Pellino ubiquitin ligases: double-edged swords in hematologic malignancies–from oncogenic stabilizers to therapeutic vulnerabilities

Abstract

The Pellino protein family is an evolutionarily conserved group of E3 ubiquitin ligases comprising Pellino1, Pellino2, and Pellino3. This family plays a central role in modulating inflammatory responses and immune signaling pathways through substrate ubiquitination. Recent studies have revealed that the Pellino family performs a unique dual regulatory function within the immune microenvironment of hematological malignancies. On the one hand, it contributes to tumor progression by promoting an immunosuppressive environment, such as enhancing the function of myeloid-derived suppressor cells (MDSCs) and increasing tumor cell drug resistance. On the other hand, it exhibits tumor-suppressive properties by activating antitumor immune responses, including the regulation of CD8⁺T-cell effector functions and the enhancement of NK cell cytotoxicity. The underlying molecular mechanisms involve bidirectional regulation of multiple signaling pathways, such as the Toll-like receptor, IL-1R, T-cell receptor, and nonclassical nuclear factor kappa B(NF-κB) pathways, thereby dynamically balancing the immune status within the tumor microenvironment. Clinical studies have demonstrated that the expression levels of Pellino family members are closely associated with the diagnosis, classification, and prognosis of hematological tumors, indicating their potential as biomarkers. Moreover, targeted intervention strategies based on their E3 ubiquitin ligase activity may offer novel approaches to increase the efficacy of immunotherapies. This review summarizes the structural and functional characteristics of the Pellino protein family, its dual regulatory mechanisms in the immune microenvironment of hematological tumors, and recent advances in clinical translation, aiming to provide a theoretical foundation for further understanding its biological roles and promoting targeted therapeutic research.

Introduction

The Pellino protein family represents a novel and highly conserved class of E3 ubiquitin ligases consisting of Pellino1, Pellino2, and Pellino3. These proteins exhibit highly conserved structural motifs that enable them to perform both cell- and tissue-specific functions while maintaining their ubiquitin ligase activity (Zhang and Li 2022). Pellino1 (PELI1), a receptor signal-responsive E3 ubiquitin ligase, plays a pivotal role in inflammation and autoimmunity through the ubiquitination of specific substrate proteins (Qi et al. 2023; Park et al. 2022). Accumulating evidence indicates that members of this family are extensively involved in pattern recognition receptor (PRR)-related signaling pathways, including the IL-1 receptor (IL-1R), Toll-like receptor (TLR), NOD-like receptor (NLR), T/B-cell signaling, and Tumor Necrosis Factor Receptor(TNFR)-mediated cell death pathways (Zhang and Li 2022). The immune microenvironment of hematological malignancies constitutes a complex network comprising peripheral blood vessels, the extracellular matrix, immune and nonimmune cells, and various signaling molecules (Zhang et al. 2024a). This microenvironment not only supports tumor progression but also poses a significant barrier to the efficacy of immunotherapies, including CAR-T-cell therapy (Wang et al. 2023; Tang et al. 2024). MDSCs, as critical immunosuppressive regulators, play a central role in tumor growth, drug resistance, recurrence, and immune evasion (Yu et al. 2022). While CD8⁺ T cells are essential for tumor clearance, the mechanisms underlying their priming and maintenance of effector functions remain incompletely understood. Additionally, the upregulation of inhibitory immune checkpoint molecules within the tumor microenvironment can impair immune cell effector functions (Liu et al. 2021).

Pellino proteins have dual regulatory effects on hematological tumors: they can act as oncogenic factors that promote tumor development and metastasis while also participating in the regulation of antitumor immune responses (Qi et al. 2023; Park et al. 2022). This dual functionality positions the Pellino family as a crucial link between basic research and clinical applications (Chen et al. 2021). In the context of CAR-T-cell therapy, which has shown promising outcomes in hematological tumors but faces challenges in solid tumors (Liu et al. 2025a; Li et al. 2024a), elucidating the regulatory mechanisms of the Pellino family in the immune microenvironment could provide a theoretical basis for developing novel immunotherapeutic strategies (Fang et al. 2023). Furthermore, Pellino1 expression levels are associated with tumorigenesis risk, suggesting its potential as a diagnostic and prognostic biomarker (Guan et al. 2022). Targeted modulation of Pellino family members may represent a promising avenue for personalized immunotherapy (Zhang et al. 2025), particularly in "cold" tumors characterized by immunosuppressive microenvironments (Ma et al. 2025).

