PROLIFERATION AND ORGAN INVASION OF EXPERIMENTAL CHLOROMA CELLS STUDIED BY CHROMOSOMAL ANALYSIS

Abstract

Shay's granulocytic sarcoma (acute myeloblastic leukemia of rat) has been maintained in our laboratory by serial subcutaneous inoculation since 1962. Stemline of this tumor cell have shown stable 43 chromosome number with one small subtelocentric extra chromosome and 3 marker chromosomes since about 245th transplant generation. The proliferation and organ invasion of leukemic cells have been studied quantitatively in chasing of these marker chromosomes. In addition, proliferation kinetics in vitro in suspension culture was also studied. Leukemic cells accumulated in the bone marrow and spleen before the appearance of subcutaneous tumor which was observed macroscopically at 5-6 days after inoculation. Leukemic cells appeared in the peripheral blood two days later than in bone marrow and spleen. It is suggested that transplanted leukemic cells migrated partially to the bone marrow and spleen where they proliferated, and then flushed out to the peripheral blood. The survival time of inoculated rats has become shorter in the course of serial transplantation. It is suggested that these leukemic cells gradually became to dedifferentiated cells without changing the generation time. Chromosomal analysis of the Shay's granulocytic sarcoma cells in suspension culture in vitro showed the similar 4 marker chromosomes as the cells in vivo. The stemline cells of this tumor in vitro showed 43 chromosomes. And cells with 42 and 44 chromosomes were observed 38 per cent. Cells with 42 and 44 chromosomes are assumed to originated from the non-disjunction of one of No. 11 chromosomes during the division of cells with 43 chromosome number.