药学学报, 2021, 56(3): 799-807
徐俊亭, 李殿龙, 王旭, 蔺洁茹, 郝燕飞, 张鑫朋, 刁爱坡, 刘振兴. 8-氮鸟嘌呤通过Akt/mTORC1/ULK1诱导细胞自噬增强其在肝癌细胞中的耐药性[J]. 药学学报, 2021, 56(3): 799-807.
XU Jun-ting, LI Dian-long, WANG Xu, LIN Jie-ru, HAO Yan-fei, ZHANG Xin-peng, DIAO Ai-po, LIU Zhen-xing. 8-Azaguanine-induced autophagy contributes to its chemoresistance in hepatic cancer cells[J]. Acta Pharmaceutica Sinica, 2021, 56(3): 799-807.

徐俊亭, 李殿龙, 王旭, 蔺洁茹, 郝燕飞, 张鑫朋, 刁爱坡, 刘振兴
天津科技大学生物工程学院, 工业发酵微生物学教育部重点实验室, 食品营养与安全国家重点实验室, 天津 300457
细胞自噬是真核生物中进化保守的对细胞内容物进行降解的生理过程,其利用溶酶体将细胞内物质降解再利用,在应激条件下可以促进癌细胞的存活。8-氮鸟嘌呤(8-azaguanine,8-AG)是一种嘌呤核苷酸生物合成的抑制剂,对多种肿瘤细胞具有抗肿瘤活性。然而,耐药性限制了8-AG作为抗癌药物的应用,其耐药性机制尚不清楚。本研究发现8-AG通过诱导细胞自噬减弱其细胞毒性而产生耐药性。利用HepG2和SMMC-7721肝癌细胞系进行药物处理,结果显示8-AG抑制肿瘤细胞活力,并且通过上调促凋亡蛋白BCL-2样蛋白11(BCL-2-like protein 11,Bim)中的BimS亚型水平来诱导内源性凋亡。此外,Western blot实验检测结果表明8-AG通过抑制Akt(protein kinase B)/mTORC1(mammalian target of rapamycin complex 1)信号通路激活ULK1(Unc-51-like autophagy activating kinase 1)蛋白,从而诱导自噬发生。敲低自噬相关基因7(autophagy-related gene 7,ATG7)显著增加BimS的蛋白水平,促进8-AG引起的细胞死亡;联合使用自噬抑制剂氯喹(chloroquine,CQ)或巴弗洛霉素A1(bafilomycin A1,Baf A1)促进8-AG诱导的肝癌细胞凋亡。以上结果表明,8-AG诱导自噬导致肿瘤细胞产生耐药性,抑制自噬可增加癌细胞对其的敏感性。
关键词:    8-氮鸟嘌呤      耐药性      细胞自噬      蛋白激酶B/哺乳动物雷帕霉素靶蛋白复合物1      细胞凋亡     
8-Azaguanine-induced autophagy contributes to its chemoresistance in hepatic cancer cells
XU Jun-ting, LI Dian-long, WANG Xu, LIN Jie-ru, HAO Yan-fei, ZHANG Xin-peng, DIAO Ai-po, LIU Zhen-xing
Key Laboratory of Industrial Fermentation Microbiology of the Ministry of Education, State Key Laboratory of Food Nutrition and Safety, School of Biotechnology, Tianjin University of Science and Technology, Tianjin 300457, China
Autophagy, an evolutionarily conserved process by which components of the cell are degraded in lysosomes, may facilitate survival of cancer cells under stress conditions. 8-Azaguanine (8-AG), an inhibitor of purine nucleotide biosynthesis, shows antineoplastic activity in multiple tumor cells. However, chemoresistance has restricted its development as an anticancer agent, and the mechanism of 8-AG resistance is not fully understood. We report here that 8-AG induces a protective autophagy to eliminate its cytotoxicity, and inhibition of autophagy increases cellular sensitivity of cancer cells to 8-AG treatment. Using HepG2 or SMMC-7721 hepatic cancer cell lines, we found that 8-AG inhibited cell viability and induced intrinsic apoptosis, accompanied by the up-regulation of the pro-apoptotic protein BimS, one of Bim (also known as BCL-2-like protein 11, BCL2L11) isoforms. Furthermore, 8-AG treatment enhanced the autophagy flux by promoting the dephosphorylation and activation of Unc-51-like autophagy activating kinase 1 (ULK1) via Akt/mTORC1 (mammalian target of rapamycin complex 1) signaling inhibition. Depletion of autophagy-related gene 7 (ATG7) markedly enhanced the level of BimS, and promoted cell death in response to 8-AG. 8-AG in combination with autophagy inhibitor chloroquine (CQ) or bafilomycin A1 (Baf A1) promoted the 8-AG-induced apoptosis in hepatic cancer cells. Altogether, these findings suggest that autophagy promotes chemoresistance of cancer cells for 8-AG, and blocking autophagy increases cellular sensitivity of cancer cells to 8-AG treatment.
Key words:    8-azaguanine    chemoresistance    autophagy    Akt/mTORC1    apoptosis   
收稿日期: 2020-09-21
DOI: 10.16438/j.0513-4870.2020-1511
基金项目: 国家重点研发项目(2017YFD0400300);天津市教委科技研究计划(2017KJ007).
通讯作者: 刘振兴,Tel:86-22-60602948,E-mail:liuzx@tust.edu.cn
Email: liuzx@tust.edu.cn
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