NF-κB and apoptosis: colorectal cancer progression and novel strategies for treatment

Abstract

Colorectal cancer (CRC), the third most prevalent cancer worldwide, presents a significant burden in terms of both mortality and morbidity. The development of CRC is a complex process, driven by a combination of genetic mutations and epigenetic alterations that disrupt normal cellular functions. These changes influence a range of cancer-regulating mechanisms, including metabolism, cell proliferation, invasion, metastasis, and apoptosis. Apoptosis, a crucial process in maintaining cellular homeostasis, plays a paradoxical role in CRC progression. While it helps eliminate damaged cells, the evasion of apoptosis allows cancer cells to thrive, gain nutrients, and avoid metabolic waste accumulation, thereby facilitating tumor growth. Additionally, the process of neovascularization, the formation of new blood vessels, is critical for tumor sustenance and expansion. The nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling pathway is a key regulator involved in multiple physiological and pathological processes, including angiogenesis, tumor migration, cell proliferation, inflammation, apoptosis, and differentiation. Dysregulation of NF-κB activity is implicated in the progression of CRC. This review provides a comprehensive evaluation of the role of NF-κB signaling in CRC, particularly its involvement in apoptosis. Moreover, it explores the therapeutic potential of targeting the NF-κB pathway with natural and synthetic compounds, highlighting their ability to modulate CRC progression and improve patient outcomes. These insights underscore the potential of NF-κB inhibition as a novel therapeutic strategy in CRC management.

Introduction

Colorectal cancer (CRC) ranks second most common cause of death from neoplasms and third most often occurring cancer worldwide [1]. CRC ranks third most common cancer worldwide with rising incidence rates linked to aging populations and lifestyle factors (e.g., diet, obesity) [2, 3]. CRC is also the Second leading cause of cancer-related deaths globally, though mortality trends vary by region and socioeconomic status [2, 3]. In China, CRC cases rose fivefold from 1990 to 2019, reflecting generational lifestyle shifts [3]. CRC results from both epigenetic and genetic dysregulation, leading to normal epithelial colon cells altering to abnormal tissues such as adenomatous polyps and invasive adenocarcinoma [4]. The pathophysiology of CRC involves dysfunction within numerous crucial pathways, which initiate tumorigenesis [5] and development through alterations in cell proliferation, apoptosis, and angiogenesis[6]. Apoptosis dysfunction contributes to the CRC's pathogenesis [7], and is associated with radiotherapy and chemotherapy resistance [8]. CRC is driven by sequential mutational events within complex multistage processes happening along with cancer progression. Many signaling pathways, including wingless/integrated (Wnt), phosphoinositide 3-kinase (PI3 K), notch, transforming growth factor beta (TGF-β), and epidermal growth factor receptor (EGFR)/(mitogen-activated protein kinase)MAPK, modulate various biological mechanisms, like cell survival, apoptosis, angiogenesis, proliferation and differentiation [9].

Recent research indicates that nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) family regulates various mechanisms in cells, notably apoptosis [10]. Additionally, NF-κB is implicated in several neoplasms, like breast, gastric cancer [11], cancer [12], and CRC [13]. The NF-κB role in CRC cells is particularly noted for its anti-apoptotic functions, with therapeutic strategies targeting this pathway to enhance CRC treatment. For instance, increasing apoptosis using the NF-κB/X-linked inhibitor of apoptosis protein (XIAP) [14] and AKT/NF-κB/multidrug resistance protein 1 (MDR1) signaling pathways [15], additionally hindering the Notch1/NF-κB/slug/E-cadherin signaling pathway [16].

This article examines the influence of the NF-κB signaling system on CRC development by assessing its role in initiating apoptosis. Also, it discusses pharmacotherapeutic approaches triggering the NF-κB pathway for improved CRC treatment, introducing an innovative approach to improve the effectiveness of treatment in colorectal cancer management.

NF-KB and its role in homeostasis

Nuclear factor kappa B (NF-κB) is a ubiquitously expressed transcription factor that has been studied for nearly 40 years and plays pivotal roles in numerous cellular processes. Initially identified as a mediator of inflammatory responses, this evolutionarily conserved protein family now represents one of the most important regulatory systems controlling gene expression in response to various cellular stimuli. NF-κB functions in virtually all cell types, orchestrating immune responses, cell survival, and developmental processes through complex activation pathways and interactions with numerous cellular components.

Structural organization of NF-κB

Family composition and subunits

The NF-κB family consists of five structurally related proteins that form various dimeric combinations: p65 (RelA), RelB, c-Rel, NF-κB1 (p50/p105), and NF-κB2 (p52/p100) [17]. These proteins share a conserved Rel homology domain (RHD) that mediates DNA binding, dimerization, and interaction with inhibitory proteins. While p65, RelB, and c-Rel contain transcriptional activation domains, NF-κB1 and NF-κB2 are synthesized as precursor proteins (p105 and p100, respectively) that require processing to generate the active p50 and p52 subunits. The most abundant and well-studied NF-κB complex is the p65/p50 heterodimer, although various other dimeric combinations exist, each with distinct functions and regulatory mechanisms [18]. Interestingly, the Salmonella effector proteins GtgA, GogA, and PipA can cleave p65, RelB, and cRel but not NF-κB1 and NF-κB2, highlighting structural differences between these subunits [17].

Regulatory complex with IκB

In resting cells, NF-κB dimers are sequestered in the cytoplasm by inhibitor of kappa B (IκB) proteins that mask the nuclear localization signals of NF-κB. This inhibitory complex keeps NF-κB in an inactive state until appropriate cellular stimulation occurs. When cells receive external signals, a cascade of events leads to IκB phosphorylation, ubiquitination, and proteasomal degradation, allowing NF-κB dimers to translocate to the nucleus and regulate gene expression (19). The structure of this regulatory complex is critical for the proper control of NF-κB activity in cellular processes.

DNA-binding domain structure

NF-κB subunits contain specific DNA-binding regions that recognize consensus sequences in the promoters of target genes. Research using the drug affinity responsive target stability (DARTS) method revealed that compounds like thiophenacetamide (TAA) can bind to the p65 subunit, forming hydrogen bonds with key residues (Lys37 and Asp125) near the DNA-binding region. These interactions can affect the association between DNA and NF-κB, highlighting the importance of this structural domain in NF-κB function [20].

