Interleukin-3-dependent expression of the c-myc and c-fos proto-oncogenes in hemopoietic cell lines.

Open Access
Publisher Website
Google Scholar
Abstract
Using Northern blot analysis the expression of several proto‐oncogenes was studied in established lines of mast cell precursors. Upon removal of interleukin‐3 (IL‐3) from the culture medium, factor‐dependent cells stop dividing. During the first 7 h, however, normal amounts of total cellular mRNAs are maintained, and this is reflected in unchanged levels of several transcripts, such as actin, c‐Ha‐ras and c‐fes. In contrast, within 1.5 h of IL‐3 removal, the levels of c‐myc and c‐fos mRNAs decrease drastically and addition of IL‐3 at that stage quickly induces back the levels found in actively growing cultures. In factor‐independent cells, which proliferate actively even in the absence of IL‐3, high levels of c‐myc and c‐fos transcripts are maintained in the absence of growth factor. In cells arrested by serum starvation, addition of 10% serum induces massive amounts of c‐fos transcripts, but not of c‐myc, and cell proliferation is not restored. The data suggest that the c‐myc and c‐fos proto‐oncogenes play an important role in mediating the multiple effects of IL‐3 on hemopoietic progenitor cells.