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Historically, evidence of chemical carcinogenesis has played a significant role in verifying conclusions draw from epidemiological studies. Chemical agents that were suspected to have a certain role in human chronic diseases, such as cancers, have been tested in animals to establish firmly a causative risk or link to risk. The three best examples are: (1) tobacco smoke and lung cancer; (2) asbestos and mesothelioma; and (3) aflatoxin and hepatic cancer. New chemical compounds are synthesized every day, and a number of natural or synthetic compounds are incorporated in foods either as a result of their processing or to preserve or enhance them. Chemical carcinogenesis studies using model animals have greatly contributed to understanding the mechanisms underlying the development and prevention of carcinogenesis. The carcinogenesis process is generally considered to include three steps: initiation, promotion, and progression. Each step is characterized by morphological and biochemical alterations resulting from genetic and epigenetic changes, including mutations in proto-oncogenes and tumor suppressor genes that control proliferation, cell death, and cellular repair. Long-term in vivo assays using laboratory animals enable the identification of carcinogenic compounds and their modes of action. Based on these findings, we should be able to establish effective strategies to treat and prevent malignancies resulting from exposure to potentially carcinogenic chemicals. [Copyright &y& Elsevier]

Background: There was few study concentrated on the correlation between the evaluated tumor markers and lymph node metastasis. In this study, we aimed to evaluate the correlation between the CA724, CA242, CAI 99, CEA and the lymph node metastasis of gastric cancer and assess the prognostic value of them in different N stage patients. Methods: We analyzed the correlation between serum level of CA724, CA242, CA199, CEA and lymph node metastasis in 1501 gastric cancer patients. Results: Lymph node metastasis of gastric cancer was related with tumor location, Bormann type, tumor size, histological type, depth of invasion and TNM stage (p<0.05). The values of CA724, CA242, CAI 99 and CEA were positively correlated with the metastatic lymph node counts and the N stage (p <0.05). The later the N stage was, the levels of CA724, CA242 and CA199 were higher. The later the N stage was, the positive rates of tumor markers were higher (p<0.05). In comparing with single tumor markers, the positive rates of tumor markers combination were higher. The combination of CA724 + CA242 + CA199 + CEA had highest positive rate. The higher CEA level related to N1 stage patients while higher CAI 99 was related with poor prognosis for N1 stage patients. For NO and N2 stage patients, evaluation of CA724 indicated poorer prognosis. For N1 and N2 stage gastric patients, the patients with increased CA242 inclined to have shorter survival time. Conclusions: The tumor makers CA724, CA242, CAI 99 and CEA were evaluated significantly in the gastric patients with later N stage. The combination of these four tumor markers maybe prefer diagnostic index of gastric cancer and its lymph node metastasis. These tumor markers can be a possible indicator of poorer prognosis in different N stage patients. [ABSTRACT FROM AUTHOR]

Exogenous and endogenous genotoxic carcinogens and their in vivo metabolites may result in DNA damage and cause adverse health effects. It is very difficult to specifically detect trace DNA damage in the presence of a large excess of unmodified nucleosides. Here we report a molecularly imprinted polymer (MIP) nanocomposite, namely nanoMIP, which can be used as a “plastic antibody” for specific recognition of benzo[a]pyrene diol epoxide (BPDE)–DNA adduct. Enhanced binding affinity (880 nM) of nanoMIPs was achieved by using two tailor-made functional monomers. The property of binding kinetics was greatly improved in virtue of the well-defined nanostructure, which was fabricated by initiators for continuous activator regeneration-atom transfer radical polymerization (ICAR-ATRP). The BPDE-adducted DNA can be specifically captured by synthetic nanoMIP. By taking advantage of this antibody-mimicking behavior, we further developed a fluorescently imaged particle counting immunoassay (FIPCIA) method for ultrasensitive detection of BPDE–ssDNA adducts using a laser scanning confocal microscope (LSCM). The number of countable fluorescent dots is proportional to the content of BPDE–ssDNA adducts in the DNA sample. The proposed plastic antibody-based FIPCIA method can detect traces of BPDE–DNA adducts as low as 18 pM in human lung carcinoma A549 cells. This highly-sensitive detection of DNA lesions offers a promising alternative to immunogenic antibody-based immunoassays for genomics and DNA modification analysis. [ABSTRACT FROM AUTHOR]

Background There are 600 million betel quid chewers around the world. betel quid chewing is a major risk factor of oral cancer. Why betel quid components induce oral cancer is not clear. Methods Cytotoxicity of areca nut extract and arecoline (an areca nut alkaloid) to SAS oral epithelial cell line was evaluated by trypan blue dye exclusion and MTT assays. Cell cycle distribution and apoptosis was analyzed by propidium iodide staining flow cytometry. Chk1 and chk2 activation was analyzed by Pathscan phospho-enzyme-linked immunosorbent assay. Metalloproteinase-9 (MMP-9), tissue inhibitors of metalloproteinase (TIMPs) production was measured by enzyme-linked immunosorbent assay. Results Areca nut extract (800 μg/mL) and arecoline (>0.4 mmol/L) caused cell death, apoptosis, and cell cycle arrest of SAS cells. Areca nut extract and arecoline stimulated Chk1 and Chk2 phosphorylation in SAS cells. Areca nut extract stimulated cellular MMP-9 but suppressed TIMP-1 and TIMP-2 production. Conclusions Areca nut components activate Chk1/Chk2, alter cell cycle regulation/apoptosis, MMP-9, and TIMPs production, contributing to the pathogenesis of oral carcinogenesis. © 2012 Wiley Periodicals, Inc. Head Neck, 2013 [ABSTRACT FROM AUTHOR]

Translation elongation factor 1A (eEF1A) directs aminoacyl-tRNA to the A site of 80S ribosomes. In addition, more than 97% homologous variants of eEF1A, A1 and A2, whose expression in different tissues is mutually exclusive, may fulfill a number of independent moonlighting functions in the cell; for instance, the unusual appearance of A2 in an A1-expressing tissue was recently linked to the induction of carcinogenesis. The structural background explaining the different functional performance of the highly homologous proteins is unclear. Here, the main difference in the structural properties of these proteins was revealed to be the improved ability of A1 to self-associate, as demonstrated by synchrotron small-angle X-ray scattering (SAXS) and analytical ultracentrifugation. Besides, the SAXS measurements at different urea concentrations revealed the low resistance of the A1 protein to urea. Titration of the proteins by hydrophobic dye 8-anilino-1-naphthalenesulfonate showed that the A1 isoform is more hydrophobic than A2. As the different association properties, lipophilicity, and stability of the highly similar eEF1A variants did not influence considerably their translation functions, at least in vitro, we suggest this difference may indicate a structural background for isoform-specific moonlighting roles. [ABSTRACT FROM AUTHOR]

Nrf2 (Nfe2l2) governs cellular defenses against oxidative and electrophilic stresses and protects against chemical carcinogenesis. However, many cancers have been found to accumulate NRF2 protein, raising questions of precisely how Nrf2 contributes to carcinogenesis. In this report, we explored such questions in an established urethane-induced multistep model of lung carcinogenesis. Consistent with earlier observations, Nrf2-deficient (Nrf2-/-) mice exhibited a relative increase in tumor foci by 8 weeks after urethane administration. However, after 16 weeks, we observed a relative reduction in the number of tumors with more malignant characteristics in Nrf2-/- mice. Furthermore, all Nrf2-/- tumors harbored activated mutations in Kras, whereas Nrf2+/+ tumors were rarely associated with similar Kras mutations. Overall, our results established that Nrf2 has two roles during carcinogenesis, one of which is preventive during tumor initiation and the second that promotes malignant progression. These findings establish Nrf2 inhibitors as rational tools to prevent malignant progression in lung cancer, whereas Nrf2 activators are more suited for lung cancer prevention. [ABSTRACT FROM AUTHOR]

