c-myc Down-regulation in suramin-treated HL60 cells precedes growth inhibition but does not trigger differentiation

N Ben-Baruch, WC Reinhold, N Alexandrova, I Ichinose, M Blake, JB Trepel and M Zajac-Kaye

Laboratory of Biological Chemistry, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892.

Down-regulation of c-myc mRNA expression is linked to growth arrest and the state of differentiation of hematopoietic cells. We showed that treatment of HL60 cells with suramin results in a rapid reduction of c- myc expression followed by an inhibition of cell growth. Both c-myc mRNA and protein levels decreased by day 1 of treatment, and, by day 4, only 10% of control c-myc protein levels were detected. In contrast to retinoic acid, dimethyl sulfoxide, and 12-O-tetradecanoylphorbol-13- acetate treatment, however, exposure of HL60 cells to suramin did not result in the induction of differentiation. These results demonstrate that suramin modulates c-myc levels in HL60 cells and that the down- regulation of c-myc is not sufficient to trigger differentiation toward either granulocytic or monocytic lineages.

Volume 46, Issue 1, pp. 73-78, 07/01/1994
Copyright © 1994 by American Society for Pharmacology and Experimental Therapeutics