Black raspberry restores the expression of the tumor suppressor p120ctn in the oral cavity of mice treated with the carcinogen dibenzo[a,l]pyrene diol epoxide
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ABSTRACT:
SUBMITTER: Stairs D
PROVIDER: S-EPMC8594836 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:We previously showed that metabolic activation of the environmental and tobacco smoke constituent dibenzo[a,l]pyrene (DB[a,l]P) to its active fjord region diol epoxide (DB[a,l]PDE) is required to induce DNA damage, mutagenesis, and squamous cell carcinoma (SCC) in the mouse oral cavity. In contrast to procarcinogens, which were employed previously to induce SCC, DB[a,l]PDE does not require metabolic activation to exert its biological effects, and thus, this study was initiated to examine, for the first time, whether black raspberry powder (BRB) inhibits postmetabolic processes, such as DNA damage, mutagenesis, and tumorigenesis. Prior to long-term chemoprevention studies, we initially examined the effect of BRB (5% added to AIN-93M diet) on DNA damage in B6C3F1 mice using LC/MS-MS and on mutagenesis in the lacI gene in the mouse oral cavity. We showed that BRB inhibited DB[a,l]PDE-induced DNA damage (P < 0.05) and mutagenesis (P = 0.053) in the oral cavity. Tumor incidence in the oral cavity (oral mucosa and tongue) of mice fed diet containing 5% BRB was significantly (P < 0.05) reduced from 93% to 66%. Specifically, the incidence of benign tumor was significantly (P < 0.001) reduced from 90% to 31% (62% to 28% in the oral cavity and 28% to 2% in the tongue), a nonsignificant reduction of malignant tumors from 52% to 45%. Our preclinical findings demonstrate for the first time that the chemopreventive efficacy of BRB can be extended to direct-acting carcinogens that do not require phase I enzymes and is not just limited to procarcinogens. Cancer Prev Res; 11(3); 157-64. ©2017 AACR.
| S-EPMC5839973 | biostudies-literature
Project description:Dibenzo[a,l]pyrene (DB[a,l]P) (dibenzo[def,p]chrysene) is a highly carcinogenic polycyclic aromatic hydrocarbon (PAH) that has been identified in tobacco smoke and is found in our environment due to incomplete combustion of organic matter. Its metabolites are known to form stable DNA adducts in bacteria and mammalian cells, and can lead to tumors in animal models. Glucuronidation of major metabolites of DB[a,l]P by the uridine-5'-diphosphate glucuronosyltransferase (UGT) family of enzymes is an important route of detoxification of this pro-carcinogen. The focus of the current study was to characterize the glucuronidation of the pro-carcinogenic enantiomers DB[a,l]P-(+)-trans-11S,12S-diol and DB[a,l]P-(-)-trans-11R,12R-diol. Glucuronidation assays with HEK293 cell lines overexpressing individual human UGT enzymes demonstrated that UGTs 1A1, 1A4, 1A7, 1A8, 1A9, 1A10, and 2B7 glucuronidated one or both DB[a,l]P-trans-11,12-diol enantiomers. Three glucuronide conjugates were observed in activity assays with UGTs 1A1 and 1A10, while two glucuronides were formed by UGTs 1A7, 1A8, and 1A9, and one glucuronide was made by UGT1A4 and UGT2B7. Enzyme kinetic analysis indicated that UGT1A9 was the most efficient UGT at forming both the (+)-DB[a,l]P-11-Gluc and (-)-DB[a,l]P-11-Gluc products, while UGTs 1A1 and 1A10 were the most efficient at forming the (+)-DB[a,l]P-12-Gluc product (as determined by k(cat)/K(M)). Incubations with human liver microsomes showed the formation of three diastereomeric glucuronide products: (+)-DB[a,l]P-11-Gluc, (+)-DB[a,l]P-12-Gluc, and (-)-DB[a,l]P-11-Gluc, with an average overall ratio of 31:32:37 in four liver specimens. Human bronchus and trachea tissue homogenates demonstrated glucuronidation activity against both DB[a,l]P-trans-11,12-diol enantiomers, with both tissues producing the (+)-DB[a,l]P-11-Gluc and (+)-DB[a,l]P-12-Gluc with little or no formation of (-)-DB[a,l]P-11-Gluc. These results indicate that multiple UGTs are involved in the stereospecific glucuronidation of DB[a,l]P-trans-11,12-diol in a pattern consistent with their expression in respiratory tract tissues and that glucuronidation may be an important first-line detoxification mechanism of DB[a,l]P metabolites.
