Release of early human hematopoietic progenitors from quiescence by antisense transforming growth factor β1 or Rb oligonucleotides

Abstract

We have used antisense oligonucleotides to study the roles of transforming growth factor β (TGF-β) and the two antioncogenes, retinoblastoma susceptibility (Rb) and p53, in the negative regulation of proliferation of early hematopoietic cells in culture. The antisense TGF-β sequence significantly enhanced the frequency of colony formation by multi-lineage, early erythroid, and granulomonocytic progenitors, but did not affect colony formation by late progenitors. Single cell culture and limiting dilution analysis indicated that autocrine TGF-β is produced by a subpopulation of early progenitors. Antisense Rb but not antisense p53 yielded similar results in releasing multipotential progenitors (colony-forming unit-granulocyte/erythroid/macrophage/megakaryocyte) from quiescence. Rb antisense could partially reverse the inhibitory effect of exogenous TGF-β. Anti-TGF-β blocking antibodies, antisense TGF-β, or Rb oligonucleotides all had similar effects. No additive effects were observed when these reagents were combined, suggesting a common pathway of action. Our results are consistent with the model that autocrine production of TGF-β negatively regulates the cycling status of early hematopoietic progenitors through interaction with the Rb gene product.