title: microRNA-17 regulates the expression of ATG7 and modulates the autophagy process, improving the sensitivity to temozolomide and low-dose ionizing radiation treatments in human glioblastoma cells.
abstract: ATG7 is a key autophagy-promoting gene that plays a critical role in the regulation of cell death and survival of various cell types. We report here that microRNAs (miRNAs), a class of endogenous 22-24 nucleotide noncoding RNA molecules able to affect stability and translation of mRNA, may represent a novel mechanism for regulating ATG7 expression and therefore autophagy. We demonstrated that ATG7 is a potential target for miR-17, and this miRNA could negatively regulate ATG7 expression, resulting in a modulation of the autophagic status in T98G glioblastoma cells. Treatment of these tumor cells with the miR-17 mimic decreased, and with the antagomir increased, the expression of ATG7 protein. Dual luciferase reporter assay confirmed that a specific miR-17 binding sequence in the 3'-UTR of ATG7 contributed to the modulation of the expression of the gene by miR-17. Interestingly, our results showed that anti-miR-17 administration activated autophagy through autophagosome formation, as resulted by LC3B and ATG7 protein expression increase, and by the analysis of GFP-LC3 positive autophagosome vesicles in living cells. Furthermore, the autophagy activation by anti-miR-17 resulted in a decrease of the threshold resistance at temozolomide doses in T98G cells, while miR-17 modulation in U373-MG glioblastoma cells resulted in a sensitization to low ionizing radiation doses. Our study of the role of miR-17 in regulating ATG7 expression and autophagy reveals a novel function for this miRNA sequence in a critical cellular event with significant impacts in cancer development, progression and treatment.
authors.affiliation: Dipartimento di Biologia e Biotecnologie, Università di Pavia, Pavia, Italy. sergio.comincini@unipv.it
authors.forename: Sergio
authors.initials: S
authors.lastname: Comincini
authors.forename: Giulia
authors.initials: G
authors.lastname: Allavena
authors.forename: Silvia
authors.initials: S
authors.lastname: Palumbo
authors.forename: Martina
authors.initials: M
authors.lastname: Morini
authors.forename: Francesca
authors.initials: F
authors.lastname: Durando
authors.forename: Francesca
authors.initials: F
authors.lastname: Angeletti
authors.forename: Luigi
authors.initials: L
authors.lastname: Pirtoli
authors.forename: Clelia
authors.initials: C
authors.lastname: Miracco
mesh_terms: D018906:Antineoplastic Agents, Alkylating / Q000494:pharmacology*; D001343:Autophagy / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects; D000071193:Autophagy-Related Protein 7; D045744:Cell Line, Tumor; D003606:Dacarbazine / Q000031:analogs & derivatives* / Q000494:pharmacology; D005909:Glioblastoma / Q000235:genetics* / Q000378:metabolism / Q000473:pathology / Q000628:therapy*; D006801:Humans; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D011839:Radiation, Ionizing; D000077204:Temozolomide; D044764:Ubiquitin-Activating Enzymes / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism
chemical_list: D018906:Antineoplastic Agents, Alkylating; C524941:MIRN17 microRNA, human; D035683:MicroRNAs; D003606:Dacarbazine; C509349:ATG7 protein, human; D000071193:Autophagy-Related Protein 7; D044764:Ubiquitin-Activating Enzymes; D000077204:Temozolomide
keywords: autophagy; glioblastoma; miR-17