自噬在熊果酸抑制人肺癌PC9细胞增殖中的作用

目的:研究自噬在熊果酸(UA)抑制人肺癌PC9细胞增殖中的作用及机制。方法:应用MTT法和台盼蓝拒染法检测UA对PC9细胞增殖的影响。吖啶橙染色法在荧光显微镜下观察UA对PC9细胞自噬的影响。Western blot检测自噬相关蛋白LC3及ATG5的表达情况。采用自噬抑制剂3-甲基腺嘌呤(3-MA)观察UA对PC9细胞增殖的抑制作用。结果:UA可以显著抑制PC9细胞的活力(P0.05或P0.01),随着给药剂量和时间的增加,UA对PC9细胞的生长抑制率显著上升。UA诱导PC9细胞自噬体表达增加,并诱导自噬相关蛋白LC3-Ⅱ和ATG5表达的增加(P0.01)。自噬抑制剂3-MA提高了UA对PC9细胞的抑制作用(P0.01)。结论:UA抑制PC9细胞的增殖,并诱导细胞发生自噬。UA诱导PC9细胞自噬的机制有可能依赖ATG5细胞自噬途径。自噬抑制剂3-MA能够增强UA对PC9细胞的增殖抑制作用,有望为肺癌的临床治疗提供新的联合治疗方案。

Role of autophagy in inhibition of human lung cancer PC9 cell proliferation by ursolic acid

AIM: To investigate the role of autophagy in inhibition of human lung cancer PC9 cell proliferation by ursolic acid (UA) as well as the underlying mechanism. METHODS: MTT assay and Trypan blue exclusion test were performed to analyze the effect of UA on the proliferation of PC9 cells. The PC9 cells were treated with UA, and autophagy was observed under fluorescence microscope through acridine orange staining. The expression of autophagy-associated proteins LC3 and ATG5 in the PC9 cells were detected by Western blot. The effect of UA, 3-methyladenine (3-MA) 3-MA or their combination on the cell viability was measured by MTT assay. RESULTS: The viability of PC9 cells was significantly inhibited by UA (P<0.05 or P<0.01). The number of bright red fluorescence positive cells was significantly increased after treatment with UA. The protein expression of LC3-Ⅱ and ATG5 was significantly up-regulated compared with control group (P<0.01). Furthermore, combination of UA and 3-MA resulted in a substantial decrease in cell viability compared with using UA alone (P<0.01). CONCLUSION: UA inhibits the proliferation and induces the autophagy of the PC9 cells, in which autophagy plays a protective role. The inhibition of autophagy significantly promotes the death of the PC9 cells induced by UA.