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Carcinogenesis

About: Carcinogenesis is a research topic. Over the lifetime, 60368 publications have been published within this topic receiving 3192599 citations. The topic is also known as: oncogenesis & tumorigenesis.


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Journal ArticleDOI
TL;DR: The ‘macrophage balance’ is discussed in the context of the apparent paradox of tumor promotion by innate immunity‐driven inflammation and the seemingly opposed tumor surveillance by adaptive immune responses.
Abstract: An intrinsic (oncogene-driven) pathway and an extrinsic (microenvironment-driven) pathway connect inflammatory reactions and cancer. M2-polarized tumor-associated macrophages and the related myeloid-derived suppressor cells are key prototypic components of smoldering inflammation driving neoplastic progression. However, mononuclear phagocytes can exert anti-tumor activity by killing tumor cells and eliciting tissue disruptive reactions (M1), a likely scenario in the early phases of carcinogenesis of immunogenic tumors and following therapeutic intervention. Shifting the macrophage balance represents a viable therapeutic target. Herein, the 'macrophage balance' is discussed in the context of the apparent paradox of tumor promotion by innate immunity-driven inflammation and the seemingly opposed tumor surveillance by adaptive immune responses.

573 citations

Journal Article
TL;DR: The overall effects of common CYP polymorphisms were found to be moderate in terms of penetrance and relative risk, with odds ratios ranging from 2 to 10.
Abstract: Tobacco use is causally associated with cancers of the lung, larynx, mouth, esophagus, kidneys, urinary tract, and possibly, breast. Major classes of carcinogens present in tobacco and tobacco smoke are converted into DNA-reactive metabolites by cytochrome P450 (CYP)-related enzymes, several of which display genetic polymorphism. Individual susceptibility to cancer is likely to be modified by the genotype for enzymes involved in the activation or detoxification of carcinogens in tobacco and repair of DNA damage. We summarize here the results of case-control studies published since 1990 on the effects of genetic variants of CYP1A1, 1A2, 1B1, 2A6, 2D6, 2E1, 2C9, 2C19, 17, and 19 alone or in combination with detoxifying enzymes as modifiers of the risk for tobacco-related cancers. The results of studies on gene-gene interactions and the dependence of smoking-related DNA adducts on genotype were also analyzed. Some CYP variants were associated with increased risks for cancers of the lung, esophagus, and head and neck. The risk was often increased in individuals who also had GSTM1 deficiency. For breast cancer in women, a few studies suggested an association with CYPs related to metabolism of tobacco carcinogens and steroidal hormones. The overall effects of common CYP polymorphisms were found to be moderate in terms of penetrance and relative risk, with odds ratios ranging from 2 to 10. Some CYP1A1/GSTM1 0/0 genotype combinations seem to predispose the lung, esophagus, and oral cavity of smokers to an even higher risk for cancer or DNA damage, requiring, however, confirmation. Future strategies in molecular cancer epidemiology for identifying such susceptible individuals are discussed with emphasis on well-designed larger studies.

573 citations

Journal Article
TL;DR: The data indicate that activation of iNOS and excess production of NO in response to inflammatory cytokines cause DNA damage and inhibit DNA repair proteins and NO inactivation of DNA repair enzymes may provide a link between inflammation and the initiation, promotion, and/or progression of cholangiocarcinoma.
Abstract: Chronic infection and inflammation are risk factors for the development of cholangiocarcinoma, a highly malignant, generally fatal adenocarcinoma originating from biliary epithelia. However, the link between inflammation and carcinogenesis in these disorders is obscure. Because nitric oxide (NO) is generated in inflamed tissues by inducible nitric oxide synthase (iNOS) and because DNA repair proteins are potentially susceptible to NO-mediated nitrosylation, we formulated the hypothesis that inflammatory cytokines induce iNOS and sufficient NO to inhibit DNA repair enzymes leading to the development and progression of cholangiocarcinoma. iNOS and nitrotyrosine were demonstrated in 18/18 cholangiocarcinoma specimens. Furthermore, iNOS and NO generation could be induced in vitro by inflammatory cytokines (mixture of interleukin-1β, IFN-γ, and tumor necrosis factorα ) in three human cholangiocarcinoma cell lines. NO-dependent DNA damage as assessed by the comet assay was demonstrated during exposure of the three cholangiocarcinoma cell lines to cytokines. Moreover, global DNA repair activity was inhibited by 70% by a NO-dependent process after exposure of cells to cytokines. Our data indicate that activation of iNOS and excess production of NO in response to inflammatory cytokines cause DNA damage and inhibit DNA repair proteins. NO inactivation of DNA repair enzymes may provide a link between inflammation and the initiation, promotion, and/or progression of cholangiocarcinoma.

573 citations

Journal ArticleDOI
TL;DR: It is suggested that miR‐122, a tumor suppressor microRNA affecting hepatocellular carcinoma intrahepatic metastasis by angiogenesis suppression, exerts some of its action via regulation of ADAM17, which is involved in metastasis.

570 citations

Journal ArticleDOI
16 Apr 2008-PLOS ONE
TL;DR: It is shown that CR induces a two-fold increase SIRT1 expression in the intestine of rodents and that ectopic induction of Sirt1 in a β-catenin-driven mouse model of colon cancer significantly reduces tumor formation, proliferation, and animal morbidity in the absence of CR.
Abstract: Numerous longevity genes have been discovered in model organisms and altering their function results in prolonged lifespan. In mammals, some have speculated that any health benefits derived from manipulating these same pathways might be offset by increased cancer risk on account of their propensity to boost cell survival. The Sir2/SIRT1 family of NAD + dependent deacetylases is proposed to underlie the health benefits of calorie restriction (CR), a diet that broadly suppresses cancer in mammals. Here we show that CR induces a two-fold increase SIRT1 expression in the intestine of rodents and that ectopic induction of SIRT1 in a b-catenin-driven mouse model of colon cancer significantly reduces tumor formation, proliferation, and animal morbidity in the absence of CR. We show that SIRT1 deacetylates b-catenin and suppresses its ability to activate transcription and drive cell proliferation. Moreover, SIRT1 promotes cytoplasmic localization of the otherwise nuclear-localized oncogenic form of b-catenin. Consistent with this, a significant inverse correlation was found between the presence of nuclear SIRT1 and the oncogenic form of b2catenin in 81 human colon tumor specimens analyzed. Taken together, these observations show that SIRT1 suppresses intestinal tumor formation in vivo and raise the prospect that therapies targeting SIRT1 may be of clinical use in b2catenin-driven malignancies.

569 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20239,028
20227,271
20213,536
20203,486
20193,433
20183,073