Transfection of Antisense Chorionic Gonadotropin β Gene into Choriocarcinoma Cells Suppresses the Cell Proliferation and Induces Apoptosis

Abstract

Choriocarcinoma cells not only synthesize human chorionic gonadotropin (hCG), but also express LH/CG receptors on the cell membrane. This suggests that the hCG and LH/CG receptors may play a role in regulating the biological function of choriocarcinoma cells in an autocrine/paracrine manner. The objective of this study was to ascertain whether the inhibition of CGbeta gene expression in choriocarcinoma cells affects their proliferation and apoptosis. Expression vector bearing antisense CGbeta gene was transfected into the choriocarcinoma cell line, JAr. CGbeta protein synthesis was monitored by Western immunoblot, and CGbeta mRNA expression was determined by RT-PCR. Cell proliferation was assessed by 3-[4,5-dimethlthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay and nuclear incorporation of 5-bromo-2'-deoxyuridine, and the apoptosis-positive rate was assessed by terminal deoxynucleotidyltransferase-mediated deoxy-UTP nick end labeling analysis and nuclear staining with Hoechst 32258. JAr cells transfected with antisense CGbeta gene (JAr-aCGbeta cells) showed a significant decrease in hCG production and cell proliferation compared with untransfected and mock-transfected cells. The apoptosis-positive rate of the JAr-aCGbeta cells significantly increased compared with that of the controls. LH/CG receptor expression in JAr-aCGbeta cells decreased compared with that in controls. By contrast, supplementation of exogenous hCG significantly increased the LH/CG receptor expression and viability of JAr-aCGbeta cells. These results suggest that hCG, through its binding to the LH/CG receptor, may augment proliferation and inhibit apoptosis in choriocarcinoma JAr cells, and that the introduction of an antisense gene may be a potential approach to the inhibition of choriocarcinoma cell growth.