Reduced type 2 epithelial-mesenchymal transition serves as a risk factor for the progression from endometriosis to endometriosis-associated ovarian cancer.

Endometriosis-associated ovarian cancer (EAOC) is a rare subtype of ovarian cancer arising from the malignant transformation of endometriosis (EMS). Despite growing clinical awareness, its underlying pathogenic mechanisms are not fully understood. Epithelial-mesenchymal transition (EMT) plays a crucial role in the progression of various diseases, but the specific EMT changes in EAOC formation remain unclear. We retrieved transcriptomic data for EAOC and single-cell data for EMS from public databases and systematically analyzed EMT levels, EMT subtypes, and factors inducing EMT in both EMS and EAOC. Immunohistochemistry and Masson staining further validated the EMT and fibrosis levels in both EMS and EAOC. The study found that the overall EMT levels in EAOC were significantly lower than in EMS, primarily due to the reduction in type 2 EMT levels associated with fibrosis. Furthermore, this study indicated that the abundant C7 fibroblasts in EMS lesions might contribute to epithelial cell proliferation and EMT. However, the abundance of C7 fibroblasts was significantly reduced in EAOC, suggesting its potential regulatory role in EMT. We found that, during the progression from EMS to EAOC, the level of type 2 EMT decreased, and we also discovered that C7 fibroblasts could act as potential regulators of EMT. These findings expand our understanding of the malignant transformation of EAOC and provide new insights for the development of new diagnostic and therapeutic strategies.