[Role of peroxisome proliferator-activated receptor beta in the inhibitory effect of epidermal growth factor on apoptosis of HaCaT].

Objective: To explore the role of EGF in regulating HaCaT apoptosis through peroxisome proliferator-activated receptor beta (PPARbeta).

Methods: Cultured HaCaT cells were divided into different groups with different additives in culture medium as control (normal culture), TNF-alpha (with addition of 10 ng/mL TNF-alpha), EGF (with addition of 20 ng/mL EGF), EGF + TNF-alpha (cells were treated with 10 ng/mL TNF-alpha for 60 mins after the exposure to 20 ng/mL EGF for 4 hs) groups. Conjugation activity and transcription activity of PPARbeta of HaCaT cells in each group were detected by electrophoretic mobility shift assay (EMSA) and luciferase gene analysis (LGA). Protein expression of PPARbeta of HaCaT cells after transfected by missense oligonucleotide (scrODN) and antisense oligonucleotide (asODN) was determined by Western blot. Caspase-3 activity and apoptosis rate were detected by flow cytometry.

Results: Conjugation and transcription activity of PPARbeta DNA were enhanced as shown in EMSA and LGA. Compared with that of cells in groups transfected by scrODN, protein expression of PPARbeta in cells of groups transfected by asODN was obviously inhibited as shown in Western blot. Caspase-3 activity of cells in TNF-alpha and EGF + TNF-alpha groups transfected by asODN was stronger than that of cells in TNF-alpha and EGF + TNF-alpha groups transfected by scrODN (P < 0.01). Apoptosis rate of cells in control, EGF, TNF-alpha, and EGF + TNF-alpha groups which were transfected by scrODN was (7.31 +/- 0.45)%, (7.43 +/- 0.21)%, (39.78 +/- 0.65)%, (28.34 +/- 0.54)% respectively, and that in those groups transfected by asODN was (8.22 +/- 0.51)%, (7.83 +/- 0.67)%, (46.78 +/- 0.48)%, (44.69 +/- 0.83)%. Apoptosis rate of cells in TNF-alpha and EGF + TNF-alpha groups transfected by asODN was respectively higher than that in TNF-alpha and EGF + TNF-alpha groups transfected by scrODN (P < 0.01).

Conclusions: EGF inhibits HaCaT KC apoptosis caused by TNF-alpha in a PPARbeta-dependent manner.