The global burden of malignant neoplasms manifests as a substantial public health challenge, characterized by escalating incidence rates, significant mortality, disability-adjusted life years and profound socioeconomic costs across healthcare systems worldwide (1, 2). Cancer treatment has advanced significantly over the past century, shifting from early methods like surgery and radiation to chemotherapy, targeted therapies, and immunotherapies (3–5). This evolution reflects a move from non-specific cytotoxic approaches to precision strategies guided by molecular and immune profiling. Currently, two major treatment paradigms are widely applied. One targets cancer cells directly through cytotoxic or molecular agents, offering rapid tumor shrinkage but often limited by drug resistance and adverse effects (6, 7). The other modulates the tumor microenvironment to restore immune surveillance and block tumor-promoting pathways, potentially offering more sustained benefits but requiring individualized adaptation (8). New therapeutic strategies are emerging that aim to combine these approaches. Innovations such as bispecific antibodies, oncolytic viruses, and personalized vaccines integrate direct tumor targeting with immune activation, offering promising directions for future cancer care (9–11).

Immunoglobulin superfamily member 8 (IGSF8), also known as CD316 or EWI-2, is a type I transmembrane protein that belongs to the immunoglobulin superfamily (12). It was initially characterized as a binding partner of tetraspanins CD9 and CD81, modulating the organization and vesicular trafficking of tetraspanin-enriched membrane domains (TEMDs) (13, 14). Through these interactions, IGSF8 influences the activity of growth factor receptors, cell adhesion proteins, and their downstream signaling cascades (15, 16). Beyond membrane organization, IGSF8 is also involved in neuronal migration, axon guidance, and synapse formation (17), suggesting its broad regulatory roles across multiple biological systems. Recent studies have linked IGSF8 dysregulation to the pathogenesis of various diseases, including neurological disorders and cancers (18). Intriguingly, IGSF8 exhibits dual roles in tumor biology, acting either as a tumor suppressor or a tumor promoter depending on the cellular context. In certain solid tumors such as melanoma, lung, prostate cancer, and glioma, IGSF8 was shown to suppress tumor progression by modulating pathways like TGF-β and EGFR-MAPK, thereby inhibiting proliferation and metastasis (19–22). In contrast, in hematological malignancies such as acute myeloid leukemia, IGSF8 sustains leukemic stemness by stabilizing β-catenin, preventing its degradation and enhancing Wnt pathway activation, which in turn promotes therapy resistance and disease progression (12). These contrasting roles suggest that IGSF8 exerts context-specific effects through distinct signaling mechanisms. Moreover, IGSF8 has emerged as an innate immune checkpoint molecule in the tumor microenvironment (TME). It suppresses NK cell-mediated cytotoxicity by interacting with immune inhibitory receptors, contributing to immune evasion particularly in “cold” tumors that are poorly infiltrated by cytotoxic immune cells (23). Blocking this interaction enhances NK cell killing capacity and promotes immune activation, offering a promising therapeutic avenue to convert immunologically “cold” tumors into “hot” ones responsive to immunotherapy. Therefore, the impact of IGSF8 on prognosis may not only reflect its intrinsic roles in tumor signaling and stemness, but also its influence on shaping immune landscapes across different cancer types.

Despite these emerging insights, a comprehensive pan-cancer evaluation of IGSF8 remains lacking. Identification of tumor biomarkers serves as the cornerstone of precision oncology, enabling the implementation of tailored therapeutic strategies that significantly enhance treatment efficacy and improve survival outcomes (24–26). To fill this knowledge gap, we conducted a systematic investigation using The Cancer Genome Atlas (TCGA) data to examine the expression, prognostic relevance, immune associations, and therapeutic implications of IGSF8 across a wide range of human cancers. Our findings reveal the multifaceted roles of IGSF8 and support its potential as a prognostic biomarker and therapeutic target in precision oncology.

IGSF8, also known as EWI-2 or CD316, is a transmembrane protein that belongs to the immunoglobulin superfamily (IgSF). It has been widely studied in various physiological contexts for its role in cell adhesion, migration, and signal transduction through interactions with tetraspanins like CD9 and CD81 (13). In non-oncological research, IGSF8 is crucial in neural development, particularly in organizing synaptic connections within the hippocampal CA3 microcircuit, which is vital for cognitive processes and neural plasticity (38). IGSF8 also plays a significant role in immune regulation, where it modulates immune responses. Although it has been suggested to be dispensable for fertility in mouse models, this might indicate a tissue-specific or condition-specific role (39). Additionally, IGSF8’s involvement in olfactory sensory neuron development further highlights its diverse functional roles across different biological systems (16).

