Abstract 1454: Estrogen receptor signaling in FTE of BRCA mutation carriers

Abstract

Genetic and reproductive factors predicate epidemiological risk factors underlying epithelial ovarian cancer. The fallopian tube epithelia (FTE), the presumptive etiological site of high-grade serous ovarian cancer (HGSC), is a hormonal responsive tissue. Estrogen is known to promote cell proliferation and its metabolism produces reactive oxygen species that damage DNA and promote tumorigenesis. Estrogen receptor (ER) is rarely mutated, amplified or deleted in HGSC, yet only 10% of patients respond to anti-estrogen treatment, suggesting that intrinsic variables to the ER pathway contribute to this clinical outcome. TP53 mutations occur in almost 100% of HGSCs, indicating that mutated p53 supports a model as an early event in the pathogenesis of HGSC. We hypothesized that in the presence of dysfunctional p53, subsequent promiscuous binding of ER will yield aberrant signaling, ultimately significantly contributing to cellular transformation. Mutant p53 and ER co-localize in FTE cells, suggesting potential synergy. We established cell lines with p53 mutations and treated them with estradiol, an estrogen analog, to observe any changes in response. The genome binding sites of ER-regulated transcription factors were then identified and mapped by whole genome chromatin immunoprecipitation-deep sequencing (ChIP-Seq). The data generated will facilitate the development of gene signatures that will predict response to anti-estrogen therapy in serous ovarian cancer patients, and contribute to the discovery of biomarkers to more accurately identify patients who will benefit from hormonal therapies. Citation Format: Leah V. Dodds, Omar L. Nelson, Ramlogan Sowamber, Andres Rodrigues, Victoria de Castro, Wendell Henry, Guillermo Morales, Brian Slomovitz, Patricia Shaw, Sophia H. George. Estrogen receptor signaling in FTE of BRCA mutation carriers [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 1454. doi:10.1158/1538-7445.AM2017-1454

Hormone Receptor Expression and Disease Prognosis in High-Grade Serous Ovarian Cancer

“…[9][10][11][12][13] The presence of both estrogen receptor alpha (ER) and progesterone receptor (PR) expression in epithelial ovarian tumors, like l LGSC tumors, has been shown to predict favorable response to estrogen antagonism 14 . PR is a classic target of ER and a biomarker of ER function 15 . LGSC tumors have a higher rate of ER/PR expression than HGSC 16,17 . In recurrent LGSC, antiestrogen therapies (aromatase inhibitors and selective estrogen receptor modulator) have low overall response rates (9-11%) but can yield stable disease (>70%) and improve progression free survival 14,18 .…”