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Myc oncoproteins are commonly upregulated in human cancers of different organ origins, stabilized by Aurora A, degraded through ubiquitin–proteasome pathway-mediated proteolysis, and exert oncogenic effects by modulating gene and protein expression. Histone deacetylases are emerging as targets for cancer therapy. Here we demonstrated that the class III histone deacetylase SIRT2 was upregulated by N-Myc in neuroblastoma cells and by c-Myc in pancreatic cancer cells, and that SIRT2 enhanced N-Myc and c-Myc protein stability and promoted cancer cell proliferation. Affymetrix gene array studies revealed that the gene most significantly repressed by SIRT2 was the ubiquitin–protein ligase NEDD4. Consistent with this finding, SIRT2 repressed NEDD4 gene expression by directly binding to the NEDD4 gene core promoter and deacetylating histone H4 lysine 16. Importantly, NEDD4 directly bound to Myc oncoproteins and targeted Myc oncoproteins for ubiquitination and degradation, and small-molecule SIRT2 inhibitors reactivated NEDD4 gene expression, reduced N-Myc and c-Myc protein expression, and suppressed neuroblastoma and pancreatic cancer cell proliferation. Additionally, SIRT2 upregulated and small-molecule SIRT2 inhibitors decreased Aurora A expression. Our data reveal a novel pathway critical for Myc oncoprotein stability, and provide important evidences for potential application of SIRT2 inhibitors for the prevention and therapy of Myc-induced malignancies.

Background Despite advances in therapeutics for adverse‐risk acute myeloid leukaemia (AML), overall survival remains poor, especially in refractory disease. Comprehensive tumour profiling and pre‐clinical drug testing can identify effective personalised therapies. Case We describe a case of ETV6‐MECOM fusion‐positive refractory AML, where molecular analysis and in vitro high throughput drug screening identified a tolerable, novel targeted therapy and provided rationale for avoiding what could have been a toxic treatment regimen. Ruxolitinib combined with hydroxyurea led to disease control and enhanced quality‐of‐life in a patient unsuitable for intensified chemotherapy or allogeneic stem cell transplantation. Conclusion This case report demonstrates the feasibility and role of combination pre‐clinical high throughput screening to aid decision making in high‐risk leukaemia. It also demonstrates the role a JAK1/2 inhibitor can have in the palliative setting in select patients with AML.

The family of tripartite-motif (TRIM) proteins are involved in diverse cellular processes, but are often characterized by critical protein–protein interactions necessary for their function. TRIM16 is induced in different cancer types, when the cancer cell is forced to proceed down a differentiation pathway. We have identified TRIM16 as a DNA-binding protein with histone acetylase activity, which is required for the retinoic acid receptor β 2 transcriptional response in retinoid-treated cancer cells. In this study, we show that overexpressed TRIM16 reduced neuroblastoma cell growth, enhanced retinoid-induced differentiation and reduced tumourigenicity in vivo . TRIM16 was only expressed in the differentiated ganglion cell component of primary human neuroblastoma tumour tissues. TRIM16 bound directly to cytoplasmic vimentin and nuclear E2F1 in neuroblastoma cells. TRIM16 reduced cell motility and this required downregulation of vimentin. Retinoid treatment and enforced overexpression caused TRIM16 to translocate to the nucleus, and bind to and downregulate nuclear E2F1, required for cell replication. This study, for the first time, demonstrates that TRIM16 acts as a tumour suppressor, affecting neuritic differentiation, cell migration and replication through interactions with cytoplasmic vimentin and nuclear E2F1 in neuroblastoma cells.

Myc oncoproteins and histone deacetylases (HDACs) modulate gene transcription and enhance cancer cell proliferation, and HDAC inhibitors are among the most promising new classes of anticancer drugs. Here, we show that N-Myc and c-Myc upregulated HDAC2 gene expression in neuroblastoma and pancreatic cancer cells, respectively, which contributed to N-Myc- and c-Myc-induced cell proliferation. Cyclin G2 (CCNG2) was commonly repressed by N-Myc and HDAC2 in neuroblastoma cells and by c-Myc and HDAC2 in pancreatic cancer cells, and could be reactivated by HDAC inhibitors. 5-bromo-2′-deoxyuridine incorporation assays showed that transcriptional repression of CCNG2 was, in part, responsible for N-Myc-, c-Myc- and HDAC2-induced cell proliferation. Dual crosslinking chromatin immunoprecipitation assay demonstrated that N-Myc acted as a transrepressor by recruiting the HDAC2 protein to Sp1-binding sites at the CCNG2 gene core promoter. Moreover, HDAC2 was upregulated, and CCNG2 downregulated, in pre-cancerous and neuroblastoma tissues from N-Myc transgenic mice, and c-Myc overexpression correlated with upregulation of HDAC2 and repression of CCNG2 in tumour tissues from pancreatic cancer patients. Taken together, our data indicate the critical roles of upregulation of HDAC2 and suppression of CCNG2 in Myc-induced oncogenesis, and have significant implications for the application of HDAC inhibitors in the prevention and treatment of Myc-driven cancers.

