Human chorionic gonadotropin β subunit affects the expression of apoptosis-regulating factors in ovarian cancer

Expression of human chorionic gonadotropin, especially its free β subunit (hCGβ) were shown to play an important role in cancer growth, invasion and metastasis. It is postulated that hCGβ is one of the factors determining cancer cell survival. To test this hypothesis, we applied two models: an in vitro model of ovarian cancer using OVCAR-3 and SKOV-3 cell lines transfected with the CGB5 gene and an in vivo model of ovarian cancer tissues. The material was tested against changes in expression level of genes encoding factors involved in apoptosis: BCL2, BAX and BIRC5. Overexpression of hCGβ was found to cause a decrease in expression of the analyzed genes in the transfected cells compared with the control cells. In ovarian cancer tissues, high expression of CGB was related to significantly lower BCL2 but higher BAX and BIRC5 transcript levels. Moreover, a low BCL2/BAX ratio, characteristic of advanced stages of ovarian cancer, was revealed. Since tumors were discriminated by a significantly lower LHCGR level than the level noted in healthy fallopian tubes and ovaries, it may be stated that the effect of hCGβ on changes in the expression of apoptosis-regulating agents observed in ovarian cancer is LHCGR-independent. The results of the study suggest that the biological effects evoked by hCGβ are related to apoptosis suppression.