Zhou Jing, Tang Yue, Xie Ze-Jun, Lu Jing-Ning, Deng Jing-Huan, Huang Xiao-Wei, Chuan Hooi Shing, He Min, Lu Guo-Dong
aDepartment of Physiology, School of Preclinical Medicine bGuangxi Universities Key Laboratory of Prevention and Control of Highly Prevalent Disease cDepartment of Toxicology, School of Public Health dDepartment of Environmental Medicine, School of Public Health, Guangxi Medical University eDepartment of Hepatobiliary Surgery, First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi Province, PR China fDepartment of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Republic of Singapore.
Anticancer Drugs. 2017 Apr;28(4):427-435. doi: 10.1097/CAD.0000000000000475.
Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related death worldwide, with a dismal 5-year survival rate less than 15%. The present study aimed to investigate whether AKT inhibition and glucose deprivation could synergistically kill HCC cells and the molecular mechanisms involved. HCC cells were starved in glucose deprivation, and then the resultant cell death was determined by flow cytometry and mitochondrial oxygen consumption rates using a Seahorse XF-24 Extracellular Flux Analyzer. Glucose deprivation reduced mitochondrial oxygen consumption rates for ATP production, enhanced mitochondrial proton leaks, reduced Mcl-1 expression, and subsequently caused significant cell death in the sensitive HepG2 and HCC-M cells. In the resistant Hep3B and Huh7 cells that survived, glucose starvation induced time-dependent AKT activation. However, blockage of AKT activation using chemical inhibitors (ZSTK474 and LY290042) or specific AKT1-targeting siRNAs could not markedly sensitize glucose deprivation-induced cell death. In contrast, AKT inhibitors or AKT1-targeting siRNAs significantly protected the sensitive HepG2 cells from glucose deprivation-induced cell death. More importantly, AKT inhibition mechanically suppressed mTOR activity and induced the prosurvival autophagy pathway in the sensitive HCC cells. Taken together, these data demonstrated that AKT activity was not essential for HCC cell survival during glucose deprivation. The reduction of mTOR activity and induction of the autophagy pathway may hinder the potential application of AKT inhibitors in the cancer therapy of solid tumors such as HCC.
肝细胞癌（HCC）是全球癌症相关死亡的第二大主要原因，其5年生存率低至不到15%，令人沮丧。本研究旨在探讨抑制AKT和剥夺葡萄糖是否能协同杀死HCC细胞以及其中涉及的分子机制。将HCC细胞置于葡萄糖剥夺环境中饥饿处理，然后使用Seahorse XF-24细胞外通量分析仪通过流式细胞术和线粒体耗氧率来测定由此产生的细胞死亡情况。葡萄糖剥夺降低了用于ATP生成的线粒体耗氧率，增强了线粒体质子泄漏，降低了Mcl-1表达，并随后在敏感的HepG2和HCC-M细胞中导致了显著的细胞死亡。在存活下来的耐药Hep3B和Huh7细胞中，葡萄糖饥饿诱导了时间依赖性的AKT激活。然而，使用化学抑制剂（ZSTK474和LY290042）或靶向AKT1的特异性小干扰RNA（siRNAs）阻断AKT激活并不能显著增强葡萄糖剥夺诱导的细胞死亡。相反，AKT抑制剂或靶向AKT1的siRNAs显著保护了敏感的HepG2细胞免受葡萄糖剥夺诱导的细胞死亡。更重要的是，抑制AKT在机制上抑制了敏感HCC细胞中的mTOR活性并诱导了促生存自噬途径。综上所述，这些数据表明，在葡萄糖剥夺期间，AKT活性对HCC细胞存活并非必不可少。mTOR活性的降低和自噬途径的诱导可能会阻碍AKT抑制剂在诸如HCC等实体瘤癌症治疗中的潜在应用。
