下调乙酰辅酶A合成酶2通过诱导自噬抑制非小细胞肺癌细胞增殖

目的：探讨乙酰辅酶A合成酶2（ACSS2）在非小细胞肺癌（NSCLC）细胞中的表达及其对细胞增殖、侵袭的调控机制。方法：采用蛋白质印迹（Western blot）实验检测并分析NSCLC细胞系A549和H1299与人成纤维细胞HFF-1中ACSS2表达的差异。利用慢病毒在NSCLC细胞系中构建ACSS2敲低（ACSS2 KD组）和对照细胞系（NC组）。采用MTT实验及细胞克隆形成实验分析ACSS2 对NSCLC细胞增殖的影响。采用划痕实验和Transwell实验分析ACSS2对NSCLC细胞的迁移和侵袭能力的影响。Western blot及免疫荧光实验分析敲低ACSS2 对细胞自噬的影响。结果：与人成纤维细胞HFF-1相比，NSCLC细胞中ACSS2 的蛋白表达水平明显升高（P ＜0.05）。与NC组相比，ACSS2 KD组细胞增殖能力和细胞活力显著降低，ACSS2 KD组细胞的迁移和侵袭能力均明显降低（均P ＜0.01）。Western blot和免疫荧光实验显示，敲低ACSS2 细胞自噬活性明显增加，自噬小体增多（P ＜0.01）。但是，敲低ACSS2几乎不影响caspase3和caspase8的蛋白表达水平（P ＞0.05）。ACSS2 shRNA+Beclin1/Atg7-shRNA共转染A549细胞（ACSS2+Beclin1/Atg7 KD组），结果显示与ACSS2KD组比，ACSS2 KD+Beclin1/Atg7 KD组细胞增殖能力有所增强，克隆形成数目明显增多（P ＜0.05）。结论：ACSS2在NSCLC细胞中高表达，促进细胞的增殖、侵袭。下调ACSS2可诱导NSCLC细胞发生自噬性细胞死亡，抑制细胞增殖。

Downregulation of acetyl-CoA synthase 2 inhibits non-small cell lung cancer cell proliferation by inducing autophagy

Objective: To investigate the expression of acetyl-CoA synthase 2 (ACSS2) in non-small cell lung cancer (NSCLC) cells and its regulatory mechanism of cell proliferation and invasion. Methods: Western blot was used to detect and analyze the difference of ACSS2 expression in NSCLC cell lines A549 and H1299 and human fibroblast cell HFF-1; ACSS2 knockdown (ACSS2 KD group) and control cell lines (NC group) were constructed in NSCLC cell lines using lentivirus. The effect of ACSS2 on the proliferation of NSCLC cells was analyzed by MTT assay and cell clone formation assay. The effect of ACSS2 on the migration and invasion ability of NSCLC cells were analyzed by scratch assay and transwell assay. The effect of ACSS2 knockdown on autophagy was analyzed. Western blot and immunofluorescence experiments. Results: The protein level of ACSS2 in NSCLC cells was significantly increased compared with human fibroblast HFF-1 (P<0.05). Knockdown of ACSS2 significantly reduced cell proliferation and cell viability. ACSS2 KD group also significantly reduced the migratory and invasive abilities of NSCLC cells (both P<0.01). Western blot and immunofluorescence experiments showed that knockdown of ACSS2 significantly increased the autophagy activity and the number of autophagosomes (P<0.01). However, knockdown of ACSS2 hardly affected the protein expression of caspase3and caspase8 (P>0.05). A549 cells were co-transfected with ACSS2-shRNA+Beclin1/Atg7-shRNA and the results showed that the cell proliferation ability of the ACSS2-shRNA+Beclin1/Atg7-shRNA group was enhanced and the number of clones increased significantly compared with the ACSS2 KD group. Conclusion: ACSS2 is highly expressed in NSCLC cells, which promotes cell proliferation and invasion. Down-regulation of ACSS2 can induce autophagic cell death in NSCLC cells and inhibit cell proliferation.