Embryonal cancer can arise from postnatally persistent embryonal remnant or rest cells, which are uniquely characterized by the absence of p53 mutations. Perinatal overexpression of the MycN oncoprotein in embryonal cancer precursor cells causes postnatal rests, and later tumor formation through unknown mechanisms. However, overexpression of Myc in adult tissues normally activates apoptosis and/or senescence signals as an organismal defense mechanism against cancer. Here, we show that perinatal neuroblastoma precursor cells exhibited a transiently diminished p53 response to MycN oncoprotein stress and resistance to trophic factor withdrawal, compared with their adult counterpart cells from the TH-MYCN +/+ transgenic mouse model of neuroblastoma. The adult stem cell maintenance factor and Polycomb group protein, Bmi1 (B-cell-specific Moloney murine leukemia virus integration site), had a critical role at neuroblastoma initiation in the model, by repressing p53 responses in precursor cells. We further show in neuroblastoma tumor cells that Bmi1 could directly bind p53 in a complex with other Polycomb complex proteins, Ring1A or Ring1B, leading to increased p53 ubiquitination and degradation. Repressed p53 signal responses were also seen in precursor cells for other embryonal cancer types, medulloblastoma and acute lymphoblastic leukemia. Collectively, these date indicate a general mechanism for p53 inactivation in some embryonal cell types and consequent susceptibility to MycN oncogenesis at the point of embryonal tumor initiation.

The N-Myc oncoprotein induces neuroblastoma, which arises from undifferentiated neuroblasts in the sympathetic nervous system, by modulating gene and protein expression and consequently causing cell differentiation block and cell proliferation. The class IIa histone deacetylase 5 (HDAC5) represses gene transcription, and blocks myoblast, osteoblast and leukemia cell differentiation. Here we showed that N-Myc upregulated HDAC5 expression in neuroblastoma cells. Conversely, HDAC5 repressed the ubiquitin–protein ligase NEDD4 gene expression, increased Aurora A gene expression and consequently upregulated N-Myc protein expression. Genome-wide gene expression analysis and protein co-immunoprecipitation assays revealed that HDAC5 and N-Myc repressed the expression of a common subset of genes by forming a protein complex, whereas HDAC5 and the class III HDAC SIRT2 independently repressed the expression of another common subset of genes without forming a protein complex. Moreover, HDAC5 blocked differentiation and induced proliferation in neuroblastoma cells. Taken together, our data identify HDAC5 as a novel co-factor in N-Myc oncogenesis, and provide the evidence for the potential application of HDAC5 inhibitors in the therapy of N-Myc-induced neuroblastoma and potentially other c-Myc-induced malignancies.

Purpose Acute lymphoblastic leukemia (ALL) survivors are the largest group of childhood cancer survivors; however, their risk for late effects is high. Cancer-related late effects have the potential to compromise health-related quality of life (HRQL) long into survivorship. None of the reviews so far have focused on ALL solely, but described HRQL for all childhood cancers. We aimed to identify ALL survivors at risk for poor HRQL and identify possible risk factors. Method Following PRISMA guidelines, we performed a systematic review, searching published literature in Pubmed, Psyclnfo, Embase, and the Cochrane database including all publications up to December 16, 2016. Two independent reviewers (JV and ER) screened eligible articles and assessed article quality. Results We found 31 studies representing 4356 survivors and 901 proxies. Thirteen studies found worse, eight found no difference, and three better, overall HRQL scores compared with healthy controls or norms. ALL survivors typically had better overall HRQL scores than survivors of other childhood cancers. Clinical variables (e.g., treatment received) were not consistently associated with HRQL; however, experiencing worse late effects was associated with lower HRQL. Survivor and parent socio-demographic factors and psychological factors such as resilience and depression were also associated with HRQL. Conclusion ALL survivors appeared to have worse or equivalent HRQL compared with controls, but better HRQL than survivors of other cancer types. However, studies reported a wide variability in HRQL and potential risk factors for poor HRQL. Measuring ALL survivors' HRQL longitudinally and comprehensively assessing potential risk factors might identify future avenues to intervene early.

