Granulosa Cell Survival and Proliferation Are Altered in Polycystic Ovary Syndrome

Abstract

Context: Polycystic ovary syndrome (PCOS) represents the most common endocrine abnormality in women of reproductive age. The cause of PCOS remains largely unknown, but studies suggest an intrinsic ovarian abnormality.Objective: The objective of the study was to test our hypothesis that differences in granulosa cell proliferation and apoptosis may underlie abnormalities that affect follicular development.Design: Granulosa cells were prepared from follicular fluid aspirated from 4-to 8-mm follicles of unstimulated ovaries during routine laparoscopy or laparotomy from women with anovulatory PCOS and those with regular ovulatory cycles. Setting:The study was conducted at a university hospital.Patients: Fourteen women with anovulatory PCOS and nine women with regular ovulatory cycles participated in the study. Main Outcome Measures:Immunocytochemistry on granulosa cells to investigate apoptotic and proliferation rates, together with real-time RT-PCR to analyze gene expression profiles of apoptotic regulators, was measured.Results: Significantly lower apoptotic rates were found in granulosa cells from patients with PCOS, compared with women with regular ovulatory cycles (P ϭ 0.004). Lower apoptotic rates were associated with decreased levels of the apoptotic effector caspase-3 (P ϭ 0.001) and increased levels of the anti-apoptotic survival factor cellular inhibitor of apoptosis proteins-2 in the PCOS group that were coupled to higher proliferation rates (P ϭ 0.032). Gene expression profiling confirmed the immunocytochemical findings. Conclusions:Our findings indicate that there are significant differences in the rate of cell death and proliferation in granulosa cell populations in PCOS patients. These are associated with decreased expression of apoptotic effectors and increased expression of a cell survival factor. These results provide new insights that may be useful in developing specific therapeutic intervention strategies in PCOS. (J Clin Endocrinol Metab 93: 881-887, 2008) P olycystic ovary syndrome (PCOS) is a common endocrine abnormality in women of reproductive age, affecting 6.6 -8% of women in this age group (1). It is the main cause of anovulatory infertility and is characterized by chronic anovulation, hyperandrogenemia, and polycystic ovaries on ultrasound scan (2). Abbreviations: Bcl, B-cell lymphoma; BMI, body mass index; cIAP, cellular IAP; DHEAS, dehydroepiandrosterone sulfate; IAP, inhibitor of apoptosis proteins; Mcl, myeloid leukemia cell differentiation protein; PCOS, polycystic ovary syndrome; TUNEL, terminal deoxynucleotidyl transferase biotin-deoxyuridine 5-triphosphate nick end labeling; XIAP, X-linked inhibitor of apoptosis protein.

Overexpression of ribosomal RNA in cumulus cells of patients with polycystic ovary syndrome

“…This assumption is in a good concordance with recent findings which demonstrate increased proliferation and decreased apoptotic rates in granulosa cells of PCOS patients [11].…”

XIAP: a potential determinant of ovarian follicular fate

“…In the human ovary, XIAP's expression level is increased in granulosa cells compared with cIAP1 and -2, but levels are more similar in oocytes and OSE (Vischioni et al 2006). In patients suffering from polycystic ovary syndrome, however, XIAP gene expression is unchanged (Das et al 2008). …”

“…In contrast, cIAP2 levels were shown to be upregulated fivefold, suggesting that functional amplification may be occurring in the ovary; however, this is in a disease state and a potential compensatory mechanism between IAPs requires further consideration in the Xiap mutant mouse model (Das et al 2008). The ability of cIAP1 and -2 to bind caspases with low affinity but not inhibit them may be the reason why ovarian research has focused on XIAP (Eckelman & Salvesen 2006).…”

Ovarian Follicular Atresia

“…Beyond these considerations, intracellular proapoptotic proteins, such as Bax and p53, also increase in cells undergoing apoptosis. A variety of extracellular and intracellular signals stimulate Bax and p53 expression in granulosa cells of follicles Amsterdam et al, 1996;Kim et al, 1999;Zwain & Amato, 2001;Das et al, 2008;Salvetti et al, 2010), which result in apoptotic effects such as the release of cytochrome C from mitochondria, further activation of caspases, and ultimately fragmentation of nuclear DNA.…”

“…In human granulosa cells obtained from 4-8 mm follicles, apoptotic rates are decreased (and proliferation rates increased) in granulosa cells from polycystic ovaries compared to normal ovaries. In these polycystic ovaries, the levels of apoptotic effectors and anti-apoptotic survival factors were decreased and increased, respectively (Das et al, 2008). Animal models of polycystic ovaries have facilitated our understanding of PCOS.…”