Background: Thousands of intragenic long interspersed element 1 sequences (LINE-1 elements or L1s) reside within genes. These intragenic L1 sequences are conserved and regulate the expression of their host genes. When L1 methylation is decreased, either through chemical induction or in cancer, the intragenic L1 transcription is increased. The resulting L1 mRNAs form RISC complexes with pre-mRNA to degrade the complementary mRNA. In this study, we screened for genes that are involved in intragenic L1 regulation networks. Results: Genes containing L1s were obtained from L1Base (http://l1base.molgen.mpg.de). The expression profiles of 205 genes in 516 gene knockdown experiments were obtained from the Gene Expression Omnibus (GEO) (http://www.ncbi.nlm.nih.gov/geo). The expression levels of the genes with and without L1s were compared using Pearson's chi-squared test. After a permutation based statistical analysis and a multiple hypothesis testing, 73 genes were found to induce significant regulatory changes (upregulation and/or downregulation) in genes with L1s. In detail, 5 genes were found to induce both the upregulation and downregulation of genes with L1s, whereas 27 and 37 genes induced the downregulation and upregulation, respectively, of genes with L1s. These regulations sometimes differed depending on the cell type and the orientation of the intragenic L1s. Moreover, the siRNA-regulating genes containing L1s possess a variety of molecular functions, are responsible for many cellular phenotypes and are associated with a number of diseases. Conclusions: Cells use intragenic L1s as cis-regulatory elements within gene bodies to modulate gene expression. There may be several mechanisms by which L1s mediate gene expression. Intragenic L1s may be involved in the regulation of several biological processes, including DNA damage and repair, inflammation, immune function, embryogenesis, cell differentiation, cellular response to external stimuli and hormonal responses. Furthermore, in addition to cancer, intragenic L1s may alter gene expression in a variety of diseases and abnormalities. [ABSTRACT FROM AUTHOR]

Squamous cell carcinoma (SCC) is the most common neoplasm of the oral cavity. It is aggressive, highly proliferative, and metastatic. This study aimed to evaluate the effect of LLLT and imiquimod on DMBA chemically induced lesions on the oral mucosa of hamsters. SCCs were induced on 25 hamsters. Animals of G1 (control 1) were killed and the presence of tumors confirmed; G2 (control 2) suffered no interventions for additional 4 weeks; animals of G3 (laser treatment) were irradiated (λ660nm, 50 mW, CW, Ø = 3 mm, 0.07 cm, 714.2 mW/cm, 133 s, 95 J/cm, 6.65 J) at every other day for 4 weeks; animals of G4 (imiquimod treatment) received 5 % imiquimod three times a week for 4 weeks; and animals of G5 (imiquimod and laser treatment) received both treatments for the same period. Samples were taken and underwent histological analysis by light microscopy and were investigated using immunohistochemistry for S-100 dendritic cells. In G1, G2, and G3, the evaluations showed malignant tumors and the absence of S-100 dendritic cells in the tumor stroma. In G4, 60 % of the animals had no malignant tumors, and S-100 dendritic cells were present in the stroma of the tumors as well as dysplasia. In G5, 40 % of the animals presented SCC, with scarce or no S-100 dendritic cells. The imiquimod treatment played a direct effect on SCC, demonstrated by the increased number of S-100 dendritic cells, which could suggest an important role of immune surveillance against neoplastic proliferation. Furthermore, its association with laser needs to be further investigated. [ABSTRACT FROM AUTHOR]

As a frontier organ, skin is exposed to different environmental and/or occupational chemicals which cause cutaneous cancers in experimental animals. In mice, 7,12-dimethylbenz[ a]anthrancene (DMBA) and the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) are frequently used as skin model tumor initiator and promoter, respectively. The sequential administration of DMBA and TPA leads to the appearance of a large number of benign papillomas, of which some convert later into invasive squamous cell carcinomas (SCC). At the molecular level, initiation of carcinogenesis in mouse skin consists in the mutational activation of the Ha-ras oncoprotein. HA- RAS mutations are rare in human SCC, but HA- RAS-mutated tumors appear in melanoma patients treated with B-raf inhibitors, indicating that initiated, HA- RAS-mutated stem cells also reside in human skin. Similarly, UV-induced human SCC show footprint mutations in the tumor suppressor gene TP53 which are also observed in UV-induced mouse SCC. Strong species differences exist with respect to phorbol ester-mediated tumor promotion. While certain mouse strains are very susceptible, other rodent species are much less sensitive. Likewise, humans appear to be much more resistant to phorbol ester-mediated skin toxicity. Papilloma formation as a result of a chemical insult is uncommon in men, questioning the relevance of this preneoplastic lesion for humans. However, skin tumorigenesis in the experimental situation and in humans appears to follow common molecular mechanisms, even though there are species differences in the morphological correlates to the preneoplastic state. Therefore, we recommend not simply labeling them as irrelevant for human risk assessment. [ABSTRACT FROM AUTHOR]

Context: Sulforaphane (SFN) [1-isothiocyanato-4-(methylsulfinyl)butane] is a naturally occurring isothiocyanate found in cruciferous vegetables such as broccoli [ Brassica oleracea L. var. italica Plenck. (Brassicaceae)]. Since it is among the most potent bioactive components with antioxidant and antitumor properties, it has received intense attention in the recent years for its chemopreventive properties. Objective: The present work determined the rehabilitating role in alleviating the oxidative damage caused by benzo(a)pyrene [B(a)P] to biomolecules and the apoptotic cascade mediated by orally administered isothiocyanate-SFN (9 µmol/mouse/day) against B(a)P (100 mg/kg body weight, i.p.) induced pulmonary carcinogenesis in Swiss albino mice. Materials and methods: Oxidative damage was assessed by measuring lipid peroxidation, 8-hydroxydeoxyguanosine, hydrogen peroxide (H2O2) production, glycoprotein components, protein carbonyl levels and DNA-protein crosslinks. DNA fragmentation by agarose gel electrophoresis and caspase-3 activity by ELISA proved apoptotic induction by SFN along with the protein expression of Bcl-2, Bax and Cyt c. Results: SFN treatment was found to decrease the H2O2 production ( p < 0.001) in cancer induced animals, proving its antioxidant potential. Apoptosis was induced by increasing the release of Cyt c ( p < 0.001) from mitochondria, decreasing and increasing the expression of Bcl-2 ( p < 0.01) and Bax ( p < 0.001), respectively. Caspase-3 activity was also enhanced ( p < 0.001) which leads to DNA fragmentation in SFN treated groups. Conclusion: Our results reflect the rehabilitating role of SFN in B(a)P induced lung carcinogenesis. [ABSTRACT FROM AUTHOR]

The primary motivation for conducting short-term tests for environmental mutagens and carcinogens has been to predict mutagens and/or carcinogens and to assess any associated risks. Organ-specific in vivo short-term tests in rodents are valuable because chemical carcinogenesis is generally organ-specific. I have attempted to develop various organ-specificin vivo short-term tests mainly in rodent liver and stomach. Recently, our collaborative study group, Toxicogenomics/Japanese Environmental Mutagen Society-Mammalian Mutagenicity Study Group (JEMS? MMS), attempted to use gene expression profiling in in vivo short-term tests, conducted DNA microarrays to extract candidate marker genes, and later shifted to quantitative real-time PCR (qPCR) to profile the expression of selected genes. We successfully discriminated 8 genotoxic hepatocarcinogens from 4 non-genotoxic hepatocarcinogens by statistical analysis using principal component analysis (PCA) based on the gene expression profiles for 12 genes (Aen, Bax, Btg2, Ccnf, Ccng1, Cdkn1a, Gdf15, Lrp1,Mbd1,Phlda3, Plk2, andTubb2c) in mouse liver at 4 and 48 h following a single intraperitoneal administration of chemicals as determined by qPCR. More recently, we successfully performed a similar study in rat liver. Previously, my collaborators and I developed various organspecific in vivo short-term test methods, including UDS (unscheduled DNA synthesis); RDS (replicative DNA synthesis) using a liquid scintillation counter in rat glandular stomach, forestomach, colon, and liver and hairless mouse epidermis; DNA single-strand scission (DSS); and ornithine decarboxylase assay (ODC) in rat glandular stomach on 62 compounds. Developing short-term tests that are helpful for the risk assessment of human mutagens and carcinogens would contribute to the development of ideal prediction methods. [ABSTRACT FROM AUTHOR]

Abstract: Assessment of risks associated with childhood exposure to ionizing radiation when combined with chemical carcinogens is of great importance. We studied the age-dependence of the effect of combined exposure to ionizing radiation (IR) and a chemical carcinogen on lung carcinogenesis. Female 1-, 5-, and 22-week-old Wistar rats were locally irradiated on the thorax with X-rays (3.18Gy) and/or were injected intraperitoneally with N-nitrosobis(2-hydroxypropyl)amine (BHP) (1g/kg body weight) 1week after X-ray exposure or at 23weeks of age. Rats were terminated at 90weeks of age. We found that: (i) the incidence of lung tumors (adenoma and adenocarcinoma) increased slightly as a function of age at X-ray exposure, although this was not statistically significant, while the incidence induced by BHP decreased with increasing age at administration; (ii) combined exposure to X-rays at 5 or 22weeks with BHP 1week later enhanced the tumor incidence, and the effect at early-life stage (5weeks irradiation) was more effective than that at late-life stage (22weeks irradiation); (iii) combined exposure preferentially enhanced malignant transformation; (iv) although a longer interval between the X-ray and BHP treatments reduced the combined effect, risks of early-life irradiation at 1 or 5weeks of age lasted into adulthood; (v) adenomas and adenocarcinomas induced by X-ray and/or BHP originated from surfactant apoprotein A-positive alveolar type II cells; and (vi), extracellular signal-regulated kinase pathway activation was observed in half the adenocarcinomas, regardless of the exposure schedule. In conclusion, combined exposure may enhance lung tumorigenesis more synergistically at early-life stage (5weeks of age) than later-life stage. [Copyright &y& Elsevier]

