XPC polymorphisms play a role in tissue-specific carcinogenesis: a meta-analysis

XPC participates in the initial recognition of DNA damage during the DNA nucleotide excision repair process in global genomic repair. Polymorphisms in XPC gene have been analyzed in case-control studies to assess the cancer risk attributed to these variants, but results are conflicting. To clarify the impact of XPC polymorphisms in cancer risk, we performed a meta-analysis that included 33 published case-control studies. Polymorphisms analyzed were Lys939Gln and Ala499Val. The overall summary odds ratio (OR) for the associations of the 939Gln/Gln genotype with risk of cancer was 1.01 (95% confidence interval (95% CI): 0.94-1.09), but there were statistically significant associations for lung cancer, observed for the recessive genetic model (Lys/Lys + Lys/Gln vs Gln/Gln), (OR 1.30; 95% CI: 1.113-1.53), whereas for breast cancer a reduced but nonsignificant risk was observed for the same model (OR 0.87; 95% CI: 0.74-1.01). The results for Ala499Val showed a significant overall increase in cancer risk (OR 1.15; 95% CI: 1.02-1.31), and for bladder cancer in both the simple genetic model (Ala/Ala vs Val/Val) (OR 1.30; 95% CI: 1.04-1.61) and the recessive genetic model (Ala/Ala + Ala/Val vs Val/Val) (OR 1.32; 95% CI: 1.06-1.63). Our meta-analysis supports that polymorphisms in XPC may represent low-penetrance susceptibility gene variants for breast, bladder, head and neck, and lung cancer. XPC is a good candidate for large-scale epidemiological case-control studies that may lead to improvement in the management of highly prevalent cancers.

Assessment of Occupational Genotoxic Risk among Brazilian Hairdressers

Objectives: To evaluate the genotoxic risk to hairdressers exposed daily to chemical substances such as hair dyes, waving and straightening preparations and manicurists` products by the Comet assay test (single-cell gel electrophoresis). Methods: The Comet assay was performed on blood samples from 69 female hairdressers (36.4 +/- 10.7 years old) currently employed in 21 different beauty institutes in Sao Paulo, Brazil, and on 55 female control blood donors (32.6 +/- 10.0 years old) from the Sao Paulo University Clinical Hospital blood bank. All the control subjects had occupations other than hairdresser. Comet assays were performed by evaluating 100 blood lymphocytes per individual and graded by visual score according to comet tail length. Results: The hairdressers showed a higher frequency of DNA damage revealed by Comet Score (159.8 +/- 71) when compared to the control group (125.4 +/- 64.1), and the difference was statistically significant by the Student`s t-test (P = 0.005). Multiple regression analysis showed that in addition to the hairdressers` profession, tobacco use contributed to the higher frequency of cells with comets (P < 0.05). Conclusions: The observed DNA damage could be associated with the hairdressers` occupational environment, where different chemicals are chronically manipulated and inhaled. Considering that this profession in many countries, including Brazil, is not officially regulated, more attention should focus on these professionals not only by legislative bodies but also by multidisciplinary teams able to develop and implement risk prevention and control strategies for chemical, physical and biological agents to which hairdressers are exposed.

Body mass index and risk of head and neck cancer in a pooled analysis of case-control studies in the International Head and Neck Cancer Epidemiology (INHANCE) Consortium

Methods We pooled data from 17 case-control studies including 12 716 cases and the 17 438 controls. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated for associations between body mass index (BMI) at different ages and HNC risk, adjusted for age, sex, centre, race, education, tobacco smoking and alcohol consumption. Results Adjusted ORs (95% CIs) were elevated for people with BMI at reference (date of diagnosis for cases and date of selection for controls) < 18.5 kg/m(2) (2.13, 1.75-2.58) and reduced for BMI > 25.0-30.0 kg/m(2) (0.52, 0.44-0.60) and BMI >= 30 kg/m(2) (0.43, 0.33-0.57), compared with BMI > 18.5-25.0 kg/m(2). These associations did not differ by age, sex, tumour site or control source. Although the increased risk among people with BMI < 18.5 kg/m(2) was not modified by tobacco smoking or alcohol drinking, the inverse association for people with BMI > 25 kg/m(2) was present only in smokers and drinkers. Conclusions In our large pooled analysis, leanness was associated with increased HNC risk regardless of smoking and drinking status, although reverse causality cannot be excluded. The reduced risk among overweight or obese people may indicate body size is a modifier of the risk associated with smoking and drinking. Further clarification may be provided by analyses of prospective cohort and mechanistic studies.