Structural and functional basis of Pellino proteins

E3 ubiquitin ligase activity and substrate specificity

The Pellino protein family comprises evolutionarily conserved E3 ubiquitin ligases, with all members (Pellino-1, Pellino-2, and Pellino-3) exhibiting highly conserved structural domains that preserve ubiquitin ligase activity while enabling cell- and tissue-specific functions (Liu et al. 2021). PELI1, as a representative member, performs key biological functions through substrate ubiquitination and plays a central role in regulating inflammation and autoimmunity (Zhang et al. 2025). Research has shown that Pellino1 effectively modulates immune cell responses to receptor signals by ubiquitinating signaling intermediates (Hwang et al. 2025). Mechanistically, Pellino1 mediates the K63-linked ubiquitination of STAT3, thereby activating the STAT3 signaling pathway (Chen et al. 2024). Additionally, Pellino1 interacts with the senescence marker p21 and regulates cellular senescence via K63 ubiquitination (Ma et al. 2022).

Functional diversity among pellino-1/2/3 family members

Despite their structural similarities, Pellino family members exhibit distinct functional characteristics (Table 1). Pellino1 has oncogenic effects on tumor initiation and metastasis (Zhang et al. 2025), whereas Pellino2 (PELI2) has been recently shown to play a vital role in early B-cell development and stress-induced hematopoiesis (Xu et al. 2024). Functional studies have revealed that Pellino2 stabilizes the PU.1 protein through K63 polyubiquitination, thereby modulating IL-7R expression levels (Xu et al. 2024). In immune regulation, Pellino1 is involved primarily in pathways such as the interleukin-1 receptor, Toll-like receptor, NF-κB, mitogen-activated protein kinase (Liu et al. 2021), and phosphatidylinositol signaling pathways, while the functional roles of Pellino3 remain to be fully characterized. The current understanding suggests that Pellino3 is associated with exerting protective functions in inflammatory responses through the NOD2-mediated signaling pathway (Yang et al. 2013). This functional heterogeneity may stem from differential expression patterns across cell types and tissues, as well as variations in substrate specificity.

Table 1.

Comparison of structural and functional details of Pellino family members

Members of the family	Structural core features	Representation of core E3 ubiquitin ligase activity	Main Biological functions	Regulation of immune cells	Known roles in hematologic malignancies	Refs.
Pellino1	Highly conserved structure containing typical ubiquitin ligase domains	polyubiquitination mediated by K63 modification (e.g. STAT3, p21	Regulation of inflammation and autoimmunity; Regulating innate and adaptive immune signals; Control of cellular senescence	CD8⁺T cells, macrophages, MDSCs, and NK cells	-Tumor promotion: promoting MDSCs function, enhancing drug resistance, activating STAT3 pathway to support tumor proliferation - Tumor suppression: enhanced CD8⁺T cell effector function and NK cell killing activity	Chen et al. (2024), Ma et al. (2022), Park et al. (2022), Poznanski et al. (2021)
Pellino2	Conserved structure containing specific substrate binding domain	PU.1 protein is stabilized by K63	Regulates early B cell development; Participate in the process of stress hematopoiesis; Regulation of IL-7R expression	B cell precursors, lymphoid progenitor cells	It may affect the tumor microenvironment by regulating the differentiation of lymphoid cells. Plays a specific role through TCF3 regulation in BCP-ALL	Xu et al. (2024), Zhou et al. (2022)
Pellino3	The structure is conserved and has high homology with family members	Ubiquitin ligase activity has been demonstrated, but substrate specificity is unknown	Involved in pattern recognition receptor signaling pathways (TLR, NOD-like receptors); Auxiliary immune signaling	The function involves immune cells, but the specific cell type is not clear	It is known to be involved in the regulation of immune signaling, but its role in promoting/suppressing tumor in hematological tumors has not been clarified	Zhang and Li (2022), Ravindran et al. (2022)

