Objective: To explore the effect of epidermal growth factor (EGF) on apoptosis induced by TNF-alpha and the expression of PPARbeta in HaCaT keratinocytes.
Methods: HaCaT keratinocytes were cultured and randomly divided into A (normal control), B (with treatment of 10 ng/ml TNF-alpha for 24 hours), C (with treatment of 20 ng/ml TNF-alpha for 24 hours), D (with treatment of 10 ng/ml TNF-alpha after 20 ng/ml EGF treatment for 4 hours), E (with treatment of 20 ng/ml TNF-alpha after 20 ng/ml EGF treatment for 4 hours) groups. The apoptosis of HaCaT keratinocytes was observed by flow cytometry. The proliferative activity of HaCaT keratinocytes was evaluated by MTT method. The activity of caspase-3 was analyzed with caspase colorimetric assay Kit. The changes in the mRNA and protein expression of PPARbeta in HaCaT keratinocytes were observed by RT-PCR and western-blotting after treatment with different concentrations (5, 10, 20, 40 ng/ml) of EGF for 4 or 24 hrs.
Results: Compared with A and B groups [(32 +/- 6)%, (57 +/- 6)%], the apoptosis of HaCaT keratinocytes in D and E groups were significantly increased [(20 +/- 3)%, (28 +/- 4)%, respectively, P < 0.01], while the survival rate of HaCaT keratinocytes in D and E groups increased, and the caspase-3 activity were decreased (P < 0.01). The expression of PPARbeta mRNA and protein in HaCaT keratinocytes reached the peak with the treatment of 20 ng/ml EGF.
Conclusion: EGF can inhibit the apoptosis of HaCaT keratinocytes induced by TNF-alpha, and it can also increase the expression of PPARbeta.