BECN1 and ATG7 are required for autophagosome formation, LAMP-2A is required for CMA, HDAC6 plays a role in the clearance of misfolded proteins by autophagy, and the Hsp70 protein family with the two major family members, Hsc70 and Hsp70, is an essential mediator of lysosomal degradation. against doxorubicin treatment through interaction with heat shock protein 70 family proteins, causing their deacetylation. Conversely, heat shock protein 70/heat shock cognate 70 was acetylated in HDAC10-depleted cells. expression levels in high-risk neuroblastomas correlated with autophagy in gene-set analysis and predicted treatment success in patients with advanced stage 4 neuroblastomas. Our results demonstrate that HDAC10 protects cancer cells from cytotoxic agents by mediating autophagy and identify this HDAC isozyme as a druggable regulator of advanced-stage tumor cell survival. Moreover, these results propose a promising way to considerably improve treatment response in the neuroblastoma patient subgroup with the poorest outcome. Autophagy is an evolutionarily highly conserved process that can be induced by metabolic or therapeutic stress, such as DNA damage-inducing drugs (1). The two dominant types of autophagy are macroautophagy and chaperone-mediated autophagy (CMA) (2). Macroautophagy is regulated by autophagy-related genes (ATGs), including beclin-1 (family members in advanced neuroblastomas were capable of predicting poor and good treatment Emodin response in this high-risk neuroblastoma subgroup commonly treated with intense multimodal chemotherapy. We then set out to unravel the HDAC10-mediated mechanism of cell survival of advanced stage neuroblastomas. Results HDAC10 Expression in Emodin Neuroblastomas Predicts Treatment Outcome. Expression levels of genes encoding single HDAC enzymes have prognostic value in pediatric tumors of the nervous system (28C30). Here, we examined whether expression levels might serve as a biomarker for treatment success in the high-risk subgroup of neuroblastoma patients. We reanalyzed publicly available expression data [Academic Medical Center (AMC) cohort; Gene Expression Omnibus (GEO) database accession no. “type”:”entrez-geo”,”attrs”:”text”:”GSE16476″,”term_id”:”16476″GSE16476] from 40 advanced stage primary neuroblastomas (INSS stage 4) from patients before treatment with multimodal chemotherapy using the Web-based R2 microarray database (http://r2.amc.nl) (31) to determine HDAC1 to -11 expression levels. From all 11 classical HDACs, only expression significantly correlated with poor overall survival in this patient cohort (Table S1). Emodin Low expression in the tumor correlated with excellent long-term patient survival, with an overall survival probability of 80%, whereas high expression reduced overall survival probability to 11% (Fig. 1expression could not significantly separate patients with low-risk tumor stages (1C3 and 4s), into different prognostic groups (Fig. 1expression in an independent patient cohort from the National Cancer Institute (NCI) Neuroblastoma Prognosis Database (32), which is publicly available at the Oncogenomics Emodin Data Center (http://home.CCR.cancer.gov/oncology/oncogenomics). Elevated expression in advanced INSS stage 4 tumors also significantly correlated with poor overall patient survival in this cohort (Fig. 1expression in other highly malignant pediatric tumors of the nervous system, such as medulloblastoma [Heidelberg cohort (33); GEO accession no. “type”:”entrez-geo”,”attrs”:”text”:”GSE28245″,”term_id”:”28245″GSE28245 (http://r2.amc.nl)] patients significantly separated recurrence and survival (Fig. S1 and expression in neuroblastomas and medulloblastomas before patient treatment separates the survival probability of patients from independent cohorts and may, therefore, serve as useful biomarker to predict treatment outcome in pediatric patients with high-risk pediatric tumors of the nervous system. Open in a separate window Fig. 1. tumor expression separates treatment outcome of high-risk neuroblastoma patients. (= 11) or high (= 29) levels of values were corrected for IGFBP2 multiple testing (Bonferroni). The R2 microarray analysis and visualization platform (http://r2.amc.nl) was used for calculations and is the source of the data. (= 18) or high (= 30) levels of = 31) whose tumors expressed low (= 24) or high (= 7) levels of value minimization check, and values were corrected for multiple testing using the Bonferroni method. HDAC10 Promotes Autophagic Processing. Correlation and gene-set analysis on the AMC neuroblastoma cohort using the R2 microarray database revealed that expression, which is necessary for autophagosome formation during the induction of autophagy, positively correlated with expression (Table S2 and Fig. S1expression in pretreatment tumors as a biomarker for response to polychemotherapy in several patient cohorts, we hypothesized that HDAC10 might have a key function in regulating autophagy and cell survival after exposure to cytotoxic agents. We performed a series of experiments to detect the involvement of HDAC10 in autophagic pathways. was depleted by specific siRNAs against different regions of the mRNA sequence but not of the closely related.