Central regulatory role in pattern recognition receptor signaling

The Pellino protein family plays a pivotal role in PRR-mediated signaling pathways, including the IL-1R, Toll-like receptor, NOD-like receptor, T-cell and B-cell signaling, and TNFR-related cell death pathways (Hwang et al. 2025) (Fig. 1). In innate immunity, Pellino1 serves as a receptor signal-responsive E3 ubiquitin ligase and functions as a key mediator of innate immune responses. Studies have demonstrated that Pellino1 influences tumor risk by modulating CD8⁺ T-cell effector responses (Choi et al. 2024). At the molecular level, Pellino proteins precisely regulate inflammatory responses by modulating the activation thresholds of various receptor signaling pathways, such as TLR and IL-1R (Yan et al. 2023). Moreover, Pellino1 has been implicated in the regulation of NF-κB and activated B-cell kappa light chain enhancer signaling pathways, which are critically involved in the pathogenesis of inflammatory skin diseases such as psoriasis (Kim et al. 2023).

Fig. 1.

The dual-edged regulatory role of Pellino in hematological malignancies. Upon TLR stimulation, PELI1 catalyzes K63-linked polyubiquitination, potently amplifying NF-κB activity while suppressing BCL-6 degradation. This promotes DLBCL oncogenesis and induces chemoresistance in AML. Paradoxically, PELI1 upregulation drives apoptosis in Hodgkin lymphoma by targeting the NF-κB/BCL6 axis. Concurrently, elevated PELI2 expression enhances the sensitivity of MM cell lines to proteasome inhibitors (bortezomib, carfilzomib, and ixazomib), thereby exerting antitumor effects

Molecular mechanisms of immune microenvironment regulation

Bidirectional regulation of the toll-like receptor signaling pathway

The Pellino protein family has a unique bidirectional regulatory function within the TLR signaling pathway (Table 2). Research indicates that PELI1, which functions as an E3 ubiquitin ligase, can precisely modulate the activation intensity of the TLR signaling pathway through the ubiquitination of its substrate proteins (Ravindran et al. 2022). In the context of TLR7/8 signaling, Pellino1 not only enhances antitumor immune responses but also prevents excessive inflammation by modulating the activity of downstream NF-κB and MAPK signaling pathways (Yan et al. 2023). This dual regulatory capability enables Pellino family members to dynamically adjust the output of TLR signals in response to microenvironmental cues, thereby influencing the transition of the tumor immune microenvironment from an immunologically "cold" to a "hot" state (Artosi et al. 2024). A predictive modeling study in acute myeloid leukemia (AML) revealed that PELI1 tends to promote a "hot tumor" immune microenvironment (Zhang et al. 2024b).

Table 2.

Key signaling pathways and molecular mechanisms regulated by Pellino protein

Signaling pathways	Regulatory body	Core regulatory mechanisms	Effects on the immune microenvironment	Key molecules/proteins involved	Biological effects in hematologic malignancies	Refs.
TLR pathway	Pellino1 was predominant	The activity of NF-κB and MAPK olecul downstream of TLR can be regulated by ubiquitination to achieve bidirectional regulation	Affecting the “cold/hot” transition of tumor microenvironment;Regulation of inflammatory factor secretion balance	NF-κB, MAPK, TLR7/8	When over-activated, it promotes the immunosuppressive microenvironment; Enhanced immune response when moderately activated	Yan et al. (2023), Ravindran et al. (2022), Artosi et al. (2024), Chen et al. (2022), Yin et al. (2021)
Il-1R-mediated inflammatory pathways	Pellino1, Pellino2	Ubiquitinating key adaptor proteins of the IL-1R signaling pathway to control inflammatory thresholds	Maintaining inflammation level to balance immune activation and tissue damage; Affect the secretion of tumor-related inflammatory factors	IL-1R adaptor protein and inflammatory factors	When the threshold is abnormal, it can promote the secretion of leukemia-related oleculeion factors and reshape the bone marrow microenvironment to support tumor survival	Thirunavukkarasu et al. (2023), Oleinikovas et al. (2024), Camacho et al. (2021)
TCR pathway	Pellino1	Ubiquitination of key olecule of TCR pathway to enhance costimulatory signal transduction and maintain effector function and persistence of CD8⁺T cells	Regulation of effector T cells and regulatory T cells balance; Enhanced antitumor activity of CD8⁺T cells	TCR key molecules, CD8⁺T cells	When depleted, it resulted in CD8⁺T cell dysfunction. Enhanced T cell cytotoxicity when normally expressed	Liu et al. (2023), Lin et al. (2025), Park et al. (2022), Guan et al. (2022), Liu et al. (2023)
Noncanonical NF-κB pathway	Pellino1 and Pellino3	NIK and other olecule are modified by ubiquitination to regulate the activation of the pathway	It affects the function of B cells and macrophages Regulates the release of immune regulatory factors	NIK, noncanonical NF-κB subunit	When activated, it enhances NK cell killing activity. When abnormally activated, it may promote the function of immunosuppressive cells	Yan et al. (2023), Ravindran et al. (2022), Thirunavukkarasu et al. (2023), Poznanski et al. (2021)

