title: 7,12-Dimethylbenzanthracene induces apoptosis in RL95-2 human endometrial cancer cells: ligand-selective activation of cytochrome P450 1B1.
abstract: 7,12-Dimethylbenzanthracene (DMBA), a polycyclic aromatic hydrocarbon, exhibits mutagenic, carcinogenic, immunosuppressive, and apoptogenic properties in various cell types. To achieve these functions effectively, DMBA is modified to its active form by cytochrome P450 1 (CYP1). Exposure to DMBA causes cytotoxicitymediated apoptosis in bone marrow B cells and ovarian cells. Although uterine endometrium constitutively expresses CYP1A1 and CYP1B1, their apoptotic role after exposure to DMBA remains to be elucidated. Therefore, we chose RL95-2 endometrial cancer cells as a model system for studying DMBA-induced cytotoxicity and cell death and hypothesized that exposure to DMBA causes apoptosis in this cell type following CYP1A1 and/or CYP1B1 activation. We showed that DMBA-induced apoptosis in RL95-2 cells is associated with activation of caspases. In addition, mitochondrial changes, including decrease in mitochondrial potential and release of mitochondrial cytochrome c into the cytosol, support the hypothesis that a mitochondrial pathway is involved in DMBA-induced apoptosis. Exposure to DMBA upregulated the expression of AhR, Arnt, CYP1A1, and CYP1B1 significantly; this may be necessary for the conversion of DMBA to DMBA-3,4-diol-1,2-epoxide (DMBA-DE). Although both CYP1A1 and CYP1B1 were significantly upregulated by DMBA, only CYP1B1 exhibited activity. Moreover, knockdown of CYP1B1 abolished DMBA-induced apoptosis in RL95-2 cells. Our data show that RL95-2 cells are susceptible to apoptosis by exposure to DMBA and that CYP1B1 plays a pivotal role in DMBA-induced apoptosis in this system.
authors.affiliation: Department of Anatomy and Cell Biology, College of Medicine, Dong-A University, Busan 602-714, Republic of Korea.
authors.forename: Ji Young
authors.initials: JY
authors.lastname: Kim
authors.forename: Seung Gee
authors.initials: SG
authors.lastname: Lee
authors.forename: Jin-Yong
authors.initials: JY
authors.lastname: Chung
authors.forename: Yoon-Jae
authors.initials: YJ
authors.lastname: Kim
authors.forename: Ji-Eun
authors.initials: JE
authors.lastname: Park
authors.forename: Seunghoon
authors.initials: S
authors.lastname: Oh
authors.forename: Se Yong
authors.initials: SY
authors.lastname: Lee
authors.forename: Hong Jo
authors.initials: HJ
authors.lastname: Choi
authors.forename: Young Hyun
authors.initials: YH
authors.lastname: Yoo
authors.forename: Jong-Min
authors.initials: JM
authors.lastname: Kim
mesh_terms: D015127:9,10-Dimethyl-1,2-benzanthracene / Q000494:pharmacology*; D000230:Adenocarcinoma / Q000188:drug therapy* / Q000201:enzymology / Q000276:immunology / Q000473:pathology; D017209:Apoptosis / Q000187:drug effects*; D001189:Aryl Hydrocarbon Hydroxylases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015153:Blotting, Western; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects / Q000276:immunology; D065633:Cytochrome P-450 CYP1B1; D016889:Endometrial Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000276:immunology / Q000473:pathology; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007150:Immunohistochemistry; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects / Q000276:immunology; D008928:Mitochondria / Q000187:drug effects / Q000201:enzymology / Q000276:immunology; D034741:RNA, Small Interfering / Q000008:administration & dosage / Q000235:genetics
chemical_list: D034741:RNA, Small Interfering; D015127:9,10-Dimethyl-1,2-benzanthracene; D001189:Aryl Hydrocarbon Hydroxylases; C585496:CYP1B1 protein, human; D065633:Cytochrome P-450 CYP1B1