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Impaired dacarbazine activation and 7-ethoxyresorufin deethylation in vitro by polymorphic variants of CYP1A1 and CYP1A2: implications for cancer therapy. Pharmacogenet Genomics 2017; 26:453-61. [PMID: 27428168 DOI: 10.1097/fpc.0000000000000236] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
OBJECTIVES To extend our understanding of how interindividual variability mediates the efficacy of cancer treatment. MATERIALS AND METHODS The kinetics of dacarbazine (DTIC) N-demethylation by the most frequent polymorphic variants of CYP1A1 (T461N, I462V) and CYP1A2 (F186L, D348N, I386F, R431W, R456H) were characterized, along with kinetic parameters for the O-deethylation of the prototypic CYP1A substrate 7-ethoxyresorufin, using recombinant protein expression and high-performance liquid chromatographic techniques. RESULTS A reduction of ∼30% in the catalytic efficiencies (measured as in-vitro intrinsic clearance, CLint) was observed for DTIC N-demethylation by the two CYP1A1 variants relative to wild type. Although a modest increase in the CLint value for DTIC N-demethylation was observed for the CYP1A2 D348N variant relative to the wild type, the CLint for the F186L variant was reduced and the I386F, R431W, and R456H variants all showed loss of catalytic function. CONCLUSION Comparison of the kinetic data for DTIC N-demethylation and 7-ethoxyresorufin O-deethylation indicated that alterations in the kinetic parameters (Km, Vmax, CLint) observed with each of the CYP1A1 and CYP1A2 polymorphic variants were substrate dependent. These data indicate that cancer patients treated with DTIC who possess any of the CYP1A1-T461N and I462V variants or the CYP1A2-F186L, D348N, I386F, R431W, and R456H variants are likely to have decreased prodrug activation, and hence may respond less favorably to DTIC treatment compared with individuals with wild-type CYP1A alleles.
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Identification of novel potential genetic predictors of urothelial bladder carcinoma susceptibility in Pakistani population. Fam Cancer 2017; 16:577-594. [DOI: 10.1007/s10689-017-9991-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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Bobrowska-Korczak B, Skrajnowska D, Tokarz A. The effect of dietary zinc--and polyphenols intake on DMBA-induced mammary tumorigenesis in rats. J Biomed Sci 2012; 19:43. [PMID: 22507225 PMCID: PMC3352242 DOI: 10.1186/1423-0127-19-43] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2012] [Accepted: 04/16/2012] [Indexed: 12/18/2022] Open
Abstract
Background The aim of the study was to investigate the effect of dietary supplementation with zinc and polyphenol compounds, i.e. resveratrol and genistein, on the effectiveness of chemically induced mammary cancer and the changes in the content of selected elements (Zn, Cu, Mg, Fe, Ca) in tumors as compared with normal tissue of the mammary gland. Methods Female Sprague-Dawley rats were divided into study groups which, apart from the standard diet and DMBA (7,12-dimethyl-1,2- benz[a]anthracene), were treated with zinc ions (Zn) or zinc ions + resveratrol (Zn + resveratrol) or zinc ions + genistein (Zn + genistein) via gavage for a period from 40 days until 20 weeks of age. The ICP-OES (inductively coupled plasma optical emission spectrometry) technique was used to analyze the following elements: magnesium, iron, zinc and calcium. Copper content in samples was estimated in an atomic absorption spectrophotometer. Results Regardless of the diet (standard; Zn; Zn + resveratrol; Zn + genistein), DMBA-induced breast carcinogenesis was not inhibited. On the contrary, in the Zn + resveratrol supplemented group, tumorigenesis developed at a considerably faster rate. On the basis of quantitative analysis of selected elements we found - irrespectively of the diet applied - great accumulation of copper and iron, which are strongly prooxidative, with a simultaneous considerable decrease of the magnesium content in DMBA-induced mammary tumors. The combination of zinc supplementation with resveratrol resulted in particularly large differences in the amount of the investigated elements in tumors as compared with their content in normal tissue. Conclusions Diet supplementation with zinc and polyphenol compounds, i.e. resveratrol and genistein had no effect on the decreased copper level in tumor tissue and inhibited mammary carcinogenesis in the rat. Irrespectively of the applied diet, the development of the neoplastic process in rats resulted in changes of the iron and magnesium content in the cancerous tissue in comparison with the healthy mammary tissue. The application of combined diet supplementation with zinc ions and resveratrol considerably promoted the rate of carcinogenesis and increased the number of DMBA-induced mammary tumors.