NF-κB signaling pathways

Canonical NF-κB pathway

The canonical pathway represents the classic mode of NF-κB activation in response to inflammatory stimuli such as cytokines, pathogens, and stress. This pathway relies on the degradation of IκBα and primarily activates p65/p50 heterodimers [18]. Upon stimulation, the inhibitor of NF-κB kinase (IKK) complex, consisting of catalytic subunits (IKKα and IKKβ) and a regulatory subunit (NEMO), phosphorylates IκBα, leading to its ubiquitination and proteasomal degradation [21]. This releases NF-κB dimers that subsequently translocate to the nucleus to regulate target gene expression.

Noncanonical NF-κB pathway

The noncanonical pathway represents an alternative mode of NF-κB activation that specifically mediates the activation of p52/RelB complexes. Unlike the canonical pathway, this mechanism relies on the inducible processing of the NF-κB2 precursor protein, p100, rather than the degradation of IκBα. A central component of this pathway is NF-κB-inducing kinase (NIK), which functions together with IKKα to induce phosphorylation-dependent ubiquitination and processing of p100 [18].

Under normal conditions, NIK is continuously degraded through a tumor necrosis factor receptor-associated factor-3 (TRAF3)-dependent E3 ubiquitin ligase. In response to specific signals from a subset of TNF receptor superfamily members, NIK becomes stabilized due to TRAF3 degradation, leading to noncanonical NF-κB activation [18]. This pathway plays crucial roles in specific immunological processes and complements the functions of the canonical pathway.

Crosstalk with other signaling pathways

NF-κB signaling does not operate in isolation but rather functions within a complex network of cellular signaling pathways. Significant cross-talk exists between NF-κB and other important pathways, including PI3 K/AKT, MAPK, JAK-STAT, TGF-β, Wnt, Notch, Hedgehog, and TLR signaling [21]. This interconnected network allows for precise regulation of cellular responses to various stimuli and enables NF-κB to influence diverse cellular processes beyond its direct transcriptional targets.

Major roles in normal cellular processes

Immune system regulation

NF-κB plays a central role in the immune system and is essential for both innate and adaptive immune responses. It regulates the development and survival of lymphocytes and other immune cells, controls the expression of cytokines and chemokines, and mediates responses to pathogen-associated molecular patterns. The evolutionary conservation of NF-κB across animal species, from invertebrates to vertebrates, underscores its fundamental importance in immune function [19].

Both canonical and noncanonical NF-κB pathways contribute to immune regulation, with the noncanonical pathway particularly important for specific immunological processes [18]. The proper functioning of these pathways is critical for mounting effective immune responses while preventing excessive inflammation that could damage host tissues.

Inflammatory response coordination

NF-κB was initially identified as a pivotal pathway in mediating inflammatory responses, and this remains one of its best-characterized functions. Upon activation by inflammatory stimuli, NF-κB induces the expression of pro-inflammatory cytokines, chemokines, adhesion molecules, and enzymes that orchestrate the inflammatory response [21]. This response is essential for host defense against infections, but must be tightly regulated to prevent chronic inflammation.

Cell survival and apoptosis regulation

NF-κB plays crucial roles in determining cell fate by regulating genes involved in cell survival and apoptosis. It typically promotes cell survival by inducing the expression of anti-apoptotic genes, such as members of the Bcl-2 family, and inhibitors of apoptosis proteins (IAPs) [19]. This pro-survival function is essential during development and immune responses, but can contribute to tumorigenesis when dysregulated.

Development and differentiation

NF-κB signaling is involved in the development and differentiation of various tissues and cell types. In particular, it has been found to be highly expressed in both mesenchymal and epithelial compartments of the developing and postnatal lung, indicating its importance in respiratory system development [22]. The evolutionarily conserved nature of NF-κB points to its fundamental role in organismal development across animal species [19].

The function of NF-κB in colorectal cancer: progression and metastasis

NF-κB family in humans consists of five DNA-binding members: NFKB2 (p52) and NFKB1 (p50) without transactivation domains; RELB, RELA, and c-REL with transactivation domains [23]. NF-κB signaling pathways mediate several processes, such as inflammation [24], immunity [25], cell proliferation [26], regulation of apoptosis [27], cellular senescence program [28], and survival [29]. In addition, in both normal and malignant cells, it functions as a physiological modulator, affecting metabolic adaptation and mitochondrial respiration [30].

Dysregulation of NF-κB plays a critical role in oncogenesis by promoting tumorigenesis through its effects on cell proliferation, survival, and inflammation. While NF-κB itself is not a tumor suppressor, its activation can contribute to cancer development by promoting cell proliferation and suppressing apoptosis, thereby enhancing the survival of transformed cells. Additionally, NF-κB dysregulation can lead to chronic inflammation, which is a well-established factor in cancer progression. The overactivation of NF-κB in certain contexts can result in the sustained expression of pro-survival and pro-inflammatory genes, facilitating the development and progression of various types of cancers [19, 31–35]. NF-kB upregulation in reacting to blocking the EGFR oncogene may have disadvantages in the population of tumor cells for removing the oncogene, allowing the tumor cells to survive. These findings highlight an imbalance in tumor response and the persistence of residual disease. Furthermore, NF-κB upregulation within tumor cells may lead to therapeutic resistance [36].

Studies on breast cancer cells in humans have proven that it is feasible to hinder the NF-κB signaling pathway in order to impede the process of cell epithelial–mesenchymal transition (EMT), as well as preventing proliferation, migration, and invasion [37]. Also, another research on the highly aggressive breast cancer model revealed that tumor necrosis factor (TNF)-α signaling inhibiting led to NF-κB activation diminishing and reduction in inflammation-related gene expression that modulates malignant cell metastasis. In addition, the TNF-α signaling block leads to low expression of autotaxin–lysophosphatidate-inflammatory cycle, suggesting an approach for reducing breast cancer metastasis [38].

