表皮生长因子通过上调环氧酶2促进人食管鳞癌细胞HKESC-1的增殖

Epidermal growth factor stimulates the proliferation of human esophageal squamous cell carcinoma HKESC-1 cells by increasing COX-2 expression

目的研究表皮生长因子(EGF)促进人食管鳞癌细胞增殖的机制。方法氚标记的脱氧胸腺嘧啶核苷掺入法检测细胞增殖。酶免疫法检测前列腺素(PGE2)的释放。免疫印迹法检测环氧酶1(COX-1),环氧酶2(COX-2),PGE2受体亚型EP1和EP2的蛋白表达。结果 EGF上调人食管鳞癌HKESC-1细胞COX-2蛋白表达,而不影响COX-1蛋白表达。EGF还能刺激HKESC-1细胞释放PGE2,并上调PGE2受体亚型EP2的蛋白表达。非选择性COX抑制剂吲哚美辛和COX-2选择性抑制剂SC-236均可完全阻断EGF刺激的PGE2释放。这两种COX抑制剂也都能够抑制EGF的促细胞增殖作用。结论 EGF对HKESC-1细胞的促增殖作用,一方面是通过诱导COX-2蛋白的表达从而促进PGE2的释放;另一方面通过上调EP2受体的蛋白表达。

Objective To investigate the mechanisms responsible for epidermal growth factor（EGF）-induced proliferation of human esophageal squamous cell carcinoma cells.Methods 3H-thymidine incorporation assay was used to assess the proliferation of HKESC-1 cells exposed to EGF stimulation.Enzyme immunoassay was used to measure PGE2 release from HKESC-1 cells,and the protein levels of cyclooxygenase 1（COX-1）,COX-2,EP1 and EP2 in EGF-stimulated cells were determined by Western blotting.Results EGF upregulated COX-2 protein expression but produced no obvious effect on COX-1 protein expression in HKESC-1 cells.As a consequence of increased COX-2,EGF further enhanced cellular PGE2 release.EGF stimulation also resulted in increased protein expression of EP2,a subtype of PGE2 receptors.Both the non-selective COX inhibitor indomethacin and the selective COX-2 inhibitor SC-236 completely abolished EGF-induced PGE2 release,and suppressed the mitogenic effect of EGF.Conclusion EGF stimulates the proliferation of HKESC-1 cells by increasing COX-2 protein expression and PGE2 release.Upregulated EP2 protein expression may further amplify the mitogenic action of PGE2.