TRANSFORMING GROWTH-FACTOR-BETA-1 FUNCTIONS IN MONOCYTIC DIFFERENTIATION OF HEMATOPOIETIC-CELLS THROUGH AUTOCRINE AND PARACRINE MECHANISMS

This study examined the role of transforming growth factor beta 1 (TGF -beta 1) in monocytic differentiation of hematopoietic cells, TGF-beta 1 and retinoic acid (RA) inhibited HL-60 cell growth in a dose-depend ent fashion. Treatment of HL-60 cells with a combination of TGF-beta 1 and a 50% optimal dose of RA (RA + TGF-beta 1) resulted in increased growth suppression compared to the individual treatments, Morphologica l studies revealed that TGF-beta 1 induced promonocytic differentiatio n (68%), RA induced granulocytic differentiation (98%), and RA + TGF-b eta 1 induced monocytic (54%) and granulocytic (46%) differentiation o f HL-60 cells. Induction of the monocyte-specific marker, nonspecific esterase, was markedly increased by TGF-beta 1 and RA + TGF-beta 1 tre atment but not by RA treatment. Both TGF-beta 1 treatment and RA treat ment increased TGF-beta ligand and TGF-beta receptor protein and mRNA levels. To determine whether RA mediated HL-60 cell growth inhibition and differentiation through the autocrine expression of TGF-beta 1, ex periments using TGF-beta 1 antisense oligonucleotides or TGF-beta 1-ne utralizing antibodies were conducted, TGF-beta 1 antisense oligonucleo tides and neutralizing antibodies partially blocked RA-induced inhibit ion of proliferation, and TGF-beta 1 antisense oligonucleotides revers ed RA-induced granulocytic maturation, demonstrating that RA signals a utocrine expression of TGF-beta 1 and TGF-beta receptors. The effect o f TGF-beta 1 on normal hematopoiesis was also studied using primary hu man fetal liver cells, TGF-beta 1 alone and in the presence of interle ukin 3 promoted macrophage differentiation of primitive fetal liver ce lls. Cell surface expression of the monocyte/macrophage-specific marke r c-fms was increased 3.1-fold following TGF-beta 1 treatment. In addi tion, TGF-beta 1-treated cells displayed a 51% increase in phagocytosi s as compared to interleukin 3-treated control cells. These studies de fine a role for TGF-beta 1 in the autocrine and paracrine regulation o f monocyte/macrophage differentiation.