Transcription from Chromatins of Human Lymphocytic Leukemia Cells and Normal Lymphocytes1

Chromatins prepared from leukemic lymphosarcoma cell(s), (LS), acute lymphoblastic leukemia cells, chronic lymphocytic leukemia cells and normal tissue culture lymphocytes (NC-37) were studied with respect to their chemical compositions, thermal denaturation profiles, and template activities. Acute lymphoblastic leukemia and LS chromatins had approximately 2 to 4 times the nonhistone protein and RNA contents of CLL chromatin. NC-37 chromatin showed increased amounts of nonhistone protein and less histone content as compared with leukemic lymphocytes. LS chromatin had the highest template activity (10% of purified DNA). The template activities of acute lymphoblastic leukemia chromatin (8%) and CLL chromatin (5%) were also higher than those of NC-37 chromatin (4%). By hybridization competition experiments, it was shown that the RNA products synthesized from acute lymphoblastic leukemia chromatin had additional RNA species which were not present in the transcripts of CLL and NC-37 chromatins. In contrast, the RNA products from NC-37 chromatin were similar to those from leukemic lymphocyte chromatins (acute lymphoblastic leukemia cell and CLL). The results also showed that leukemic lymphocyte chromatins, especially from LS and acute lymphoblastic leukemia had more transcribable repetitive DNA sequences than did NC-37 chromatin. The data suggest that transcription of additional families of repetitive DNA sequences accompany the transition to cancer in the hematopoietic system.