Chronic myelogenous leukemia (CML) is a clonal disorder of the hematopoietic stem cell characterized by a chimeric BCR/ABL gene giving rise to a 210-kD fusion protein with dysregulated tyrosine kinase activity. We investigated the effect of genistein, a protein tyrosine kinase inhibitor, on the in vitro growth of CML and normal marrow-derived multipotent (colony- forming unit-mix [CFU-Mix]), erythroid (burst-forming unit-erythroid [BFU- E]), and granulocyte-macrophage (colony-forming unit-granulocyte-macrophage [CFU-GM]) hematopoietic progenitors. Continuous exposure of CML and normal marrow to genistein induced a statistically significant and dose-dependent suppression of colony formation. Genistein doses causing 50% inhibition of CML and normal progenitors were not significantly different for CFU-Mix (27 μmol/L v 23 μmol/L), BFU-E (31 μmol/L v 29 μmol/L), and CFU-GM (40 μmol/L v 32 μmol/L). Preincubation of CML and normal marrow with genistein (200 μmol/L for 1 to 18 hours) induced a time-dependent suppression of progenitor cell growth, while sparing a substantial proportion of long-term culture-initiating cells (LTC-IC) from CML (range, 91% ± 9% to 32% ± 3%) and normal marrow (range, 85% ± 8% to 38% ± 9%). Analysis of individual CML colonies for the presence of the hybrid BCR/ABL mRNA by reverse transcription-polymerase chain reaction (RT-PCR) showed that genistein treatment significantly reduced the mean ± SD percentage of marrow BCR/ABL+ progenitors both by continuous exposure (76% ± 18% v 24% ± 12%, P ≤ .004) or preincubation (75% ± 16% v 21% ± 10%, P ≤ .002) experiments. Preincubation with genistein reduced the percentage of leukemic LTC-IC from 87% ± 12% to 37% ± 12% (P ≤ .003). Analysis of individual colonies by cytogenetics and RT-PCR confirmed that genistein-induced increase in the percentage of nonleukemic progenitors was not due to suppression of BCR/ABL transcription. Analysis of nuclear DNA fragmentation by DNA gel electrophoresis and terminal deoxynucleotidyl transferase assay showed that preincubation of CML mononuclear and CD34+ cells with genistein induced significant evidence of apoptosis. These observations show that genistein is capable of (1) exerting a strong antiproliferative effect on CFU-Mix, BFU-E, and CFU-GM while sparing the more primitive LTC-IC and (2) selecting benign hematopoietic progenitors from CML marrow, probably through an apoptotic mechanism.
|Number of pages||10|
|Publication status||Published - Oct 15 1996|
ASJC Scopus subject areas