ATF4对皮肤癌细胞增殖的影响及相关机制

目的：探讨沉默/过表达ATF4对人皮肤癌细胞增殖的影响及其相关作用机制。方法：Western blot技术检测不同类型皮肤癌细胞中ATF4的蛋白表达水平。构建ATF4沉默/过表达的A431皮肤癌细胞株，采用CCK-8法、克隆形成实验和流式细胞术检测A431细胞增殖能力的变化及细胞周期分布；Western blot技术检测细胞周期调控因子cyclin D1、cyclin E、P21和p-Rb/Rb的蛋白表达水平。结果：ATF4在3种不同类型的皮肤癌细胞中均呈高表达。CCK-8法和克隆形成实验结果显示沉默ATF4的A431细胞存活率和增殖能力均显著降低(P<0.05)，而过表达ATF4可促进A431细胞的增殖；流式细胞仪检测结果显示沉默ATF4可明显抑制A431细胞从G0/G1期向S期转换，过表达ATF4则促进其G1/S转换。同时Western blot实验结果显示沉默ATF4后，cyclin D1、cyclin E和p-Rb的蛋白水平均显著降低，而P21的蛋白表达显著增加(P<0.05)，过表达ATF4后则cyclin D1、cyclin E和p-Rb的蛋白水平显著增加，而P21的蛋白表达显著降低(P<0.05)。结论：ATF4能够促进人皮肤鳞状细胞癌细胞株A431的增殖，其潜在作用机制可能与促进细胞周期G1/S转换及影响相关周期调控因子的表达有关，提示AT F 4可作为治疗皮肤癌的一个潜在作用靶点。

Effects and mechanisms of ATF4 on skin cancer cell proliferation

Objective: To investigate the effects and mechanisms of knockdown/over-expression of ATF4 on the skin cancer cell proliferation.Methods: hTe expression of ATF4 in different types of skin cancer cells was measured by Western blot. Atfer knockdown or over-expression of ATF4 in A431 cells, the proliferation and cell cycle distribution were measured by CCK-8 assay, colony formation assay or lfow cytometry. hTe protein levels of some cell cycle regulators, such as cyclin D1, cyclin E, P21 and p-Rb/Rb were determined by Western blot. Results: ATF4 was highly expressed in all 3 types of skin cancer cells (P<0.05). ATF4 knockdown repressedthe cell cycle entrance into S-phase from G0/G1 phase followed by a lower cell proliferation rate. Over-expression of ATF4 increased A431 cell proliferation and facilitated cell cycle progression (P<0.05). Furthermore, the protein levels of cyclin D1, cyclin E and p-Rb were significantly decreased after ATF4 knockdown, but the expression of P21 was increased. Over-expression of ATF4 increased the protein levels of cyclin D1, cyclin E and p-Rb, but decreased the P21 expression (P<0.05).Conclusion: ATF4 promotes human squamous cell carcinoma, and its potential mechanisms may be related to promotion of cell cycle transition and expression of cell cycle regulators, suggesting that ATF4 may be a potential new target of treating skin cancer.