Effect of tetrachlorodibenzo-p-dioxin on the expression of cytochrome P4501A1 in human SZ95 sebocytes and its significance

Abstract

Objective To estimate the effect of the enviromental pollutant 2,3,7,8-tetrachlorodibenzo-pdioxin (TCDD),a representative of the dioxin family,on the expression of cytochrome P4501A1 (CYP1A1) in cultured human immortalized SZ95 sebocytes in vitro,so as to improve understanding of the pathogenesis of chloracne.Methods SZ95 sebocytes were cultured with or without the presence of 10 nmol/L TCDD for two hours or three days.Real time fluorescence-based PCR was performed to quantify the mRNA expression of CYP1A1,immunohistochemistry and Western blot to determine the expression level of CYP1A1 protein,in the SZ95 cells.Chi-square test was done to compare the protein and mRNA expressions of CYP1A1 between untreated and treated SZ95 cells.Results Real time PCR showed that the mRNA expression of CYP1A1 was low in SZ95 sebocytes,and increased by 5.622 times after 2-hour treatment with TCDD(P ＜ 0.05).Immunohistochemistry revealed a weak expression of CYP1A1 protein in the cytoplasm and nuclei of untreated SZ95 sebocytes,which was also significantly enhanced by the TCDD treatment.Western blot results showed that the relative expression level of CYP1A1 protein was 4.233 ± 0.252 in SZ95 sebocytes treated by TCDD for three days,significantly higher than that in untreated sebocytes(0.123 ± 0.208,P ＜ 0.05).Conclusions There is a low expression of CYP1A1 mRNA and protein in SZ95 sebocytes,which can be upregulated by TCDD,suggesting that the CYP1A1 gene is a downstream target of the aryl hydrocarbon receptor responsible for the abnormal differentiation of human sebocytes. Key words: Cytochrome P4501A1; Tetrachlorodibenzo-p-dioxin; Sebaceous glands; Cell