Expression of target genes in cumulus cells derived from human oocytes with and without blastocyst formation

Objective: The transcriptional profile of cumulus cells (CCs) during oocyte maturation provides information for predicting oocyte developmental competence. Our previous study using a mouse model indicated that there were nine different genes related to oocyte development potential expressed in CCs during oocyte maturation. The purpose of this study was to elucidate whether gene expression levels of CCs during oocyte maturation are associated with oocyte developmental competence. Methods: The human CCs collected from each oocyte were divided into two groups after tracking depending on whether or not they developed to the blastocyst stage: (1) the oocytes were developed to blastocyst stage after fertilization (B+) and (2) the oocytes were not developed to blastocyst stage after fertilization (B). The expression levels of the nine selected genes (ARRB1, ATP2C1, CDH5, CNTNAP1, LGR4, MKLN1, RHOBTB1, SIX2, and SMC2) were examined. CCs were obtained from 29 women who were undergoing intracytoplasmic sperm injection treatment cycles. Quantitative reverse transcriptase-polymerase chain reaction analysis was performed on cumulus masses collected before insemination. Each sample was run three times. Statistically significant differences in mRNA expression of the target genes in independent samples were evaluated by two-tailed Student's t-test, and P < 0.05 was considered significantly different. Results: There were significant differences in the mRNA expression levels of ARRB1 (P = 0.016), LGR4 (P = 0.025), and SMC2 (P = 0.013) between the groups B+ and B. Gene expression of ARRB1, LGR4, and SMC2 in CCs is related to blastocyst development. Conclusions: Analysis of expression of ARRB1, LGR4, and SMC2 genes in CCs as biomarkers may provide predictive information on oocyte developmental competence before insemination and fertilization.