| S-EPMC3177992 | biostudies-literature
Project description:Genotoxic agents cause cellular DNA damage and stress responses, including transcriptional changes. Here we focused on the early transcriptional responses of human cells to benzo(a)pyrene diol epoxide (BPDE), which causes bulky DNA adduct damage. Human amnion epithelial FL cells were exposed to three doses of BPDE (5, 50, and 500 nM) and the vehicle control DMSO, and differential gene expression profiles were obtained 4 h after exposure using oligonucleotide microarrays followed by validation with quantitative real-time RT-PCR. Compared with a few genes affected by the low and medium-dose exposure, extensive and robust changes in gene expression were induced by the high-dose BPDE. We found that the expression of cell cycle-regulators, signaling molecules and transcription factors were significantly altered and important signaling pathways related to cell survival or apoptosis were affected by BPDE. Several genes and related regulatory pathways that were previously not known to be responsive to this genotoxic agent have now been implicated, which helps to draw the whole picture of how cells respond to environmental chemical exposure via transcriptional regulation. Experiment Overall Design: Human amnion epithelial FL cells were exposed to vehicle control (dimethyl sulfoxide) and increasing doses (5, 50, 500 nM) of anti-benzo(a)pyrene diol epoxide (anti-BPDE), respectively. The transcriptomes of the three treatments were compared to that of the control, respectively, to test the hypothesis that a characterized differential expression profile would be generated by exposure to various doses of this genotoxic agent.
2008-04-08 | E-GEOD-7675 | biostudies-arrayexpress
Project description:Genotoxic agents cause cellular DNA damage and stress responses, including transcriptional changes. Here we focused on the early transcriptional responses of human cells to benzo(a)pyrene diol epoxide (BPDE), which causes bulky DNA adduct damage. Human amnion epithelial FL cells were exposed to three doses of BPDE (5, 50, and 500 nM) and the vehicle control DMSO, and differential gene expression profiles were obtained 4 h after exposure using oligonucleotide microarrays followed by validation with quantitative real-time RT-PCR. Compared with a few genes affected by the low and medium-dose exposure, extensive and robust changes in gene expression were induced by the high-dose BPDE. We found that the expression of cell cycle-regulators, signaling molecules and transcription factors were significantly altered and important signaling pathways related to cell survival or apoptosis were affected by BPDE. Several genes and related regulatory pathways that were previously not known to be responsive to this genotoxic agent have now been implicated, which helps to draw the whole picture of how cells respond to environmental chemical exposure via transcriptional regulation. Keywords: Dose response
2008-01-01 | GSE7675 | GEO
Project description:Poly(ADP-ribosyl)ation (PARylation) is a complex and reversible posttranslational modification catalyzed by poly(ADP-ribose)polymerases (PARPs), which orchestrates protein function and subcellular localization. The function of PARP1 in genotoxic stress response upon induction of oxidative DNA lesions and strand breaks is firmly established, but its role in the response to chemical-induced, bulky DNA adducts is understood incompletely. To address the role of PARP1 in the response to bulky DNA adducts, we treated human cancer cells with benzo[a]pyrene 7,8-dihydrodiol-9,10-epoxide (BPDE), which represents the active metabolite of the environmental carcinogen benzo[a]pyrene [B(a)P], in nanomolar to low micromolar concentrations. Using a highly sensitive LC-MS/MS method, we revealed that BPDE induces cellular PAR formation in a time- and dose-dependent manner. Consistently, PARP1 activity significantly contributed to BPDE-induced genotoxic stress response. On one hand, PARP1 ablation rescued BPDE-induced NAD+ depletion and protected cells from BPDE-induced short-term toxicity. On the other hand, strong sensitization effects of PARP inhibition and PARP1 ablation were observed in long-term clonogenic survival assays. Furthermore, PARP1 ablation significantly affected BPDE-induced S- and G2-phase transitions. Together, these results point towards unresolved BPDE-DNA lesions triggering replicative stress. In line with this, BPDE exposure resulted in enhanced formation and persistence of DNA double-strand breaks in PARP1-deficient cells as evaluated by microscopic co-localization studies of 53BP1 and ?H2A.X foci. Consistently, an HPRT mutation assay revealed that PARP inhibition potentiated the mutagenicity of BPDE. In conclusion, this study demonstrates a profound role of PARylation in BPDE-induced genotoxic stress response with significant functional consequences and potential relevance with regard to B[a]P-induced cancer risks.
