Altered gene expression profile in cumulus cells of mature MII oocytes from patients with polycystic ovary syndrome

STUDY QUESTION: Oocyte developmental competence is altered in patients with polycystic ovary syndrome (PCOS); is gene expression in cumulus cells (CCs) from mature metaphase II oocytes of patients with PCOS altered as well? SUMMARY ANSWER: Compared with CCs from non-PCOS patients, the gene expression profile of CCs isolated from mature oocytes of patients with PCOS present alterations that could explain the abnormal folliculogenesis and reduced oocyte competence in such patients. WHAT IS KNOWN ALREADY: Abnormal mRNA expression of several members of the insulin-like growth factor (IGF) family in CCs from PCOS patients was previously reported. Moreover, the whole transcriptome has been investigated in cultured CCs from PCOS patients. STUDY DESIGN, SIZE AND DURATION: This retrospective study included six PCOS patients diagnosed following the Rotterdam Criteria and six non-PCOS patients who all underwent ICSI for male infertility in the assisted reproduction technique (ART) Department of Montpellier University Hospital, between 2009 and 2011. PARTICIPANTS/MATERIALS, SETTING AND METHODS: CCs from PCOS and non-PCOS patients who underwent controlled ovarian stimulation (COS) were isolated mechanically before ICSI. Gene expression profiles were analysed using the microarray technology and the Significance Analysis of Microarray was applied to compare the expression profiles of CCs from PCOS and non-PCOS patients. MAIN RESULTS: The gene expression profile of CCs from patients with PCOS was significantly different from that of CCs from non-PCOS patients. Specifically, CCs from women with PCOS were characterized by abnormal expression of many growth factors, including members of the epidermal growth factor-like (EGFR, EREG and AREG) and IGF-like families (IGF1R, IGF2R, IGF2BP2 and IGFBP2), that are known to play a role in oocyte competence. In addition, mRNA transcripts of factors involved in steroid metabolism, such as CYP11A1, CYP1B1, CYP19A1 and CYP2B7P1, were deregulated in PCOS CCs, and this could explain the abnormal steroidogenesis observed in these women. Functional annotation of the differentially expressed genes suggests that defects in the transforming growth factor and estrogen receptors signalling cascades may contribute to the reduced oocyte developmental competence in patients with PCOS. LIMITATIONS AND REASONS FOR CAUTION: Owing to the strict selection criteria (similar age, weight and reasons for ART), this study included a small sample size (six cases and six controls), and thus, further investigations using a large cohort of patients are needed to confirm these results. WIDER IMPLICATIONS OF THE FINDINGS: This study opens a new perspective for understanding the pathogenesis of PCOS.