Impact of Mutated p53 on Type I Interferon Pathway Expression in Endometrial Cancer: Immune Modulatory Insights

Introduction

Endometrial cancer (EC), representing a significant gynecologic malignancy, continues to pose clinical challenges related to prognosis and therapeutic responsiveness. The tumor suppressor protein p53, encoded by the TP53 gene, is a crucial regulator of cellular stress responses including DNA repair, cell cycle arrest, and apoptosis. TP53 mutations—in particular, missense and truncating variants—are frequent in EC and correlate with distinct immunohistochemical (IHC) phenotypes and prognostic outcomes. Emerging evidence implicates p53 in modulating innate immune responses, specifically via the type I interferon (IFN-I) signaling pathway, which orchestrates antiviral defense and inflammatory responses. This study investigates the differential expression and signaling of IFN-I pathway components in EC stratified by p53 IHC status to explore immunologic distinctions with biological and clinical implications.

Study Background

Aberrant p53 function in EC is well-recognized as a marker of aggressive disease. Missense TP53 mutations typically manifest as aberrant nuclear p53 accumulation (overexpression) detectable by IHC, while truncating mutations often generate a null p53 phenotype. The IFN-I pathway encompasses interferons (IFN-α/β), pattern recognition receptors (PRRs), adaptor proteins, and downstream effectors that collectively regulate innate immunity and influence tumor microenvironment immune modulation. Alterations in IFN-I signaling may contribute to tumor immune escape, chronic inflammation, or immunosuppression, thereby affecting disease progression and treatment response. Clarifying the interplay between p53 mutation subtype and IFN-I pathway status could uncover novel biomarkers or therapeutic targets.

Study Design and Methods

This study utilized a convenience sampling of 50 EC specimens categorized by p53 IHC phenotype into three groups: p53 wild-type (n=25), p53 missense mutation with overexpression (n=15), and p53 truncating mutation with null phenotype (n=10). Multiplex immunohistochemistry was performed to assess expression of key IFN-I pathway components, including ADAR1, STING, MDA5, RIG-I, PKR, and the double-stranded RNA (dsRNA) marker K1. Quantitative digital image analysis provided objective expression metrics.

Complementary transcriptomic validation was conducted using The Cancer Genome Atlas (TCGA) dataset by applying single sample gene set enrichment analysis (ssGSEA) to evaluate the IFN-I gene expression program in EC samples stratified by TP53 mutation subtype. Pairwise Pearson correlation coefficients analyzed signaling network interactions. Clinicopathological variables and patient outcomes were correlated with protein expression findings using univariate statistical models.

Key Findings

The study revealed significant differences in IFN-I pathway component expression across p53 IHC subgroups. Notably, tumors with p53 missense mutations and overexpression exhibited the highest levels of ADAR1, STING, MDA5, and RIG-I, indicating an active IFN-I signaling state. In contrast, p53 null tumors showed the lowest expression, consistent with a suppressed innate immune environment.

Increased staining for K1, recognizing dsRNA substrates required for pathway activation, was significantly enriched in the p53 overexpressed group, suggesting elevated endogenous ligand availability driving IFN-I activation. Network analysis highlighted DHX9 as a central signaling hub with greater network connectivity in mutated p53 overexpressed tumors compared to wild-type or null groups, implying altered regulatory crosstalk.

Transcriptomic data from TCGA supported these findings; ssGSEA confirmed distinct IFN-I gene expression signatures segregated by missense versus truncating p53 mutations, reinforcing the notion of functionally divergent immune states associated with p53 mutation subtypes in EC.

Clinically, elevated PKR protein expression—a key antiviral kinase within the pathway—correlated with reduced recurrence risk (odds ratio 0.13, 95% CI: 0.03-0.68, p=0.02) in univariate analysis, suggesting a potential protective immunologic mechanism in these tumors.

Expert Commentary and Interpretation

This investigation provides compelling evidence linking p53 mutational status to modulation of the tumor immune milieu via differential IFN-I pathway activity in EC. Overexpressed p53 mutant tumors represent a chronic inflammatory phenotype, potentially reflecting sustained innate immune activation. Conversely, the null phenotype aligns with immunosuppression, which may facilitate tumor evasion.

Such immune divergence offers biological plausibility for varied clinical behaviors and may inform biomarkers for immunotherapy selection or surveillance strategies. The identification of DHX9 as a network hub suggests novel mechanistic insights warranting further functional studies.

Limitations include the modest sample size and retrospective design, which restrict generalizability. Larger prospective cohorts and mechanistic experimentation are necessary to validate these observations and explore therapeutic targeting opportunities.

Conclusion

This study elucidates distinct patterns of type I interferon pathway expression and signaling in endometrial cancer stratified by p53 IHC status. Missense mutations manifest with an inflammatory IFN-I profile, while truncating mutations associate with immunosuppression. Notably, PKR expression correlates with favorable clinical outcomes. These findings advance our understanding of tumor-immune interactions mediated by p53 alterations and open avenues for integrating immune biomarkers into precision management of EC. Future studies should aim to replicate these findings in expanded cohorts and evaluate the therapeutic implications of modulating IFN-I signaling in mutated p53-driven endometrial cancers.

Funding and Clinical Trials

The original study did not specifically disclose funding sources or registered clinical trial numbers within the abstract. Further details may be accessible through the published article or institutional repositories.

References

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