title: Expression of cytochrome P450 1B1 and catechol-O-methyltransferase in breast tissue and their associations with breast cancer risk.
abstract: Cytochrome P450 1B1 (CYP1B1) and catechol-O-methyltransferase (COMT) are important estrogen-metabolizing enzymes that may affect breast cancer risk. Few studies have directly measured the expression of CYP1B1 and COMT genes in breast tissue samples. The subjects in this study were a subgroup of participants of the Shanghai Breast Cancer Study including 64 patients diagnosed with breast cancer and 68 patients diagnosed with benign breast diseases (BBD) who provided samples of tumor tissue and adjacent nontumor tissue to the study. We compared CYP1B1 and COMT mRNA expression in tumor tissue and adjacent nontumor tissue in both breast cancer patients and BBD patients. High levels of CYP1B1 expression and low levels of COMT expression in adjacent nontumor tissue were associated with a significantly increased breast cancer risk in a nonlinear manner. Odds ratios and 95% confidence intervals (in parentheses) for the midpoints of the first, second, fourth, and fifth quintiles of gene expression levels compared with the overall median levels in BBD subjects were 0.21 (0.07-0.67), 0.81 (0.69-0.95), 1.20 (1.05-1.38), and 1.55 (1.12-2.15) for CYP1B1 and 1.72 (1.17-2.55), 1.19 (1.05-1.35), 0.83 (0.73-0.95), and 0.78 (0.65-0.93) for COMT, respectively. These results support the hypothesis that the formation and accumulation of catechol estrogens in breast tissue through increased CYP1B1 expression and reduced COMT expression may play a significant role in breast cancer risk.
authors.affiliation: Vanderbilt Epidemiology Center, Vanderbilt University School of Medicine, Nashville, TN 37232, USA. wanqing.wen@vanderbilt.edu
authors.forename: Wanqing
authors.initials: W
authors.lastname: Wen
authors.forename: Zefang
authors.initials: Z
authors.lastname: Ren
authors.forename: Xiao Ou
authors.initials: XO
authors.lastname: Shu
authors.forename: Qiuyin
authors.initials: Q
authors.lastname: Cai
authors.forename: Chuanzhong
authors.initials: C
authors.lastname: Ye
authors.forename: Yu-Tang
authors.initials: YT
authors.lastname: Gao
authors.forename: Wei
authors.initials: W
authors.lastname: Zheng
mesh_terms: D000328:Adult; D001189:Aryl Hydrocarbon Hydroxylases / Q000096:biosynthesis / Q000235:genetics*; D001940:Breast / Q000201:enzymology* / Q000473:pathology; D001941:Breast Diseases / Q000201:enzymology / Q000453:epidemiology / Q000235:genetics; D001943:Breast Neoplasms / Q000201:enzymology / Q000453:epidemiology / Q000235:genetics*; D016022:Case-Control Studies; D002394:Catechol O-Methyltransferase / Q000096:biosynthesis / Q000235:genetics*; D002681:China / Q000453:epidemiology; D016001:Confidence Intervals; D065633:Cytochrome P-450 CYP1B1; D004967:Estrogens / Q000378:metabolism; D005260:Female; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D005838:Genotype; D006801:Humans; D016015:Logistic Models; D008875:Middle Aged; D016017:Odds Ratio; D012307:Risk Factors
chemical_list: D004967:Estrogens; D001189:Aryl Hydrocarbon Hydroxylases; C585496:CYP1B1 protein, human; D065633:Cytochrome P-450 CYP1B1; D002394:Catechol O-Methyltransferase