Inhibition of the in vitro growth of blast progenitors from acute myeloblastic leukemia patients by transforming growth factor-beta (TGF-beta).

The effects of transforming growth factor-beta (TGF-beta) on the blast progenitors from nine acute myeloblastic leukemia patients were studied in methylcellulose and suspension cultures. Leukemic blast progenitors undergo terminal divisions with a limited differentiation in methylcellulose culture, making blast colonies. Blast progenitors can renew themselves. The self-renewal can be reflected by secondary colony formation after replating primary blast colonies in fresh methylcellulose media and by the exponential growth of clonogenic cells in suspension culture. TGF-beta suppressed primary and secondary colony-formation in methylcellulose culture. Furthermore, TGF-beta suppressed the recovery of clonogenic cells in suspension. The results indicate that TGF-beta is effective in inhibiting not only terminal divisions but also self-renewal of leukemic blast progenitors.