Abstract: Liver cancer, predominantly hepatocellular carcinoma (HCC), represents a complex and fatal malignancy driven primarily by oxidative stress and inflammation. Due to dismal prognosis and limited therapeutic intervention, chemoprevention has emerged as a viable approach to reduce the morbidity and mortality of HCC. Pomegranate fruit is a rich source of phytochemicals endowed with potent antioxidant and anti-inflammatory properties. We previously reported that pomegranate phytochemicals inhibit diethylnitrosamine (DENA)-initiated hepatocarcinogenesis in rats though nuclear factor E2-related factor 2 (Nrf2)-mediated antioxidant mechanisms. Since Nrf2 also acts as a key mediator of the nuclear factor-kappaB (NF-κB)-regulated inflammatory pathway, our present study investigated the anti-inflammatory mechanisms of a pomegranate emulsion (PE) during DENA-induced rat hepatocarcinogenesis. Rats were administered with PE (1 or 10 g/kg) 4 weeks before and 18 weeks following DENA initiation. There was a significant increase in hepatic expressions of inducible nitric oxide synthase, 3-nitrotyrosine, heat shock protein 70 and 90, cyclooxygenase-2 and NF-κB in DENA-exposed rat livers. PE dose-dependently suppressed all aforementioned elevated inflammatory markers. A conspicuous finding of this study involves lack of cardiotoxicity of PE as assessed by monitoring cardiac function using noninvasive echocardiography. Our results provide substantial evidence that suppression of the inflammatory cascade through modulation of NF-κB signaling pathway may represent a novel mechanism of liver tumor inhibitory effects of PE against experimental hepatocarcinogenesis. Data presented here coupled with those of our earlier study underline the importance of simultaneously targeting two interconnected molecular circuits, namely, Nrf2-mediated redox signaling and NF-κB-regulated inflammatory pathway, by pomegranate phytoconstituents to achieve chemoprevention of HCC. [Copyright &y& Elsevier]

Thousands of untested chemicals in the environment require efficient characterization of carcinogenic potential in humans. A proposed solution is rapid testing of chemicals using in vitro high-throughput screening (HTS) assays for targets in pathways linked to disease processes to build models for priority setting and further testing. We describe a model for predicting rodent carcinogenicity based on HTS data from 292 chemicals tested in 672 assays mapping to 455 genes. All data come from the EPA ToxCast project. The model was trained on a subset of 232 chemicals with in vivo rodent carcinogenicity data in the Toxicity Reference Database (ToxRefDB). Individual HTS assays strongly associated with rodent cancers in ToxRefDB were linked to genes, pathways, and hallmark processes documented to be involved in tumor biology and cancer progression. Rodent liver cancer endpoints were linked to well-documented pathways such as peroxisome proliferator–activated receptor signaling and TP53 and novel targets such as PDE5A and PLAUR. Cancer hallmark genes associated with rodent thyroid tumors were found to be linked to human thyroid tumors and autoimmune thyroid disease. A model was developed in which these genes/pathways function as hypothetical enhancers or promoters of rat thyroid tumors, acting secondary to the key initiating event of thyroid hormone disruption. A simple scoring function was generated to identify chemicals with significant in vitro evidence that was predictive of in vivo carcinogenicity in different rat tissues and organs. This scoring function was applied to an external test set of 33 compounds with carcinogenicity classifications from the EPA’s Office of Pesticide Programs and successfully (p = 0.024) differentiated between chemicals classified as “possible”/“probable”/“likely” carcinogens and those designated as “not likely” or with “evidence of noncarcinogenicity.” This model represents a chemical carcinogenicity prioritization tool supporting targeted testing and functional validation of cancer pathways. [ABSTRACT FROM PUBLISHER]

Differences in cancer incidences between men and women are often explained by either differences in environmental exposures or by influences of sex hormones. However, there are few studies on intrinsic gender differences in susceptibility to chemical carcinogens. We have analyzed the National Toxicology Program (NTP) database for sex differences in rat responses to chemical carcinogens. We found that the odds that male rat bioassays were assigned a higher level of evidence than female rat bioassays was 1.69 (p < .001). Of 278 carcinogenic chemicals in the database, 201 (72%) exhibited statistical gender differences (p ≤ .05) in at least one nonreproductive organ. One hundred thirty of these 201 chemicals induced gender-specific tumors in male rats and 59 in female rats. Sixty-eight chemicals induced tumors in males but no tumors in females. Less than one third (i.e., 19 chemicals) induced tumors in females but not males. Male-specific tumors included pancreatic and skin tumors, and female-specific tumors included lung tumors. For some tumor sites, these differences in gender susceptibility can be associated with literature data on sex hormone receptor expression. In conclusion, gender-specific tumors were common. The male dominance is in line with recent human data, and the male susceptibility to carcinogens should be further studied. [ABSTRACT FROM AUTHOR]

Whole-genome transcriptome measurements are pivotal for characterizing molecular mechanisms of chemicals and predicting toxic classes, such as genotoxicity and carcinogenicity, from in vitro and in vivo assays. In recent years, deep sequencing technologies have been developed that hold the promise of measuring the transcriptome in a more complete and unbiased manner than DNA microarrays. Here, we applied this RNA-seq technology for the characterization of the transcriptomic responses in HepG2 cells upon exposure to benzo[a]pyrene (BaP), a well-known DNA damaging human carcinogen. Based on EnsEMBL genes, we demonstrate that RNA-seq detects ca 20% more genes than microarray-based technology but almost threefold more significantly differentially expressed genes. Functional enrichment analyses show that RNA-seq yields more insight into the biology and mechanisms related to the toxic effects caused by BaP, i.e., two- to fivefold more affected pathways and biological processes. Additionally, we demonstrate that RNA-seq allows detecting alternative isoform expression in many genes, including regulators of cell death and DNA repair such as TP53, BCL2 and XPA, which are relevant for genotoxic responses. Moreover, potentially novel isoforms were found, such as fragments of known transcripts, transcripts with additional exons, intron retention or exon-skipping events. The biological function(s) of these isoforms remain for the time being unknown. Finally, we demonstrate that RNA-seq enables the investigation of allele-specific gene expression, although no changes could be observed. Our results provide evidence that RNA-seq is a powerful tool for toxicology, which, compared with microarrays, is capable of generating novel and valuable information at the transcriptome level for characterizing deleterious effects caused by chemicals. [ABSTRACT FROM PUBLISHER]

Abstract: To better understand the relationships between chemical exposures and human cancer causation, incidence data for human cancer types were identified and pancreatic and colorectal cancers were studied in-depth to assess whether data supporting the causation of pancreatic or colorectal tumors by chemicals in rodents is predictive of causation by the same chemicals of the same tumors in humans. A search of the Carcinogenic Potency Database, the National Toxicology Program (NTP) technical report database, and the published literature identified 38 and 39 chemicals reported to cause pancreatic and colorectal tumors, respectively, in mice or rats. For each of these chemicals, searches were conducted of the International Agency for Research on Cancer monographs, the NTP Report on Carcinogens, and the published literature for evidence of induction of the same tumors in humans. Based on this evaluation, no conclusive evidence was identified to suggest that chemicals reported to cause pancreatic or colorectal tumors in rodents also cause these tumors in humans. These findings suggest that pancreatic tumor data from mouse and rat bioassays are of limited utility with regard to predicting similar tumor induction in humans. For colorectal cancer, a lack of correlation was noted for the vast majority of chemicals. [Copyright &y& Elsevier]

