HE4 Might Participate in Extracellular Matrix Remodeling in Ovarian Cancer via Activation of Fibroblasts.

Objectives: High-grade serous ovarian cancer (HGSOC), the most common subtype of epithelial ovarian cancer (EOC), exhibits a mesenchymal phenotype characterized by fibrotic stroma and poor prognosis. Human epididymis protein 4 (HE4), a key diagnostic biomarker for ovarian cancer, is involved in fibrotic processes in several non-malignant diseases. Given the clinical significance of stromal fibrosis in HGSOC and the potential link between HE4 and fibrosis, this study aimed to investigate the role of HE4 in the formation of stromal fibrosis in HGSOC. Methods: A total of 126 patients with gynecological conditions were included and divided into normal, benign, and EOC groups. Tissue stiffness was quantitatively measured and analyzed for its correlation with clinicopathological features. We further investigated the correlation between tumor stiffness and the expression levels of HE4 and fibroblast activation markers (α-smooth muscle actin (α-SMA) and fibroblast activation protein (FAP)) in tumor tissues from 22 HGSOC patients. In vitro, primary fibroblasts were treated with recombinant HE4 (rHE4) or conditioned media from HE4-knockdown ovarian cancer cells to assess fibroblasts activation and matrix contractility (Collagen gel contraction assays). In vivo, a subcutaneous xenograft model using HE4-knockdown cells was established to evaluate the effects of HE4 suppression on tumor growth and extensive extracellular matrix (ECM) remodeling. Results: Ovarian cancer tissues showed significantly increased stiffness compared to benign/normal groups, showing positive correlation with serum HE4 levels. High-stiffness HGSOC tumors exhibited upregulated expression of HE4, α-SMA, FAP, and collagen I. rHE4 stimulated fibroblast activation and enhanced matrix contractility, whereas HE4 knockdown in cancer cells abrogated these pro-fibrotic effects. In vivo, HE4-silenced xenografts displayed restricted tumor growth accompanied by reduced stromal expression of α-SMA, FAP, and collagen I. Conclusion: Our findings suggest that HE4 may facilitate ECM remodeling in HGSOC through promoting fibroblast activation and increasing collagen deposition.