Kinesin family member (KIF)14 upregulates the NF-κB pathway by increasing NF-κB promoter activity, increasing migration, invasion, and proliferation of cholangiocarcinoma (CCA) cells. Besides, this activation contributes to chemotherapy resistance, particularly to gemcitabine-based treatments, lymphatic metastasis, and inducing an immunosuppressive microenvironment. Investigations have found that NF-κB significantly functions in invasion, cell proliferation, and migration in lung and CRCs [39–42].

Identifying and targeting the pathways involved in these cancers offer potential therapeutic strategies. The migration and proliferation of non-small cell lung cancer (NSCLC) cells are inhibited by polydatin, a component extracted from traditional medicine of China. It suppresses NLRP3 inflammasome expression and downregulates phosphorylated NF-κB p65 expression, effectively hindering the activation of the NF-κB pathway [43]. MiR-130b directly influences TNF-α and its downstream gene, VEGFA, by reducing NF-κB signaling activity. However, abnormal expression of VEGFA declines the anti-angiogenic effect of miR-130b, creating a negative feedback loop that promotes angiogenesis in prostate cancer [44]. Furthermore, recent research suggests combining ferroptosis induction and aspirin treatment may effectively treat hepatocellular carcinoma (HCC). This study found that aspirin inhibits the expression of Solute Carrier Family 7 Member 11 (SLC7 A11), a process mediated by NF-κB p65, through ferroptosis induction. In Huh7 and HepG2 cells, NF-κB p65 binding to the SLC7 A11 promoter prevents ferroptosis. Overexpression of p65 protects cells from ferroptosis induced by aspirin. Importantly, patients diagnosed with HCC who have elevated levels of both SLC7 A11 and p65 demonstrate reduced survival rates [45].

In conclusion, the main focus of these researches highlights the immense importance of NF-κB in the advancement of cancer and the possibility of utilizing NF-κB targeted treatments to improve the outlook for those impacted (Fig. 1).

Fig. 1.

Inflammation is governed by 1 NF-κB, a transcription factor that manages the activity of genes related to its development and advancement. Upon activation, it can prompt the transcription of a multitude of genes, granting it the ability to oversee different aspects of the inflammatory reaction. These roles include boosting the synthesis of inflammatory substances and overseeing other cellular process like specialization, proliferation, and apoptosis

The activation of NF-κB in colorectal cancer involves complex molecular events that can be triggered by various stimuli including inflammatory cytokines, bacterial products, and environmental stress factors. These triggers initiate signaling cascades that ultimately result in the phosphorylation and degradation of inhibitory proteins, allowing NF-κB dimers to translocate to the nucleus and regulate target gene expression. This process is tightly regulated under normal physiological conditions but becomes dysregulated in cancer, leading to persistent activation and subsequent promotion of proliferation, survival, and invasion. In conditions such as ulcerative colitis, NF-κB upregulation can intensify inflammation, potentially leading to colorectal cancer development through sustained inflammatory signaling [46].

Apoptosis in colorectal cancer

Apoptosis is a programmed cellular death mechanism crucial for aging and optimal cellular development. It also has a homeostatic function in regulating cell population equilibrium [47]. There is a balance between cell death and expansion in normal tissues. Cells generally die through apoptosis [48]. In CRC and other malignancies, the molecular foundation of apoptosis includes a complex interaction of genes and signaling pathways [49]. Dysfunctional apoptosis leads to prolonged malignant cell survival. This also provides more time for mutations to accumulate, increasing tumor invasiveness, interfering with differentiation, dysregulating cell proliferation, and inducing angiogenesis [50]. Essential genes involved in apoptosis include the tumor suppressor gene p53 [51–53] and the BCL-2 family, which has both anti-apoptotic members (e.g., BCL-XL,BCL-2) and pro-apoptotic (e.g., Bcl-2-associated X protein (BAX), Bcl-2 antagonist/killer (BAK))[54, 55]. Additionally, studies have identified genes such as AXIN, small mothers against decapentaplegic proteins (SMADs), transforming growth factor beta receptor (TGFBR)1, TGFBR2, Notch-1, rapidly accelerated fibrosarcoma (RAF), RAS, Jagged-1, phosphatase and tensin homolog (PTEN), EGFR, phosphoinositide-3-kinase catalytic subunit alpha (PIK3 CA), and CTNNB1 as responsible for invasion, regulating proliferation, apoptosis, and progression in CRC cells [56–59].

In colon carcinomas, mutations in Caspase-8 can induce cell death and promote the growth of CRC, particularly in advanced stages [60]. The mitochondria secrete the serine protease HtrA2/Omi and the SMAC/DIABLO, in addition to cytochrome c [61]. These elements inhibit the inhibitors of apoptosis proteins (IAPs) function, thereby enhancing the apoptosis initiation [6]. Damage to DNA, endoplasmic reticulum (ER) stress, a lack of growth factors, cytokines, or hormones, toxins, radiation, and viruses are some of the conditions that can cause mitochondrial outer membrane permeabilization (MOMP) [7]. Furthermore, numerous other molecular pathways have recently been assessed, such as the Wnt/β-catenin [62], JAK/STAT [63], TGF/SMAD [64], WDR12/RAC1[65], hedgehog/Gli-1 signaling pathways [66].

The Wnt/β-catenin pathway is a crucial signaling mechanism that plays a complex function in the formation and progression of CRC, and has the ability to activate apoptotic regulators, causing cell death [67]. This pathway’s activation is initiated by the Wnt proteins binding to a core receptor complex containing the FZD family members and either LRP5 or LRP6 [68]. In the absence of Wnt ligands, β-catenin remains in the cytoplasm and undergoes modification by a complex comprising GSK3β, Axin, CK I, and APC. This phosphorylation targets β-catenin for ubiquitin-mediated degradation. Upon binding to its receptors, Wnt forms a complex that builds up and secures β-catenin in the cytoplasm, causing a destabilization. Consequently, the translocation of β-catenin into the nucleus initiates the transcription of Wnt target genes, thereby influencing the activity of TCF/LEF transcription factors [69, 70]. Also, another study indicated that elevated nuclear β-catenin levels, associated with cancer metastasis, transform FOXO3a from a tumor suppressor into a metastasis promoter. Additionally, it uncovered that the anti-cancer properties of AKT inhibitors, such as API-2, which are expected to trigger FOXO3a-mediated apoptosis, are negated by nuclear β-catenin, resulting in therapeutic resistance [71].