Abstract: Objective: To find out the anticancer effect of Indigofera aspalathoides (I. aspalathoides) on 20-methylcholanthrene induced fibrosarcoma in rats. Methods: Fibrosarcoma was induced in Wistar strain male albino rats by 20-methylcholanthrene. Intraperitoneous (i.p.) administration of 250 mg/kg body weight/day of aqueous extract of I. aspalathoides for 30 d effectively suppressed chemically induced tumors. Parameters such as body weight, liver and kidney weight, tumor weight, mean survival time, behavioral changes, blood glucose, blood glycogen and marker enzymes such as alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), acid phosphatase (ACP) and 5′-nucleiotidase (5′-NT) in serum, liver and kidney and lipid profiles such as total cholesterol, phospholipids, free fatty acids in liver and kidney of control and experimental animals were studied. Results: Fibrosarcoma bearing animals were ferocious and anxious. The mean survival time was found to increase after the treatment. The body weights were significantly decreased (P < 0.001) in group II fibrosarcoma animals which steadily increased after the treatment with I. aspalathoides. The liver and kidney weights were significantly increased whereas the tumor weights decreased as compared to the weights in untreated fibrosarcoma bearing rats. The blood glucose and the liver and kidney glycogen levels were found to decrease significantly (P < 0.001) in group II animals. Elevated activities of marker enzymes were observed in serum, liver and kidney of fibrosarcoma bearing Group II animals which were normalize after I. aspalathoides treatment. In the liver and kidney of Group II animals the total cholesterol increased whereas the phospholipids and free fatty acid levels decreased (P < 0.001) which were normalized after treatment. Conclusions: The treatment by I. aspalathoides on fibrosarcoma bearing rats has improved the levels of various parameters indicating its antiproliferative and anticancer activity. [Copyright &y& Elsevier]

Abstract: Cigarette smoke is composed of over 4000 chemicals many of which are strong oxidizing agents and chemical carcinogens. Chronic cigarette smoke exposure (CSE) induces mild alterations in liver histology indicative of toxicity though the molecular pathways underlying these alterations remain to be explored. Utilizing a mouse model of ‘active’ developmental CSE (gestational day (GD) 1 through postnatal day (PD) 21; cotinine >50ng/mL) characterized by low birth weight offspring, the impact of developmental CSE on liver protein abundances was determined. On PD21, liver tissue was collected from pups for 2D SDS-PAGE based proteome analysis with statistical analysis by Partial Least Squares-Discriminant Analysis (PLS-DA). Protein spots of interest were identified by ESI-MS/MS with impacted molecular pathways identified by Ingenuity Pathway Analysis. Developmental CSE decreased the abundance of proteins associated with the small molecule biochemistry (includes glucose metabolism), lipid metabolism, amino acid metabolism, and inflammatory response pathways. Decreased gluconeogenic enzyme activity and lysophosphatidylcholine availability following developmental CSE were found and supports the impact of CSE on these pathways. Proteins with increased abundance belonged to the cell death and drug metabolism networks. Liver antioxidant enzyme abundances [glutathione-S-transferase (GST) and peroxiredoxins] were also altered by CSE, but GST enzymatic activity was unchanged. In summary, cigarette smoke exposure spanning pre- and post-natal development resulted in persistent decreased offspring weights, decreased abundances of liver metabolic proteins, decreased gluconeogenic activity, and altered lipid metabolism. The companion paper details the kidney proteome alterations in the same offspring. [Copyright &y& Elsevier]

Previously, we have shown a role of cytosolic NAD(P)H:quinone oxidoreductase 1 (NQO1) in the stabilization of p63 against 20S proteasomal degradation resulting in thinning of the epithelium and chemical-induced skin cancer (Oncogene (2011) 30, 1098-1107). Current studies have demonstrated that NQO1 control of CCAAT-enhancer binding protein (C/EBPα) against 20S proteasomal degradation also contributes to the upregulation of p63 expression and protection. Western and immunohistochemistry analysis revealed that disruption of the NQO1 gene in mice and mouse keratinocytes led to degradation of C/EBPα and loss of p63 gene expression. p63 promoter mutagenesis, transfection and chromatin immunoprecipitation assays identified a C/EBPα-binding site between nucleotide position −185 and −174 that bound to C/EBPα and upregulated p63 gene expression. Co-immunoprecipitation and immunoblot analysis demonstrated that 20S proteasomes directly interacted and degraded C/EBPα. NQO1 direct interaction with C/EBPα led to stabilization of C/EBPα against 20S proteasomal degradation. NQO1 protection of C/EBPα required binding of NADH with NQO1. Exposure of skin and keratinocytes to the chemical stress agent benzo(a)pyrene led to induction of NQO1 and stabilization of C/EBPα protein, resulting in an increase in p63 RNA and protein in wild-type but not in NQO1−/− mice. Collectively, the current data combined with previous data suggest that stress induction of NQO1 through both stabilization of C/EBPα and increase in p63 and direct stabilization of p63 controls keratinocyte differentiation, leading to protection against chemical-induced skin carcinogenesis. The studies are significant as 2-4% human individuals are homozygous and 23% are heterozygous for the NQO1P187S mutation and might be susceptible to stress-induced skin diseases. [ABSTRACT FROM AUTHOR]

As the Ah receptor target gene products play a critical role in chemical carcinogenesis, antagonists are considered as potential chemopreventive agents. It is demonstrated in this paper that the isothiocyanates R,S-sulforaphane and erucin are non-competitive antagonists of the aryl hydrocarbon (Ah) receptor. Both isothiocyanates were poor agonists for the receptor and elevated CYP1A1 mRNA levels only modestly when incubated with precision-cut rat liver slices. In contrast, the classical Ah receptor agonist benzo[a]pyrene was a potent inducer of CYP1A1 mRNA levels, with this effect being effectively antagonized by the two isothiocyanates. In further studies, it was demonstrated that R,S-sulforaphane could both prevent the interaction of and displace already bound benzo[a]pyrene from the Ah receptor, but no concentration dependency was observed with respect to the isothiocyanate. Both erucin and R,S-sulforaphane antagonized the benzo[a]pyrene-mediated increase in the CYP1A-mediated O-deethylation of ethoxyresorufin in rat precision-cut liver slices. Of the two isomers of R,S-sulforaphane, the naturally occurring R-isomer was more effective than the S-isomer in antagonizing the activation of the Ah receptor by benzo[a]pyrene. Antagonism of the Ah receptor may be a major contributor to the established chemoprevention of aliphatic isothiocyanates. [ABSTRACT FROM AUTHOR]

Mice deficient either in subtypes of immune cells, cytokines or lytic pathways have been subjected to chemical carcinogenesis by methylcholanthrene to evaluate whether these components of the immune system affect tumor development. Inbred mice of the same genotype but from different sources differed in tumor development in magnitude comparable to that previously attributed to differences in immunocompetence. This suggested that genetic drift between separate inbred colonies of mice and/or environmental factors ( e.g., transport of the animals) influenced carcinogenesis. Therefore, littermates were used as control in subsequent experiments. Although deficiency of T-cells, NKT-cells, perforin, Fas-ligand, TNF-α-receptor failed to reveal significant differences in tumor development, the presence of B-cells and IL-4 enhanced tumor development under similar experimental conditions. [ABSTRACT FROM AUTHOR]

Seroepidemiological studies imply a correlation between Epstein-Barr virus (EBV) reactivation and the development of nasopharyngeal carcinoma (NPC). N-nitroso compounds, phorbols, and butyrates are chemicals found in food and herb samples collected from NPC high-risk areas. These chemicals have been reported to be risk factors contributing to the development of NPC, however, the underlying mechanism is not fully understood. We have demonstrated previously that low dose N-methyl-N'-nitro-N-nitrosoguanidine (MNNG, 0.1 µmg/ml) had a synergistic effect with 12-O-tetradecanoylphorbol- 13-acetate (TPA) and sodium butyrate (SB) in enhancing EBV reactivation and genome instability in NPC cells harboring EBV. Considering that residents in NPC high-risk areas may contact regularly with these chemical carcinogens, it is vital to elucidate the relation between chemicals and EBV and their contributions to the carcinogenesis of NPC. In this study, we constructed a cell culture model to show that genome instability, alterations of cancer hallmark gene expression, and tumorigenicity were increased after recurrent EBV reactivation in NPC cells following combined treatment of TPA/SB and MNNG. NPC cells latently infected with EBV, NA, and the corresponding EBV-negative cell, NPC-TW01, were periodically treated with MNNG, TPA/SB, or TPA/SB combined with MNNG. With chemically-induced recurrent reactivation of EBV, the degree of genome instability was significantly enhanced in NA cells treated with a combination of TPA/SB and MNNG than those treated individually. The Matrigel invasiveness, as well as the tumorigenicity in mouse, was also enhanced in NA cells after recurrent EBV reactivation. Expression profile analysis by microarray indicates that many carcinogenesis-related genes were altered after recurrent EBV reactivation, and several aberrations observed in cell lines correspond to alterations in NPC lesions. These results indicate that cooperation between chemical carcinogens can enhance the reactivation of EBV and, over recurrent reactivations, lead to alteration of cancer hallmark gene expression with resultant enhancement of tumorigenesis in NPC. [ABSTRACT FROM AUTHOR]

