Diabetes Mellitus Enhances Immune Suppression in Ovarian Cancer via CD155 Upregulation Mediated by the HSP70/P65 Axis

Diabetes mellitus (DM) is increasingly recognized for its role in modifying the tumor microenvironment, but its influence on immune checkpoints in cancer remains underexplored. This study investigates how diabetes-associated conditions influence CD155 expression and immune evasion in ovarian cancer using murine preclinical models. Utilizing the murine ID8 ovarian cancer cell line and NOD mice, a widely used model of non-obese diabetes, we assessed the impact of diabetes-associated conditions on CD155 expression and immune cell infiltration. Our methodologies included overexpression and knockdown studies, Western blotting, PCR, flow cytometry, and tumor growth assays in murine models. We found that diabetes-associated conditions enhanced HSP70 levels in ovarian cancer cells, facilitating P65 activation and subsequent upregulation of CD155. Elevated CD155 expression correlated with reduced efficacy of immune checkpoint blockade, decreased CD8 T-cell infiltration, and impaired T-cell activation and proliferation in the tumor microenvironment. Notably, diabetes-associated conditions did not affect cancer cell stemness markers (CD44, CD271, GPR49) or regulatory T-cell (Treg) infiltration, indicating that the immune modulation was specifically mediated through the HSP70/P65-CD155 pathway. In vivo, knockdown of HSP70 in diabetic murine tumor models reversed the upregulation of CD155, restoring immune surveillance and reducing tumor growth. These findings identify a diabetes-associated HSP70/P65-CD155 signaling axis that promotes immune evasion in murine models of ovarian cancer. This study provides preclinical, hypothesis-generating evidence for the role of metabolic stress in modulating tumor immune escape mechanisms, without implying direct clinical applicability. This research elucidates how diabetes mellitus exacerbates immune suppression in ovarian cancer by upregulating CD155 through the HSP70/P65 axis, contributing to diminished cytotoxic T-cell activity and increased resistance to immune checkpoint blockade (ICB) therapies. These findings emphasize the critical interplay between metabolic disorders and tumor immunology, suggesting potential therapeutic targets to enhance the efficacy of immunotherapy in diabetic cancer patients.