How did cadmium affect oncogene expression in myoblast cultures?

Details

Researchers exposed L6J1 myoblast cultures to different doses of cadmium chloride and analyzed oncogene transcript abundance to study effects on c-jun, c-fos and c-myc expression.

Cadmium caused a transient accumulation of c-jun and c-myc mRNA, with maximum expression at 2–4 hours. During this time, c-fos transcripts remained below the detection level. However, insulin treatment could induce both c-fos and c-jun in the myoblasts. Cadmium induction of c-jun and c-myc mRNA was concentration-dependent, with maximum stimulation at 5–10 µM.

In the presence of cycloheximide, adding cadmium superinduced c-jun and c-myc and also produced a marked increase in c-fos transcripts. Blocking transcription with actinomycin D abolished the induction of c-myc and c-jun by cadmium and of c-fos by cadmium combined with cycloheximide.

The cadmium-induced increase in c-jun and c-myc mRNA was enhanced in myoblasts stably transfected with a mouse c-fos gene under a metallothionein promoter. The researchers concluded that cadmium has the potential to deregulate the expression of several important oncogenes.