CYP1B1 induces cancer progression through regulation of TRAIL pathway and uPA-uPAR system

초록

Human CYP1B1 is known as a major metabolizer for estrogen and shows tumor-specific hyper-expression. To explore the role of CYP1B1 on progression of human cancer cells, we studied the effects of CYP1B1 in MCF-7, MDA-MB-231, and HeLa cells. CYP1B1 significantly induced invasion of cancer cells while strongly inhibited cancer cell apoptosis. Suppression of CYP1B1 by si/shRNA or treatment with TMS, a specific inhibitor for CYP1B1, markedly increased the protein expression level along with the level of release from cells of TNF-related apoptosis inducing ligand (TRAIL), a death ligand for cancer cells, whereas significantly decreased the expression of urokinase-type plasminogen activator receptor (uPAR) as well as uPA. We also found that CYP1B1 showed to inhibit the expression of key factors in TRAIL-induced apoptotic pathway and promote the inducers in uPA-uPAR metastasis system including integrin β1 and α5. Interestingly, uPAR overexpression only caused a significant increase of integrin β1 and α5 in protein levels, indicating protein degradation may play an important role in regulating integrin protein level. Surprisingly, CYP1B1 down-regulated p53 expression through MDM2 activation and nutlin-3a, an inhibitor for MDM2, blocked the promoting effects of CYP1B1 inducer, DMBA, on uPAR, which explains that CYP1B1 induced uPAR expression through regulation of MDM2-p53 system. Furthermore, we found that CYP1B1 suppresses TRAIL-related apoptosis through not only inhibition of TRAIL expression but also induction of DNA methylation on the promoter region of DR4, a receptor for TRAIL. Taken together, our data suggest that CYP1B1 promotes cancer cell metastasis via activating uPA-uPAR pathway which is one of the targets of p53 signaling and suppresses cancer cell apoptosis through inhibition of TRAIL-induced apoptosis by suppression of TRAIL release as well as post-translational regulation on DR4.