Comparison of the effects of epidermal growth factor and fetal calf serum in human endometrial carcinoma RL95-2 cells

This study was designed to evaluate if c-myc expression could influence RL95-2 cell proliferation after EGF or fetal calf serum (FCS) stimulation. Upon FCS addition, c-myc mRNAs slightly increased in the first 30 minutes, peaked at 75 minutes (2.2 fold induction) and returned to the control value within 24 hours. This slight and transient FCS effect on cmyc expression contrasted with the marked and long-lasting EGF effect (17 fold induction up to 48 hours). The increase of cell number by FCS was partially but significantly reduced in the presence of c-myc antisense oligodeoxynucleotides (ODNs). The EGF inhibitory effect on cell growth was not reversed by c-myc antisense ODNs whatever the backbone may be (phosphorothioate or phosphodiester). It appears that EGF and FCS have differential effects on c-myc and RL95-2 cell proliferation and that c-myc is necessary but insufficient for proliferation.