[Differentiation antigens in tumors: dependence on carcinogenesis mechanisms and progression (a hypothesis)].

The data considered in the paper indicate that a tumor clone resulting from cell transformation, in order to develop, should overcome a microenvironmental constraint. This destroys intercellular contacts and cell interactions with extracellular matrix required for induction and maintenance of epithelium differentiation. The possible reasons for this lie in mutations of genes that control cell adhesion molecules and integrins, as well as proteases secreted by a tumor. These events lead to partial loss of differentiation antigens by a cell or to their incorrect localization in a cell. Simultaneously, the expression of embryo-specific genes is unblocked, leading to overexpression of embryonic antigens and their abnormal secretion into blood, which results in appearance of oncofetal markers in blood. Discussed from this point of view are alpha-fetoprotein, the carcinoembryonic antigen, and the prostate-specific antigen, which are used as tumor markers.