Objectives: Esophageal squamous-cell carcinoma (ESCC) incidence has been increasing rapidly, with an imbalanced ratio of occurrence in men more often than in women. The expression of sex hormone receptors is associated with the prognosis of ESCC. However, the exact roles of sex hormones and hormone receptors in ESCC remain unclear. We systematically evaluated the effects and the underlying mechanism of sex hormones and their receptors on esophageal carcinogenesis and malignant proliferation to clarify the extent to which sex hormones pathways contribute to the gender disparity of ESCC.
Methods: To determine the roles of hormones in vivo, we used a 4NQO-induced esophageal carcinogenesis model, a xenograft model and the castrated BALB/c Nude mouse model. To observe the function of hormones on the proliferation of ESCC cells in vitro, we performed colony formation, Cell Counting Kit-8, and EdU assays. To elucidate the precise molecular mechanism by which hormone receptors exert their functions, we performed ChIP-seq and RNA-seq to comprehensively identify the ESCC-specific hormone responsive genes and regulatory networks.
Results: There is a large male predominance in the 4NQO-induced esophageal carcinogenesis C57BL/6J mouse model. AR-positive esophageal cancer cells grow more rapidly in the male BALB/c Nude mice than the female mice. ERα-positive esophageal cancer cells possess faster proliferative capability in the female BALB/c Nude mice compared to the male mice, whereas ERβ-positive cells exhibit the opposite gender disparity in phenotypes. Moreover, the above proliferative effect is attenuated in castrated or ovariectomized mice. Furthermore, exogenous supplementation of estrogen pellet in ovariectomized female mice enhances ERα-positive cell growth but suppresses ERβ-positive cell growth. In vitro experimental data show that dihydrotestosterone treatment promotes the growth of AR positive ESCC cells, while 17-β estradiol (E2) exerts opposite functions depending on the estrogen receptor subtypes. Integrative analysis of ChIP-seq and RNA-seq data reveals that AR/ER is transactivated upon hormone treatment and binds to the promoter or enhancer of hormone responsive genes to induce differential gene expression. These genes are responsible for the malignant development of ESCC and may provide a new explanation of the gender disparity of ESCC.
Conclusions: Androgen promotes the proliferation of ESCC cells via AR while estrogen exerts dual functions dependent on the specific estrogen receptor subtypes, which may provide new insight into the etiology, prevention, and hormone-based treatment of ESCC.
Citation Format: Furong Huang, Hongyan Chen, Qianben Wang, Zhihua Liu. Roles of sex hormone pathways in the gender disparity of esophageal squamous-cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5421.