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Affiliation(s)
- Barbara Bobrowska-Korczak
- Department of Bromatology, Faculty of Pharmacy, Medical University of Warsaw, Banacha 1, Warsaw 02-097, Poland
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Chakrabarti S, Ghanekar Y, Kaur K, Kaur I, Mandal AK, Rao KN, Parikh RS, Thomas R, Majumder PP. A polymorphism in the CYP1B1 promoter is functionally associated with primary congenital glaucoma. Hum Mol Genet 2010; 19:4083-90. [DOI: 10.1093/hmg/ddq309] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Salama SA, Kamel MW, Diaz-Arrastia CR, Xu X, Veenstra TD, Salih S, Botting SK, Kumar R. Effect of tumor necrosis factor-alpha on estrogen metabolism and endometrial cells: potential physiological and pathological relevance. J Clin Endocrinol Metab 2009; 94:285-93. [PMID: 18957495 PMCID: PMC2630861 DOI: 10.1210/jc.2008-1389] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
CONTEXT Estrogen and its metabolites play a critical role in the pathophysiology of the endometrium. The bioavailability of estrogen and estrogen metabolites in endometrial tissues depends on the expression of enzymes involved in estrogen biosynthesis and metabolism. Substantial evidence indicates that estrogen-dependent endometrial disorders are also associated with proinflammatory milieu. However, the mechanism whereby inflammation contributes to these conditions is not known. OBJECTIVE The objective of the study was to investigate the effect of TNF-alpha on estrogen metabolism and the expression of estrogen-metabolizing genes in human endometrial glandular epithelial cells (EM1). DESIGN EM1 were treated with 17beta-estradiol (E2) with or without TNF-alpha. Capillary liquid chromatography-tandem mass spectrometry analysis was used for quantitative measurement of estrogens and estrogen metabolites. Western blot analysis, reporter gene assay, and real-time RT-PCR were used to assess the expression of estrogen-metabolizing genes. RESULTS TNF-alpha treatment significantly increased the level of total estrogen and estrogen metabolites and significantly increased the rate of conversion of estrone (E1) into E2. TNF-alpha also enhanced the oxidative metabolism of estrogen into catecholestrogens with concomitant inhibition of their conversion into methoxyestrogens. Gene expression analysis revealed that TNF-alpha induced the expression of genes involved in E2 biosynthesis (steroidogenic factor-1 and aromatase) and activation (17beta- hydroxysteroid dehydrogenase type 1 and cytochrome P-450, 1B1) with simultaneous repression of genes involved in estrogen inactivation (17beta-hydroxysteroid dehydrogenase type 2; catechol O-methyltransferase; and nicotinamide adenine dinucleotide phosphate-quinone oxidoreductase 1). CONCLUSION TNF-alpha increases the local estrogen biosynthesis in human endometrial glandular cells and directs estrogen metabolism into more hormonally active and carcinogenic metabolites. These effects may impact many physiological and pathological processes that occur within the endometrium.
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Affiliation(s)
- Salama A Salama
- Division of Gynecologic Oncology, Department of Obstetrics and Gynecology, University of Texas Medical Branch at Galveston, 300 University Boulevard, Galveston, Texas 77555, USA.