Threshold control of the IL-1R-mediated inflammatory response

Pellino proteins play crucial roles in modulating the inflammatory response threshold within the IL-1R signaling pathway. Pellino1, through its E3 ubiquitin ligase activity, specifically identifies and ubiquitinates key adaptor proteins in this pathway, thereby enabling precise control over the magnitude of the inflammatory response (Thirunavukkarasu et al. 2023). This regulatory mechanism is vital for maintaining an optimal level of inflammation in the tumor microenvironment, preventing tissue damage caused by excessive inflammation while ensuring sufficient immune activation (Oleinikovas et al. 2024). Furthermore, studies have revealed functional heterogeneity among Pellino family members in the IL-1R signaling pathway, suggesting that these differences may underlie their distinct regulatory roles in the microenvironments of various hematologic malignancies (Ravindran et al. 2022).

Costimulatory effects on T-cell receptor signaling

Pellino1 plays a pivotal role in modulating the effector functions of CD8⁺ T cells in the regulation of T-cell-mediated immunity. Experimental evidence has revealed a strong correlation between Pellino1 expression levels and T-cell antitumor activity, with Pellino1 depletion leading to functional impairments in CD8⁺ T cells (Liu et al. 2023). In T cells, Pellino1 suppresses T-cell activation and autoimmune responses by ubiquitinating c-Rel (Jensen 2023). Its expression is regulated by miR-155, a mechanism that helps maintain T-cell homeostasis. Pellino1 deficiency leads to increased T-cell activation, which may contribute to the development of autoimmune diseases. Pellino proteins influence the efficiency of costimulatory signal transmission by regulating the ubiquitination of key molecules within the T-cell receptor (TCR) signaling cascade (Thirunavukkarasu et al. 2023). This regulatory function extends beyond the initial activation of naïve T cells, also contributing to the persistence and functional integrity of effector T cells within the tumor microenvironment (Liu et al. 2023). Notably, the expression level of Pellino1 in T cells may determine the equilibrium between effector and regulatory T-cell populations in the tumor immune microenvironment (Lin et al. 2025).

Noncanonical NF‒κB activation pathways

Members of the Pellino family are also implicated in the regulation of the noncanonical NF‒κB signaling pathway. Through ubiquitin-mediated modification of key signaling components such as NIK, Pellino proteins can influence the activation status of the noncanonical NF-κB pathway (Choi et al. 2024). This regulatory mechanism is particularly important in the tumor microenvironment, where noncanonical NF-κB signaling is closely associated with the production and secretion of various immunomodulatory factors (Zhou et al. 2022). Studies have demonstrated that Pellino1-mediated ubiquitination dynamically modulates the activity of the noncanonical NF-κB pathway, thereby influencing the functional state of immune cells such as B cells and macrophages within the tumor microenvironment (Kim et al. 2023). This modulation may account for the distinctive role of Pellino proteins in the remodeling of the immune microenvironment in hematologic cancers.