JAK/STAT signaling pathway is another pathway that accounts for contributors to colon cancer progression and it has a potential role as a prognostic indicator [72]. Various substances, such as SRC, oncogenes, TGF-β, interleukins, and interferons, are the main activators of this pathway [73–75]. JAK1 and JAK2 enzymes bind to receptors with γ chain (γc) and IL6ST subunits in the JAK–STAT signaling pathway [76]. This contact modifies receptor conformation, activating JAKs to phosphorylate receptor tyrosine motifs [77]. The phosphorylated motifs serve as designated locations for STAT proteins containing SH2 domains to attach and initiate activation [78]. Also, PIAS and SOCS block STATs and JAKs, degrading active pathway components and maintaining pathway balance [79]. Former CRC cell investigations demonstrated that inhibiting STAT2/3 and JAK1 signaling reduces invasion, arrest, cell cycle, and death [80].

The TGF-β pathway participates in numerous biological functions such as differentiation, EMT, cellular movement, programmed cell death, restructuring of the extracellular matrix, angiogenesis, and immune responses [81]. The TGF-β signaling pathway conveys signals from the cell membrane to the nucleus via SMAD-dependent (canonical) and SMAD-independent (noncanonical) mechanisms [82]. TGF-β ligands, activated by specific integrins, initiate a cascade by binding to TGFBR2 and TGFBR1, leading to SMAD2/3 phosphorylation. These phosphorylated SMADs, along with SMAD4, regulate gene expression in the nucleus. SMAD7 inhibits this process by preventing SMAD2/3 phosphorylation [83]. Noncanonical pathways, including MAPK, PI3 K/AKT, and ROCK, modulate TGF-β signaling, indicating a complex regulatory network [84]. Some mutations, such as SMAD proteins and TGF-β receptors in CRC, become more prevalent, leading to malignant phenotypes, although TGF-β ligand mutations are relatively rare [64].

WD repeat domain 12 (WDR12) is an essential gene significantly overexpressed in CRC cells, suggesting its potential role as an oncogene. More analysis demonstrated that WDR12 inhibits apoptosis and enhances CRC cell proliferation. WDR12 degradation led to diminished proliferation and increased apoptosis, implicating the WDR12/RAC1 axis in tumor progression [65].

The Hedgehog (Hh) signaling pathway is crucial during embryonic and postembryonic generations, modulating the progression of multiple tissues and organs, such as the gastrointestinal tract [66]. The process of Hh activation begins when Hh ligands bind to the Patched (Ptc) receptor, removing the obstruction caused by Ptc on the Smoothened (Smo) protein [85, 86]. Smo upregulation results in Gli transcription factors activation, which modulates Hh target genes'regulation [87]. Hh dysregulation is involved in intestinal epithelial cell hyperplasia as well as the progression and growth of neoplasms like CRC [66].

In addition, the activation of NF-κB results in an upregulation of many Bcl-2 family proteins, such as A1/Bfl-1 and Bcl-XL. These proteins stop cytochrome c from being released, which stops apoptosis, maintaining the polarized state of mitochondria, and inhibiting permeability transition. [88]. Previous research indicates that NF-κB has a vital role in increasing tumor growth and angiogenesis in CRC, potentially leading to chemotherapy resistance [89]. Figure 2 also provides two contrasting roles of NF-κB signaling in cancer cells.

Fig. 2.

The image illustrates two contrasting roles of NF-κB signaling in cancer cells, depending on the cellular context and downstream effects. A NF-κB signaling promoting escape from programmed cell death in cancer. This panel depicts a scenario where a cancer signal activates NF-κB. In the cytoplasm, NF-κB is typically bound to its inhibitor, IκBα. Upon receiving the cancer signal, IκBα is degraded, allowing NF-κB to translocate to the nucleus. Within the nucleus, NF-κB acts as a transcription factor, leading to increased expression of the c-myc oncogene. Subsequently, c-myc upregulation results in the downregulation of GADD45α, β, and γ (indicated as GADD45 α,γ). The reduced levels of GADD45 proteins lead to the repression of MEKK4/MTK1, a kinase involved in stress signaling. Consequently, JNK activity is decreased, ultimately leading to the cancer cell escaping programmed cell death (apoptosis). This pathway highlights how NF-κB activation in certain contexts can contribute to cancer progression by promoting cell survival. B NF-κB signaling leading to apoptosis in cancer. This panel illustrates an alternative scenario where NF-κB signaling, possibly triggered by different stimuli or occurring in a different cellular environment, leads to apoptosis. In this case, NF-κB activation in the cytoplasm results in a decrease in c-myc expression. The downregulation of c-myc leads to an increase in the expression of GADD45α, β, and γ (indicated as GADD45 α,γ). The increased GADD45 proteins then bind to and activate MEKK4/MTK1. Activated MEKK4/MTK1 subsequently increases JNK activity. Elevated JNK activity, in this context, triggers apoptosis, leading to cancer cell death. This pathway demonstrates that NF-κB signaling can have tumor-suppressing effects under specific conditions by promoting programmed cell death

NF-κB-linked apoptosis in colorectal cancer (CRC) development

The human NF-κB superfamily includes five transcription factors: RelA (p65), REL (c-Rel), RelB,, NF-κB2 (p52) and NF-κB1 (p50). All of these proteins present a Rel homology domain (RHD)[90], which is vital for DNA binding, dimerization, and nuclear localization, underscoring its importance in these proteins’ roles [91]. This group of transcription factors functions and modifies several biological mechanisms in tumor cells [35] and promotes the inhibition of apoptosis [92], cell proliferation [93], differentiation [94], migration [95], angiogenesis [96], and resistance to radiotherapies or chemotherapies [97]. Previous studies on many neoplasms have shown the inhibition of NF-κB function, like breast cancer [98], lung cancer [99], brain cancer [100], lymphoma [101], and CRC [102, 103].

The relationship between inflammation and NF-κB in colorectal cancer development represents a critical axis in carcinogenesis. NF-κB plays a crucial role in regulating inflammatory processes by altering the release of inflammatory factors such as TNF-α, IL-6, and IL-1β, which are key mediators in cancer development. In conditions such as ulcerative colitis, NF-κB upregulation can intensify inflammation, potentially leading to colorectal cancer development through sustained inflammatory signaling [46]. This inflammation–cancer connection is particularly evident in colitis-associated colorectal cancer, where chronic inflammation creates a microenvironment conducive to genetic alterations and malignant transformation.