Summary: Nucleotide excision repair (NER) has long been known to remove DNA lesions induced by chemical carcinogens, and the molecular mechanism has been partially elucidated. Here we demonstrate that in Schizosaccharomyces pombe a DNA recognition protein, alkyltransferase-like 1 (Atl1), can play a pivotal role in selecting a specific NER pathway, depending on the nature of the DNA modification. The relative ease of dissociation of Atl1 from DNA containing small O 6-alkylguanines allows accurate completion of global genome repair (GGR), whereas strong Atl1 binding to bulky O 6-alkylguanines blocks GGR, stalls the transcription machinery, and diverts the damage to transcription-coupled repair. Our findings redraw the initial stages of the NER process in those organisms that express an alkyltransferase-like gene and raise the question of whether or not O 6-alkylguanine lesions that are poor substrates for the alkyltransferase proteins in higher eukaryotes might, by analogy, signal such lesions for repair by NER. [Copyright &y& Elsevier]

During the past half-century, incidences of breast cancer have increased globally. Various factors—genetic and environmental—have been implicated in the initiation and progression of this disease. One potential environmental risk factor that has not received a lot of attention is the exposure to heavy metals. While several mechanisms have been put forth describing how high concentrations of heavy metals play a role in carcinogenesis, it is unclear whether chronic, low-level exposure to certain heavy metals (i.e., cadmium and nickel) can directly result in the development and progression of cancer. Cadmium and nickel have been hypothesized to play a role in breast cancer development by acting as metalloestrogens—metals that bind to estrogen receptors and mimic the actions of estrogen. Since the lifetime exposure to estrogen is a well-established risk factor for breast cancer, anything that mimics its activity will likely contribute to the etiology of the disease. However, heavy metals, depending on their concentration, are capable of binding to a variety of proteins and may exert their toxicities by disrupting multiple cellular functions, complicating the analysis of whether heavy metal-induced carcinogenesis is mediated by the estrogen receptor. The purpose of this review is to discuss the various epidemiological, in vivo, and in vitro studies that show a link between the heavy metals, cadmium and nickel, and breast cancer development. We will particularly focus on the studies that test whether these two metals act as metalloestrogens in order to assess the strength of the data supporting this hypothesis. [ABSTRACT FROM PUBLISHER]

β-glucans are naturally occurring polysaccharides that are found in baker's yeast, oats, barley fibre as well as medicinal mushrooms. Literary data show that they produce various biological effects (immune modulating, anticarcinogenic, lipid and body weight lowering). In the present study, the possible modulative effect of β-glucan (from yeast) on lung carcinogenesis was evaluated. We used 224 BALB/c mice both sexes divided into 6 groups. During the experimental period, the animals were treated with aqueous solutions of β-glucan, with a dry weight of 100, or 500 µg/ml, respectively (solutions were offered to mice ad libitum). Lung tumours were induced by organotropically acting urethane (given by intraperitoneal injections 10 mg/mouse, twice a week, total dose 50 mg/mouse). After 4 months, all mice were killed by cervical dislocation. Lungs were examined macroscopically and microscopically. The results of our study showed that β-glucan from yeast did not significantly inhibit lung adenamogenesis induced by urethane. Considering the known beneficial effects of β-glucans in other assay systems, future efforts should direct at performing experiments to verify the actual efficacy of β-glucans or β-glucans containing compounds on chemically induced carcinogenesis. [ABSTRACT FROM AUTHOR]

In recent years, chemical cancer risk assessment has faced major challenges: the demand for cancer risk assessment has grown considerably with strict legislation regarding chemical safety, whereas cancer hazard identification has turned increasingly complex due to the rapid development and high publication rate in biomedical sciences. Thus, much of the scientific evidence required for hazard identification is hidden in large collections of biomedical literature. Extensive guidelines have been produced to support cancer risk assessment under these circumstances. We evaluated whether these guidelines support the first, critical step of this task-data and literature gathering-and found that the guidance is vague. We propose ways to improve data and literature gathering for cancer risk assessment and suggest developing a computational literature search and analysis tool dedicated to the task. We describe the first prototype tool we have developed and discuss how it could help to improve the quality, consistency, and effectiveness of cancer risk assessment when developed further. Fully reliable automatic data and literature gathering may not be realistic; the retrieved articles will always need to be examined further by risk assessors. However, our proposal offers a starting point for improved data and literature gathering that can benefit the whole cancer risk assessment process. Integr Environ Assess Manag 2012; 8: 412-417. © 2012 SETAC [ABSTRACT FROM AUTHOR]

The aim of the present study was to evaluate the effect of the new probiotic strain Lactobacillus plantarum on chemically induced carcinogenesis in rats. Sprague dowley rats (n = 33) were divided into control and experimental groups and were fed a conventional laboratory diet. In the experimental group, rats were treated with the probiotic at the dose of 1 x 109 CFU (colonyforming units)/ml. Two weeks after the beginning of the trial, N,N-dimethylhydrazine (chemical carcinogen) injections were applied s.c. at the dose of 21 mg/kg b.w., 5 x weekly. At the end of the 8-month experimental period, faeces samples were taken from the rats and used for laboratory analysis. The counts of lactobacilli and coliforms and bacterial enzyme activity were determined. The probiotic strain L. plantarum as single species or in combination with oil (Lini oleum virginale) decreased the count of total coliforms and increased lactobacilli in faeces of rats. Application of probiotic microorganisms significantly (P < 0.05) decreased the activities of bacterial enzymes (β-galactosidase and β-glucuronidase) compared to the control group rats. The results of this study indicate that probiotic microorganisms could exert a preventive effect on colon carcinogenesis induced by N,N-dimethylhydrazine. [ABSTRACT FROM AUTHOR]

Abstract: In vitro cell transformation is a process characterized by a series of progressive distinctive events that often emulate manifestations occurring in vivo and which are associated with neoplasia. Attendant cellular and sub-cellular alterations include, among others: cellular immortality, phenotypic changes, aneuploidy, genetic variability, cellular disarray, anchorage-independent growth, and tumorigenicity in vivo. Early chemically induced neoplastic transformation studies involved the use of normal diploid (Syrian) hamster embryo (SHE) cells and monitored the formation of morphologically altered colonies. Later investigations employed primarily two established mouse cell lines, i.e. the BALB/c 3T3 A31 cell line and the C3H 10T 1/2 cell line, and monitored the induction of morphologically aberrant foci. In either case, such transformed cellular clusters (colonies and foci) could induce tumors upon inoculation in vivo. Some subsequent noteworthy advancements using these systems included pH adjustments, metabolic supplementation, amplification of expression of formerly latent transformed foci, concurrent detection of mutagenesis and transformation, and use of a Bhas 42 cell line (v-Ha-ras transfected BALB/c 3T3 cells) to detect both tumor initiators and promoters. Over time, such transformation assay systems have been found useful in academic, industry and regulatory laboratories, generally for research purposes, but also occasionally as screening tools for potential chemical carcinogens. Nevertheless, to date, use of these assays for decision-making purposes in the regulatory arena remains elusive and will require comprehensive validation to gain universal acceptance. [Copyright &y& Elsevier]

In the current study, we assessed the global DNA methylation changes in human lymphoblastoid (TK6) cells in vitro in response to 5 direct and 10 indirect-acting genotoxic agents. TK6 cells were exposed to the selected agents for 24 h in the presence and/or absence of S9 metabolic mix. Liquid chromatography-mass spectrometry was used for quantitative profiling of 5-methyl-2'-deoxycytidine. The effect of exposure on 5-methyl-2'-deoxycytidine between control and exposed cultures was assessed by applying the marginal model with correlated residuals on % global DNA methylation data. We reported the induction of global DNA hypomethylation in TK6 cells in response to S9 metabolic mix, under the current experimental settings. Benzene, hydroquinone, styrene, carbon tetrachloride and trichloroethylene induced global DNA hypomethylation in TK6 cells. Furthermore, we showed that dose did not have an effect on global DNA methylation in TK6 cells. In conclusion we report changes in global DNA methylation as an early event in response to agents traditionally considered as genotoxic. [ABSTRACT FROM AUTHOR]