Dual mechanism of action of Pellino in hematologic oncogenesis

The Pellino protein family plays extensive roles in immune signaling and cell cycle regulation, exhibiting functional duality in tumorigenesis—either promoting or suppressing cancer progression under different biological conditions (Huoh and Ferguson 2014). Early studies in breast cancer models revealed that the functional output of Pellino is significantly influenced by distinct upstream and downstream networks. For instance, high expression of FSCN1 enhances tumor migratory capacity, whereas low levels result in reduced invasiveness (Chang et al. 2023), a divergence primarily governed by metabolic pathways, mitochondrial remodeling, and glycolipid metabolism. Evidence suggests that in certain cancers, Pellino1 facilitates tumor cell invasion and metastasis by mediating K63-linked ubiquitination to stabilize transcription factors such as Jeon et al. (2017). This mechanism may be functionally linked to the findings of Wu et al. (2020), who proposed that molecules like FGD1 can activate the PI3K/AKT pathway via interference with PTEN, thereby driving aggressive cancer growth and invasion. Furthermore, Pellino1 contributes to chemoresistance and tumor relapse by upregulating anti-apoptotic proteins such as cIAP2 (Jeon et al. 2016). This may be associated with the induction of stem-like properties mediated by ABC transporters like ABCG1, which confers chemoresistance across multiple cancer types (Xinyi and Gong 2024). Pellino-mediated signaling may further reinforce therapy resistance through downstream phosphorylation events. Conversely, certain studies indicate that Pellino proteins may also exert tumor-suppressive functions under specific conditions. Park et al. (2017) demonstrated that Pellino1 targets the key cell cycle regulator BubR1 for ubiquitin-mediated degradation, disrupting the mitotic spindle checkpoint and altering cell cycle dynamics, thereby either accelerating or delaying tumor progression. Moreover, overexpression of genes such as SPRYD4 can induce programmed cell death in cancers including HCC (Zahid et al. 2019), suggesting a potential regulatory role of Pellino-associated networks in these processes. Although the involvement of Pellino proteins has been relatively well-documented in various solid tumors (Liu et al. 2025b; Zhou et al. 2024a), their roles in hematological malignancies remain less explored. The following section thus focuses on summarizing evidence within hematopoietic cancers.

Tumor-promoting effect: pellino proteins promote the immunosuppressive microenvironment

The Pellino protein family performs key immunosuppressive functions within the hematological tumor microenvironment through its E3 ubiquitin ligase activity (Fig. 2). Research indicates that PELI1, which functions as an oncogenic protein, contributes to tumorigenesis and metastasis via the ubiquitination of substrate proteins (Zhou et al. 2024b). In a large-scale study encompassing 502 cases (including 406 B-cell lymphomas, 76 T/NK-cell lymphomas, and 20 Hodgkin lymphomas) (Choe et al. 2016), immunohistochemical analysis of PELI1 expression revealed that high expression of PELI1 was observed in high-grade B-cell lymphomas such as diffuse large B-cell lymphoma (DLBCL), Burkitt lymphoma, and plasmablastic lymphoma. In contrast, significantly lower expression levels were detected in low-grade B-cell lymphomas, T/NK-cell lymphomas, and Hodgkin lymphoma cases. Within the bone marrow microenvironment, Pellino family members facilitate the formation of an immunosuppressive environment by modulating the activity of MDSCs. This modulation primarily involves the negative regulation of the TLR and IL-1R signaling pathways, thereby suppressing antitumor immune responses (Chen et al. 2022; Yin et al. 2021). Similarly, in a cohort of 104 treatment-naïve DLBCL patients (Shin et al. 2024), Shin et al. reported that elevated PELI1 expression in CD20⁺ tumor cells was associated with poor prognosis, potentially through NF-κB pathway-driven tumor proliferation and the induction of cytotoxic T-cell exhaustion. These findings align with those of Lee et al. (2022), who reported that PELI1 promoted lymphomagenesis in DLBCL by stabilizing the BCL6 protein via K63-linked ubiquitination, ultimately contributing to poor clinical outcomes.

Fig. 2.

Pellino family proteins serve as ubiquitination signaling hubs. Pellino1/2 integrates three major pathways—TLR → MyD88, TNFR1 → TRADD, and NOD2 → RIP2. By catalyzing K63-linked Ub, Pellino amplifies the assembly of downstream complexes (TRAF6–IRAK1, TRAF2–RIP1, TRAF3–NIK), thereby driving dual activation axes: TAK1–IKKα/β and NIK–IKKα. This cascade ultimately induces the nuclear translocation of NF-κB and IRF3 to promote IFN/inflammatory gene expression, while Pellino activity is bidirectionally modulated by deubiquitinases (A20, CYLD, SPATA2) and E3 ligases (XIAP, c-IAP1/2)

