subtypes, such as angiogenesis in HGSC may be multifactor-dependent (such as PDGF, FGF), whereas in CCC it is more singularly dependent on the VEGF pathway, resulting in a more pronounced response to VEGF inhibitors in the latter [177]. LGSC and mucinous carcinoma are more sensitive to VEGF-targeted therapy [178, 179], and endometrioid carcinoma is more sensitive to VEGF-targeted therapy, especially in patients with ARID1A mutation, so VEGF inhibitors can achieve better therapeutic effect in endometrioid carcinoma [20].However, most of the existing studies of VEGF-targeted therapy included mixed histological types, without stratification by molecular subtype. For example, the phase III trial of bevacizumab in ovarian cancer (such as GOG-0218) did not differentiate between HGSC and CCC, resulting in the difference in efficacy not being clearly expressed [170]; therefore, future studies need to carry out a more refined stratification analysis for ovarian cancer of different molecular subtypes to optimize the therapeutic regimen.In addition, the current molecular classification is mainly based on histological subtypes, but there may be further molecular heterogeneity within different subtypes. For example, HGSC has been subcategorized based on chromosomal instability, mRNA expression profiles, or candidate biomarkers [173]. Given the essential differences in origin, molecular changes, and clinical behavior among histologic subtypes, the sensitivity of different molecular subtypes to VEGF-targeted therapy varies significantly. Individualized treatment based on the molecular characteristics of different subtypes is the key development direction of the treatment strategy for ovarian cancer in the future.

There are also a number of issues that need to be addressed in existing clinical trials, such as the lack of data on long-term benefits in first-treatment patients, which have focused on platinum-resistant or relapsed patients; for example, aflibercept has shown preliminary activity in platinum-resistant patients, but the improvement in OS was not statistically significant [170]. The main sources of VEGF in ascites include ovarian cancer cells and peritoneal mesothelial cells, which promote tumor neovascularisation and vascular permeability through microenvironmental cellular communication with peritoneal mesothelial cells, thereby increasing VEGF production. Studies have suggested that anti-VEGF therapies may target only tumor cell-derived VEGF, whereas mesothelial cells may not be the only source of VEGF. Studies suggest that anti-VEGF therapies may only target tumor cell-derived VEGF, whereas mesothelial cell-derived VEGF continuously activates the vascular pathway through paracrine secretion, leading to drug resistance [180]. Therefore, clinical trial design needs to pay more attention to the heterogeneity of the tumor microenvironment, in order to explore more effective therapeutic strategies.

Since the activation of the VEGF signaling pathway is closely related to tumor angiogenesis, this pathway has shown a wide potential in the treatment of gynecological tumors, not only ovarian cancer but also cervical cancer and endometrial cancer, etc. VEGF induces vascular endothelial cell proliferation, migration, and lumen formation by activating VEGFR-1 and VEGFR-2 receptors on the endothelial cells, thus increasing the microvessel density (MVD) of the tumors. MVD In cervical cancer, high vascular density is associated with enhanced tumor invasiveness and metastatic ability [181]. High levels of VEGF are also closely associated with enhanced invasiveness and increased risk of metastasis in cervical cancer [182].In endometrial cancer, stabilization of HIF-1α in hypoxic environments directly up-regulates VEGF expression, further driving angiogenesis and tumor progression [183]. Hyperglycemia can also increase VEGF secretion through the ER/GLUT4 pathway, activate the AMPK/mTOR/S6 and MAPK pathways, and promote the proliferation of endometrial cancer cells [184]. Therefore, targeting drugs against the VEGF signaling pathway may have significant clinical value in the treatment of these gynecological tumors, providing new therapeutic strategies and hope for gynecological tumors.

In the future treatment of ovarian cancer, one of the key directions for VEGF pathway therapy is to explore the combined application of Chinese and Western targeted medicine and immunotherapy, aiming to enhance the efficacy and reduce the side effects. Among them, Chinese medicinal ingredients, such as curcumin, ginsenoside Rg3, and baicalein, have attracted much attention because of their anti-angiogenic effects. Curcumin is a polyphenolic compound mainly found in the root and dried tubers of turmeric [185]. It can exert its antiangiogenic effects by inhibiting VEGF secretion, and cell proliferation, inducing apoptosis, reducing the expression of inflammatory factors, and inhibiting the NF-κB and MAPK signaling pathways [186, 187]. Ginsenoside Rg3 is one of the active ingredients extracted from ginseng, and it has been shown to exhibit potential anticancer activities in a variety of malignant tumors [188]. Ginsenoside Rg3 inhibited angiogenesis by reducing VEGF expression in HCC cell lines [189]. In addition, ginsenoside Rg3 inhibited VEGF expression through the PI3K-Akt/mTOR signaling pathway in an endometriosis model [190]. Baicalin is a natural active flavonoid extracted from Scutellaria baicalensis, which is widely used for its anti-inflammatory, anti-tumor, and neuroprotective effects [191]. Baicalein inhibits proliferation and angiogenesis in lung cancer by inhibiting the expression of VEGF [192]. Although its specific role in ovarian cancer requires further study, its anti-inflammatory, anti-tumor, and neuroprotective effects provide a new idea for targeted therapy in Chinese and Western medicine. The incorporation of these Chinese medicinal ingredients into targeted therapies is expected to combine them with the existing therapeutic means or immunotherapy to form a new treatment method. Current studies have shown that at the level of DNA damage repair mechanism, curcumin can effectively inhibit homologous recombination repair pathway by down-regulating RAD51 protein expression, and then significantly enhance the sensitivity of PEO1 ovarian cancer cell lines to PARPi niraparib [193]. In the reversal of chemoresistance, the combination of curcumin and cisplatin can not only improve the sensitivity of drug-resistant ovarian cancer cells to drugs, but also play a synergistic anti-tumor effect by inhibiting cell proliferation, migration and inducing apoptosis [194]. Ginsenoside Rg3 shows a dual regulatory effect on tumor angiogenesis: RT-PCR and Western blot experiments confirmed that its treatment could significantly reduce the mRNA and protein expression levels of VEGF in ovarian cancer cells [195], and the study of Ni Zhiqiang et al. further verified the results in nude mice transplanted tumor model. Rg3 combined with cytokine-induced killer cells can significantly inhibit tumor growth through the synergistic mechanism of inhibiting angiogenesis and enhancing immune killing. These findings provide more scientific basis for exploring the combination of traditional Chinese and western medicine targeted therapy and immunotherapy for ovarian cancer.In the meantime, through rigorous clinical trial design and the development of efficacy predictive markers, we aim to achieve a more precise and individualized treatment plan, which will bring better survival benefits and quality of life to patients. This research direction is not only applicable to ovarian cancer but is also expected to bring breakthroughs in the treatment of other gynecological malignant tumors, such as cervical cancer and endometrial cancer.

