GRHL3 promotes tumor growth and metastasis via the TGF-β signaling pathway in human epithelial ovarian cancer

Grainyhead-like 3 (GRHL3) has been implicated in the biology of several epithelial malignancies, yet its function in epithelial ovarian cancer (EOC) remains insufficiently defined. Given the high mortality associated with advanced-stage diagnosis and treatment resistance, delineating molecular drivers of EOC progression is essential for identifying clinically meaningful biomarkers and therapeutic targets. GRHL3 expression in epithelial ovarian cancer (EOC) was examined using immunohistochemistry in 63 tumor samples and 6 normal ovarian tissues, complemented by analyses of public datasets (GEPIA, TCGA) for external validation and prognostic assessment through Kaplan–Meier survival curves. Functional characterization of GRHL3 was performed in A2780, SKOV3, and HEY cell lines using siRNA-mediated knockdown, followed by evaluations of proliferative, migratory, and invasive capacity through CCK-8, colony formation, wound-healing, and Transwell assays. Transcriptome sequencing of GRHL3-silenced HEY cells enabled identification of differentially expressed genes and pathway alterations based on GO and KEGG enrichment analyses. Changes in TGF-β/Smad3 signaling were examined by Western blotting, focusing on both total and phosphorylated protein levels. GRHL3 expression was markedly elevated in EOC tissues compared with normal ovarian controls ( P < 0.001) and was associated with advanced TNM stage, higher tumor grade, metastasis ( P < 0.05), and reduced overall and progression-free survival ( P < 0.01). Silencing GRHL3 significantly suppressed proliferation, colony formation, migration, and invasion across multiple EOC cell models (all P < 0.05). Transcriptomic profiling indicated substantial gene expression changes following GRHL3 knockdown, with enrichment analyses highlighting the TGF-β signaling pathway. Although total TGF-β and Smad3 levels were unchanged, phosphorylation of both proteins was significantly reduced ( P < 0.01), indicating attenuation of TGF-β/Smad3 pathway activation. GRHL3 is overexpressed in EOC and associates with aggressive disease features and poor patient outcomes. Functional and transcriptomic analyses support a tumor-promoting role for GRHL3, likely mediated through enhanced activation of the TGF-β/Smad3 pathway. These findings highlight GRHL3 as a promising biomarker and potential therapeutic target in epithelial ovarian cancer.