Notably, elevated expression of Pellino-1 is associated with tumor cell resistance to conventional cancer therapies. In p53-mutant models, Pellino protein deficiency increases tumor cell sensitivity to chemotherapy (Li et al. 2023), thus providing a mechanistic explanation for the frequent refractory nature of p53-mutated hematologic malignancies. Modarres et al. (2021) reported that PELI2 was significantly upregulated in the chemoresistant group of AML patients, which is likely attributed to the promotion of AML cell survival and immune escape by IL-1β/IL-18. Furthermore, Pellino-1 regulates the threshold of inflammatory responses and promotes the secretion of leukemia-associated inflammatory factors, thereby remodeling the bone marrow microenvironment and fostering conditions conducive to the survival and proliferation of hematopoietic tumor cells (Hwang et al. 2025; Camacho et al. 2021).

Tumor suppression effect: activation of antitumor immunity

While the Pellino family exhibits tumor-promoting properties, recent studies have revealed its critical role in promoting antitumor immune activation. The expression level of Pellino-1 in CD8⁺ T cells is significantly correlated with the risk of tumorigenesis, highlighting its importance in the acquisition and maintenance of CD8⁺ T-cell effector functions (Guan et al. 2022). Experimental evidence has demonstrated that Pellino-1-deficient mice exhibit impaired antitumor immune responses, confirming its costimulatory role in T-cell receptor signaling (Guan et al. 2022; Chen et al. 2022). This viewpoint is supported by the study of Yuan et al. (Yuan et al. 2018), who reported that inhibition of miR-21-5p led to significant upregulation of PELI1 protein expression in cHL cell lines. These findings suggest that low PELI1 protein expression may contribute to resistance to apoptosis in Hodgkin lymphoma through the inhibition of NF-κB/BCL6.

In the context of natural killer (NK) cell-mediated antitumor immunity, the Pellino protein family enhances NK cell cytotoxicity against hematological tumor cells via the noncanonical NF-κB activation pathway (Poznanski et al. 2021). Additionally, PELI2, a recently identified E3 ubiquitin ligase, plays a pivotal regulatory role in lymphoid progenitor cell differentiation and may influence antitumor immune responses by modulating immune cell development (Hodges et al. 2024). In a relapsed and refractory multiple myeloma (MM) patient, Masuda et al. (Masuda et al. 2022) reported that MM cell lines (KMS-34) overexpressing PELI2 exhibited significantly increased sensitivity to proteasome inhibitors (PIs). Furthermore, among 188 MM patients treated with bortezomib monotherapy, those with high PELI2 expression demonstrated significantly better overall survival than did those with low PELI2 expression. These findings suggest that Pellino family members perform pleiotropic functions across various immune cell subsets, participating in the dynamic regulation of both pro- and antitumor processes.

Progress in clinical translational research

The differential expression patterns of Pellino family proteins in hematological malignancies suggest their potential utility as diagnostic biomarkers (Table 3). Studies have demonstrated that PELI1 is overexpressed in multiple hematological cancers, and its expression levels are closely associated with disease subtypes and clinical stages (Regen-Tuero et al. 2021). Analysis of the TCGA database revealed that Pellino gene expression profiles are significantly correlated with patient prognosis and clinical stage, providing a theoretical foundation for the development of a molecular classification system based on Pellino proteins (Guan et al. 2022). Notably, Pellino protein expression also reflects the status of the tumor immune microenvironment, showing a positive correlation with the infiltration levels of MDSCs (Schenker and Ortiz-Hernández 2025). These findings indicate that the Pellino protein family may serve as a novel set of biomarkers for the precise diagnosis of hematological malignancies.

Table 3.

