[Age-related differences in hematopoietic progenitor cells and the problems of carcinogenesis]

In the past years the authors advanced a hypothesis of the "age-associated layers" of parent hemopoietic cells. The hypothesis was based first of all on the differences in the patterns of leukemias and noncancerous diseases (of the hemopoietic tissues) in children and adults. The nature of the changing age-associated characteristics of parent cells remained obscure. Analysis of leukemias and epithelial tumors of radiation nature, formed in the victims to nuclear bomb explosion in Japan in 1945, analysis of leukemias occurring in persons with genetic diseases characterized by the known chromosomal aberrations (Down's syndrome, Louis-Bar syndrome, etc.), studies into the inherited forms of leukemias (chronic lympholeukemia, subleukemic myelosis, etc.--all these conditions are marked by the unstable genetic apparatus and high mutability) allowed the authors to make a conclusion about a kit of active differentiation genes which are replaced in health with age. Cancerous transformation may take place just at the level of those genes in parent cells with an unstable genome, since there appear specific mutation (in contrast to nonspecific ones characterizing the unstable genome) and a cancerous clone.