The bidirectional relationship between inflammation and NF-κB creates a self-reinforcing cycle that can promote tumor development and progression. Inflammatory stimuli activate NF-κB, which in turn upregulates genes encoding pro-inflammatory cytokines, creating a positive feedback loop that sustains inflammatory conditions favorable to tumorigenesis. Understanding this relationship has led to investigations of anti-inflammatory strategies targeting NF-κB for both prevention and treatment of colorectal cancer, particularly in high-risk inflammatory bowel disease patients.

NF-κB signaling in colorectal cancer engages in complex cross-talk with multiple other pathways, most notably the Wnt/β-catenin pathway. Both pathways play critical roles in CRC development and progression, and their interaction significantly influences tumor behavior [104, 105]. Research examining Salmonella AvrA-related colorectal cancer tumorigenesis has demonstrated significant direct effects of TLR4 on β-catenin expression, which subsequently affects NF-κB signaling [105]. NF-κB also maintains connections with inflammatory cytokine signaling networks, functioning both as a responder to and regulator of various cytokines and chemokines. Traditional Chinese medicine has demonstrated efficacy in reducing inflammation by interfering with NF-κB-related signaling pathways, improving intestinal inflammation, and inhibiting progression to tumors. Additionally, NF-κB can be co-regulated as downstream factors of other signaling pathways such as TLR4, MAPK, STAT, and PI3 K, creating a complex regulatory network that collectively influences colorectal cancer biology [106].

Beyond Wnt/β-catenin, NF-κB interacts with several other signaling networks relevant to colorectal cancer. The TGF-β/SMAD pathway, which typically suppresses tumor growth in normal colorectal epithelium but often becomes tumor-promoting in advanced cancer, shows significant cross-talk with NF-κB signaling [104]. This interaction contributes to the complex regulation of cell proliferation, apoptosis, and differentiation in the colonic epithelium, with important implications for cancer development and progression.

NF-κB also maintains connections with inflammatory cytokine signaling networks, functioning both as a responder to and regulator of various cytokines and chemokines. Traditional Chinese medicine has demonstrated efficacy in reducing inflammation by interfering with NF-κB-related signaling pathways, improving intestinal inflammation, and inhibiting progression to tumors. Additionally, NF-κB can be co-regulated as downstream factors of other signaling pathways such as TLR4, MAPK, STAT, and PI3 K, creating a complex regulatory network that collectively influences colorectal cancer biology [106].

NF-κB activation typically promotes cell growth while inhibiting apoptosis, creating conditions favorable for tumor expansion. Studies have identified Adenomatous Polyposis Coli-like protein (APCLP) as a novel negative regulator of NF-κB signaling in colon cancer cells. Overexpression of APCLP decreased NF-κB activity, reduced cellular proliferation, migratory ability, and anchorage-independent growth of cells, while knockdown had the opposite effect [107, 108]. These findings demonstrate the direct impact of NF-κB signaling on fundamental aspects of cancer cell behavior and highlight the potential therapeutic value of targeting this pathway.

The anti-apoptotic function of NF-κB represents a particularly important mechanism by which this pathway promotes cancer cell survival. By upregulating various anti-apoptotic proteins, NF-κB enables cancer cells to evade programmed cell death signals that would normally eliminate damaged or aberrant cells. This survival advantage contributes significantly to therapeutic resistance, as many conventional cancer treatments rely on inducing apoptosis in tumor cells. Understanding these molecular mechanisms provides rationale for combining NF-κB inhibitors with conventional therapies to overcome treatment resistance.

Boosting the Nrf2 biological mechanism in colon cancer cells can significantly reduce their capacity to generate clusters and reproduce, given that it results in the suppression of the NF-κB molecular pathway and promotes cell death [103]. KiSS-1 is a gene that suppresses the spread of melanoma and when its expression is increased, the invasion and growth of HCT-119 cells decreases, but apoptotic processes are enhanced. Additionally, the production of p65, PI3 K, and MMP-9, as well as Akt phosphorylation, are significantly diminished by elevated levels of KiSS. KiSS-1 overexpression inhibited CRC cell invasiveness by decreasing MMP-9 production and inhibiting the PI3 K/Akt/NF-κB pathway [109]. Another study on the CRC cells investigated the involvement of ART1 in survival and apoptosis. By silencing ART1 and inducing apoptosis with cisplatin (CDDP), the research found that ART1 knockdown increases apoptosis and decreases cell survival in CT26 colon carcinoma cells. Several factors were found to contribute to a decrease in survival, including a decrease in both phos-IκBa and phos-AktThr308 levels. Additionally, there was a decrease in the nuclear translocation of NF-κB p65 and a reduction in the levels of anti-apoptotic proteins, including Bcl-2 and BCL-XL. Additionally, there was an increase in the pro-apoptotic protein BAX. [110]. Mesenchymal stem cell-conditioned media (MSC-CM) modulates the cancer-promoting environment by increasing IL-6 and IL-8 levels, downregulating AMPK phosphorylation, and upregulating mTOR phosphorylation, leading to NF-κB pathway activation. The molecular alterations facilitate the inhibition of apoptosis, consequently enhancing the proliferation and metastasis of CRC, as confirmed in an in vivo mouse model [111].