Based on the study of voltammetric behavior of carcinogenic 1-nitropyrene (1-NP), 1-aminopyrene (1-AP), and 1-hydroxypyrene (1-HP), optimum conditions have been found for the determination of these analytes by differential pulse voltammetry (DPV) at a boron-doped diamond film electrode. The optimum medium was methanol-Britton–Robinson buffer (BR buffer) pH 3.0 (70:30) for 1-NP and 1-AP, and methanol-BR buffer pH 5.0 (70:30) for 1-HP. Concentration dependences of the DPV response were measured in the range 1 · 10−6–1 · 10−4 mol dm−3 (R = −0.9998) with the limit of detection (LOD) 3 · 10−7 mol dm−3 for 1-NP, 1 · 10−7–1 · 10−5 mol dm−3 (R = 0.9971) with LOD 6 · 10−8 mol dm−3 for 1-AP, and 1 · 10−7–1 · 10−5 mol dm−3 (R = 0.9934) with LOD 1 · 10−7 mol dm−3 for 1-HP. Simultaneous determination of 1-NP and 1-AP in a mixture was tested in the methanol-BR buffer pH 3.0 (70:30) medium as well. The content of 1-AP in the concentration range from 1 · 10−6 to 1 · 10−4 mol dm−3 had no effect on the sensitivity of the determination of 1-NP, and vice versa. Due to the close peak potentials of 1-AP and 1-HP, the direct determination of their mixture using voltammetric methods is impossible. [ABSTRACT FROM AUTHOR]

Although platelet-activating factor (PAF) is a well-known acute inflammatory mediator, little is known regarding the role of PAF in chronic inflammation. Phorbol esters are known to stimulate PAF production. Moreover, the ability of repeated applications of phorbol esters to induce a sustained inflammatory response is crucial to their tumorigenic activity. We therefore examined whether PAF acts as a mediator of phorbol ester-induced inflammation and tumorigenesis. While PAF receptor knockout mice (PAFR (−/−)) showed an expected but modest reduction in the acute inflammatory response to phorbol 12-myristate 13-acetate (PMA), these mice exhibited a surprising increase in inflammation following chronic PMA application. This increased inflammation was documented by a number of findings that included: increased skin thickness, increased myeloperoxidase activity and expression and increased expression of known inflammatory mediators. Interestingly, vehicle-treated PAFR(−/−) mice also exhibited modest increases in levels of inflammatory markers. This suggests that the platelet activating factor receptor (PAFR) acts to suppress chronic inflammation in response to other stimuli, such as barrier disruption. The idea that chronic PAFR activation is anti-inflammatory was documented by repetitive topical PAFR agonist administration that resulted in reduced myeloperoxidase activity in skin. We next utilized a 7,12-dimethylbenz(a)anthracene/PMA carcinogenesis protocol to demonstrate that PAFR (−/−) mice exhibit significantly increased tumor formation and malignant progression compared with wild-type control mice. These studies provide evidence for two important, unexpected and possibly interrelated pathological roles for the PAFR: first, the PAFR acts to suppress PMA-induced chronic inflammation; secondly, the PAFR acts to suppress neoplastic development in response to chemical carcinogens. [ABSTRACT FROM AUTHOR]

Toluene diisocyanates (2,4-TDI and 2,6-TDI) are important intermediates in the chemical industry. Among the main damages after low levels of TDI exposure are lung sensitization and asthma. It is therefore necessary to have sensitive and specific methods to monitor isocyanate exposure of workers. Urinary metabolites or protein adducts have been used as biomarkers in workers exposed to TDI. However, with these methods it was not possible to determine if the biomarkers result from exposure to TDI or to the corresponding toluene diamines (TDA). This work presents a new procedure for the determination of isocyanate-specific albumin adducts. Isotope dilution mass spectrometry was used to measure the adducts in albumin present in workers exposed to TDI. 2,4-TDI and 2,6-TDI formed adducts with lysine: Nεϵ-[({{3-amino-4-methylphenyl}}amino)carbonyl]-lysine, Nεϵ-[({{5-amino-2-methylphenyl}}amino)carbonyl]-lysine, and Nεϵ- [({{3-amino-2-methylphenyl}}amino)carbonyl]-lysine. In future studies, this new method can be applied to measure TDI-exposures in workers. [ABSTRACT FROM AUTHOR]

Carcinogenic agents such as N-methyl- N-nitrosourea can cause tumors. The aims of the present study were to evaluate and classify a subtype of AML (acute myeloid leukemia) that was induced by NMU. According to previous publications, NMU induces not only mammary cancer but also leukemia in Sprague-Dawley (S-D) rats. However, the subtype of leukemia involved in NMU-treated rats is unknown. We found that both organ weight and relative organ weights were significantly higher in NMU-exposed rats than in controls. Morphological changes of rat livers and spleens were assessed by histological evaluation (H&E staining), which found that these tissues were abnormal in appearance. Also, cytological examination of the blood showed immature white blood cells in a smear using Liu's and Papanicolaou stains, indicating that gross abnormalities and histopathological changes were pathologically observed. NMU leukemia incidence was 97.1%. In this study, immunohistochemical (IHC) analysis was valuable in classifying the leukemia of poorly differentiated blasts induced by NMU. Paraffin blocks were stained for MPO, CD3, CD15, CD20, and CD34 markers. The NMU-induced group was positive for MPO, but negative for CD3, CD15, CD20, and CD34. These CD markers suggest that they are useful in helping diagnose APL (M3) leukemia. The model of NMU-induced leukemogenesis in an S-D rat suggests a more definite way to classify APL. This APL will provide an important tool for chemical carcinogenesis and leukemia studies. [ABSTRACT FROM AUTHOR]

Identification of aberrant microRNA (miRNA) expression during chemical carcinogen–induced cell transformation will lead to a better understanding of the substantial role of miRNAs in cancer development. To explore whether aberrant miRNAs expression can be used as biomarkers of chemical exposure in risk assessment of chemical carcinogenesis, we analyzed miRNA expression profiles of human bronchial epithelial cells expressing an oncogenic allele of H-Ras (HBER) at different stages of transformation induced by benzo(a)pyrene (BaP) by miRNA array. It revealed 12 miRNAs differentially expressed in HBER cells at both pretransformed and transformed stages. Differentially expressed miRNAs were confirmed in transformed cells and examined in 50 pairs of primary human non–small-cell lung cancer (NSCLC) tissues using real-time PCR. Among these miRNAs, downregulation of miR-638 was found in 68% (34/50) of NSCLC tissues. However, the expression of miR-638 in HBER cells increased upon treatment of BaP in a dose-dependent manner. The expression of miR-638 was also examined in peripheral lymphocytes from 86 polycyclic aromatic hydrocarbons (PAHs)-exposed (PE) workers. We found that the average expression level of miR-638 in peripheral lymphocytes from 86 PE workers increased by 72% compared with control group. The levels of miR-638 were correlated with the concentration of urinary 1-hydroxypyrene (1-OHP) and external levels of PAHs. Overexpression of miR-638 aggravated cell DNA damage induced by BaP, which might be mediated by suppression of breast cancer 1 (BRCA1), one of the target genes of miR-638. In summary, we suggest that miR-638 is involved in the BaP-induced carcinogenesis by targeting BRCA1. [ABSTRACT FROM PUBLISHER]

Acetaldehyde interacts covalently with DNA to form major stable acetaldehyde-DNA adduct N2- ethyl-2'- de-oxyguanosine, which may be critical initiating event in the multistage process of chemical carcinogenesis primarily observed in gastroesophageal cancers. In the present study, RT-PCR experiment results showed increased expression of ADH and decreased expression of ALDH2 in GE cancerous conditions when compared with the normal GE tissue indicating the variation in the catabolism of acetaldehyde to acetate in the cancerous tissue. These results were further corroborated by enzyme assay where increased ADH enzyme activity was observed (0.445±0.02μM/ml/minute) in cancerous tissue compared to normal tissue (0.335±0.01 μM/ml/minute) whereas; ALDH2 enzyme activity (0.15±0.01 μM/ml/minute) decreased appreciably in cancerous tissue and compared to normal tissue (0.356±0.04 μM/ml/minute). Further, SDS-PAGE results too indicated differential expression of 40KD and 55KD proteins in normal and in GE cancerous tissue. Therefore, detection of ADH and ALDH2 expression levels in alcoholics will assist in the early diagnosis of gastro esophageal cancers. [ABSTRACT FROM AUTHOR]

