Molecular-genetic mechanisms of initiation, promotion and progression of tumors

Abstract

Carcinogenesis - the process of turning a normal cell into a tumor cell under the influence of the mutations that accumulate in the cell. The cause of tumor cells is the accumulation of her mutation. The accumulation of cell mutations occurs as a result of the occurrence of genetic instability. The process of tumor development is divided into 3 main stages: initiation, promotion and progression. At the stage of initiation of cell receives the first mutational hit, which leads to disruption of its genetic stability. Most often, mutations are subjected to proto-oncogenes, genes-tumor suppressors, and genes governing DNA repair processes. At this stage there is an accumulation in the cell genetic damage that lead to an increase of the degree of malignancy. The next step in the transformation of cells in a tumor is promoted. This period has transformed as a result of mutations cells acquire a number of properties that help it to survive in the environment. They no longer respond to signals from the environment, acquire, auto- and paracrine stimulation signals of proliferation, the inhibition of apoptosis, genetic instability, changes in the morphology of the cells, the lack of replicative aging. Cells of tumour clone is constantly mutating under the pressure of selection by the immune system of the body. This leads to qualitative changes of the phenotype of tumor cells, the emergence is one of many tumor clones. This stage is called “tumor progression”. As a result of increasing tumor mass requires greater amount of nutrients. The stimulation of angiogenesis. By reducing the degree of affinity of the cells to the substrate and increase its mobility, there are secondary foci, metastases. The development of tumor process captures new areas in the body in Spite of the constant improvement of methods of therapy of tumors, the number of patients who achieve long-term remission is not great. So researchers are looking for ways for more complete and in-depth study of the pathogenesis of tumors, since this will facilitate the development of more effective approaches to therapy of tumors. This article briefly describes the main stages of tumor development.