Is Chlamydia-infected tubal fimbria the origin of ovarian cancer?

Ovarian cancer is a highly lethal disease and its underlying biology is poorly understood. Prophylactic salpingo-oophorectomies in BRCA + women have recently implicated the fimbria as a site of origin for high-grade serous carcinoma and its intraepithelial precursors. This suggests that at least some ovarian cancers, probably the most aggressive ones, may not originate in the ovary itself, but rather may arise in the uterine tubes. Chronic inflammation is associated with carcinogenesis in several tissues, including liver, esophagogastric junction (cardia), and the uterine cervix. The mechanisms underlying the relationship between inflammation and cancer are complex and involve common pathways, in addition to DNA damage. A critical source of uterine tube inflammation is infection with Chlamydia trachomatis. We hypothesize that C. trachomatis infection may be involved in chronic tubal, inflammation and subsequent fimbrial carcinogenesis. Fimbrial intraepithelial precursors can evolve into high grade serous carcinomas that spread rapidly to the ovarian surface and peritoneum; such tumors may appear to be primary ovarian neoplasia, though in reality being a secondary malignancy. This hypothesis must be further investigated to understand the intracellular signaling pathways involved in Chlamydia infection and its heating, and their relationship to carcinogenesis in order to discover potential therapeutic molecular targets. If our hypothesis were confirmed, salpingectomy instead of ovariectomy may also become the recommended surgery for high risk women. (C) 2008 Elsevier Ltd. All rights reserved.

Homocysteine and cysteine concentrations are modified by recent exposure to environmental air pollution in Sao Paulo, Brazil

Millions of people worldwide are affected by anthropogenic air pollution derived from the combustion of fossil fuels. In this work, we tested the effects of fetal, lactation and post-weaning ambient air pollution exposure on total homocysteine (tHcy) concentrations and on a downstream pathway element, the plasma cysteine (Cys) concentration. Two similar exposure chambers (polluted and filtered chamber) were located near an area with heavy traffic in Sao Paulo, Brazil, and male Swiss mice were housed there from the pre-natal period until 3 months of age. Groups during fetal, lactation and adult periods of exposure were apportioned, and tHcy and Cys plasma concentrations were assessed when the animals were 3 months old. In our study, both the tHcy and Cys concentrations were decreased in groups that spent their final stage of life in polluted chambers, suggesting recent alterations in tHcy and Cys concentrations due to air pollution exposure. The possible relationship of these data with cardiovascular dysfunction is still a matter of controversy in animals; nevertheless, epigenetic mechanisms emerge as a possible issue to consider in the investigation of the link between air pollution and Hcy measurement. (C) 2009 Elsevier Inc. All rights reserved.

Transcriptional changes in U343 MG-a glioblastoma cell line exposed to ionizing radiation

Glioblastoma multiforme (GBM) is a highly invasive and radioresistant brain tumor. Aiming to study how glioma cells respond to gamma-rays in terms of biological processes involved in cellular responses, we performed experiments at cellular context and gene expression analysis in U343-MG-a GBM cells irradiated with 1 Gy and collected at 6 h post-irradiation. The survival rate was approximately 61% for 1 Gy and was completely reduced at 16 Gy. By performing the microarray technique, 859 cDNA clones were analyzed. The Significance Analysis of Microarray algorithm indicated 196 significant expressed genes (false discovery rate (FDR) = 0.42%): 67 down-regulated and 97 up-regulated genes, which belong to several classes: metabolism, adhesion/cytoskeleton, signal transduction, cell cycle/apoptosis, membrane transport, DNA repair/DNA damage signaling, transcription factor, intracellular signaling, and RNA processing. Differential expression patterns of five selected genes (HSPA9B, INPP5A, PIP5K1A, FANCG, and TPP2) observed by the microarray analysis were further confirmed by the quantitative real time RT-PCR method, which demonstrated an up-regulation status of those genes. These results indicate a broad spectrum of biological processes (which may reflect the radio-resistance of U343 cells) that were altered in irradiated glioma cells, so as to guarantee cell survival.

