表皮生长因子对肿瘤坏死因子α致HaCaT细胞凋亡的抑制作用

目的了解肿瘤坏死因子α（TNF-α）导致HaCaT细胞凋亡过程中过氧化物酶体增殖物激活受体B（PPAR3）的表达情况，探讨表皮生长因子（EGF）对HaCaT细胞的保护机制。方法将培养的HaCaT细胞分为正常对照组（不作任何处理）、TNF—α小剂量组（10ng／ml TNF-α处理）、TNF—α大剂量组（20ng／mlTNF-α处理）、EGF＋TNF—α小剂量组、EGF＋TNF—α大剂量组，后2组先用20ng／mlEGF培养4h后，再分别予以10、20ng／ml TNF—α处理。采用流式细胞仪检测细胞凋亡情况，半胱氨酸天冬氨酸蛋白酶3（easpase．3）荧光检测试剂盒测定caspase-3的活性，噻唑蓝比色法检测细胞存活率。以5、10、20、40ng／ml的EGF处理HaCaT细胞，采用反转录．PCR和蛋白质印迹法检测PPAR3mRNA及其蛋白的表达。结果与TNF-α小剂量组（32±6）％]、TNF-ct大剂量组（57±6）％]比较，EGF＋TNF—α小剂量组、EGF＋TNF-α大剂量组细胞凋亡率（20±3）％、（28±4）％]明显下降（P〈0．01），caspase-3活性降低、存活率上升（P〈0．01）。20ng／mlEGF处理细胞时，PPAR3mRNA及其蛋白表达最强。结论EGF在抑制TNF-α导致的HaCaT细胞凋亡的同时，亦增强细胞中PPARβ的表达。

Inhibitory effect of epidermal growth factor on apoptosis in HaCaT keratinocytes induced by TNF-α

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.