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Acta Medica Medianae
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EPIGENETIC MECHANISMS OF THE CANCEROGENESIS
Ninoslav ĐELIĆ
Faculty of Veterinary Medicine, Belgrade
The biological acitivity of many cancerogenic agents is manifested in geno-toxic mechanisms by changing the information encoded in the DNA molecules. However, it becomes much clearer that there are non-genotoxic (epigenetic) cancerogens whose action is manifested through changes of the genes'activity without causing mutations. The transfonnation of the normal cell into a malign one requires a greater number of genetic and/or epigenetic changes that undergo at least three phases, namely, initiation, promotion and progression. The epigenetic cancerogenes. realize their effect primarily in the promotion phase, primarily, by stimulating the cell division (mitogenesis). Unlike the genotoxic agents affecting the DNA molecule, the non-genotoxic cancerogenes can affect a considerably greater number of cell constituents and products, that is, the components of the signal transduction system, the protein factors involved in the regulation of replication, reparation and transcription of the DNA. Besides, the non-genotoxic cancerogenes can change a degree of methylation of the nucleus DNA and chromatin conformation. Despite prominent differences between the genotoxic and the non-genotoxic cancerogenes, it is necessary to stress that such a way of division is somewhat imprecise regarding the fact that the chemical cancerogenes often exert their effect through a combination of mechanisms while the primary mechanisms of effect can vary depending on the type of the cell.
Key words: Adolescence, pregnancy, child delivery |