The Protective Effect of CAPE on Hepatic Ischemia/Reperfusion Injury in Rats

Background/Aims. The transcription factor nuclear factor-kappa B (NF-kappa B) exerts a pivotal role in the pathogenesis of hepatic ischemia/reperfusion (I/R) injury. Caffeic acid phenyl ester (CAPE), a potent and specific NF-kappa B inhibitor, presents protective effects on I/R injury in some tissues. This study aimed to evaluate the effect of CAPE on hepatic I/R injury in rats. Materials and methods. Wistar rats were submitted to a sham operation, 60 min ischemia, or 60 min ischemia plus saline or CAPE treatment followed by 6 h reperfusion. Liver tissue injury was evaluated by alanine aminotransferase, aspartate aminotransferase, and tissue glutathione measurement, and histological damage score. Apoptotic hepatocytes were determined by the transferase-mediated dUTP-biotin nick-end labeling assay. Hepatic neutrophil accumulation was assessed by the naphthol method. Lipid peroxidation and NF-kappa B activation were evaluated by 4-hydroxynonenal and NF-kappa B p65 immunohistochemistry, respectively. Results. Animals submitted to ischemia showed a marked increase of alanine aminotransferase and aspartate aminotransferase after reperfusion, but with lower levels in CAPE group. Tissue glutathione content declined gradually during ischemia to reperfusion and was partially recovered with CAPE treatment. The histological damage score, apoptosis index, and neutrophil infiltration, as well as 4-hydroxynonenal and NF-kappa B p65 nuclear labeling, were higher in the liver of animals submitted to I/R compared to the ischemia group. However, the CAPE treatment significantly reduced all of these alterations. Conclusions. CAPE was able to protect the liver against normothermic I/R injury in rats. This effect may be associated with the inhibition of the NF-kappa B signaling pathway and decrease of the acute inflammatory response following I/R in the liver. (C) 2008 Elsevier Inc. All rights reserved.

Folic acid supplementation during early hepatocarcinogenesis: cellular and molecular effects

Folic acid (FA) supplementation during carcinogenesis is controversial. Considering the impact of liver cancer as a public health problem and mandatory FA fortification in several countries, the role of FA supplementation in hepatocarcinogenesis should be elucidated. We evaluated FA supplementation during early hepatocarcinogenesis. Rats received daily 0.08 mg (FA8 group) or 0.16 mg (FA16 group) of FA/100 g body weight or water (CO group, controls). After a 2-week treatment, animals were subjected to the ""resistant hepatocyte"" model of hepatocarcinogenesis (initiation with diethylnitrosamine, selection/promotion with 2-acetylaminofluorene and partial hepatectomy) and euthanized after 8 weeks of treatment. Compared to the CO group, the FA16 group presented: reduced (p < 0.05) number of persistent and increased (p < 0.05) number of remodeling glutathione S-transferase (GST-P) positive preneoplastic lesions (PNL); reduced (p < 0.05) cell proliferation in persistent GST-P positive PNL; decreased (p < 0.05) hepatic DNA damage; and a tendency (p < 0.10) for decreased c-myc expression in microdissected PNL. Regarding all these parameters, no differences (p > 0.05) were observed between CO and FA8 groups. FA-treated groups presented increased hepatic levels of S-adenosylmethionine but only FA16 group presented increased S-adenosylmethionine/S-adenosylhomocysteine ratio. No differences (p > 0.05) were observed between experimental groups regarding apoptosis in persistent and remodeling GST-P positive PNL, and global DNA methylation pattern in microdissected PNL. Altogether, the FA16 group, but not the FA8 group, presented chemopreventive activity. Reversion of PNL phenotype and inhibition of DNA damage and of c-myc expression represent relevant FA cellular and molecular effects.

Differential gene expression of peripheral blood mononuclear cells from rheumatoid arthritis patients may discriminate immunogenetic, pathogenic and treatment features

This study aimed to evaluate the association between the differential gene expression profiling of peripheral blood mononuclear cells of rheumatoid arthritis patients with their immunogenetic (human leucocyte antigen shared-epitope, HLA-SE), autoimmune response [anti-cyclic citrullinated peptide (CCP) antibodies], disease activity score (DAS-28) and treatment (disease-modifying antirheumatic drugs and tumour necrosis factor blocker) features. Total RNA samples were copied into Cy3-labelled complementary DNA probes, hybridized onto a glass slide microarray containing 4500 human IMAGE complementary DNA target sequences. The Cy3-monocolour microarray images from patients were quantified and normalized. Analysis of the data using the significance analysis of microarrays algorithm together with a Venn diagram allowed the identification of shared and of exclusively modulated genes, according to patient features. Thirteen genes were exclusively associated with the presence of HLA-SE alleles, whose major biological function was related to signal transduction, phosphorylation and apoptosis. Ninety-one genes were associated with disease activity, being involved in signal transduction, apoptosis, response to stress and DNA damage. One hundred and one genes were associated with the presence of anti-CCP antibodies, being involved in signal transduction, cell proliferation and apoptosis. Twenty-eight genes were associated with tumour necrosis factor blocker treatment, being involved in intracellular signalling cascade, phosphorylation and protein transport. Some of these genes had been previously associated with rheumatoid arthritis pathogenesis, whereas others were unveiled for future research.

