Regulation of the Genes Encoding Steroidogenic Enzymes in the Human Ovary

The cellular mechanisms underlying excess ovarian androgen production in patients with polycystic ovary syndrome (PCOS) are unknown. The central research emphasis of my laboratory involves the examination of the intrinsic defects in steroidogenic enzyme expression that result in increased androgen production in patients with insulin resistance and PCOS. For a number of years, it has been proposed that excessive androgen production in PCOS results from intrinsic abnormalities in steroid production by ovarian theca interna cells. During the past 6 years, my primary interest has been to develop long-term functional culture systems for normal and PCOS theca interna and granulosa cells which can be grown and propagated for successive population doublings with maintenance of inducible steroidogenic capacity. Using these conditions, we have established for the first time, that increased androgen production is a stable phenotype of PCOS theca cells that not only results from preferentially increased 17a-hydroxylase (CYP17) expression, but involves the upregulation of other steroidogenic enzymes including cholesterol side-chain cleavage (CYP11A), and 3b-hydroxysteroid dehydrogenase (3b-HSDII). We have also obtained the first data to show that the mitogen activated protein kinase signaling pathway (MAPK) is aberrant in PCOS granulosa and theca cells. My laboratory is currently in the process of examining the relative contributions of transcriptional and post-transcriptional regulation to CYP17, CYP11A, and 3b-HSDII gene expression in normal and PCOS theca cells. We are in the process of characterizing the specific components of the MAPK pathway that are altered in PCOS theca and granulosa cells. We are also in the process of utilizing microarray analysis, serial analysis of gene expression (SAGE) and suppressive subtractive hybridization (SSH), to characterize the complete repertoire of differentially transcribed genes, the common transcription factor mediators, and additional signal transduction cascade(s) that are abnormal in PCOS granulosa and theca cells. As a consequence of these ongoing studies, we believe that critical information regarding the cellular basis for increased androgen production in the PCOS ovary will be obtained, which will be applicable to other clinical manifestations of PCOS, such as follicular growth arrest, infertility, endometrial hyperplasia/cancer, obesity, and insulin resistance.