ABSTRACT
Cytochrome P450(CYP450),one of the most important enzymes in the human body,medi?ates the activation and toxicity of indirect poisons as well as indirect carcinogens. CYP450 is a super?family mainly composed of CYP1A, CYP1B, CYP2A, CYP2B, CYP2C, CYP2E, CYP2W, CYP3A and their activities are widely modulated by epigenetic manners, such as DNA methylation, histone modifi?cation and microRNA interference.Indirect carcinogens including benzo(a)pyrene,2,3,7,8-tetrachlorod?ibenzo-p-dioxin,diethylstilbestrol,aflatoxin B1 and cyclophosphamide,can change epigenetic modifica?tions, such as specific changes in DNA methylation, histone acetylation, methylation or ubiquitination, and up-or down-regulation of microRNA expression,which affect the function of the major subtypes of CYP450 and their role in indirect carcinogen activation.