Project description:Neuroblastoma is a pediatric cancer characterized by variable outcomes ranging from spontaneous regression to life-threatening progression. High-risk neuroblastoma patients receive myeloablative chemotherapy with hematopoietic stem-cell transplant followed by adjuvant retinoid differentiation treatment. However, the overall survival remains low; hence, there is an urgent need for alternative therapeutic approaches. One feature of high-risk neuroblastoma is the high level of DNA methylation of putative tumor suppressors. Combining the reversibility of DNA methylation with the differentiation-promoting activity of retinoic acid (RA) could provide an alternative strategy to treat high-risk neuroblastoma. Here we show that treatment with the DNA demethylating drug 5-Aza-deoxycytidine (AZA) restores high-risk neuroblastoma sensitivity to RA. Combined systemic distribution of AZA and RA impedes tumor growth and prolongs survival. Genomewide analysis of treated tumors reveals that this combined treatment rapidly induces a HIF2α-associated hypoxia-like transcriptional response followed by an increase in neuronal gene expression and a decrease in cell-cycle gene expression. A small-molecule inhibitor of HIF2α activity diminishes the tumor response to AZA+RA treatment, indicating that the increase in HIF2α levels is a key component in tumor response to AZA+RA. The link between increased HIF2α levels and inhibited tumor growth is reflected in large neuroblastoma patient datasets. Therein, high levels of HIF2α, but not HIF1α, significantly correlate with expression of neuronal differentiation genes and better prognosis but negatively correlate with key features of high-risk tumors, such as MYCN amplification. Thus, contrary to previous studies, our findings indicate an unanticipated tumor-suppressive role for HIF2α in neuroblastoma.
Project description:Neuroblastoma is a pediatric cancer characterized by variable outcomes ranging from spontaneous regression to life-threatening progression. High-risk neuroblastoma patients receive myeloablative chemotherapy with hematopoietic stem-cell transplant followed by adjuvant retinoid differentiation treatment. However, the overall survival remains low; hence, there is an urgent need for alternative therapeutic approaches. One feature of high-risk neuroblastoma is the high level of DNA methylation of putative tumor suppressors. Combining the reversibility of DNA methylation with the differentiation-promoting activity of retinoic acid (RA) could provide an alternative strategy to treat high-risk neuroblastoma. Here we show that treatment with the DNAdemethylating drug 5-Aza-deoxycytidine (AZA) restores high-risk neuroblastoma sensitivity to RA. Combined systemic distribution of AZA and RA impedes tumor growth and prolongs survival. Genomewide analysis of treated tumors reveals that this combined treatment rapidly induces a HIF2α-associated hypoxia-like transcriptional response followed by an increase in neuronal gene expression and a decrease in cell-cycle gene expression. A small-molecule inhibitor of HIF2α activity diminishes the tumor response to AZA+RA treatment, indicating that the increase in HIF2α levels is a key component in tumor response to AZA+RA. The link between increased HIF2α levels and inhibited tumor growth is reflected in large neuroblastoma patient datasets. Therein, high levels of HIF2α, but not HIF1α, significantly correlate with expression of neuronal differentiation genes and better prognosis but negatively correlate with key features of high-risk tumors, such as MYCN amplification. Thus, contrary to previous studies, our findings indicate an unanticipated tumor-suppressive role for HIF2α in neuroblastoma.