Glutathione transferases (GST) are essentially known as enzymes that catalyse the conjugation of glutathione to various electrophilic compounds such as chemical carcinogens, environmental pollutants, and antitumor agents. However, this protein family is also involved in the metabolism of endogenous compounds which play critical roles in the regulation of signaling pathways. For example, the lipid peroxidation product 4-hydroxynonenal (4-HNE) and the prostaglandin 15-deoxy-Δ12,14- prostaglandin J2 (15d-PGJ2) are metabolized by GSTs and these compounds are known to influence the activity of transcription factors and protein kinases involved in stress response, proliferation, differentiation, or apoptosis. Furthermore, several studies have demonstrated that GSTs are able to interact with different protein partners such as mitogen activated protein kinases (i.e., c-jun N-terminal kinase (JNK) and apoptosis signal-regulating kinase 1 (ASK1)) which are also involved in cell signaling. New functions of GSTs, including S-glutathionylation of proteins by GSTs and ability to be a nitric oxide (NO) carrier have also been described. Taken together, these observations strongly suggest that GST might play a crucial role during normal or cancer cells proliferation or apoptosis. [ABSTRACT FROM AUTHOR]

Abstract: In this study we evaluated the effects of morin on the mitochondrial functions with reference to mitochondrial citric acid cycle enzymes, respiratory chain complex enzymes, membrane bound ATPases and protein-bound carbohydrates in mammary tissues of 7,12-dimethyl benz(a)-anthracene (DMBA)-induced mammary carcinoma of Sprague-Dawley rats. Adult female Sprague-Dawley rats were induced mammary carcinoma by administration of DMBA (25mg/kg b.wt.) orally. The normal and cancer-induced rats were treated with morin (50mg/kg b.wt.) for three times per week for 13 weeks. Cancer-induced rats showed a significantly increased level of lipid peroxidation (LPO) products and protein-bound carbohydrates with concomitant decreased levels of nonenzymic antioxidants (vitamin C, reduced glutathione [GSH]) and vitamin E and enzymic antioxidants (superoxide dismutase [SOD]), catalase (CAT) and glutathione peroxidase (GPx) in the mammary tissue. Decreased levels of ATPases, citric acid cycle enzymes and respiratory chain enzymes were observed in the mammary tissue of tumor bearing group of rats. Treatment with morin brought back lipid peroxidation products, nonenzymic and enzymic antioxidants to near normalcy. Since morin treatment decreases lipid peroxidation and enhances antioxidants and enzymes involved in the biochemical pathways, it may play a critical role in oxidative stress-related changes in cancer-induced rats and may possess a potent antioxidant potential to protect subcellular organelles being damaged by oxidative stress. [Copyright &y& Elsevier]

Abstract: Heme oxygenase-1 (HO-1) is an antioxidative and cytoprotective enzyme, which may protect neoplastic cells against anticancer therapies, thereby promoting the progression of growing tumors. Our aim was to investigate the role of HO-1 in cancer induction. Experiments were performed in HO-1+/+, HO-1+/−, and HO-1−/− mice subjected to chemical induction of squamous cell carcinoma with 7,12-dimethylbenz[a]anthracene and phorbol 12-myristate 13-acetate. Measurements of cytoprotective genes in the livers evidenced systemic oxidative stress in the mice of all the HO-1 genotypes. Carcinogen-induced lesions appeared earlier in HO-1−/− and HO-1+/− than in wild-type animals. They also contained much higher concentrations of vascular endothelial growth factor and keratinocyte chemoattractant, but lower levels of tumor necrosis factor-α and interleukin-12. Furthermore, tumors grew much larger in HO-1 knockouts than in the other groups, which was accompanied by an increased rate of animal mortality. However, pathomorphological analysis indicated that HO-1−/− lesions were mainly large but benign papillomas. In contrast, in mice expressing HO-1, most lesions displayed dysplastic features and developed to invasive carcinoma. Thus, HO-1 may protect healthy tissues against carcinogen-induced injury, but in already growing tumors it seems to favor their progression toward more malignant forms. [Copyright &y& Elsevier]

Abstract: To know whether the molecular responses to chemical carcinogens reflect only cell line specific molecular responses, or whether they can be regarded as characteristic of breast tissue, we have characterized four human breast cancer cell lines (MDA-MB-231, MDA-MB-468, T47-D, ZR-75-1). The activation of benzo(a)pyrene (BP), a model compound of polycyclic aromatic hydrocarbons, to its genotoxic BP-diolepoxide (BPDE) and p53 response and cell viability after BP exposure, and the p53 status in these cell lines were analyzed. Both TP53 (exons 5–8) mutations and total and phospho-p53 were analyzed. Three of the four cell lines clearly activated BP to BPDE-DNA adducts (MDA-MB-468, T47-D, ZR-75-1) and three had a mutation in the TP53 gene (MDA-MB-231, MDA-MB-468, T47-D). After BP-treatment the strongest p53 protein induction and phosphorylation at serine 392 was found in ZR-75-1 cells with a wt TP53 gene. Viability decreased dramatically only in ZR-75-1 and MDA-MB-468 cells although the relative cell number was reduced in all the cell lines suggesting that BP affects cell proliferation. In conclusion, a TP53 mutation does not necessarily lead to a loss of p53 protein response. This study stresses the importance of characterization of all human cancer cell lines for the intended targets of study. [Copyright &y& Elsevier]

Kaempferia galanga L. (K. galanga L.), belonging to the Zingiberaceae family, has been widely used in Thai traditional medicine for treatment of hypertension, asthma, rheumatism, indigestion, cold and headache and relief abdominal pain. This study aimed to investigate the effect of dichloromethane extract of K. galanga L. (DEK) and its major component ethyl-p-methoxycinnamate (EPMC) on hepatic microsomal cytochrome P450s enzyme activities in mice. After oral administration with DEK (100 mg/kg which is equivalent to EPMC 80 mg/kg), EPMC (120 and 160 mg/kg) for 28 consecutive days, the microsomal P450 content decreased. The CYP1A1 and CYP2B activities significantly increased, whereas CYP2E1 activity was significant inhibited only at the highest concentration of EPMC (160 mg/kg). None of the treatments did affect CYP1A2 and CYP3A4 activity when compared to the control group. The results indicated that K. galanga L. and its active compound, EPMC may participate in herbal-drug interaction and may also increase risk of toxicity and chemical carcinogenesis from drugs and compounds that are metabolized via CYP1A1, CYP2B and CYP2E1. [ABSTRACT FROM AUTHOR]

This review is focused on current information of avoidable environmental pollution and occupational exposure as causes of cancer. Approximately 2% to 8% of all cancers are thought to be due to occupation. In addition, occupational and environmental cancers have their own characteristics, e.g., specific chemicals and cancers, multiple factors, multiple causation and interaction, or latency period. Concerning carcinogens, asbestos/silica/wood dust, soot/polycyclic aromatic hydrocarbons [benzo(a) pyrene], heavy metals (arsenic, chromium, nickel), aromatic amines (4-aminobiphenyl, benzidine), organic solvents (benzene or vinyl chloride), radiation/radon, or indoor pollutants (formaldehyde, tobacco smoking) are mentioned with their specific cancers, e.g., lung, skin, and bladder cancers, mesothelioma or leukemia, and exposure routes, rubber or pigment manufacturing, textile, painting, insulation, mining, and so on. In addition, nanoparticles, electromagnetic waves, and climate changes are suspected as future carcinogenic sources. Moreover, the aspects of environmental and occupational cancers are quite different between developing and developed countries. The recent follow-up of occupational cancers in Nordic countries shows a good example for developed countries. On the other hand, newly industrializing countries face an increased burden of occupational and environmental cancers. Developing countries are particularly suffering from preventable cancers in mining, agriculture, or industries without proper implication of safety regulations. Therefore, industrialized countries are expected to educate and provide support for developing countries. In addition, citizens can encounter new environmental and occupational carcinogen nominators such as nanomaterials, electromagnetic wave, and climate exchanges. As their carcinogenicity or involvement in carcinogenesis is not clearly unknown, proper consideration for them should be taken into account. For these purposes, new technologies with a balance of environment and gene are required. Currently, various approaches with advanced technologies—genomics, exposomics, etc.—have accelerated development of new biomarkers for biological monitoring of occupational and environmental carcinogens. These advanced approaches are promising to improve quality of life and to prevent occupational and environmental cancers. [ABSTRACT FROM PUBLISHER]