Constitutional hypomorphic telomerase mutations in patients with acute myeloid leukemia

Loss-of-function mutations in telomerase complex genes can cause bone marrow failure, dyskeratosis congenita, and acquired aplastic anemia, both diseases that predispose to acute myeloid leukemia. Loss of telomerase function produces short telomeres, potentially resulting in chromosome recombination, end-to-end fusion, and recognition as damaged DNA. We investigated whether mutations in telomerase genes also occur in acute myeloid leukemia. We screened bone marrow samples from 133 consecutive patients with acute myeloid leukemia and 198 controls for variations in TERT and TERC genes. An additional 89 patients from a second cohort, selected based on cytogenetic status, and 528 controls were further examined for mutations. A third cohort of 372 patients and 384 controls were specifically tested for one TERT gene variant. In the first cohort, 11 patients carried missense TERT gene variants that were not present in controls (P<0.0001); in the second cohort, TERT mutations were associated with trisomy 8 and inversion 16. Mutation germ-line origin was demonstrated in 5 patients from whom other tissues were available. Analysis of all 3 cohorts (n = 594) for the most common gene variant (A1062T) indicated a prevalence 3 times higher in patients than in controls (n = 1,110; P = 0.0009). Introduction of TERT mutants into telomerase-deficient cells resulted in loss of enzymatic activity by haploinsufficiency. Inherited mutations in TERT that reduce telomerase activity are risk factors for acute myeloid leukemia. We propose that short and dysfunctional telomeres limit normal stem cell proliferation and predispose for leukemia by selection of stem cells with defective DNA damage responses that are prone to genome instability.

An evaluation of the genotoxic and cytotoxic effects of the anti-obesity drugs sibutramine and fenproporex

Anti-obesity medications deserve special considerations at the present time due to an increasing number of overweight and obese people who require these therapeutic alternatives. Obesity is positively associated with several chronic illnesses, including cancer. In this work, we evaluated the possible genotoxic and/or cytotoxic actions of two drugs, sibutramine and fenproporex, in the doses of 10, 20 and 40 mg/kg body weight (bw), administered intraperitoneally in male Swiss mice. The genotoxic effect was analyzed by comet assay and micronucleus test. We found that both drugs increased the frequency of genotoxic damage in Swiss mice, but did not present cytotoxic activities towards the polychromatic erythrocytes of the bone marrow of these animals.

Occurrence of TRGV-BJ hybrid gene in SV40-transformed fibroblast cell lines

Illegitimate V(D)J-recombination in lymphoid malignancies involves rearrangements in immunoglobulin or T-cell receptor genes, and these rearrangements may play a role in oncogenic events. High frequencies of TRGV-BJ hybrid gene (rearrangement between the TRB and TRG loci at 7q35 and 7p14-15, respectively) have been detected in lymphocytes from patients with ataxia telangiectasia (AT), and also in patients with lymphoid malignancies. Although the TRGV-BJ gene has been described only in T-lymphocytes, we previously detected the presence of TRGV-BJ hybrid gene in the genomic DNA extracted from SV40-transformed AT5BIVA fibroblasts from an AT patient. Aiming to determine whether the AT phenotype or the SV40 transformation could be responsible for the production of the hybrid gene by illegitimate V(D)J-recombination, DNA samples were extracted from primary and SV40-transformed (normal and AT) cell lines, following Nested-PCR with TRGV- and TRBJ-specific primers. The hybrid gene was only detected in SV40-transformed fibroblasts (AT-5BIVA and MRC-5). Sequence alignment of the cloned PCR products using the BLAST program confirmed that the fragments corresponded to the TRGV-BJ hybrid gene. The present results indicate that the rearrangement can be produced in nonlymphoid cells, probably as a consequence of the genomic instability caused by the SV40-transformation, and independently of ATM gene mutation.

