Downregulation of PDCD4 induced by progesterone is mediated by the PI3K/AKT signaling pathway in human endometrial cancer cells.

ABSTRACT

Programmed cell death 4 (PDCD4) has been identified as a tumor­suppressor gene that inhibits neoplastic transformation, tumor progression, and protein translation. It has been reported that multiple factors participate in the regulation of PDCD4 mRNA and protein. The endometrium is regulated by changing concentrations of ovarian hormones, such as estrogen and progesterone, and shows periodical changes. However, whether ovarian hormones regulate PDCD4 expression remains unclear. This study aimed to explore the effect and mechanism of estrogen or progesterone on PDCD4 mRNA and protein expression in human endometrial cancer cells. The expression of PDCD4 mRNA and protein in Ishikawa and HEC­1­A cells was detected by quantitative real­time PCR and western blot analysis. The signaling pathway­related proteins were detected by western blot analysis. The results showed that PDCD4 mRNA levels exhibited no significant changes after treatment with estrogen or progesterone in both Ishikawa and HEC­1­A cell lines. Estrogen also had no obvious effect on PDCD4 protein expression. However, progesterone effectively decreased the expression of PDCD4 protein and the PI3K/AKT pathway may be involved in the downregulation of PDCD4 protein induced by progesterone. These results suggest that the downregulation of PDCD4 induced by progesterone affects the therapeutic efficacy of progesterone in human endometrial cancer or endometriosis, which may have important implications for progesterone treatment in the clinic.