In the context of oncology, IGSF8 has gained attention due to its oncogenic potential across various cancer types. It has been identified as a key regulator in maintaining the stemness of myeloid leukemia cells by inhibiting the degradation of β-catenin, thus promoting leukemogenesis and therapy resistance (12). In gliomas, IGSF8 has been recognized as a potential therapeutic target due to its role in enhancing tumor cell invasiveness and resistance to conventional treatments, making it a critical factor in glioma progression (18). Furthermore, studies have shown that IGSF8 may contribute to the progression of melanoma by negatively regulating TGF-β signaling, further demonstrating its involvement in tumor growth and metastasis (40). The current study builds upon these findings by conducting a pan-cancer analysis of IGSF8, revealing its broader oncogenic role across multiple cancer types. Unlike previous research, which has primarily focused on specific cancers, our study provides a comprehensive overview of IGSF8’s dual role in promoting tumor growth and modulating immune responses, suggesting its potential as a universal therapeutic target in cancer (23). This expanded understanding of IGSF8’s function underscores the necessity for further exploration of its role as a critical mediator in tumor biology and immune evasion. Although research in the field of cancer is limited, some studies have indicated that IGSF8 expression may serve as a biomarker for ovarian cancer (41). Additionally, in vitro experiments have demonstrated that IGSF8 expression is associated with the growth of androgen-deficient prostate cancer cells (42). Our study revealed that IGSF8 exhibited differential expression in various tumors, including UCEC, BRCA, LUAD, PRAD, and STAD, suggesting its relevance to solid tumors. Furthermore, we observed a correlation between IGSF8 expression and advanced age across multiple tumor types. Aging is a dynamic process, and the accompanying epigenetic changes contribute to tumor occurrence and development (43–46). The association between IGSF8 expression in tumors and advanced age underscores the importance of investigating the genetic interplay between aging and tumorigenesis.

This study investigated the correlation between IGSF8 expression levels and immune regulatory genes, immune checkpoints, and tumor-infiltrating cells. Our results consistently demonstrate a strong and recurrent positive correlation between IGSF8 and CD276 (also known as B7-H3) across multiple solid tumors. CD276 is a transmembrane immune checkpoint molecule expressed on various tumor and stromal cells, exerting context-dependent co-stimulatory or co-inhibitory effects (47, 48). It is well recognized for its role in facilitating tumor immune evasion by suppressing T cell activation and reducing cytokine secretion (49, 50), and its high expression is associated with poor prognosis in numerous cancer types (51). Currently, CD276-targeted monoclonal antibodies and antibody-drug conjugates are undergoing clinical trials as promising cancer immunotherapies (52). Beyond co-expression, our findings raise the possibility of functional synergy between IGSF8 and CD276. IGSF8 is known to cluster in TEMDs by interacting with CD9 and CD81, which are involved in the trafficking and membrane stability of transmembrane proteins. It is plausible that IGSF8 may stabilize or facilitate the surface retention of CD276 within these microdomains, thereby amplifying its immunosuppressive effects in the TME. The co-localization and cooperative immunomodulatory functions of these two molecules may constitute a dual mechanism driving immune escape, especially in immunologically “cold” tumors. From a therapeutic standpoint, co-targeting IGSF8 and CD276 may provide synergistic benefits by simultaneously enhancing T and NK cell activity and reversing tumor immune evasion. Future functional studies are warranted to investigate whether IGSF8 directly regulates CD276 expression, localization, or recycling, and to assess the immune and clinical consequences of their co-inhibition.

The TME plays a central role in regulating cancer progression, therapeutic response, and immune evasion (53, 54). It consists of a dynamic interplay between malignant cells, immune infiltrates, stromal elements and extracellular matrix components, which collectively determine the balance between tumor-promoting and tumor-suppressive forces (55, 56). In this context, IGSF8 has emerged as a key modulator of immune cell behavior. Li et al. (23) demonstrated that IGSF8 acts as an innate immune checkpoint by interacting with NK cell inhibitory receptors, thereby suppressing NK-mediated cytotoxicity. Their study further showed that blockade of IGSF8 restores NK function and enhances antigen presentation and T cell activation in vivo, underscoring its mechanistic role in immune escape. While Li et al. (23) uncovered a direct molecular mechanism in selected tumor models, our pan-cancer analysis expands this paradigm by demonstrating that IGSF8 expression is broadly correlated with alterations in immune cell infiltration across multiple solid tumor types. In addition, IGSF8 expression was associated with shifts in stromal components such as cancer-associated fibroblasts and macrophages, further indicating its influence on both structural and immunological features of the TME. These findings position IGSF8 not only as a molecular immune checkpoint but also as a regulatory hub in tumor ecosystems, supporting its therapeutic relevance in diverse oncologic contexts.

