INDUCTION OF MORPHOLOGICAL CHANGE OF HUMAN MYELOID LEUKEMIA AND ACTIVATION OF PROTEIN KINASE C BY A NOVEL ANTIBIOTIC, TAUTOMYCIN

Abstract

A novel antibiotic tautomycin induced many blebs on the surface of K562 human chronic myeloid leukemia cells, similar to the morphological change induced by phorbol esters. However, tautomycin did not induce nitroblue tetrazolium reducing activity, when HL60 human promyelocytic leukemia cells were caused to differentiate by quinomycin into mature granulocytes. It did not induce spread of HL60 cells, one of the phenotypes of mature macrophages. In addition, it did not compete with phorbol dibutyrate to bind to the cell surface of K562 cells. However, tautomycin significantly activated protein kinase C (PKC) extracted from K562 cells. These results indicate that tautomycin is a new activator of PKC, distinct from phorbol esters.