title: Functional role and tobacco smoking effects on methylation of CYP1A1 gene in prostate cancer.
abstract: Cytochrome P450 (CYP) 1A1 is a phase I enzyme that can activate various compounds into reactive forms and thus, may contribute to carcinogenesis. In this study, we investigated the expression, methylation status, and functional role of CYP1A1 on prostate cancer cells. Increased expression of CYP1A1 was observed in all cancer lines (PC-3, LNCaP, and DU145) compared to BPH-1 (P < 0.05); and was enhanced further by 5-aza-2'-deoxycytidine treatment (P < 0.01). Methylation-specific PCR (MSP) and sequencing of bisulfite-modified DNA of the xenobiotic response element (XRE) enhancer site XRE-1383 indicated promoter methylation as a regulator of CYP1A1 expression. In tissue, microarrays showed higher immunostaining of CYP1A1 in prostate cancer than normal and benign prostatic hyperplasia (BPH; P < 0.001), and methylation analyses in clinical specimens revealed significantly lower methylation levels in cancer compared to BPH at all enhancer sites analyzed (XRE-1383, XRE-983, XRE-895; P < 0.01). Interestingly, smoking affected the XRE-1383 site where the methylation level was much lower in cancer tissues from smokers than non-smokers (P < 0.05). CYP1A1 levels are thus increased in prostate cancer and to determine the functional effect of CYP1A1 on cells, we depleted the gene in LNCaP and DU145 by siRNA. We observe that CYP1A1 knockdown decreased cell proliferation (P < 0.05) and increased apoptosis (P < 0.01) in both cell lines. We analyzed genes affected by CYP1A1 silencing and found that apoptosis-related BCL2 was significantly down-regulated. This study supports an oncogenic role for CYP1A1 in prostate cancer via promoter hypomethylation that is influenced by tobacco smoking, indicating CYP1A1 to be a promising target for prostate cancer treatment.
authors.affiliation: Department of Surgery/Urology, Veterans Affairs Health Care System, San Francisco, California 94121, USA.|Department of Urology, University of California, San Francisco, California 94121, USA.|Department of Urology, Shimane University Faculty of Medicine, Izumo, 693-8501, Japan.
authors.forename: Yozo
authors.initials: Y
authors.lastname: Mitsui
authors.affiliation: Department of Oral Biology, Yonsei University College of Density, Seoul, 120-752, South Korea.
authors.forename: Inik
authors.initials: I
authors.lastname: Chang
authors.affiliation: Department of Surgery/Urology, Veterans Affairs Health Care System, San Francisco, California 94121, USA.|Department of Urology, University of California, San Francisco, California 94121, USA.
authors.forename: Taku
authors.initials: T
authors.lastname: Kato
authors.affiliation: Department of Surgery/Urology, Veterans Affairs Health Care System, San Francisco, California 94121, USA.|Department of Urology, University of California, San Francisco, California 94121, USA.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Hashimoto
authors.affiliation: Department of Surgery/Urology, Veterans Affairs Health Care System, San Francisco, California 94121, USA.|Department of Urology, University of California, San Francisco, California 94121, USA.
authors.forename: Soichiro
authors.initials: S
authors.lastname: Yamamura
authors.affiliation: Department of Urology, Osaka University Graduate School of Medicine, Suita, 565-0871, Japan.
authors.forename: Shinichiro
authors.initials: S
authors.lastname: Fukuhara
authors.affiliation: Department of Surgery/Urology, Veterans Affairs Health Care System, San Francisco, California 94121, USA.
authors.forename: Darryn K
authors.initials: DK
authors.lastname: Wong
authors.affiliation: Department of Surgery/Urology, Veterans Affairs Health Care System, San Francisco, California 94121, USA.
authors.forename: Marisa
authors.initials: M
authors.lastname: Shiina
authors.affiliation: Department of Surgery/Urology, Veterans Affairs Health Care System, San Francisco, California 94121, USA.|Department of Urology, University of California, San Francisco, California 94121, USA.
authors.forename: Mitsuho
authors.initials: M
authors.lastname: Imai-Sumida
authors.affiliation: Department of Surgery/Urology, Veterans Affairs Health Care System, San Francisco, California 94121, USA.|Department of Urology, University of California, San Francisco, California 94121, USA.
authors.forename: Shahana
authors.initials: S
authors.lastname: Majid
authors.affiliation: Department of Surgery/Urology, Veterans Affairs Health Care System, San Francisco, California 94121, USA.|Department of Urology, University of California, San Francisco, California 94121, USA.
authors.forename: Sharanjot
authors.initials: S
authors.lastname: Saini
authors.affiliation: Department of Urology, Shimane University Faculty of Medicine, Izumo, 693-8501, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Shiina
authors.affiliation: Department of Urology, Toho University Faculty of Medicine, Tokyo, 143-8540, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Nakajima
authors.affiliation: Department of Surgery/Urology, Veterans Affairs Health Care System, San Francisco, California 94121, USA.|Department of Urology, University of California, San Francisco, California 94121, USA.
authors.forename: Guoren
authors.initials: G
authors.lastname: Deng
authors.affiliation: Department of Surgery/Urology, Veterans Affairs Health Care System, San Francisco, California 94121, USA.|Department of Urology, University of California, San Francisco, California 94121, USA.
authors.forename: Rajvir
authors.initials: R
authors.lastname: Dahiya
authors.affiliation: Department of Surgery/Urology, Veterans Affairs Health Care System, San Francisco, California 94121, USA.|Department of Urology, University of California, San Francisco, California 94121, USA.
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Tanaka
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D017209:Apoptosis; D001374:Azacitidine / Q000031:analogs & derivatives / Q000737:chemistry; D045744:Cell Line, Tumor; D018899:CpG Islands; D019363:Cytochrome P-450 CYP1A1 / Q000235:genetics / Q000378:metabolism*; D019175:DNA Methylation; D000077209:Decitabine; D004742:Enhancer Elements, Genetic; D044127:Epigenesis, Genetic; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008297:Male; D008875:Middle Aged; D020411:Oligonucleotide Array Sequence Analysis; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D011470:Prostatic Hyperplasia / Q000235:genetics / Q000378:metabolism*; D011471:Prostatic Neoplasms / Q000235:genetics / Q000378:metabolism*; D013447:Sulfites / Q000737:chemistry; D046888:Tissue Array Analysis; D000073869:Tobacco Smoking / Q000009:adverse effects*; D015262:Xenobiotics / Q000737:chemistry
chemical_list: D013447:Sulfites; D015262:Xenobiotics; D000077209:Decitabine; C569463:CYP1A1 protein, human; D019363:Cytochrome P-450 CYP1A1; D001374:Azacitidine; C042345:hydrogen sulfite
keywords: cytochrome P450 1A1; methylation; prostate cancer; tobacco smoking