Abstract
Bisphenol A (BPA) is a common environmental hormone which competes with estrogen to disrupt human endocrine system. BPA is widely used to plastic production such as baby bottles, cans and dental composites. Human would expose low doses of BPA in daily life because common use for plastics products. Our laboratory previously found that the women with endometrial hyperplasia have the higher blood BPA levels than normal women as well as the HOXA10 gene expression (relevant to endometrial growth). In order to understand the impact of BPA for endometrial development, the purpose of this study was to investigate whether BPA caused abnormal gene expression in human endometrial cells and illustrate gene regulatory pathways, and to explore whether BPA would affect specific micro-RNA regulation corresponding to gene expression in endometrial cells. Human endometrial cancer (RL95-2) cells were treated with 10, 103 and 105 nM BPA, and determined the mRNA and miRNA expression respectively using Phalanx Human OneArray® v5 chip and Phalanx Human miRNA OneArray® v4 chip. The analysis of gene cluster and GO term described gene classification and gene function of chip data. The gene functions of changed expression were related to signal transduction, stress response, wound healing and proliferation. This study explored BPA induced the gene expression of PIK3CB (phosphoinositide-3-kinase), IL-8 (interleukin 8), CDKN1A (cyclin-dependent kinase inhibitor 1A) and Casp9 (caspase 9) in a dose-response manner. According to KEGG pathway, the changed gene expression in exposure BPA was illustrated to the regulation path of cell proliferation and inflammation. In cancer pathway, the elevated upstream PIK3CB increased phosphorylation of Casp9 and CDKN1A protein resulting in proliferation of endometrial cells underlying the occurrence of endometriosis. This study also found that BPA affected the expression of miRNA in RL95-2 cells. The study singled out 21 miRNAs statistical significantly affected by BPA exposure from III miRNA chip data, and used miRDB database for miRNA corresponding to the possible combination of mRNA. The sequence of miRNA-1973 can combine with IL-8 thereby inhibiting the expression of IL-8 gene. The results of gene chip and real-time PCR both showed BPA exposure increased IL-8 mRNA expression and reduced miRNA-1973 expression. It suggested that BPA exposure attenuated miRNA-1973 expression to increase the expression of IL-8. This study investigated BPA exposure influenced gene expression and miRNA regulation in human endometrial cancer cells. BPA would alter the expression of IL-8 by modulating hsa-miR-1973 expression for inflammation, and change the expression of PIK3CB, CDKN1A and Casp9 to process cells carcinogenesis.