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Crous-Bou M, De Vivo I, Porta M, Pumarega JA, López T, Alguacil J, Morales E, Malats N, Rifà J, Hunter DJ, Real FX. CYP1B1 polymorphisms and k-ras mutations in patients with pancreatic ductal adenocarcinoma. Dig Dis Sci 2008; 53:1417-21. [PMID: 18347981 DOI: 10.1007/s10620-008-0235-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2007] [Accepted: 02/28/2007] [Indexed: 12/21/2022]
Abstract
The frequency of CYP1B1 polymorphisms in pancreatic cancer has never been reported. There is also no evidence on the relationship between CYP1B1 variants and mutations in ras genes (K-, H- or N-ras) in any human neoplasm. We analyzed the following CYP1B1 polymorphisms in 129 incident cases of pancreatic ductal adenocarcinoma (PDA): the m1 allele (Val to Leu at codon 432) and the m2 allele (Asn to Ser at codon 453). The calculated frequencies for the m1 Val and m2 Asn alleles were 0.45 and 0.68, respectively. CYP1B1 genotypes were out of Hardy-Weinberg equilibrium; this was largely due to K-ras mutated PDA cases. The Val/Val genotype was over five times more frequent in PDA cases with a K-ras mutation than in wild-type cases (OR = 5.25; P = 0.121). In PDA, polymorphisms in CYP1B1 might be related with K-ras activation pathways.
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Affiliation(s)
- Marta Crous-Bou
- Institut Municipal d'Investigació Mèdica (IMIM), CIBER de Epidemiología y Salud Pública (CIBERESP), Barcelona, Spain
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Gaudet MM, Chanock S, Lissowska J, Berndt SI, Yang XR, Peplonska B, Brinton LA, Welch R, Yeager M, Bardin-Mikolajczak A, Sherman ME, Sutter TR, Garcia-Closas M. Genetic variation of Cytochrome P450 1B1 (CYP1B1) and risk of breast cancer among Polish women. Pharmacogenet Genomics 2006; 16:547-53. [PMID: 16847423 DOI: 10.1097/01.fpc.0000215067.29342.6f] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Four single nucleotide polymorphisms (SNPs) in CYP1B1 (Ex2 + 143 C > G, Ex2 + 356 G > T, Ex3 + 251 G > C, Ex3 + 315 A > G) cause amino acid changes (R48G, A119S, L432V and N453S, respectively) and are associated with increased formation of catechol estrogens; however, epidemiologic evidence only weakly supports an association between these variants and breast cancer risk. Because genetic variability conferring increased susceptibility could exist beyond these putative functional variants, we comprehensively examined the common genetic variability within CYP1B1. A total of eight haplotype-tagging (ht)SNPs (including Ex3 + 315 A > G), in addition to two putatively functional SNPs (Ex2 + 143 C > G and Ex3 + 251 G > C), were selected and genotyped in a large case-control study of Polish women (1995 cases and 2296 controls). Haplotypes were estimated using the expectation-maximization algorithm, and overall differences in the haplotype distribution between cases and controls were assessed using a global score test. We also evaluated levels of tumor CYP1B1 protein expression in a subset of 841 cases by immunohistochemistry, and their association with genetic variants. In the Polish population, we observed two linkage disequilibrium (LD)-defined blocks. Neither haplotypes (global P-value of 0.99 and 0.67 for each block of LD, respectively), nor individual SNPs (including three putatively functional SNPs) were associated with breast cancer risk. CYP1B1 was expressed in most tumor tissues (98%), and the level of expression was not related to the studied genetic variants. We found little evidence for modification of the estimated effect of haplotypes or individual SNPs by age, family history of breast cancer, or tumor hormone receptor status. The present study provides strong evidence against the existence of a substantial overall association between common genetic variation in CYP1B1 and breast cancer risk.
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Affiliation(s)
- Mia M Gaudet
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, Department of Health and Human Services, Bethesda, Maryland 20852, USA.
