Bradykinin upregulates immediate-early gene mRNA in human keratinocytes

We investigated the effect of bradykinin on the expression of the proto-oncogenes c-fos, c-jun and c-myc and on cell proliferation in the human keratinocyte cell line, HaCaT. Analysis of mRNAs was done by Northern blotting with single-stranded DNA hybridization probes. Bradykinin caused a rapid and transient accumulation in c-fos and c-jun mRNAs. In contrast, c-myc mRNA increased more slowly. Moreover, we report that bradykinin was a weak stimulator of HaCaT cell proliferation whereas epidermal growth factor, which induced the same degree of mRNA elevation, was shown as a powerful mitogen. Thus, while in HaCaT cells bradykinin promotes the expression of the proto-oncogenes c-fos, c-jun and c-myc, other biochemical events appear to be necessary for cell division.