Abstract
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.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1100-1111 |
| Number of pages | 12 |
| Journal | Autophagy |
| Volume | 15 |
| Issue number | 6 |
| DOIs | |
| State | Published - Jun 3 2019 |
Funding
This work was supported by the US National Institutes of Health [NS093843, NS095634]. This work was supported by the US National Institutes of Health [NS093843, NS095634]. We thank Dr. Y. Deng for providing reagents. We also thank members of the Cheng Laboratory for the discussion and edits for this manuscript. This work was supported by US National Institutes of Health (NIH) grants NS093843, NS095634 (S.-Y.C.); a Brain Cancer Research Award from James S. McDonnell Foundation (B.H.); NIH grants L32 MD010147 and T32 CA070085 (A.A.A.), F31 CA232630 (N.S.), NS080619 (C.D.J.), NS083767 (I.N.), support from Lou and Jean Malnati Brain Tumor Institute at Northwestern University (S.-Y.C. and B.H.). We thank Dr. Y. Deng for providing reagents. We also thank members of the Cheng Laboratory for the discussion and edits for this manuscript. This work was supported by US National Institutes of Health (NIH) grants NS093843, NS095634 (S.-Y.C.); a Brain Cancer Research Award from James S. McDonnell Foundation (B.H.); NIH grants L32 MD010147 and T32 CA070085 (A.A.A.), F31 CA232630 (N.S.), NS080619 (C.D.J.), NS083767 (I.N.), support from Lou and Jean Malnati Brain Tumor Institute at Northwestern University (S.-Y.C. and B.H.).
Keywords
- Autophagy
- cancer stem cell
- glioblastoma
- glioma subtypes
- microRNA
- therapy response
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology
