CHI3L1 regulates gene methylation modifications in ovarian cancer cells

Adipocyte-tumor interaction plays a critical role in tumor microenvironment. Typically, high-grade serous ovarian carcinoma (HGSOC) preferentially metastasizes to the omentum, an adipocyte-rich tissue, and obesity correlates with worse patient prognosis. However, the underlying mechanisms remain poorly understood. Here, we identify a bidirectional adipocyte–cancer cell axis in which HGSOC cells stimulate lactate metabolism in adjacent adipocytes, leading to hypoxia-inducible factor 1α (HIF-1α) activation and subsequent secretion of chitinase 3-like 1 (CHI3L1). On the one hand, CHI3L1 acts as an inflammatory factor that promotes the secretion of additional cytokines, perpetuating omental inflammation, driving CD8⁺ T cell exhaustion, and shaping an immunosuppressive microenvironment that favors tumor metastasis. On the other hand, CHI3L1 binds to and stabilizes protein arginine methyltransferase 5 (PRMT5) in tumor cells, thereby enhancing its methyltransferase activity. This upregulation suppresses dual-specificity phosphatase 1 (DUSP1), a phosphatase of mitogen-activated protein kinase (MAPK), and sustains oncogenic MAPK signaling across multiple tumor models. Obesity amplifies this pathway by heightening HIF-1α activity and elevating CHI3L1 levels in adipose tissue, which drives both tumor progression and resistance to anti-angiogenic therapy. Pharmacological inhibition of CHI3L1 disrupts this signaling loop and restores therapeutic sensitivity, while also alleviating immune exhaustion in the tumor microenvironment. Collectively, our findings establish CHI3L1 as a key mediator of a unified mechanism that drives omental tropism and obesity-associated aggressive phenotypes, highlighting its potential as a prognostic biomarker and therapeutic target to improve anti-angiogenic therapy.