Clinical translational value and application direction of Pellino protein family

Direction of clinical application	Core Evidence	Specific application scenarios	Future development Directions	Refs.
Biomarkers (diagnostic/subtyping)	Pellino1 is highly expressed in hematological tumors, and is related to disease subtypes and clinical stages Expression profile is positively correlated with the degree of MDSCs infiltration	Accurate classification of hematological tumors (such as differentiation of BCP-ALL subtypes); Auxiliary diagnosis of malignant degree	Pellino-based molecular typing diagnostic system was developed Combining imaging or other markers to improve diagnostic accuracy	Guan et al. (2022), Regen-Tuero et al. (2021) Schenker and Ortiz-Hernández (2025)
Prognosis evaluation and efficacy monitoring	High expression of Pellino1 is associated with poor prognosis Expression changes reflect remodeling of immune microenvironment (e.g., reduction of MDSCs/TAMs)	Predicting the survival risk of patients; Monitoring the efficacy of immunotherapy such as CAR-T	A dynamic monitoring kit for Pellino expression was developed Optimization of prognostic model based on multi-omics data	Yu et al. (2022), Regen-Tuero et al. (2021), Chen et al. (2025), Ma et al. (2023)
Development of targeted therapy strategies	Its E3 ubiquitin ligase activity is the target for intervention Can regulate the efficacy of CAR-T cells	Small molecule inhibitors block the tumor-promoting effect; Regulation of its expression enhances CD8⁺T cell function	Development of selectively targeted drugs (differentiating between pro-tumor and anti-tumor functions); Optimizing CAR-T Therapy with Gene Editing	Park et al. (2022), Camacho et al. (2021), Webb et al. (2025) Bahrami et al. (2023)

Targeted therapeutic strategies against Pellino proteins are currently in preclinical development. Given its oncogenic role in tumorigenesis and metastasis, Pellino-1 represents a promising therapeutic target because of its E3 ubiquitin ligase activity (Regen-Tuero et al. 2021). Research has shown that small molecule inhibitors capable of blocking Pellino’s ubiquitin ligase activity can effectively suppress the aberrant activation of the TLR and IL-1R signaling pathways, thereby alleviating the immunosuppressive state within the tumor microenvironment (Camacho et al. 2021). In the field of CAR-T-cell therapy, the modulation of Pellino protein expression has been shown to enhance CD8⁺ T-cell effector function and improve antitumor immune responses (Park et al. 2022). Moreover, the combination of Pellino-targeted therapy with other immune checkpoint inhibitors, such as anti-CD70 antibodies, is under investigation, offering new strategies to overcome therapeutic resistance in hematological malignancies (Webb et al. 2025).

The Pellino protein family has significant potential for dynamic monitoring in the prognostic evaluation of hematological tumors. Clinical data indicate that high Pellino-1 expression is strongly associated with poor clinical outcomes and can serve as an independent prognostic indicator (Regen-Tuero et al. 2021). In terms of therapeutic response monitoring, fluctuations in Pellino protein expression can sensitively reflect immune remodeling within the tumor microenvironment. For example, the downregulation of Pellino is often accompanied by a reduction in immunosuppressive cell populations, such as tumor-associated macrophages (TAMs) and MDSCs (Yu et al. 2022; Li et al. 2024b). Continuous monitoring of Pellino expression levels enables the assessment of immunotherapy efficacy, such as in CAR-T-cell therapy, and supports timely adjustments to treatment strategies (Chen et al. 2025). Through the construction of an AML predictive model, Zhang et al. (Zhang et al. 2024b) identified PELI1 as a key oncogenic driver in AML and screened candidate drugs targeting PELI1, providing a theoretical rationale for combination immunotherapy and targeted therapy. Importantly, Pellino expression profiles can also predict patient responsiveness to specific therapeutic regimens, including BET inhibitors, thereby offering valuable guidance for personalized treatment decisions (Ma et al. 2023).

Current challenges and future directions

Mechanistic elucidation of tissue-specific regulation

The expression patterns and functional heterogeneity of Pellino protein family members in different hematopoietic tissues are still unclear. Studies have shown that PELI2 regulates TCF3 protein stability through K63 polyubiquitination, thereby affecting IL-7R expression, which has a specific effect on B-cell precursor acute lymphoblastic leukemia (BCP-ALL) (Zhou et al. 2022). However, there is still a lack of systematic studies on the tissue-specific regulatory mechanism of the Pellino family in myeloid and lymphoid development. The latest single-cell sequencing technology provides a new tool for analyzing the differential expression of Pellino proteins in different cell subsets in the hematopoietic microenvironment (Liu et al. 2024).

