Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0037116 (silicosis)
 1,822 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The carcinogenic effects of crystalline silica in rat lungs were extensively demonstrated by many experimental long-term studies, showing a marked predominance for adenocarcinomas originating from alveolar type II cells and associated with areas of pulmonary fibrosis (silicosis). In contrast with its effects in rats, silica did not induce alveolar type II hyperplasia and lung tumors in mice and hamsters, pointing to a critical role for host factors. Using these animal models, we are investigating the role of cytokines and other cellular mediators on the proliferation of alveolar type II cells. Immunohistochemical localization of TGF-beta 1 precursor in alveolar type II cells adjacent to silicotic granulomas was shown to occur in rats, but not in mice, and hamsters, suggesting a pathogenetic role for this regulatory growth factor. Recent investigations in our laboratory on the biologic mechanisms of crystalline silica included determination of anionic sites on crystalline silica surfaces by binding of the cationic dye Janus Green B; binding of crystalline silica to DNA, demonstrated by infrared spectrometry; production of oxygen radicals by crystalline silica in aqueous media; induction of DNA strand breakage and base oxidation in vitro and its potentiation by superoxide dismutase and by hydrogen peroxide; and induction by crystalline silica of neoplastic transformation and chromosomal damage in cells in culture. On the basis of these in vitro studies, we propose that DNA binding to crystalline silica surfaces may be important in silica carcinogenesis by anchoring DNA close to sites of oxygen radical production on the silica surface, so that the oxygen radicals are produced within a few A from their target DNA nucleotides.
 ...
PMID:Mechanisms of carcinogenesis by crystalline silica in relation to oxygen radicals. 770 91

The development of our studies on silica carcinogenesis and its mechanisms is reviewed. Starting from an analysis of the cellular reactions to silica in the pathogenesis of silicosis in the rat, followed by an analysis of the carcinogenic response to silica in the lungs of rats (but not in mice and hamsters), we went on to develop cellular models for culture and neoplastic transformation of rat alveolar epithelial cells. We studied the binding of silica to DNA, the generation of reactive oxygen species and the DNA damage mediated by hydroxyl radicals, showing marked differences among silica samples of varying purity. Then we investigated the role of peptides induced by silica in various cells, including cytokines and growth factors. Tumor necrosis factor (TNF)-alpha, which can cause activation of DNA transcription and is required for silica-induced fibrosis, was found to inhibit neoplastic transformation by quartz in cell cultures. Transforming growth factor (TGF)-beta was found to be produced in hyperplastic alveolar type II cells and to reach fibroblasts, macrophages and the connective tissue matrix adjacent to silicotic granulomas. Neuroendocrine cells and their peptides were found to be increased in alveolar and bronchiolar epithelia of silica lesions in rats, in contrast with mice and hamsters. Expression of adhesion molecules was found to be altered in silica-induced carcinogenesis and epithelial-mesenchymal transition was revealed by mesenchymal markers in the induced carcinomas. Promoter hypermethylation of adhesion genes in the induced carcinomas indicated a role for epigenetic mechanisms.
 ...
PMID:Silicosis and lung cancer: a fifty-year perspective. 1635 May 47

Glyoxalase I (Glo1) is the main scavenging enzyme of methylglyoxal (MG), a potent precursor of advanced glycation end products (AGEs). AGEs are known to control multiple biological processes, including epithelial to mesenchymal transition (EMT), a multistep phenomenon associated with cell transformation, playing a major role in a variety of diseases, including cancer. Crystalline silica is a well-known occupational health hazard, responsible for a great number of human pulmonary diseases, such as silicosis. There is still much debate concerning the carcinogenic role of crystalline silica, mainly due to the lack of a causal demonstration between silica exposure and carcinogenesis. It has been suggested that EMT might play a role in crystalline silica-induced lung neoplastic transformation. The aim of this study was to investigate whether, and by means of which mechanism, the antiglycation defence Glo1 is involved in Min-U-Sil 5 (MS5) crystalline silica-induced EMT in BEAS-2B human bronchial epithelial cells chronically exposed, and whether this is associated with the beginning of a neoplastic-like transformation process. By using gene silencing/overexpression and scavenging/inhibitory agents, we demonstrated that MS5 induced hydrogen peroxide-mediated c-Jun-dependent Glo1 up-regulation which resulted in a decrease in the Argpyrimidine-modified Hsp70 protein level which triggered EMT in a novel mechanism involving miR-21 and SMAD signalling. The observed EMT was associated with a neoplastic-like phenotype. The results obtained provide a causal in vitro demonstration of the MS5 pro-carcinogenic transforming role and more importantly they provide new insights into the mechanisms involved in this process, thus opening new paths in research concerning the in vivo study of the carcinogenic potential of crystalline silica.
...
PMID:Glyoxalase I drives epithelial-to-mesenchymal transition via argpyrimidine-modified Hsp70, miR-21 and SMAD signalling in human bronchial cells BEAS-2B chronically exposed to crystalline silica Min-U-Sil 5: Transformation into a neoplastic-like phenotype. 2678 15