The progression of tumor malignancy is significantly influenced by the interaction between tumor microenvironment (TME) and cancer cells. In this regard, the NF-κB signaling pathway assumes a vital function, as it regulates immune cell behavior [112], cytokine production [113], cancer cell invasion [114], proliferation, and survival. A study showed treatment with resveratrol which decreases the secretion of pro-inflammatory proteins from T-lymphocytes and fibroblasts, suppressing the activation of NF-κB and lowering the levels of biomarkers implicated in the proliferation, invasion, and survival of CRC cells [115]. A study revealed the p50 NF-κB subunit as a critical regulator of the TME in CRC by modulating macrophage polarization. Lack of p50 resulted in a microenvironment characterized by stronger anti-tumor immunity and reduced tumor growth [112]. Another study on colon cancer cells showed that inhibiting NF-κB promotes an anti-tumor microenvironment by polarizing macrophages towards an M1 phenotype, which enhances pro-inflammatory responses and effector T cell activation in a mouse model [116]. The study examines the effect of oxygen-deprived EVs that contain miR-361-3p on the development of CRC in the TME. miR-361-3p contributes to the enlargement of CRC cells and inhibits their apoptosis through the activation of the noncanonical NF-κB pathway [117]. A study demonstrated that miR-34a promotes immune evasion in CRC by activating the SIRT1/NF-κB/B7-H3/TNF-α pathway. This activation results in the upregulation of the immune checkpoint molecule B7-H3 through SIRT1 inhibition and NF-κB acetylation. Consequently, this mechanism increases the production of pro-inflammatory cytokines, such as TNF-α, thereby modifying the TME and facilitating cancer progression [113].

CXCL1 is markedly overexpressed in CRC, contributing to tumor progression, angiogenesis, and migration, partially through activation of the NF-κB pathway. This chemokine also affects the tumor microenvironment by attracting M2 macrophages and dispersing CD8 + and CD4 + T cells, further facilitating cancer progression [114]. PRL-3 enhances CRC metastasis by modulating the tumor microenvironment, particularly by activating MAPK pathways in tumor-associated macrophages (TAMs) and triggering the NF-κB pathway to promote angiogenesis, thereby driving tumor invasion and growth [118]. Matrix Gla protein (MGP) upregulates in CRC, enhancing PD-L1 expression through NF-κB activation, resulting in CD8 + T cell exhaustion and promotes liver metastasis [119]. Conversely, the study demonstrated that Prolyl hydroxylases domain 2 (PHD) serves as a crucial inhibitor of tumor progression and inflammation in colon cancer through the modulation of the microenvironment and the NF-κB signaling pathway. The overexpression of PHD2 in colon cancer cells resulted in decreased proliferation and migration, as well as changes in the expression of proteins associated with the cell cycle and EMT, and suppressed tumor growth in xenograft mice. Notably, PHD2 diminished intratumoral inflammation by reducing myeloid-derived suppressor cells, M2-like macrophages, and pro-inflammatory cytokines [120].

Epigenetics includes the heritable alteration of histones and DNA, hence modifying gene expression without affecting the genetic coding [121]. By using Fe-metal–organic framework (Fe-MOF) nanoplatforms that carry MG132, a 26S proteasome inhibitor, this approach blocks the ubiquitination process, preventing the subsequent phosphorylation of transcription factors like NF-κB p65. This inhibition results in the accumulation of pro-apoptotic and misfolded proteins, disturbing tumor homeostasis and decreasing the expression of genes that drive CRC metastasis [122]. In CRC, PRKCDBP serves as a pro-apoptotic factor that helps prevent tumor growth. However, its activity is hindered due to epigenetic silencing through excessive methylation of its promoter region. This gene is activated by NF-κB signaling when cells are exposed to TNFα, and involves in regulating cell growth arrest and programmed cell death [123]. Chen et al. showed acetylation by decreasing Sirtuin1 (SIRT1) and increasing MOF and EP300 expression, which enhances acetylation on specific lysine sites of histone H4. The epigenetic modification is associated with the activation of the NF-κB signaling pathway, as indicated by increased acetylation of the p65 subunit. This activation results in alterations in the levels of essential proteins, facilitating apoptosis and cell cycle arrest while diminishing inflammation in CRC cells [110]. Another study showed lncRNA-HEIH interacting with miR-939, which disrupts miR-939's regulation of NF-κB, thereby enhancing NF-κB's transcriptional activity on the BCL-XL promoter and upregulating BCL-XL expression which is positively related to invasion depth, tumor size, and poor prognosis cases with CRC [124]. In an investigation, Lnc-GNAT1-1 displayed cancer-suppressing abilities in CRC through promoting the RKIP-NF-κB-Snail signaling pathway [125].

The NF-κB pathway is vital in advancing CRC by regulating essential mechanisms, including cell migration, proliferation, and survival. It interacts with the tumor microenvironment to influence cytokine production and immune responses. Targeting NF-κB signaling could offer a means of treating CRC.

Treatment strategies targeting the NF-κB pathway in CRC

Surgery and anti-cancer medications are the main treatments for colon cancer [126]. Depending on the cancer stage and case characteristics, the management of CRC involves a combination of chemotherapy drugs and diet modifications. Medications such as 5-fluorouracil (5-FU), foundational to neoadjuvant therapies like FOLFOX and FOLFIRI, are often used in conjunction with bevacizumab, panitumumab, or cetuximab [127]. Furthermore, the increasing adverse effects of drug treatment led to frequent changes in treatment plans, resulting in multidrug resistance [128]. Hence, it is crucial to discover effective and less toxic chemotherapy drugs for colon cancer and identify therapeutic targets to enhance the well-being and longevity of individuals rates of individuals with CRC [129]. While current treatments often come with side effects, plant-derived extracts could offer a promising alternative with fewer adverse reactions (130). Given the challenges of current treatment methods, exploring new therapeutic strategies is essential. In this segment, we have examined research studies focusing on therapeutic approaches that target the NF-κB cascade in CRC, which are summarized in Table 1. Figure 3 also provides an overview about dual mechanism of regorafenib in cancer cells.

Table 1.

