Abstract 5755: In vitro reconstitution of high-grade serous ovarian carcinoma from primary fallopian tube secretory epithelial cells

Purpose: Recent studies suggest that fallopian tube secretory epithelial cells (FTSECs) are potential cells-of-origin for high-grade serous ovarian carcinoma (HGSOC). Several genetic alterations are involved in HGSOC carcinogenesis, but the minimal requirement for tumor initiation remains unclear. Therefore, we sought to identify oncogenic mutations indispensable for HGSOC carcinogenesis in a stepwise model using immortalized FTSECs. Experimental Design: We established an in vitro stepwise carcinogenesis model using immortalized FTSECs overexpressing cyclin D1, CDK4R24C, and hTERT, and mimicked select genetic abnormalities identified as gene alterations essential for carcinogenesis, including p53, c-Myc, or RAS/PI3K pathway mutations. Results: Our analyses revealed two distinct patterns of gene alterations essential for HGSOC carcinogenesis: p53/KRAS/AKT and p53/KRAS/c-Myc. Dominant-negative p53 expression alone or in combination with oncogenic KRAS (KRASV12), constitutively active AKT (CA-AKT), or c-Myc in immortalized cells failed to induce a tumorigenic phenotype; however, overexpression of either CA-AKT or c-Myc in combination with dominant-negative p53 and KRASV12 was sufficient to confer tumorigenic potential. Importantly, all transformed FTSECs formed tumors in xenograft mice, which were grossly, histologically, and immunohistochemically similar to human HGSOC. Interestingly, mice harboring tumors with c-Myc amplifications displayed extensive metastases, consistent with the increased dissemination observed in their human counterparts. C-Myc is associated with cell proliferation in vitro; therefore, this genetic abnormality may promote HGSOC progression. Conclusions: Collectively, our data showed that aberrant p53/KRASV12/c-Myc or p53/KRASV12/PI3K-AKT signaling is the minimal requirement for FTSEC carcinogenesis. Moreover, the model generated with this evidence will likely facilitate analysis of early events in HGSOC carcinogenesis. Citation Format: Kohei Nakamura, Kentaro Nakayama, Tohru Kiyono, Noriyoshi Ishikawa, Toshiko Minamoto, Tomoka Ishibashi, Kaori Sanuki, Hitomi Yamashita, Ruriko Ono, Kouji Iida, Hiroki Sasamori, Razia Sultana, Mohammad Mahmud Hossain, Masako Ishikawa, Satoru Kyo. In vitro reconstitution of high-grade serous ovarian carcinoma from primary fallopian tube secretory epithelial cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5755. doi:10.1158/1538-7445.AM2017-5755