Regulation of the tumor suppressor gene PAEP in the transition from serous borderline ovarian tumors to low-grade serous ovarian carcinomas.

5074 Background: Serous borderline ovarian tumors (SBOT) and low grade serous ovarian carcinomas (LG) form a molecular continuum, and SBOT may recur as LG. BRAF mutations are common in SBOT, but are rare in LG carcinomas. In an expression analysis comparing SBOT with and without BRAF mutations, BRAF mutation was correlated with upregulation of tumor suppressor genes, one of which was progestagen-associated endometrial protein (PAEP). Therefore, we sought to validate the overexpression of PAEP in SBOT as a possible mechanism of oncogene-induced senescence. Methods: Gene expression profiling of borderline tumors with BRAF and wild-type (wt) mutations was performed. Overexpression of PAEP in SBOT with BRAF mutations was validated by quantitative real-time polymerase chain reaction (qRT-PCR). Protein expression of PAEP was evaluated by immunohistochemistry (IHC) on SBOT and LG paraffin sections with and without known BRAF and KRAS mutations. Two LG cell lines (HOC-7, MPSC-1) were transduced with lentiviral PA...