Follicle stimulating hormone receptor in ovarian surface epithelium and epithelial ovarian cancer

Epithelial ovarian cancer (EOC) has remained an enigmatic disease, the etiology of which is mostly unknown. Considering the age incidence around menopause, a "gonadotrophin theory" has been proposed, and considering the association with infertility, an "incessant ovulation" theory has been proposed. EOC originates from ovarian surface epithelium (OSE), which not only secretes cytokines/growth factors and steroids but expresses gonadotrophin and steroid hormone receptors as well. The most important gonadotrophin receptor is the follicle stimulating hormone receptor (FSHR), which has definite oncogenic potential and is a probable candidate for oncogenesis. In this article, we review existing knowledge of FSHR in ovary, in OSE, and in epithelial ovarian cancer and try to establish relative importance of this receptor over its ligand. A systematic review through PubMed was done on the subject of FSHR and its metabolism. For the obvious difficulty of meager amounts of tissue available, most of studies so far see it in granulosa cells and cell lines rather than in OSE. Thus, effort was made to deduce workable knowledge that can establish its role and can then be applied in OSE and EOC. There is great deal of information regarding metabolism of FSHR, including regulation of its gene expression, isoforms, and pathways of desensitization and degradation with which ovarian cancer etiology researchers have to be familiar with, and there are a number of steps where manipulation may stop carcinogenesis. Hormone therapy of such cancer has so far been only mildly active, probably because we do not understand the role and mechanism of action of FSH and FSHR in the hypothalamo-pituitary-ovarian axis in development of such cancer.