Alteration of p60c-src expression in human leukemia-lymphoma cells correlated with induced differentiation.

Abstract

KUBOTAExpression of cellular src-gene product (p60c"src) in human leukemia-lymphoma cell lines was analysed by flow cytometry using a monoclonal antibody (McAb), H2B4 which recognizes p60c"lSrc protein in human cells. In several human leukemia-lymphoma cell lines (K562, Namalva, HL60, U937), p60c"src expression was higher than in peripheral mononuclear cells from healthy volunteers.S omenon-lymphoid leukemia cells can be induced to differentiate into monocyte-macrophages by 12-O-tetradecanoyl phorbol-13-acetate (TPA). K562 cells were also induced to differentiate not only morphologically but also functionally into monocyte-macrophages by TPA. Flow cytometric analyses using the McAb H2B4 revealed that the amount of p60c**rc expression in K562 cells markedly decreased during TPA induced differentiation.The activity of protein kinase associated with p60c"src in K562 cells was determined employing IgG of immunized rabbit serum specific for p60c'src. The immunized rabbit IgG heavy chain phosphorylation by protein kinase also decreased after the induced differentiation. We detected p60c"5rc protein in acute lymphoid leukemia cells as well as acute non-lymphoid leukemia cells freshly isolated from patients. The amount of p60c"src protein decreased in some acute non-lymphoid leukemia cases, but it increased in others after TPA induced differentiation.No correlation was observed between FAB classification of acute leukemias and the amount of endogenous p60C 5rc expression.