Retinoids induce growth arrest, differentiation, and cell death in many cancer cell types. One factor determining the sensitivity or resistance to the retinoid anticancer signal is the transcriptional response of retinoid-regulated target genes in cancer cells. We used cDNA microarray to identify 31 retinoid-regulated target genes shared by two retinoid-sensitive neuroblastoma cell lines, and then sought to determine the relevance of the target gene responses to the retinoid anticancer signal. The pattern of retinoid responsiveness for six of 13 target genes (RAR β 2, CYP26A1, CRBP1, RGS16, DUSP6, EGR1) correlated with phenotypic retinoid sensitivity, across a panel of retinoid-sensitive or -resistant lung and breast cancer cell lines. Retinoid treatment of MYCN transgenic mice bearing neuroblastoma altered the expression of five of nine target genes examined (RAR β 2, CYP26A1, CRBP1, DUSP6, PLAT) in neuroblastoma tumour tissue in vivo . In retinoid-sensitive neuroblastoma, lung and breast cancer cell lines, direct inhibition of retinoid-induced RAR β 2 expression blocked induction of only one of eight retinoid target genes (CYP26A1). DNA demethylation, histone acetylation, and exogenous overexpression of RAR β 2 partially restored retinoid-responsive CYP26A1 expression in RA-resistant MDA-MB-231 breast, but not SK-MES-1 lung, cancer cells. Combined, rather than individual, inhibition of DUSP6 and RGS16 was required to block retinoid-induced growth inhibition in neuroblastoma cells, through phosphorylation of extracellular-signal-regulated kinase. In conclusion, sensitivity to the retinoid anticancer signal is determined in part by the transcriptional response of key retinoid-regulated target genes, such as RAR β 2, DUSP6, and RGS16.

We retrospectively analysed the outcomes of children transplanted for high-risk neuroblastoma (NB) at a single institution predominantly transplanted with total body irradiation and chemotherapy. The aims of this study were to determine the prognostic impact of clinical and biological features and to document long-term health outcomes. Forty patients were transplanted with a single unpurged autograft. Fourteen patients died from disease progression and two from late complications of treatment. Twenty-three patients are alive at a median of 4.6 years from diagnosis. Kaplan-Meier estimates of overall survival at 2, 5 and 10 years are 76+/-7.0, 60.2+/-8.4 and 54.7+/-9.3% following transplant. Response to induction therapy was significantly associated with survival (P<0.01). Long-term complications included growth (100%) and pubertal failure (83%), hearing impairment (73%), orthopaedic complications (63%), renal impairment (47%) and thyroid abnormalities (36%). Intrinsic and acquired resistance to chemotherapy remains the major obstacle to improving outcomes in high-risk NB. Although patients with chemo-sensitive disease are less likely to experience a relapse, substantial therapy-related toxicities result in poor long-term health outcomes for survivors.

Increased retinoic acid receptor β (RAR β 2 ) gene expression is a hallmark of cancer cell responsiveness to retinoid anticancer effects. Moreover, low basal or induced RAR β 2 expression is a common feature of many human cancers, suggesting that RAR β 2 may act as a tumour suppressor gene in the absence of supplemented retinoid. We have previously shown that low RAR β 2 expression is a feature of advanced neuroblastoma. Here, we demonstrate that the ABC domain of the RAR β 2 protein alone was sufficient for the growth inhibitory effects of RAR β 2 on neuroblastoma cells. ATP7A, the copper efflux pump, is a retinoid-responsive gene, was upregulated by ectopic overexpression of RAR β 2 . The ectopic overexpression of the RAR β 2 ABC domain was sufficient to induce ATP7A expression, whereas, RAR β 2 siRNA blocked the induction of ATP7A expression in retinoid-treated neuroblastoma cells. Forced downregulation of ATP7A reduced copper efflux and increased viability of retinoid-treated neuroblastoma cells. Copper supplementation enhanced cell growth and reduced retinoid-responsiveness, whereas copper chelation reduced the viability and proliferative capacity. Taken together, our data demonstrates ATP7A expression is regulated by retinoic acid receptor β and it has effects on intracellular copper levels, revealing a link between the anticancer action of retinoids and copper metabolism.