Abstract B01: Mutagenic and tumorigenic effects of follicular fluid in the context of p53 loss: Initiation of fimbria carcinogenesis.

Ovulation is the strongest risk factor for ovarian high-grade serous carcinoma (HGSC) that largely originates from the fallopian tube fimbriae and always carries loss-of-function mutations of TP53 in both early and late lesions. Mature ovarian follicle contains high level of reactive oxygen species (ROS). When released from ovulation, follicular fluid (FF) bathes the fimbriae and may lead to DNA double strand break (DSB) and neoplastic transformation. In this study, we examined the mutagenic and tumorigenic activities of human pre-ovulatory FFs. A subset (6/11) of FFs was found with high levels of ROS whereas the antioxidant capacities were indifferent. These ROS-high FFs induced intracellular ROS and DSBs in the secretory cell population of fimbriae epithelium. In the context of p53 and Rb deficiency in an E6/E7 immortalized fimbria secretory cell line, FF-exposed secretory cells overcame apoptosis and maintained the population carrying ROS and DSB. The cancer initiation effects of FF were further recapitulated in Trp53 -/- mice. When introduced into the mammary fat pad, ROS-high but not ROS-low FFs induced early-onset B-cell lymphoma. Cotreatment with physiological concentration of melatonin, a potent antioxidant, ameliorated the mutagenic and tumorigenic effect of ROS-high FF in vitro and in vivo . The study revealed ROS and mitogens in mature ovarian follicles could initiate the transformation of fimbria epithelium in the context of p53 loss and melatonin is a potent preventive agent. Citation Format: Tang-Yuan Chu, Hsuan-Shun Huang, Che-Fang Hsu. Mutagenic and tumorigenic effects of follicular fluid in the context of p53 loss: Initiation of fimbria carcinogenesis. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: Exploiting Vulnerabilities; Oct 17-20, 2015; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2016;22(2 Suppl):Abstract nr B01.