NF-κB-linked apoptosis in CRC

Agent	Source	Sample study	Target	Effect	Author, year
Baicalin	Scutellaria baicalensis	In vivo/in vitro	TLR4/NF-κB signaling modulation	The administration of baicalin resulted in apoptosis, impeded cellular migration, and enhanced the body's ability to fight against tumor growth in cases of CRC via the mechanism of TLR4/NF-κB signaling	Song et al., 2021 [135]
Cyanidin chloride (CyCl)	Anthocyanins	In vitro	The NF-κB and Nrf2 signaling pathways in colon cancer cells induced by TNF-α	CyCle induces apoptosis in CRC cells through the inhibition of NF-kB signaling and the activation of Nrf2	Lee et al., 2020 [103]
Codonopsis bulleynana Forest	–	Animal model nude mice	cbFeD inhibits autophagy via NF‑κB activation, showing promise for cancer therapy	Codonopsis bulleynana Forest ex Diels triggers apoptosis in colon cancer cells through NF-κB activation, inhibiting autophagy	Luan et al., 2017 [137]
Astragalin	–	In vivo/in vitro	P21, BAX, P53, Bcl-2, caspase-6, caspase 3, caspase 8, caspase 7, caspase 9, Cyclin E, Cyclin D1, P27, CDK4, and CDK2 protein express, MMP-2, MMP-9	Astragalin regulates NF-κB signaling to inhibit HCT116 cell growth and migration	Yang et al., 2021[142]
Onosma species (Boraginaceae)	–	In vivo/in vitro	NF-κB and BAX/Bcl-2 signaling pathways	In rats, the plant Onosma mutabilis has been shown to have chemopreventive properties against colon cancer induced by azoxymethane. This is accomplished via the modulation of the BAX/Bcl-2 and NF-κB signaling pathways	Jabbar et al., 2023 [146]

Fig. 3.

The figure illustrates the proposed dual mechanism by which regorafenib exerts its anti-cancer effects. On the left (orange background), regorafenib inhibits AKT signaling, subsequently suppressing NF-κB activation and the expression of pro-survival factors (XIAP, cFLIP, MCL1, Survivin, VEGF, MMP-9, CyclinD1), thereby reducing angiogenesis, proliferation, and anti-apoptotic pathways. On the right (blue background), regorafenib is shown to promote both extrinsic apoptosis (potentially by modulating FAS/FASL interactions and overcoming C-FLIP inhibition of Caspase-8) and intrinsic apoptosis (possibly by downregulating MCL-1, leading to mitochondrial dysfunction and Caspase-3 activation)

Baicalin, a crucial compound extracted from Scutellaria baicalensis, is prevalent in many Asian regions as a traditional herbal remedy. In cancer cells, it exhibits powerful antioxidant and anti-tumor properties as a type of glycoside derived from natural flavonoids [131, 132]. Research on baicalein indicates its potential to inhibit cancer cell proliferation through the MAPK pathway and to induce apoptosis via the PI3 K/Akt, ROS, and 12-lipoxygenase pathways. Baicalein's anti-cancer effects are significant, including promoting autophagy, decreasing cell proliferation, promoting apoptosis, and blocking metastasis. The data demonstrate that enhancing tumor suppressor p53 expression and decreasing anti-apoptotic protein levels can effectively suppress tumor cells [133].

Studies have shown that baicalin protects against chronic stomach inflammation induced by ethanol and inhibits the transition of epithelial cells to those resembling connective tissue by blocking NF-κB activity. Importantly, baicalein is identified as a potent NF-κB inhibitor, suggesting that baicalin may offer promising therapeutic benefits in CRC management [134].

For example, Song L. et al. [135], demonstrated that baicalin, a potent NF-κB inhibitor, exhibits promising anti-tumor effects in CRC. The experiments demonstrated that baicalin significantly inhibited the proliferation and growth of CRC cell lines, as indicated by CCK8 and colony formation assays. Baicalin induced mitochondrial-mediated apoptosis in CRC cell lines, characterized by mitochondrial membrane impairment and elevated levels of ROS. Baicalin effectively inhibited the motility and invasiveness of colon cancer cells by disrupting the TLR4/NF-κB signaling pathway. This targeting of the pathway by Baicalin consequently facilitates apoptosis via mitochondrial mechanisms, impedes cell migration, and augments the body's defense against cancerous growths in the colon.

Anthocyanins belong to a group of flavonoids that can be found in many different foods and have essential effects on the body. One common type of anthocyanin is cyanidin chloride (CyCl), which has properties that can help prevent damage from harmful molecules and reduce inflammation. A recent study revealed that CyCl treatment induced apoptosis in colon tumors while suppressing their proliferation and colony-forming capacity. This effect was noted in three colon cell lines: SW620, HCT116, and HT29 [103].

Additionally, researchers found that CyCl suppresses NF-κB activity and activates Nrf2 signaling pathway in CRC cells in response to TNF-α. Nrf2 and NF-κB interaction is critical for regulating stress responses and promoting cell development. Utilizing siRNA to inhibit Nrf2 activity demonstrated a reduction in the impact of CyCl on NF-κB signaling and cell death, suggesting a mutual dependence between Nrf2 and NF-κB in these mechanisms [103]. Also, research shows that Nrf2 is fundamental in CRC cells, inducing cell death through regulation of the NF-κB signaling pathway. This evidence suggests that CyCl could be a viable treatment option for CRC [136].

Research showed that the resistant cells were less sensitive to oxaliplatin (OXA). Additionally, the resistant cells had a long and thin shape, which suggested they had a specific type of cell structure. Cell death elevation was observed when cyanidin-3-O-glucoside (C3G) and OXA were used together in the resistant cells. The resistant cells'moving ability from one place to another was more significant than that of the original cells, but treatment with C3G reduced the speed at which the HCT-116-ROx cells moved. In comparison to the HCT-116-ROx cells, HCT-116 cells no longer had the original cell structure like E-cadherin and a different kind of cell structure like vimentin and N-cadherin, analysis of specific markers. Nevertheless, therapy with C3G in the resistant cells reversed the different cell structures. In summary, their findings indicate that cells resistant to oxaliplatin change from one cell structure to another, suggesting a possible role of cell structure transition in acquired OXA resistance in CRC. Also, C3G reversed the process of cell structure transition and reduced the movement of the resistant cell, with CRC resistance showing potential in overcoming acquired OXA resistance [136].

The plant Radix Codonopsis, also known as Dangshen in Chinese, plays a significant role in various Traditional Chinese Medicine (TCM) formulations. Codonopsis bulleynana Forest ex Diels is a plant species that can often be observed thriving on the edges of forests and in shrubby areas within the Yunnan region of China [137, 138].

In clinical settings, oxaliplatin-based chemotherapy is effective but often results in liver damage, leading to therapy discontinuation in individuals with colon cancer. Thus, new drugs that safely enhance or replace oxaliplatin are needed. cbFeD has many pharmacological benefits, including anti-cancer potential [137].

