Vol. 125, No. 1, 1984 November 30, 1984 BIOCHEMICAL AND BIOPHYSICAL RESEARCHCOMMUNICATIONS Pages 90-96 HUMANLEUKEMIA K562 CELLS: RELATIONSHIP BETWEEN HEMIN-MEDIATED ERYTHROID INDUCTION, CELL PROLIFERATIONAND EXPRESSION OF c-ABL AND c-MYC ONCOGENES 1,2 1 1 1 Roberto Gambar~, Laura del Senno I Roberta Piva, Raffaella Barbieri, 2 Francesca Amelotti. Francesco Bemardi, Giovanna Marchetti I, Franca Citarella, Marco Tripodi 2 and Antonio Fantoni2 1 Centro di Studi Biochimici sul Morbo di Cooley, Ferrara and 2Dipartimento di Biopatologia Umana, UniversitA degli Studi di Roma, Italy Received September 24, 1984 We have studied the expression of the c-myc and c-abl oncogenes in two h~nan leukemic K562 cell lines which do express hemoglobin genes retaining a differential rate of cell proliferation. Our data indicate that in heroin-indu- ced K562(S) cells the expression of c-abl oncogene decreases and appears to be related to a decrease in the proliferation capacity rather than to the activa- tion of differentiated functions. The K562(hC) cell line, which produces large amounts of Hb Gower 1 retaining an efficient rate of cell proliferation, expresses indeed the c-abl oncogene at high level. © i9~4Academic~ ..... Zne. The implication of a ntm~oer of cellular oncogenes in tunor cell growth has recently arisen growing interest in many laboratories (1-4). Cellular oncoge- nes are indeed homologous to the transforming sequences of certain retroviruses and are expressed at high level in many tumor cell lines (5,6). A decrease in the expression of some oncogenes seems to be associated with the activation of differentiated functions (7-10). This decrease has been for instance observed during the terminal differentiation of HL60 cells, which after induction with dimethylsulfoxide or retinoic acid stop dividing and accu~nulate at lower le- vels c-myc transcripts (7,8). In the present study the relationship between the expression of oncogenes, cell proliferation and differentiation was investigated by examining the accu- mulation of c-abl and c-myc sequences in two human leukemia K562 cell lines which do express hemoglobin genes while retaining a differential rate of cell proliferation. K562 is a cell line which was isolated from a patient with chronic myelogeneous leukemia in blast crisis (ii). These cells retain a nunber of tt~nor-associated markers but can be induced by treatment with a variety of chemicals to express erythroid differentiation with acctm~tlation of 0006-291X/84 $1.50 Copyright © 1984 by Academic Press, Inc. All rights of reproduction in any form reserved. 90