a The Ken & Ruth Devee Department of Neurology, Lou and Jean Malnati Brain Tumor Institute , The Robert H. Lurie Comprehensive Cancer Center, Northwestern Universityd Feinberg School of Medicine , Chicago , IL , USA.
b Department of Neurological Surgery , Lou and Jean Malnati Brain Tumor Institute, The Robert H. Lurie Comprehensive Cancer Center, Northwestern University Feinberg School of Medicine , Chicago , IL , USA.
Autophagy. 2019 Jun;15(6):1100-1111. doi: 10.1080/15548627.2019.1569947. Epub 2019 Jan 31.
Macroautophagy/autophagy is a natural intracellular process that maintains cellular homeostasis and protects cells from death under stress conditions. Autophagy sustains tumor survival and growth when induced by common cancer treatments, including IR and cytotoxic chemotherapy, thereby contributing to therapeutic resistance of tumors. In this study, we report that the expression of MIR93, noted in two clinically relevant tumor subtypes of GBM, influenced GSC phenotype as well as tumor response to therapy through its effects on autophagy. Our mechanistic studies revealed that MIR93 regulated autophagic activities in GSCs through simultaneous inhibition of multiple autophagy regulators, including BECN1/Beclin 1, ATG5, ATG4B, and SQSTM1/p62. Moreover, two first-line treatments for GBM, IR and temozolomide (TMZ), as well as rapamycin (Rap), the prototypic MTOR inhibitor, decreased MIR93 expression that, in turn, stimulated autophagic processes in GSCs. Inhibition of autophagy by ectopic MIR93 expression, or via autophagy inhibitors NSC (an ATG4B inhibitor) and CQ, enhanced the activity of IR and TMZ against GSCs. Collectively, our findings reveal a key role for MIR93 in the regulation of autophagy and suggest a combination treatment strategy involving the inhibition of autophagy while administering cytotoxic therapy. Abbreviations: ACTB: actin beta; ATG4B: autophagy related 4B cysteine peptidase; ATG5: autophagy related 5; BECN1: beclin 1; CL: classical; CQ: chloroquine diphosphate; CSCs: cancer stem cells; GBM: glioblastoma; GSCs: glioma stem-like cells; HEK: human embryonic kidney; IB: immunoblotting; IF: immunofluorescent staining; IR: irradiation; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MES: mesenchymal; MIR93: microRNA 93; MIRC: a control miRNA; miRNA/miR: microRNA; MTOR: mechanistic target of rapamycin kinase; NSC: NSC185085; PN: proneural; qRT-PCR: quantitative reverse transcription-polymerase chain reaction; Rap: rapamycin; SQSTM1/p62: sequestosome 1; TCGA: the cancer genome atlas; TMZ: temozolomide; WT: wild type; ZIP93: lentiviral miRZIP targeting MIR93; ZIPC: lentiviral miRZip targeting control miRNA.
自噬是一种维持细胞内环境稳定和保护细胞免受应激条件下死亡的天然细胞内过程。自噬在常见的癌症治疗(包括辐射和细胞毒性化疗)诱导时维持肿瘤的存活和生长,从而导致肿瘤的治疗抵抗。在这项研究中,我们报告了 MIR93 的表达,在两种临床上相关的 GBM 肿瘤亚型中被注意到,通过其对自噬的影响影响 GSC 表型以及肿瘤对治疗的反应。我们的机制研究表明,MIR93 通过同时抑制多个自噬调节剂,包括 BECN1/Beclin 1、ATG5、ATG4B 和 SQSTM1/p62,调节 GSCs 中的自噬活性。此外,两种一线治疗 GBM 的方法,即辐射和替莫唑胺(TMZ)以及雷帕霉素(Rap),即典型的 MTOR 抑制剂,降低了 MIR93 的表达,进而刺激了 GSCs 中的自噬过程。通过外源性 MIR93 表达或通过自噬抑制剂 NSC(ATG4B 抑制剂)和 CQ 抑制自噬,增强了辐射和 TMZ 对 GSCs 的活性。总之,我们的发现揭示了 MIR93 在自噬调节中的关键作用,并提出了一种联合治疗策略,即抑制自噬同时进行细胞毒性治疗。缩写:ACTB:β 肌动蛋白;ATG4B:自噬相关 4B 半胱氨酸肽酶;ATG5:自噬相关 5;BECN1:beclin 1;CL:经典;CQ:氯喹二磷酸盐;CSCs:癌症干细胞;GBM:胶质母细胞瘤;GSCs:神经胶质瘤样干细胞;HEK:人胚胎肾;IB:免疫印迹;IF:免疫荧光染色;IR:辐射;MAP1LC3/LC3:微管相关蛋白 1 轻链 3;MES:间质;MIR93:microRNA 93;MIRC:对照 miRNA;miRNA/miR:microRNA;MTOR:雷帕霉素机制靶标激酶;NSC:NSC185085;PN:原神经;qRT-PCR:定量逆转录聚合酶链反应;Rap:雷帕霉素;SQSTM1/p62:自噬体 1;TCGA:癌症基因组图谱;TMZ:替莫唑胺;WT:野生型;ZIP93:靶向 MIR93 的慢病毒 miRZIP;ZIPC:靶向对照 miRNA 的慢病毒 miRZip。