Abstract: It is well established that genotoxic reactivity of chemical carcinogens or their metabolites is a critical event in the initiation of tumorigenesis. However, the underlying mechanisms of events following initiation are less well understood, and with respect to genotoxic liver carcinogenesis, it is largely unknown how the initiated cells progress to form preneoplastic hepatic foci. In the present study, we investigated the underlying events associated with tumor-promoting activity of 2-acetylaminofluorene (2-AAF), a powerful complete genotoxic rat liver carcinogen. Male Sprague–Dawley rats were fed NIH-31 diet containing 0.02% of 2-AAF for 24 weeks, and the status of cytosine DNA methylation, histone methylation, and microRNA expression was determined in the livers of control and 2-AAF-fed rats. The results demonstrate that stages of multistage carcinogenesis following the initiation are driven primarily by carcinogen-induced epigenetic alterations. This was evidenced by altered global histone lysine methylation patterns, increased histone H3 lysine 9 and histone H3 lysine 27 trimethylation in the promoter regions of Rassf1a, p16INK4a, Socs1, Cdh1, and Cx26 tumor suppressor genes, early Rassf1a and p16INK4a promoter CpG island hypermethylation, and altered microRNA expression in preneoplastic livers of rats exposed to 2-AAF. These changes were accompanied by dysregulation of the balance between cell proliferation and apoptosis, a fundamental pro-tumorigenic event in hepatocarcinogenesis. These results signify the fundamental role of epigenetic alterations in genotoxic liver carcinogenesis. [Copyright &y& Elsevier]

Context: Benzene is a ubiquitous pollutant; smoking habit, genetic polymorphisms, and analytical difficulties impact the identification of the best biomarker. Objective: To apply a systematic quantitative approach to evaluate urinary benzene (BEN-U) and S-phenylmercapturic acid (SPMA) as biomarkers of low benzene exposures. Methods: Seventy-one blue collar refinery workers, 97 white collar refinery workers and 108 general population subjects were included. Intrinsic characteristics, sampling and analytical issues were compared. Results: BEN-U and SPMA were detected in 99% and 78% of samples, which correlated with benzene exposure ( r == 0.456 and r == 0.636, respectively) and with urinary cotinine ( r == 0.630 and r == 0.570, respectively). Intrinsic characteristics were similar for the two biomarkers: specificity (0.64 and 0.69 for BEN-U and SPMA), sensitivity (0.74 and 0.83), as well as intra- and inter-individual variability (150% and >14 for both). Conclusion: BEN-U and SPMA show similar intrinsic characteristics; analytical issues in detecting SPMA suggest that BEN-U is more convenient for investigating low exposure levels. [ABSTRACT FROM AUTHOR]

Carcinogenesis is a multistage process involving a number of molecular pathways sensitive to intervention. Chemoprevention is defined as the use of natural and/or synthetic substances to block, reverse, or retard the process of carcinogenesis. To achieve greater inhibitory effects on cancer cells, combination of two or more chemopreventive agents is commonly considered as a better preventive and/or therapeutic strategy. Lunasin is a promising cancer preventive peptide identified in soybean and other seeds. Its efficacy has been demonstrated by both in vitro and in vivo models. This peptide has been found to inhibit human breast cancer MDA-MB-231 cells proliferation, suppressing cell cycle progress and inducing cell apoptosis. Moreover, lunasin potentiates the effects on these cells of different synthetic and natural compounds, such as aspirin and anacardic acid. This study explored the role of lunasin, alone and in combination with aspirin and anacardic acid on cell proliferation and foci formation of transformed NIH/3T3 cells induced by chemical carcinogens 7,12-dimethylbenz[a]anthracene or 3-methylcholanthrene. The results revealed that lunasin, acting as a single agent, inhibits cell proliferation and foci formation. When combined with aspirin, these effects were significantly increased, indicating that this combination might be a promising strategy to prevent/treat cancer induced by chemical carcinogens. [ABSTRACT FROM AUTHOR]

olein, a reactive electrophilic α, β-unsaturated aldehyde, is known to be an alkylating chemical carcinogen. The effect of acrolein on the activation of NF-κB in human malignant epidermal keratinocytes was examined to elucidate the molecular mechanism associated with this NF-κB-acrolein regulation and its consecutive sequence, nitric oxide (NO) production. Acrolein significantly downregulated the cellular NF-κB activity up to 60% compared with control as well as the lipopolysaccharide (LPS)-induced NO production in a dose response manner at concentrations of 10~30 μM. To investigate the regulatory mechanism associated with this NF-κB-acrolein downregulation, the relative level of phosphorylation of I-κBα (serines-32 and -36), a principle regulator of NF-κB activation, represented by acrolein, was quantified. Acrolein inhibited NF-κB activity without altering cellular levels of the phosphorylated and nonphosphorylated forms of I-κBα, implying that the downregulatory effect of acrolein on cellular NF-κB activity in human skin cells is an I-κBα-independent activation pathway. The results suggests that acrolein causes the decrease in nitric oxide production as an I-κBα-independent downregulator of NF-κB activity in human malignant keratinocytes, and acrolein-induced carcinogenesis may be associated with the modulation of cellular NF-κB activity. [ABSTRACT FROM AUTHOR]

Oxygen serves as an essential factor for oxidative stress, and it has been shown to be a mutagen in bacteria. While it is well established that ambient oxygen can also cause genomic instability in cultured mammalian cells, its effect on de novo tumorigenesis at the organismal level is unclear. Herein, by decreasing ambient oxygen exposure, we report a ∼50% increase in the median tumor-free survival time of p53-/- mice. In the thymus, reducing oxygen exposure decreased the levels of oxidative DNA damage and RAG recombinase, both of which are known to promote lymphomagenesis in p53-/- mice. Oxygen is further shown to be associated with genomic instability in two additional cancer models involving the APC tumor suppressor gene and chemical carcinogenesis. Together, these observations represent the first report directly testing the effect of ambient oxygen on de novo tumorigenesis and provide important physiologic evidence demonstrating its critical role in increasing genomic instability in vivo. [ABSTRACT FROM AUTHOR]

The aromatic amine 4-aminobiphenyl (4-ABP) is present in tobacco smoke. In humans, it is also a known bladder carcinogen. We describe here a method for the quantification of total 4-ABP in urine using capillary gas chromatography/tandem mass spectrometry, with an effective detection limit in urine samples of approximately 0.87 pg/mL. We also examined the efficiency of chemical or enzymatic hydrolysis of urinary aromatic amine metabolites. Although we found acidic or basic hydrolysis effective, we found enzymatic hydrolysis (ββ-glucuronidase with either Escherichia coli or Helix pomatia) ineffective. As part of this work, we also confirm the presence of N-acetyl-4-ABP and 4-ABP glucuronide in human urine samples from smokers. These metabolites have been reported in animal studies, but previously they have not been identified in human samples. These metabolites, however, were found to be unstable and thus infeasible for biomonitoring. The final validated urinary total 4-ABP assay was applied to the analysis of samples from smokers and nonsmokers, whose status was confirmed from cotinine EIA measurements. Among 41 confirmed nonsmokers, the geometric mean (95% CI) of 4-ABP concentration was 1.64 pg/mg creatinine (1.30--2.07). Conversely, in 89 smokers, the geometric mean of 4-ABP concentration was significantly greater, at 8.69 pg/mg creatinine (7.43--10.16), p < 0.001. Our results indicate that following tobacco smoke exposure, total urinary 4-ABP is a reliable biomarker for exposure to this carcinogen. [ABSTRACT FROM AUTHOR]

Arsenic is a well-recognized human carcinogen, yet the mechanism by which it causes human cancer has not been elucidated. MicroRNAs (miRNAs) are a big family of small noncoding RNAs and negatively regulate the expression of a large number of protein-coding genes. We investigated the role of miRNAs in arsenic-induced human bronchial epithelial cell malignant transformation and tumor formation. We found that prolonged exposure of immortalized p53-knocked down human bronchial epithelial cells (p53lowHBECs) to low levels of arsenite (NaAsO2, 2.5 μM) caused malignant transformation that was accompanied by epithelial to mesenchymal transition (EMT) and reduction in the levels of miR-200 family members. Stably reexpressing miR-200b in arsenite-transformed cells (As-p53lowHBECs) completely reversed their transformed phenotypes, as evidenced by inhibition of colony formation in soft agar and prevention of xenograft tumor formation in nude mice. Moreover, stably expressing miR-200b alone in parental nontransformed p53lowHBECs was sufficient to completely prevent arsenite exposure from inducing EMT and malignant transformation. Further mechanistic studies showed that depletion of miR-200 in arsenite-transformed cells involved induction of the EMT-inducing transcription factors zinc-finger E-box-binding homeobox factor 1 (ZEB1) and ZEB2 and increased methylation of miR-200 promoters. Stably expressing ZEB1 alone in parental nontransformed p53lowHBECs was sufficient to deplete miR-200, induce EMT and cause cell transformation, phenocopying the oncogenic effect of 16-week arsenite exposure. These findings establish for the first time a causal role for depletion of miR-200b expression in human cell malignant transformation and tumor formation resulting from arsenic exposure. [ABSTRACT FROM PUBLISHER]