Project description:High-risk neuroblastoma is often distinguished by amplification of MYCN and loss of differentiation potential with tumors refractory to retinoic acid differentiation based therapies. Here, we leverage high-throughput drug screening of epigenetic targeted therapies across a large and diverse tumor cell line panel to uncover the hypersensitivity of neuroblastoma cells to GSK-J4, a small molecule dual inhibitor of H3K27 demethylases UTX and JMJD3. Mechanistically, GSK-J4 induced neuroblastoma differentiation and ER stress with accompanying upregulation of PUMA and apoptosis induction. Retinoic acid (RA)-resistant neuroblastoma cells were sensitive to GSK-J4. Additionally, GSK-J4 was effective at blocking the growth of chemorefractory and patient-derived xenograft models of high-risk neuroblastoma in vivo. Further, GSK-J4 and RA combined to induce differentiation, ER-stress and limit the growth of neuroblastomas resistant to either drug alone. In MYCN-amplified neuroblastoma, which is the most prevalent driver gene alteration in the refractory population, PUMA induction by GSK-J4 sensitized tumors to the BCL-2 inhibitor venetoclax, demonstrating that epigenetic targeted therapies and BH3 mimetics can be rationally combined to treat high-risk subset of neuroblastoma. Therefore, H3K27 demethylation inhibition is a promising therapeutic target to treat high-risk neuroblastoma, and H3K27 demethylation can be part of rational combination therapies to induce robust anti-neuroblastoma activity.
Project description:We asked whether combining Notch and VEGF blockade would enhance suppression of tumor angiogenesis and growth, using the NGP neuroblastoma model. NGP tumors were engineered to express a Notch1 decoy construct (N1D), which restricts Notch signaling, and then treated with either the anti-VEGF antibody bevacizumab or vehicle. Combining Notch and VEGF blockade led to blood vessel regression, increasing endothelial cell apoptosis and disrupting pericyte coverage of endothelial cells. Combined Notch and VEGF blockade did not affect tumor weight, but did additively reduce tumor viability. Our results indicate that Notch and VEGF pathways play distinct but complementary roles in tumor angiogenesis, and show that concurrent blockade disrupts primary tumor vasculature and viability further than inhibition of either pathway alone. 6 neuroblastoma tumors were transfected with Notch1 decoy, 6 with Notch1 decoy and treated with bevacizumab, 6 tumors treated with bevacizumab, and 6 control tumors were profiled by human 133A 2.0 arrays
Project description:Neuroblastoma susceptibility in TH-MYN mice is heavily influence by mouse strain background. We have combined linkage analysis of tumor susceptibility with expression QTL analysis of superior cervical ganglia (pure peripheral symptathetic nervous tissue) to identify genes underlying tumor formation The development of targeted therapeutics for neuroblastoma, the third most common tumor in children, has been limited by a poor understanding of growth signaling mechanisms unique to the peripheral nerve precursors from which tumors arise. In this study, we combined genetics with gene expression analysis in the peripheral sympathetic nervous system to implicate arginase 1 and GABA signaling in tumor formation in vivo. In human neuroblastoma cells, activation of GABA-A receptors by a benzodiazepine induced apoptosis and inhibited mitogenic signaling through AKT and MAPK. These results suggest that GABA influences both neural development and neuroblastoma, and that benzodiazepines in clinical use may have potential for neuroblastoma therapy. 224 backcrossed mice were genotyped at 349 markers to identify susceptibility loci for neuroblastoma. Gene expression from Superior Cervical Ganglia from 116 of these mice were correlated with genotyping data to identify putative eQTL.
Project description:Background: in clear cell renal cell carcinoma (ccRCC), 80% of cases have biallelic inactivation of VHL gene, leading to constitutive activation of both HIF1α and HIF2α. As HIF2α is the driver of the disease promoting tumour growth and metastasis, drugs targeting HIF2α have been developed. However, resistance is common, therefore new therapies are needed. Methods: we generated the 786-0 HIF2α knockout (KO) cell line and assessed the HIF2α antagonist PT2385 in several steps of tumour development. RNA sequencing was performed to identify genes differentially expressed between them and a drug screening was used to identify drugs with differential effects on HIF2α-expressing and KO cells. Results: HIF2α KO promoted cell migration, reduced proliferation and clonogenicity, as well as metastasis, whereas PT2385 treatment only inhibited tumour cell invasion. There was a large set of co-ordinately regulated genes, but HIF2α KO cells also had up-regulation of genes related to EMT and downregulation of genes involving cell migration and extracellular matrix. The HIF2α KO increased sensitivity to statins, while PT2385 had no effect. Conclusions: this study shows new pathways that could be targeted combined with PT2385 to enhance its therapeutic effects and delay resistance.