The analysis of the mutation landscape across different cancer types, based on IGSF8 expression levels, shows distinct patterns of gene mutations. This suggests that IGSF8 may be involved in regulating specific oncogenic pathways in different cancers. In COAD, mutations in APC and PIK3CA are well-known drivers of tumorigenesis. APC is central to the Wnt signaling pathway, and its mutation leads to uncontrolled cell proliferation, while PIK3CA mutations activate the PI3K-Akt pathway, which promotes tumor cell survival and growth (57). The correlation between IGSF8 expression and these mutations suggests that IGSF8 may modulate these critical pathways, potentially affecting tumor proliferation or response to targeted therapies. In LGG, TP53 and ATRX mutations are frequent in gliomas. TP53 is a tumor suppressor that controls the cell cycle and apoptosis, and its mutation disrupts genomic stability (58). ATRX mutations impact chromatin remodeling and telomere maintenance (59). IGSF8’s association with these mutations hints at a role in DNA repair mechanisms or in controlling glioma cell differentiation and survival, particularly in the context of these chromatin and genome stability regulators. Notably, in LIHC, mutations in CTNNB1, which encodes β-catenin, drive aberrant activation of the Wnt/β-catenin signaling pathway, contributing to liver cancer progression (60). The connection between IGSF8 and CTNNB1 mutations in liver cancer suggests that IGSF8 could influence the regulation of Wnt signaling, possibly affecting tumor cell growth or differentiation. Overall, the mutation landscape analysis suggests that IGSF8 might act as a modulator of oncogenic pathways, influencing tumor progression and potentially serving as a biomarker for identifying mutation-driven therapeutic targets.

Importantly, although our study identifies BX-795 and tozasertib as candidate compounds for tumors with high IGSF8 expression, neither drug has yet been approved for clinical use in oncology (61, 62). To validate their therapeutic relevance, future studies should evaluate their efficacy across cancer cell line panels, organoid model and patient-derived xenograft (PDX) models (63). BX-795, a TBK1 and IKKϵ inhibitor (64), may be tested alone or in combination with immunomodulatory genes to determine whether it can enhance immune cell activity and suppress immune evasion in tumors characterized by IGSF8 and CD276 co-expression. These approaches may uncover synergistic anti-tumor effects that support clinical translation. PDX models preserve patient-specific tumor architecture, histological features, and microenvironmental interactions more effectively than conventional xenografts. Therefore, they represent a more reliable system for preclinical drug evaluation. Several recent studies have highlighted the power of PDX models in translational oncology research. For example, they have been used to investigate the effects of anesthetic techniques on breast cancer metastasis, to dissect how metabolic pathways contribute to colorectal cancer development, and to validate the in vivo functions of tumor-suppressive microRNAs in lung cancer (65–67). Incorporating PDX models, potentially augmented by humanized immune systems, would enhance the biological and translational relevance of future IGSF8-targeted drug studies. Such approaches may accelerate the development of precision therapies for immunologically cold tumors where IGSF8 acts as a central immune regulatory hub.

While this work offers a broad investigation into the biological and clinical relevance of IGSF8, several limitations should be acknowledged. First, although preliminary in vitro experiments confirmed the biological effects of IGSF8, further in vivo validation is essential to clarify its mechanistic role in tumor progression and therapeutic modulation. Second, the analyses rely on publicly available datasets such as TCGA, which are susceptible to cohort selection bias, batch effects, and incomplete clinical annotation (68). These factors may affect the accuracy and generalizability of the conclusions, particularly in the context of patient heterogeneity. In addition, the immune microenvironment analysis employed the EPIC deconvolution algorithm, which is not considered a gold standard. Bulk transcriptomic approaches may misestimate immune cell proportions and fail to detect rare or spatially distinct populations (69). To improve resolution and accuracy, future studies should incorporate multiplex immunohistochemistry (mIHC) for spatial mapping of immune and stromal components, and single-cell RNA sequencing (scRNA-seq) to characterize cell-specific expression and validate deconvolution results (70–72). These complementary methods would provide more refined insight into the immunological role of IGSF8. Despite these limitations, the present findings offer a solid framework for further exploration. Incorporating multi-modal and high-resolution technologies in subsequent research will help to strengthen mechanistic understanding and accelerate translational development of IGSF8 as a potential therapeutic target.

In summary, this study provides a comprehensive characterization of IGSF8 across multiple cancer types, integrating transcriptomic data analysis with preliminary in vitro validation. We demonstrate that IGSF8 expression is associated with unfavorable prognosis, enhanced tumor cell proliferation, and suppression of immune infiltration in several malignancies. Importantly, these findings highlight IGSF8’s dual role as both an oncogenic driver and an immune regulator, positioning it as a central modulator of tumor progression and immune evasion. This dual functionality underscores the potential of IGSF8 as a candidate for prognostic stratification and targeted therapy development. Future research should prioritize mechanistic studies and translational efforts to explore IGSF8-directed interventions in immunologically cold tumors.