Benzyl butyl phthalate induces necrosis by AhR mediation of CYP1B1 expression in human granulosa cells

This study investigated the signalling pathway of the arylhydrocarbon receptor (AhR) on HO23 cells (immortalised human granulosa cells (hGC)) mediated by benzyl butyl-phthalate (BBP).BBP (1 ?M) significantly increased the mRNA and protein levels of AhR, aryl hydrocarbon receptor nuclear translocator (ARNT) and cytochrome-P 450 (CYP)1B1 in HO23 cells. Treatment with 3′,4′-dimethoxyflavone (3′,4′-DMF) or AhR siRNA significantly reduced AhR and CYP1B1, but CYP1A1 was not affected by 3′,4′-DMF or AhR siRNA. This suggested that increases in CYP1A1 might not be regulated by AhR. BBP induced the AhR fusion protein to localise and accumulate around the nucleus, and AhR heterodimerisation with ARNT was observed in the nucleus by immunoprotein. Chromatin immunoprotein and reporter assays revealed the effect of BBP on CYP1B1, but not CYP1A1. Necrosis was significantly increased in HO23 cells after BBP treatment, and 3′,4′-DMF, AhR siRNA or CYP1B1 siRNA knockdown blocked this phenomenon. The data suggested that BBP induced HO23 cell necrosis is AhR and CYP1B1 dependent.