The use of naturally occurring plant compounds is gaining importance in cancer treatment due to their substantial therapeutic potential and lower toxicity levels. Raddeanin A (RadA), derived from Anemone raddeana Regel, demonstrates significant anti-cancer properties. RadA inhibits metastasis, proliferation, and angiogenesis while promoting cell death in cancer cell lines and experimental models.

RadA can trigger cell death and influence several proteins, including poly-ADP ribose polymerase (PARP), BAX, cytochrome c, Bcl-2, caspase-8, caspase-3, and caspase-9. The PI3 K/Akt pathway, a crucial molecular pathway, undergoes alteration due to its impact. Moreover, research indicates that RadA effectively suppresses cell growth in CRC cells by targeting the Wnt/β-catenin pathway and inhibiting the STAT3 and NF-κB pathways, which are involved in cancer invasion and metastasis. Additionally, RadA demonstrates considerable potential in addressing drug-resistant cells and may enhance the effectiveness of multiple chemotherapy agents [139].

Retinoic acid (RA) induces cell death and inhibits the proliferation of SW480 and LOVO cells in a dose-dependent manner. Additionally, RADA shows notable anti-cancer effects in a mouse model featuring xenograft tumors. The mechanism underlying these effects entails the downregulation of the Wnt/β-catenin signaling pathway through the reduction of p-LRP6, β-catenin, and active AKT levels, alongside the reactivation of GSK-3β. Additionally, RA inhibits IKBα phosphorylation, resulting in the suppression of the NF-κB pathway and an increase in apoptosis [59].

Astragalin (kaempferol-3-O-glycoside) is a plant compound frequently present in herbs and healing plants such as the Moringa tree leaf, water lily leaf, and oriental peony [140, 141]. Astragalin reduces inflammation and oxidative stress and it is proved it blocks the development of specific kinds of malignant cells. Astragalin has efficiently reduced both the metastasis and proliferation of HCT116 cells through modulating specific proteins, for example P53, BCL-2, BAX, and numerous caspases, by triggering programmed cell death leading to block cell expansion by modifying levels of P27, cyclin-dependent kinase (CDK)2, CDK4, P21, Cyclin E, and Cyclin D1. Furthermore, HCT116 cell migration is inhibited by astragalin via decreasing the activity of MMP-9 and MMP-2. Additionally, astragalin reduced the synthesis of essential proteins associated with cellular signaling pathways and decreased the activity of particular molecules that facilitate inflammation, ultimately resulting in a reduction of colon cancer cell proliferation [142].

Astragalin directly inhibits the NF-κB p65 subunit, reducing its transcriptional activity. This is particularly evident under TNF-α stimulation, where astragalin blocks TNF-α-induced nuclear translocation of p65, thereby preventing the activation of pro-survival and inflammatory genes [143]. Astragalin reduces expression of upstream regulators (e.g., IKK) and downstream targets (e.g., COX-2, iNOS) linked to inflammation and tumor progression. Furthermore, it could decrease matrix metalloproteinases (MMP-2 and MMP-9), critical for cancer cell invasion and metastasis via modulation of NF-κB [143].

The species Onosma represents a collection of renowned ancient healing herbs that consist of various plant compounds providing diverse effects against a variety of common and serious illnesses affecting humans [144, 145]. OME displayed anti-cancer activity against CRC cells, including Caco-2 and HT-29. OME resulted in a reduction in Aberrant Crypt Foci (ACF) values and enhancements in the expression of BAX and Bcl-2 proteins in rodents, indicating a potential protective impact against chemotherapy-triggered colon cancer by decreasing ACF formation through the suppression of free radicals and inflammation. OME also enhanced the antioxidant defense mechanisms in the colon and triggered the Nrf2-Keap1 signaling pathway [146].

Table 1 lists some studies on NF-κB-related apoptosis in CRC.

Conclusion

This review highlights the critical role of the NF-κB pathway in CRC progression and the potential therapeutic benefits of targeting this pathway with natural substances. Compounds such as CyCl, baicalin, retinoic acid (RA), omeprazole (OME), and cbFeD have demonstrated promising effects in preclinical studies, including the induction of apoptosis, inhibition of cell growth, and suppression of NF-κB activation. These findings suggest that targeting NF-κB signaling could enhance current CRC treatment strategies, overcome drug resistance, and improve patient outcomes. Clinically, incorporating these natural compounds into CRC therapies may offer safer, more effective alternatives to conventional treatments, though further clinical trials are needed to confirm their efficacy and safety in human populations. However, several limitations exist, including the lack of large-scale, multicenter human trials, potential variability in patient responses, and the need for standardization of natural compound formulations. As research progresses, these compounds could become key components of personalized medicine for CRC patients, offering potential for better management and improved prognosis. Single-cell sequencing approaches are revealing previously unappreciated heterogeneity in NF-κB pathway activation within tumors, potentially explaining variable treatment responses and disease outcomes. Additionally, patient-derived xenografts (PDX) and organoid models are providing valuable platforms for testing NF-κB-targeted therapies in systems that more accurately recapitulate human disease than traditional cell line models. These emerging technologies promise to accelerate the translation of basic NF-κB research into clinical applications for colorectal cancer patients.

Computational approaches integrating multi-omics data are also advancing our understanding of NF-κB in colorectal cancer. By analyzing genomic, transcriptomic, proteomic, and clinical data together, researchers can identify complex patterns of NF-κB pathway dysregulation and their associations with disease features and outcomes. These integrative analyses may reveal novel therapeutic vulnerabilities and biomarker opportunities that would not be apparent from studying individual data types in isolation. As these computational methods continue to evolve, they will likely play an increasingly important role in unraveling the complexities of NF-κB signaling in colorectal cancer.

Author contributions

Hamed Mirzaei and Reza Eshraghi contributed to the conception, design, statistical analysis and reviewing, writing and final drafting of the manuscript. Amirreza Khalaji, Ali Bonyad, Sara Khoshdooz, Kosar Sadat Hosseini kolbadi, Ashkan Bahrami, Mohammad Saeid Moeinfar, Arash Raisi, Amireza Ghamsaraian, Majid Eterafi, Mahmood Khaksary Mahabady, contributed to data collection and manuscript drafting (writing, and finalizing). All authors approved the final version for submission.

Funding

Not applicable.

Availability of data and materials

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.