The Mechanism Of Cd Regulating AR Transcriptional Activity

Cadmium is an important industrial and environmental pollutant, which is widely spread in air, soil and water. Through disrupting hormone’s synthesis, release, transportation and metabolism, Cd acts as an endocrine disruption. Based on epidemic research, Cd may result in structure changes and disfuntion of testicle, epididymis and seminal vesicle. And it will enhance the risk of catching prostate cancer. The prostate is an endocrine dependent organ, whose growth and differentiation are regulated by androgen. Androgen receptor plays a vital role in the function of androgen. AR is a transcriptional actor, which regulate the transcription of downstream genes. The AR involved signal pathways have multiple effects in prostate growth and prostate related diseases. However, the mechanism of Cd on AR transcriptional activity needs to be clarified.Our research focus on AR transcriptional activity in order to research the effects of Cd on AR expression, transcriptional activity and AR related signal pathways. To study the effects of Cd on AR transcriptional activity, we choose293T cells, an AR negative cell lines and LNCaP cells, which express AR endogenously. Before transcriptional activity analysis, cytotoxicity is measured to choose appropriate dosages for the following experiments. The CCK8results show that there is no clear effect on cell viability under16μM. Flow cytometry results show that Cd influences LNCaP cell proliferation by promoting G1/S transition. Then we investigate the effect of Cd on AR transcriptional activity by luciferase assay. By cotransfection of AR and ARE-luc plasmid within293t cells, the transcriptional activity is determined by luciferase reporter genes. Cd increases PSA expression. At the meanwhile, Cd has no significant effect on AR expression which indicates that Cd-induced PSA changes do not rely on AR expression.Sumoylation is one of the most important parts of post translational modification. Sumoylated AR shows a lower transcriptional activity. SENP1, deconjugating AR-SUMO covalent bond, decreases AR sumoylation. So we hypothesize that Cd regulates AR transcriptional activity through SENP1. To verify this hypothesis, we measure SENP1expression. Then through RNA interference, we demonstrate that PSA expression is down regulated by knocking down SENP1. At last, we test sumoylation of AR by co-IP, which shows that sumoylated AR is decreased after Cd treatment. All the results above indicate that Cd-induced SENP1enhances AR transcriptional activity by decresing AR sumoylation. Our research shows a new aspect of androgen-like endocrine disruption. It provides a rationale for diseases control and prevention of Cd pollution.