Several Apoptosis Related Genes Differentially Expressed in Human Granulosa Cells of the Embryos With Different Developmental Potential

Abstract

Background: In humans, growing oocytes derive most substrates for energy metabolism and biosynthesis from cumulus granulosa cells. Abnormal patterns of gene expression in cumulus cells could represent either causes or consequences of abnormal oocyte development. Studies of gene expression in cumulus cells might help to determine molecular markers for the developmental potential of their enclosed oocyte. Objective: To compare differential expression of INHBB, INHBA, PTX3, PCNA, BAX, BIRC5, PUM1 and 2, INT1B, and BAG3 genes in cumulus granulosa cells derived from human oocytes that: 1) either resulted in pregnancy vs. failed to develop; and 2) were from patients with normal vs. decreased ovarian reserve. Methods: 68 patients undergoing IVF were enrolled in the study. After oocyte retrieval, cumulus granulosa cells were trimmed from the oocytes and processed for RNA extraction. Real-time PCR was used to quantify the expression of the genes listed above. Oocytes were cultured individually, and monitored for fertilization and embryo development. Embryos were selected for transfer based on morphology. Results: Levels of PCNA and BIRC5 gene mRNA were two and four times up-regulated in the cumulus cells of the embryos that failed to develop in vivo when compared to the cumulus cells of the embryos that resulted in pregnancy. mRNA levels of PCNA, INT1B, and PUM1 genes were more than two times upregulated (P<0.05) in embryos derived from the patients with decreased ovarian reserve (FSH above 7 mU/mL). Removal of the cumulus granolusa cells did not affect embryo development, as the pregnancy rates in the study group were not significantly different from the other patients in the practice. Conclusions: In this study we determined that PCNA and BIRC5 gene are upregulated in the cumulus granulosa cells of the embryos that failed to develop in vivo when compared to the cumulus cells of the embryos that resulted in pregnancy. We also found that PCNA, INT1B, and PUM1 genes are upregulated in the cumulus granulosa cells in patients with decreased ovarian reserve. With further research, we hope to confirm molecular targets that will be predictive of successful embryo development and pregnancy to increase elective single embryo transfer rates and to decrease the rate of multiple births with ART.