title: Modulation of pediatric brain tumor autophagy and chemosensitivity.
abstract: Brain and spinal tumors are the second most common malignancies in childhood after leukemia, and they remain the leading cause of death from childhood cancer. Autophagy is a catabolic cellular process that is thought to regulate chemosensitivity, however its role in pediatric tumors is unknown. Here we present studies in pediatric medulloblastoma cell lines (DAOY, ONS76) and atypical teratoid/rhabdoid tumor cell lines (BT-16, BT-12) to test this role. Autophagy was inhibited using siRNA against autophagy-related genes ATG12 and ATG7 or pharmacologically induced or inhibited using rapamycin and chloroquine to test the effect of autophagy on chemosensitivity. Autophagic flux was measured using Western blot analysis of LC3-II and p62 and cell viability was determined using MTS assays and clonogenic growth. We found that when pediatric brain tumor cells under starvation stress, exposed to known autophagy inducers such as rapamycin, or treated with current chemotherapeutics (lomustine, cisplatin), all stimulate autophagy. Silencing ATG12 and ATG7 or exposure to a known autophagy inhibitor, chloroquine, could inhibit this autophagy increase; however, the effect of autophagy on tumor cell killing was small. These results may have clinical relevance in the future planning of therapeutic regimens for pediatric brain tumors.
authors.affiliation: Department of Pediatrics, University of Colorado, 12801 E 17th Ave, RC-1 South, Rm 6400D, Mail Stop 8303, Aurora, CO 80045, USA.
authors.forename: Jean M Mulcahy
authors.initials: JM
authors.lastname: Levy
authors.forename: Andrew
authors.initials: A
authors.lastname: Thorburn
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D001343:Autophagy / Q000187:drug effects* / Q000502:physiology*; D000071192:Autophagy-Related Protein 12; D000071193:Autophagy-Related Protein 7; D015153:Blotting, Western; D001932:Brain Neoplasms / Q000473:pathology* / Q000503:physiopathology; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D002648:Child; D019008:Drug Resistance, Neoplasm / Q000502:physiology*; D006801:Humans; D034741:RNA, Small Interfering; D025841:Small Ubiquitin-Related Modifier Proteins / Q000235:genetics / Q000378:metabolism; D014162:Transfection; D044764:Ubiquitin-Activating Enzymes / Q000235:genetics / Q000378:metabolism
chemical_list: C466624:ATG12 protein, human; D000970:Antineoplastic Agents; D000071192:Autophagy-Related Protein 12; D034741:RNA, Small Interfering; D025841:Small Ubiquitin-Related Modifier Proteins; C509349:ATG7 protein, human; D000071193:Autophagy-Related Protein 7; D044764:Ubiquitin-Activating Enzymes