Dual-acting dynamic balance control

Pellino1 plays a paradoxical dual role in tumor immunity: it can promote macrophage migration through STAT3 ubiquitination, leading to colitis-related cancer (Hwang et al. 2025), and it can enhance the antitumor effect of CD8⁺ T cells (Zhong et al. 2025). This duality may result from its differential regulation of different signaling pathways, such as TLR signaling activation and IL-1R-mediated threshold control of inflammation (Zhang and Li 2022). Establishing a quantitative model to predict the effect of the Pellino activity threshold on immune balance will be the key to achieving precise regulation (Krenn and Aberger 2023). Previous studies have shown that the carcinogenic effect of PELI1 is closely related to its abnormally high expression in the TME.

Application prospects of gene editing technology

CRISPR-Cas9 technology has been successfully used to construct a Pellino1 conditional knockout mouse model, confirming its key role in monocyte-specific functions (Hwang et al. 2025). In the field of hematological tumors, Pellino mutants constructed on the basis of gene editing can be used to analyze E3 ligase activity and substrate recognition characteristics accurately (Yan et al. 2023). Recent studies have also developed a conditional knockout model targeting PELI2, which provides a new tool for studying its role in lymphoid progenitor cell differentiation (Xu et al. 2024). These techniques lay the foundation for the development of gene therapy strategies based on Pellino protein conformational modulation (Bahrami et al. 2023).

Value of organoid models in mechanistic studies

The blood tumor organoid model can simulate the microenvironment interaction mediated by the Pellino protein, especially the reappearance of the bone marrow microenvironment-induced chemoprotection (BMC) phenomenon (Quagliano et al. 2023). Recent studies have successfully captured the dormancy characteristics of leukemia stem cells regulated by Pellino via a patient-derived xenograft (PDX) model (Bahrami et al. 2023). Organoid systems can also be used to test dual regulatory strategies targeting Pellino, such as simultaneously blocking its tumor-promoting effect and preserving antitumor immune activation function (Flieswasser et al. 2022). This model has unique advantages for studying Pellino-mediated regulation of immune checkpoints such as SIRPα/TIPE2 (Sun et al. 2024).

Conclusion and prospects

The highly evolutionarily conserved Pellino family of E3 ubiquitin ligases exhibits unique dual mechanisms in regulating the tumor immune microenvironment of hematologic malignancies. However, owing to current limitations in related research and incomplete coverage across various hematologic malignancies, Pellino proteins remain promising therapeutic targets with substantial unexplored potential. Nevertheless, from a clinical translation perspective, the established correlations between the expression levels of these family members and patient prognosis, immune infiltration characteristics, and drug sensitivity provide a robust theoretical basis for developing novel diagnostic biomarkers. The development of selective targeted intervention strategies based on the dual regulatory characteristics of the Pellino protein family will be an important direction for the immunotherapy of hematological tumors in the future. In the remodeling of the tumor microenvironment, the Pellino protein affects the formation of an immunosuppressive microenvironment by regulating the functional status of MDSCs and TAMs. These findings provide new ideas for overcoming the obstacles of the immune microenvironment faced by CAR-T-cell therapy in solid tumors (Zhang et al. 2022). On the basis of recent advances in gene editing technology and organoid models, future studies can further explore the tissue-specific regulatory mechanism of Pellino family members and the dynamic balance control strategy in different hematological tumor subtypes. In addition, the combination of Pellino-targeted therapy with existing treatment methods such as traditional chemotherapy and immune checkpoint inhibitors is expected to lead to the development of a more precise combined treatment regimen and provide personalized treatment options for patients with hematological tumors (Guo et al. 2024).

Abbreviations

MDSCs

Myeloid-derived suppressor cells

NF-κB

Nuclear factor kappa-B

PRR

Pattern recognition receptor

TLR

Toll-like receptor

NLR

NOD-like receptor

TNFR

Tumor necrosis factor receptor

STAT3

Signal transducer and activator of transcription

MAPK

Mitogen-activated protein kinase

TCR

T-cell receptor

DLBCL

Diffuse large B-cell lymphoma

AML

Acute Myelocytic Leukemia

MM

Multiple myeloma

TAMs

Tumor-associated macrophages

Author contributions

YMF was the major contributors in writing the manuscript, making the figures, and making the tables. LY was the main reviser of the manuscript. WJH made substantial contributions to the design of the work. All authors read and approved the final manuscript.

Funding

None.

Data availability

No datasets were generated or analysed during the current study.

Declarations

Competing interests

The authors declare no competing interests.

Ethics approval and consent to participate

Not applicable.

Consent for publication

Not applicable.