Abstract TMEM-018: IN VITRO MODELS OF HGSC BASED ON MURINE OVIDUCTAL EPITHELIAL ORGANOIDS

Abstract

Abstract Mouse models of high-grade serous carcinoma (HGSC) arising from oviductal epithelium provide excellent in vivo systems with which to define the cellular and molecular events associated with HGSC development and progression. However, tumors in mice typically develop over months rather than weeks, and tumor progression in vivo cannot be easily monitored. Murine organoid models that closely mimic the biology of fallopian tube epithelium would facilitate research exploring HGSC pathogenesis. We have developed Ovgp1-iCreERT2 mice in which the Ovgp1 promoter controls expression of tamoxifen (TAM)-inducible Cre recombinase in the oviductal epithelium – the murine equivalent of human fallopian tube epithelium. We have established long-term, 3-dimensional oviductal epithelial organoid cultures from Ovgp1-iCreERT2;R26LSL-EYFP double transgenic mice, and show that the organoids contain both ciliated and secretory cells, and express oviductal epithelial markers including cytokeratin 8, ER, PAX8 and OVGP1. Organoids treated in vitro with 4-hydroxy-tamoxifen (4-OH-TAM) activate the EYFP reporter. Oviductal epithelial organoids established from Ovgp1-iCreERT2;Brca1del/fl; Trp53mut/fl;Rb1fl/fl (BPR) mice and treated in vitro with 4-OH-TAM show selection for the recombined tumor suppressor gene alleles by passage 6, accompanied by morphological and behavioral changes associated with neoplastic transformation. Stable organoid cultures can also be established from the oviductal epithelium of BPR mice treated in vivo with Tamoxifen (TAM). We show that long-lived 3-dimensional organoids can be generated from normal oviductal tissue; can undergo Cre-mediated recombination in vitro to inactivate tumor suppressor genes relevant to human HGSC pathogenesis; and can acquire properties associated with neoplastic transformation in a relatively short period of time (weeks). As we have already generated Ovgp1-iCreERT2 mice with various combinations of constitutional and Cre-inducible mutant tumor suppressor gene (Trp53, Rb1, Brca1, Pten, Nf1, Apc) and oncogene (PIK3CA, KRAS) alleles, the roles of specific genetic alterations in HGSC pathogenesis can be explored in a relatively rapid and controlled experimental system. Citation Format: Yali Zhai, Eric R. Fearon, and Kathleen R. Cho. IN VITRO MODELS OF HGSC BASED ON MURINE OVIDUCTAL EPITHELIAL ORGANOIDS [abstract]. In: Proceedings of the 11th Biennial Ovarian Cancer Research Symposium; Sep 12-13, 2016; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2017;23(11 Suppl):Abstract nr TMEM-018.