Activation of the c-jun protooncogene in human myeloid leukemia cells treated with etoposide

E Rubin, S Kharbanda, H Gunji and D Kufe

Laboratory of Clinical Pharmacology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02115.

The epipodophyllotoxin etoposide is an inhibitor of topoisomerase II. The effects of this agent on gene expression, particularly the transcriptional induction of genes implicated in growth control, are unknown. The present results demonstrate that etoposide induces expression of the c-jun protooncogene in HL-60 myeloid leukemia cells. This induction of c-jun expression was maximal at 3 hr and was transient. Similar findings were obtained in the human U-937 myeloid leukemia cell line. Nuclear run-on assays demonstrated that the induction of c-jun expression by etoposide is regulated at the transcriptional level. The results further demonstrate that etoposide- induced c-jun expression occurs in association with the appearance of c- fos transcripts. Moreover, the c-jun gene is induced by etoposide during periods of oligonucleosomal DNA cleavage, which is characteristic of programmed cell death. These findings suggest that transcriptional induction of c-jun expression represents a signaling pathway activated in the cellular response to etoposide-induced DNA damage.

Volume 39, Issue 6, pp. 697-701, 06/01/1991
Copyright © 1991 by American Society for Pharmacology and Experimental Therapeutics