Abstract
A number of FSH receptor (FSH-R) isoforms with distinct structural motifs and signaling paradigms have been described, including a single transmembrane domain variant that functions as a growth factor type receptor (FSH-R3). This study tested the hypothesis that FSH can stimulate ovarian cancer cell proliferation by acting on FSH-R3, using the tumorigenic mouse ovarian surface epithelial cell (MOSEC) line ID8. FSH enhanced ID8 proliferation in a concentration-dependent fashion. Moreover, FSH-treatment of ID8 elicited intracellular events consistent with activation of FSH-R3 and distinct from those associated with activation of the canonical G-protein coupled FSH-R isoform (FSH-R1). Specifically, the FSH-R3 signaling pathway included cAMP-independent activation of ERK downstream of an SNX-482 sensitive component likely to be the Cav2.3 calcium channel. Northern analysis using probes specific for exons 7 and 11 of FSH-R identified consistently only one 1.9kb transcript. Immunoblot analysis confirmed expression of FSH-R3 but not FSHR-1 in ID8. Together, these data suggest that FSH-R3 signaling promotes proliferation of ovarian cancer cells.