| S-EPMC5866831 | biostudies-other
Project description:Cellular responses to carcinogens are typically studied in transformed cell lines, which do not reflect the physiological status of normal tissues. To address this question, we have characterized the transcriptional program and cellular responses of normal human lung WI-38 fibroblasts upon exposure to the ultimate carcinogen benzo[a]pyrene diol epoxide (BPDE). Exposure to BPDE induces a strong inflammatory response in WI-38 primary fibroblasts. Whole-genome microarray analysis shows induction of several genes related to the production of inflammatory factors, including those that encode interleukins (ILs), growth factors, and enzymes related to prostaglandin synthesis and signaling. This is the first demonstration that a strong inflammatory response is triggered in primary fibroblasts in response to a reactive diol epoxide derived from a polycyclic aromatic hydrocarbon.
2010-01-01 | GSE19510 | GEO
Project description:A diastereoselective synthesis of the nucleoside adducts corresponding to a cis ring-opening of the carcinogen (+/-)-7 beta, 8 alpha-dihydroxy-9 alpha,10 alpha-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BaP DE-2) by 2'-deoxyadenosine and 2'-deoxyguanosine is described. The key intermediate (+/-)-10alpha-amino-7beta,8alpha,9alpha-trihydroxy-7,8,9,10-tetrahydrobenzo[a]pyrene was synthesized by a highly diastereoselective dihydroxylation wherein phenylboronic acid was a water surrogate. The resulting boronate ester was converted to a tetraol derivative in which two of the four hydroxyl groups (trans 7, 8) were protected as benzoate esters while the remaining two (cis 9, 10) were free. The cis glycol entity was then subjected to a reaction with 1-chlorocarbonyl-1-methylethylacetate to yield an intermediate chloro monoacetoxy dibenzoate. Displacement of the halide with azide, complete cleavage of the esters, and catalytic reduction of the azide yielded the requisite amino triol. Fluoride displacement from appropriately protected nucleoside derivatives, 6-fluoropurine 2'-deoxyribonucleoside and 2-fluoro-2'-deoxyinosine, by the amino triol then yielded diastereomeric pairs of diol epoxide-adducted 2'-deoxyadenosine (dA) and 2'-deoxyguanosine (dG) nucleosides. Small aliquots of these adducts were separated for characterization purposes. The present approach provides the first diastereoselective synthesis of the cis adducts of BaP DE-2 with 2'-deoxyguanosine as well as the first synthesis of both dA and dG adducts from a common intermediate. An informative analysis of the 1H NMR spectra of the cis adducts synthesized and comparisons to the trans adducts are reported. To gain insight into the diastereoselectivity in the key dihydroxylation step, a computational analysis, including molecular mechanics (MMFF94) and semiempirical AM1 geometry optimizations, yielded results that are in fairly good agreement with the experimental observations.
| S-EPMC2659345 | biostudies-literature
Project description:The first occupation-associated cancers to be recognized were the sooty warts (cancers of the scrotum) suffered by chimney sweeps in 18th century England. In the 19th century, high incidences of skin cancers were noted among fuel industry workers. By the early 20th century, malignant skin tumors were produced in laboratory animals by repeatedly painting them with coal tar. The culprit in coal tar that induces cancer was finally isolated in 1933 and determined to be benzo[a]pyrene (BP), a polycyclic aromatic hydrocarbon. A residue of fuel and tobacco combustion and frequently ingested by humans, BP is metabolized in mammals to benzo[a]pyrene diol epoxide (BPDE), which forms covalent DNA adducts and induces tumor growth. In the 70 yr since its isolation, BP has been the most studied carcinogen. Yet, there has been no crystal structure of a BPDE DNA adduct. We report here the crystal structure of a BPDE-adenine adduct base-paired with thymine at a template-primer junction and complexed with the lesion-bypass DNA polymerase Dpo4 and an incoming nucleotide. Two conformations of the BPDE, one intercalated between base pairs and another solvent-exposed in the major groove, are observed. The latter conformation, which can be stabilized by organic solvents that reduce the dielectric constant, seems more favorable for DNA replication by Dpo4. These structures also suggest a mechanism by which mutations are generated during replication of DNA containing BPDE adducts.
