The immediate early gene response to a differentiative stimulus is disrupted by the v-abl and v-ras oncogenes

The immediate early gene activation in response to a differentiative stimulus was investigated in the hematopoietic progenitor cell line 32DC13(G). A transient and coordinated increase in mRNA levels for c-fos, c-jun, jun-B, TIS-7/PC-4, TIS-8/egr-1, and TIS-11 occurred during the first 2 h of treatment with granulocyte colony stimulating factor (G-CSF), which ultimately induces the 32DC13(G) cells to terminally differentiate into neutrophilic granulocytes. This pattern of mRNA induction was disrupted by v-abl and v-ras, two oncogenes known to interfere with G-CSF-induced differentiation of 32DC13(G) cells. Induction of the mRNAs for c-jun and TIS-7/PC-4 was blocked by the presence of v-abl, whereas v-ras caused constitutive expression of c-fos mRNA and blocked the c-jun, jun-B and TIS-7/PC-4 mRNA response. Release of the differentiation block in the ras-transformed 32DC13(G) cells by co-treatment with retinoic acid and G-CSF partially restored the normal c-fos and c-jun mRNA induction pattern, suggesting that the proper activation of these genes may be important for myeloid differentiation.