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Han W, Cauchi S, Herman JG, Spivack SD. DNA methylation mapping by tag-modified bisulfite genomic sequencing. Anal Biochem 2006; 355:50-61. [PMID: 16797472 DOI: 10.1016/j.ab.2006.05.010] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2006] [Revised: 04/13/2006] [Accepted: 05/09/2006] [Indexed: 11/25/2022]
Abstract
A tag-modified bisulfite genomic sequencing (tBGS) method employing direct cycle sequencing of polymerase chain reaction (PCR) products at kilobase scale, without conventional DNA fragment cloning, was developed for simplified evaluation of DNA methylation sites. The method entails subjecting bisulfite-modified genomic DNA to a second-round PCR amplification employing GC-tagged primers. Qualitative results from tBGS closely correlated with those from conventional BGS (R=0.935, p=0.002). In application, the intertissue and interindividual CpG methylation differences in promoter sequence for two genes, CYP1B1 and GSTP1, were then explored across four human tissue types (peripheral blood cells, exfoliated buccal cells, paired nontumor-tumor lung tissues), and two lung cell types in culture (normal NHBE and malignant A549). Predominantly conserved methylation maps for the two gene promoters were apparent across donors and tissues. At any given CpG site, variation in the degree of methylation could be determined by the relative height of C and T peaks in the sequencing trace. Methylation maps for the GSTP1 promoter diverged between NHBE (unmethylated) and A549 (completely methylated) cells in a previously unexplored upstream region, correlating with a 2.7-fold difference in GSTP1 mRNA expression (p<0.01). The tBGS method simplifies detailed methylation scanning of kilobase-scale genomic DNA, facilitating more ambitious genomic methylation mapping studies.
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Affiliation(s)
- Weiguo Han
- Laboratory of Human Toxicology and Molecular Epidemiology, Wadsworth Center, NYS Department of Health, Albany, NY 12201, USA
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Larsen JE, Colosimo ML, Yang IA, Bowman R, Zimmerman PV, Fong KM. Risk of non-small cell lung cancer and the cytochrome P4501A1 Ile462Val polymorphism. Cancer Causes Control 2005; 16:579-85. [PMID: 15986113 DOI: 10.1007/s10552-004-7842-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2004] [Accepted: 12/20/2004] [Indexed: 10/25/2022]
Abstract
OBJECTIVE The Ile462Val substitution in the cytochrome P450 1A1 gene (CYP1A1) results in increased enzymatic activity. Preliminary data suggesting a link between this polymorphism and lung cancer risk in Caucasians are inconsistent, reflecting small sample sizes and the relatively low frequency of the variant. METHODS The data set consisted of 1050 primary non-small cell lung cancer cases and 581 controls, a large homogenous population designed specifically to address previous inconsistencies. Patients were genotyped using a PCR-RFLP technique. RESULTS Carriers of the valine allele, CYP1A1*2C, (Ile/Val or Val/Val genotypes) were significantly over-represented in non-small cell lung cancer compared to controls (OR=1.9; 95% CI=1.2-2.9; p=0.005) when adjusted for confounders, particularly in women (OR=4.6; 95% CI=1.7-12.4; p=0.003). The valine variant was statistically significantly over-represented in cases of lung cancer younger than the median age (64 years) (OR=2.5; 95% CI=1.3-4.8; p=0.005) and cases with less than the median cumulative tobacco-smoke exposure (46 pack-years) (OR=2.4; 95% CI=1.3-4.7; p=0.007). CONCLUSIONS These new data establish an association between the CYP1A1 Ile462Val polymorphism and the risk of developing non-small cell lung cancer, especially among women.
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Affiliation(s)
- Jill Everland Larsen
- Department of Thoracic Medicine, The Prince Charles Hospital, Brisbane, Australia.