| S-EPMC356939 | biostudies-literature
Project description:Tobacco smoke is an important risk factor for various human cancers, including esophageal cancer. How benzo [a]pyrene diol epoxide (BPDE), a carcinogen present in tobacco smoke as well as in environmental pollution, induces esophageal carcinogenesis has yet to be defined. In this study, we investigated the molecular mechanism responsible for BPDE-suppressed expression of retinoic acid receptor-beta2 (RAR-beta2) in esophageal cancer cells. We treated esophageal cancer cells with BPDE before performing methylation-specific polymerase chain reaction (MSP) to find that BPDE induced methylation of the RAR-beta2 gene promoter. We then performed chromatin immunoprecipitation (ChIP) assays to find that BPDE recruited genes of the methylation machinery into the RAR-beta2 gene promoter. We found that BPDE recruited DNA (cytosine-5-)-methyltransferase 3 alpha (DNMT3A), but not beta (DNMT3B), in a time-dependent manner to methylate the RAR-beta2 gene promoter, which we confirmed by reverse transcription-polymerase chain reaction (RT-PCR) analysis of the reduced RAR-beta2 expression in these BPDE-treated esophageal cancer cell lines. However, BPDE did not significantly change DNMT3A expression, but it slightly reduced DNMT3B expression. DNA methylase inhibitor 5-aza-2'-deoxycytidine (5-Aza) and DNMT3A small hairpin RNA (shRNA) vector antagonized the effects of BPDE on RAR-beta2 expressions. Transient transfection of the DNMT3A shRNA vector also antagonized BPDE's effects on expression of RAR-beta2, c-Jun, phosphorylated extracellular signal-regulated protein kinases 1/2 (ERK1/2), and cyclooxygenase-2 (COX-2), suggesting a possible therapeutic effect. The results of this study form the link between the esophageal cancer risk factor BPDE and the reduced RAR-beta2 expression.
| S-EPMC2867823 | biostudies-literature
Project description:The mutagen sensitivity assay is an in vitro measure of DNA repair capacity used to evaluate intrinsic susceptibility for cancer. The high heritability of mutagen sensitivity to different mutagens validates the use of this phenotype to predict cancer susceptibility. However, genetic determinants of mutagen sensitivity have not been fully characterized. Recently, several studies found that three major cytosine DNA methyltransferases (DNMTs), especially DNMT1, have a direct role in the DNA damage response, independent of their methyltransferase activity. This study evaluated the hypothesis that sequence variants in DNMT1, DNMT3A and DNMT3B are associated with mutagen sensitivity induced by the tobacco carcinogen benzo[a]pyrene diol epoxide (BPDE) in 278 cancer-free smokers. Single-nucleotide polymorphisms (n = 134) dispersed over the entire gene and regulatory regions of these DNMTs were genotyped by the Illumina Golden Gate Assay. DNA sequence variation in the DNMT1 and DNMT3B loci was globally associated with breaks per cell (P < 0.04 for both). No global association between DNMT3A and breaks per cell was seen (P = 0.09). Two haplotypes in block1 of DNMT1 (H284) and 3B (H70) were associated with 16 and 24% increase in breaks per cell, respectively. Subjects with three or four adverse haplotypes of both DNMT1 and 3B had a 50% elevation in mean level of breaks per cell compared with persons without adverse alleles (P = 0.004). The association between sequence variants of DNMT1 and 3B and mutagen sensitivity induced by BPDE supports the involvement of these DNMTs in protecting the cell from DNA damage.
| S-EPMC2899849 | biostudies-literature