Epigallocatechin-3-gallate stimulates StAR expression and progesterone production in human granulosa cells through the 67-kDa laminin receptor-mediated CREB signaling pathway

Epigallocatechin-3-gallate (EGCG) is the most abundant and biologically active catechins extracted from green tea. The health benefits of EGCG have been extendedly studied. Ovarian steroidogenesis plays a pivotal role in maintaining normal reproductive function. Granulosa cells in the ovary are essential for steroid hormone production. To date, the effect of EGCG on steroidogenesis in human granulosa cells remains unclear. In the present study, we examine the physiological concentrations of EGCG on steroidogenesis in a steroidogenic human granulosa-like tumor cell line, KGN. Our results demonstrate that treatment with EGCG upregulates steroidogenic acute regulatory protein (StAR) expression and increases progesterone (P4) production. EGCG does not affect the expression levels of other steroidogenesis-related enzymes, such as P450 side-chain cleavage enzyme, 3 beta-hydroxysteroid dehydrogenase, and aromatase. In addition, we identify the expression of 67-kDa laminin receptor (67LR) in KGN cells. Moreover, EGCG-induced StAR expression and P4 production require the 67LR-mediated activation of the PKA-CREB signaling pathway. These results provide a better understanding of the function of EGCG on ovarian steroidogenesis, which may lead to the development of alternative therapeutic approaches for reproductive disorders.