Inhibition of interleukin 3 and granulocyte-macrophage colony-stimulating factor stimulated increase of active ras.GTP by herbimycin A, a specific inhibitor of tyrosine kinases.

Interleukin 3 (IL-3) and granulocyte-macrophage colony-stimulating factor (GM-CSF) stimulate the proliferation of several kinds of cultured hematopoietic cell lines. Growth signals from IL-3 and GM-CSF cause accumulation of active Ras.GTP complexes in PT18 mouse mast cell line (Satoh, T., Nakafuku, M., Miyajima, A., and Kaziro, Y. (1991) Proc. Natl. Acad. Sci. U. S. A. 88, 3314-3318). In this paper we describe the effect of herbimycin A, a tyrosine kinase-specific inhibitor, on the activation of Ras. The increase of Ras.GTP induced by IL-3 and GM-CSF diminished in cells treated with 0.5 approximately 1 micrograms/ml of herbimycin A for 24 h prior to the addition of the growth factors. Under this condition, the extent of phosphorylation on tyrosine residues of proteins decreased. However, the activity of cAMP-dependent protein kinase and protein kinase C did not change. Growth of cells in the presence of IL-3 or GM-CSF was also completely inhibited. These observations suggest that tyrosine kinases are involved in the pathways between IL-3 and GM-CSF receptors and Ras and that they are essential for the growth stimulated by these growth factors.