Overexpression of TEM8 promotes ovarian cancer progression via Rac1/Cdc42/JNK and MEK/ERK/STAT3 signaling pathways.

Tumor endothelial cell marker 8 (TEM8) is a type I transmembrane protein, that has been widely studied in the areas of anthrax toxin infection and tumor angiogenesis. However, the role of TEM8 in the progression of epithelial ovarian cancer (EOC) remains unclear. In this study, we determined that TEM8 was highly expressed in ovarian cancer and associated with poor prognosis in EOC patients. In vitro experiments showed that TEM8 overexpression significantly promoted ovarian cancer proliferation. TEM8 overexpression also promoted the G0/G1 phase transition, migration, and invasion of ovarian cancer cells but suppressed apoptosis. Moreover, experimental verification confirmed that TEM8 overexpression increased the expression of Ki-67, cyclin D1, Bcl2/Bax, MMP2, MMP9, and VEGFA and the phosphorylation of Rac1/Cdc42, JNK, MEK, ERK, and STAT3 (Ser727). Subsequently, the addition of RAC1 (EHop-016) and MEK (PD98059) pathway inhibitors suppressed malignant behaviors in the TEM8 overexpression group, which robustly indicated that TEM8 activated Rac1/Cdc42/JNK and MEK/ERK/STAT3 signaling pathways. In addition, we also revealed that the transcription factor GATA2 bound to the TATTAGTTATCTTT site of the TEM8 promoter region and regulated its expression. In conclusion, our study may provide a new theoretical basis for TEM8 application as a clinical biomarker and potential target in EOC patients.