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Han W, Pentecost BT, Pietropaolo RL, Fasco MJ, Spivack SD. Estrogen receptor alpha increases basal and cigarette smoke extract-induced expression of CYP1A1 and CYP1B1, but not GSTP1, in normal human bronchial epithelial cells. Mol Carcinog 2005; 44:202-11. [PMID: 16010691 PMCID: PMC1266285 DOI: 10.1002/mc.20128] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Gender-specific estrogen receptor alpha (ERalpha) expression may plausibly influence lung carcinogenesis in females. Initial genome-wide microarray studies confirmed that carcinogen metabolism genes (CYP1A1, CYP1B1) were those most responsive to cigarette smoke extract (CSE) in normal bronchial epithelial (NHBE) cells. These two genes encoding phase I bioactivating enzymes and the GSTP1 gene encoding a phase II deactivating enzyme were then tested for induction by ERalpha. NHBE cells (native ERalpha-) were transfected with wild-type ERalpha-adenoviral constructs, and then exposed to CSE, 17beta-estradiol (E2), and/or the ERalpha inhibitor, ICI 182,780. The expression levels of CYP1A1, CYP1B1, and GSTP1 were then determined by RNA-specific quantitative RT-PCR and immunoassay. ERalpha increased the basal expression of CYP1B1 4.04-fold (P < 0.01) at the mRNA level and 6.5-fold at the protein level. ERalpha also increased the CSE-induced mRNA expression of CYP1B1 2.26-fold (P < 0.01), but not the protein expression. ERalpha did not alter the CYP1A1 mRNA levels, but did increase protein expression 2.0-fold (P < 0.01) on CSE exposure, and 6.2-fold (P < 0.01) upon E2 exposure. These effects could be inhibited by ICI 182,780. ERalpha did not alter the expression of GSTP1. Chromatin immunoprecipitation assay (ChIP) assay confirmed ERalpha binding to CYP1B1 promoter near the transcription start site. These results suggest that ERalpha regulates the CYP1B1 expression at a transcriptional level, and CYP1A1 expression at a translational level. These data raise the possibility that inter-gender differences in expression of ERalpha that are known to exist in human lung may contribute to inter-individual expression differences in CYP1A1 and CYP1B1, and to differences in carcinogen metabolism and mutation.
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Affiliation(s)
- W Han
- Laboratory of Human Toxicology & Molecular Epidemiology, Wadsworth Center, NYS Department of Health, Albany, New York 12201-0509, USA
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Kumar SV, Jain R, Mokhiber K, Venezia A, Sheehan A, Spivack SD. Exfoliated buccal and microdissected lung cell expression of antioxidant enzymes. ACTA ACUST UNITED AC 2005; 29:552-61. [PMID: 16289618 DOI: 10.1016/j.cdp.2005.09.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/23/2005] [Indexed: 12/31/2022]
Abstract
INTRODUCTION An exfoliated buccal cell biomarker assay for antioxidant gene transcript levels was used to measure inter-tissue concordance with lung, and inter-subject variability in a lung cancer case-control study. METHODS First, qualitative RNA-specific RT-PCR was used to compare expression in exfoliated buccal cells with that in laser microdissected lung tissue remote from the tumor from 14 individuals providing both specimens. RESULTS There was complete [100% for quinone oxidoreductase 1 (NQO1), glutathione peroxidase (GPX), and superoxide dismutase 1 (SOD1)], or predominant [85.7% for catalase (CAT)] inter-tissue concordance for qualitative expression. Second, quantitative real-time RT-PCR for antioxidant enzyme transcript levels was performed in exfoliated buccal samples from these same 14 individuals, as well as 28 additional individuals providing buccal cells only, for a total of 42 buccal specimens (19 current smokers and 23 ex- or never-smokers), of whom 26 (61.39%) had a new diagnosis of lung cancer. DISCUSSION Wide inter-individual expression differences for each gene transcript (>10(1)-10(4)-fold) were observed in the exfoliated buccal cells, unrelated to smoking and case-control status. In multivariate analyses, family history of tobacco-related malignancy correlated inversely with buccal NQO1 and CAT mRNA levels (p=0.003, p<0.001, respectively). This antioxidant expression trait may relate to family risk of cancer, but is notably unrelated to oxidant challenges inherent in cigarette smoke.