Isoproterenol induces primary loss of dystrophin in rat hearts: correlation with myocardial injury

The mechanism of isoproterenol-induced myocardial damage is unknown, but a mismatch of oxygen supply vs. demand following coronary hypotension and myocardial hyperactivity is the best explanation for the complex morphological alterations observed. Severe alterations in the structural integrity of the sarcolemma of cardiomyocytes have been demonstrated to be caused by isoproterenol. Taking into account that the sarcolemmal integrity is stabilized by the dystrophin-glycoprotein complex (DGC) that connects actin and laminin in contractile machinery and extracellular matrix and by integrins, this study tests the hypothesis that isoproterenol affects sarcolemmal stability through changes in the DGC and integrins. We found different sensitivity of the DGC and integrin to isoproterenol subcutaneous administration. Immunofluorescent staining revealed that dystrophin is the most sensitive among the structures connecting the actin in the cardiomyocyte cytoskeleton and the extracellular matrix. The sarcomeric actin dissolution occurred after the reduction or loss of dystrophin. Subsequently, after lysis of myofilaments, gamma-sarcoglycan, beta-dystroglycan, beta 1-integrin, and laminin alpha-2 expressions were reduced followed by their breakdown, as epiphenomena of the myocytolytic process. In conclusion, administration of isoproterenol to rats results in primary loss of dystrophin, the most sensitive among the structural proteins that form the DGC that connects the extracellular matrix and the cytoskeleton in cardiomyocyte. These changes, related to ischaemic injury, explain the severe alterations in the structural integrity of the sarcolemma of cardiomyocytes and hence severe and irreversible injury induced by isoproterenol.

Genotoxic effect of Physalis angulata L. (Solanaceae) extract on human lymphocytes treated in vitro

Physalis angulata L (Solanaceae) is a medicinal plant from North of Brazil, whose different extracts and infusions are commonly used in the popular medicine for the treatment of malaria, asthma, hepatitis, dermatitis and rheumatism. However, the genotoxic effects of P. angulata on human cells is not well known. The main purpose of the present study was to evaluate the in vitro genotoxic effects of aqueous extract of P angulata using the comet assay and the micronucleus assay in human lymphocytes provided from 6 healthy donors. Treatments with P angulata extracts were performed in vitro in order to access the extent of DNA damage. The comet assay has shown that treatments with P angulata at 0.5, 1.0, 2.0, 3.0 and 6.0 mu g/mL in Culture medium were genotoxic. Lymphocytes treated with P angulata at the concentrations of 3.0 and 6.0 mu g/mL in culture medium showed a statistically significant increase in the frequency of micronucleus (p<0.05), however, the cytokinesis blocked proliferation index (CBPI) was not decreased after P angulata treatment. In conclusion, the present work demonstrated the genotoxic effects of P angulata extract on human lymphocytes in vitro.

Pfaffia paniculata (Brazilian ginseng) roots decrease proliferation and increase apoptosis but do not affect cell communication in murine hepatocarcinogenesis

Pfaffia paniculata (Brazilian ginseng) roots and/or its extracts have shown anti-neoplastic, chemopreventive, and anti-angiogenic properties. The aim of this work was to investigate the chemopreventive mechanisms of this root in Mice Submitted to the infant model of hepatocarcinogenesis, evaluating the effects oil cellular proliferation, apoptosis. and intercellular communication. Fifteen-day-old BALB/c male mice were given, i.p., 10 mu g/g of the carcinogen N-nitrosodiethylamine (DEN). Animals were separated into three groups at weaning and were given different concentrations of powdered P. paniculata root (0%, 2%, or 10%) added to commercial food for 27 weeks. Control group (CT) was not exposed to the carcinogen and was given ration without the root. After euthanasia, the animals` liver and body weight were measured. Liver fragments were sampled to Study intercellular communication, molecular biology, and histopathological analysis. Cellular proliferation was evaluated by immunohistochemistry for PCNA, apoptosis was evaluated by apoptotic bodies count and alkaline cornet technique, and inter-cellular communication by diffusion of lucifer yellow dye, immunofluorescence, western blot and real-time PCR for connexins 26 and 32. Chronic treatment with powdered P. paniculata root reduced cellular proliferation and increased apoptosis in the 2%, group. Animals in the 10% group had an increase in apoptosis with chronic inflammatory process. Intercellular communication showed no alterations in any of the groups analyzed. These results Indicate that chemopreventive effects of P. paniculata are related to the control of cellular proliferation and apoptosis, but not to cell communication and/or connexin expression, and are directly Influenced by the root concentration. (C) 2009 Elsevier GmbH. All rights reserved.