Meanwhile, from the above review, we can deeply understand that there is a close connection between the VEGF signaling pathway and the microenvironment of tumor cells, and the aptamer, as an emerging class of targeted drugs, is gradually showing its unique advantages in targeting the VEGF signaling pathway. As an emerging discipline with great potential in biology and medical research, multi-omics has made remarkable progress in recent years, which can reveal the internal rules and operating mechanisms of biological systems from different levels and angles by organically combining data from genomics, transcriptomics, proteomics, and metabolomics [196]. This method of integrating data from multiple organisms provides a new way of comprehensively analyzing the biological characteristics of organisms and their dynamic changes under different conditions. For example, single-cell sequencing can reveal the spatial heterogeneity of VEGF expression in the tumor microenvironment and identify the key subpopulations (such as mesothelial cells, and tumor-associated fibroblasts) and their interactions with angiogenesis [197], and multi-omics analyses can identify drug-resistance markers associated with the VEGF pathway. Multi-omics of body fluids (such as ascites metabolome) can also dynamically monitor the response to treatment and predict the risk of recurrence of ascites [198]. This dynamic monitoring of the response to treatment and the prediction of the risk of recurrence provide new ideas and methods and are expected to promote the development of tumor treatment in the direction of more accuracy and effectiveness.

Conclusion

Anti-angiogenic therapy has become a cornerstone of ovarian-cancer treatment, grounded in decades of vascular biology that reveal VEGF as the master regulator of tumor neovascularization; this growth factor is almost universally overexpressed in ovarian tumors and is strongly linked to aggressive disease and poor prognosis. Despite the clinical introduction of VEGF blockade—bevacizumab followed by newer TKIs and biologics—the survival gains achieved so far fall well short of theoretical expectations, largely because optimal drug partners (chemotherapy, PARP inhibitors, immunotherapeutics) and their precise sequencing remain undefined. Tumor and micro-environmental heterogeneity further complicate the picture: genomic, epigenetic, and metabolic diversity continually rewire the VEGF axis and spawn adaptive resistance through compensatory angiogenic pathways, pro-angiogenic stromal crosstalk, and metabolic reprogramming. Unlocking the full potential of anti-angiogenesis in ovarian cancer therefore demands rational combination strategies, biomarker-guided patient selection, and a systematic dissection of resistance mechanisms—only then can VEGF-directed therapy shift from incremental benefit to transformative impact.

Abbreviations

VEGF

Vascular endothelial growth factor

NRPs

neurophospholipids

NRP1

Neurofilament Protein 1

NRP2

Neurofilament Protein 2

PI3K

Phosphatidylinositol 3-kinase

AKT

Protein kinase B

mTOR

Mammalian target of rapamycin

ERK

Extracellular signal-regulated kinase

HIF-1α

Hypoxia-inducible factor HIF-1α

TNF-α

Tumour necrosis factor α

TNFR1

Tumour necrosis factor receptor 1

IL-1β

Interleukin-1β

IL-1R1

Interleukin-1 receptor 1

ROS

Reactive oxygen species

miRNAs

microRNAs

DFS

Disease-free survival

OS

Overall survival

ESCC

Esophageal squamous cell carcinoma

HCC

Hepatocellular carcinoma

LPA

Lysophosphatidylcholine

vWF

von Willebrand factor

p38 MAPK

p38 MAP kinase

EMT

Epithelial-mesenchymal transition

PFS

Progression-free survival

PROC

Platinum-resistant ovarian cancer

PARPi

PARP inhibitor

OC-PDX

Patient-derived xenograft model of ovarian cancer

TKIs

Tyrosine kinase inhibitors

PDGF

Platelet-derived growth factor receptor

VEGF Trap

VEGF trap protein

PR

Partial response

SD

Stable disease

HGSC

High-grade plasma carcinoma

CCC

Clear cell carcinoma

LGSC

Low-grade plasma carcinoma

Authors’ contributions

Y. Zhao: Conceptualization, Methodology, Investigation, Formal analysis, Drawing, Writing – Original Draft. Q. Chen: Drawing, Revising the manuscript. K. Dong: Writing.; J. Li, F. Liu: Resources, Supervision, Project administration.; F. Han: Supervision, Funding acquisition, Writing.

Funding

The study was supported by the National Natural Science Foundation of China (82274566).

Data availability

No datasets were generated or analysed during the current study.

Declarations

Ethics approval and consent to participate

Not applicable.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.