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Affiliation(s)
- Shalini V Kumar
- Laboratory of Human Toxicology and Molecular Epidemiology, Wadsworth Center, New York State Department of Health, P.O. Box 509, Albany, NY 12201-0509, USA
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Spivack SD, Hurteau GJ, Jain R, Kumar SV, Aldous KM, Gierthy JF, Kaminsky LS. Gene-environment interaction signatures by quantitative mRNA profiling in exfoliated buccal mucosal cells. Cancer Res 2004; 64:6805-13. [PMID: 15375000 DOI: 10.1158/0008-5472.can-04-1771] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Exfoliated cytologic specimens from mouth (buccal) epithelium may contain viable cells, permitting assay of gene expression for direct and noninvasive measurement of gene-environment interactions, such as for inhalation (e.g., tobacco smoke) exposures. We determined specific mRNA levels in exfoliated buccal cells collected by cytologic brush, using a recently developed RNA-specific real-time quantitative reverse transcription-PCR strategy. In a pilot study, metabolic activity of exfoliated buccal cells was verified by 3-[4,5-dimethylthiazol-2-yl]-2,5- diphenyltetrazolium assay in vitro. Transcriptional activity was observed, after timed in vivo exposure to mainstream tobacco smoke resulted in induction of CYP1B1 in serially collected buccal samples from the one subject examined. For a set of 11 subjects, mRNA expression of nine genes encoding carcinogen- and oxidant-metabolizing enzymes qualitatively detected in buccal cells was then shown to correlate with that in laser-microdissected lung from the same individuals (Chi2 = 52.91, P < 0.001). Finally, quantitative real-time reverse transcription-PCR assays for seven target gene (AhR, CYP1A1, CYP1B1, GSTM1, GSTM3, GSTP1, and GSTT1) and three reference gene [glyceraldehyde-3-phosphate dehydrogenase (GAPDH), beta-actin, and 36B4] transcripts were performed on buccal specimens from 42 subjects. In multivariate analyses, gender, tobacco smoke exposure, and other factors were associated with the level of expression of CYP1B1, GSTP1, and other transcripts on a gene-specific basis, but substantial interindividual variability in mRNA expression remained unexplained. Within the power limits of this pilot study, gene expression signature was not clearly predictive of lung cancer case or control status. This noninvasive and quantitative method may be incorporated into high-throughput human applications for probing gene-environment interactions associated with cancer.
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Affiliation(s)
- Simon D Spivack
- Laboratory of Human Toxicology and Molecular Epidemiology, New York State Department of Health, Albany, NY 12201-0509, USA.
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Rodriguez-Melendez R, Griffin JB, Zempleni J. Biotin supplementation increases expression of the cytochrome P450 1B1 gene in Jurkat cells, increasing the occurrence of single-stranded DNA breaks. J Nutr 2004; 134:2222-8. [PMID: 15333708 DOI: 10.1093/jn/134.9.2222] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
DNA microarray studies provided evidence that biotin supplementation increases the abundance of mRNA encoding cytochrome P(450) 1B1 (CYP1B1) in human lymphocytes. CYP1B1 hydroxylates procarcinogens, generating electrophilic mutagens. Here, we sought to identify the signaling pathways that increase the expression of CYP1B1 in biotin-supplemented human T (Jurkat) cells and to determine whether activation of the CYP1B1 gene is associated with increased occurrence of single-stranded DNA breaks. Jurkat cells were cultured in biotin-deficient (0.025 nmol/L) and biotin-supplemented (10 nmol/L) media. The transcriptional activity of a CYP1B1 reporter gene construct was 24% greater in biotin-supplemented compared with biotin-deficient cells (P < 0.01). Similarly, the abundance of CYP1B1 mRNA was 72% greater in biotin-supplemented than in biotin-deficient cells (P < 0.05). Electrophoretic mobility shift assays suggested that Sp1 sites in the regulatory region of the CYP1B1 gene play important roles in transcriptional activation by biotin. The abundance of CYP1B1 protein and activity of CYP1B1 were 124 and 35% greater, respectively, in biotin-supplemented compared with biotin-deficient cells (P < 0.05). The increased expression of CYP1B1 in biotin-supplemented cells was associated with an increase in the occurrence of single-stranded DNA breaks compared with biotin-deficient cells; synthetic inhibitors of CYP1B1 prevented strand breaks, suggesting that the effects of biotin were specific for CYP1B1. These studies provide evidence that transcription factors with an affinity for Sp1 sites mediate transcriptional activation of the CYP1B1 gene in biotin-supplemented T cells, increasing the occurrence of single-stranded DNA breaks.
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Affiliation(s)
- Rocio Rodriguez-Melendez
- Departments of Nutrition and Health Sciences, University of Nebraska at Lincoln, Lincoln, NE, USA
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