No abstract

These results demonstrate that cooption of host vasculature is an early event in tumor formation, and that persistence of this effect is related to the degree of blockade of VEGF activity.

The MYCN protooncogene is amplified in a number of advanced-stage human tumors such as neuroblastomas. Like other members of Myc family proteins, N-Myc is a transcription factor and its stability and activity are tightly controlled by ubiquitination-dependent proteasome degradation1-4. Although numerous studies demonstrate that N-Myc acts as a driver of neuroblastoma tumorigenesis, therapies that directly suppress N-Myc activity in human tumors are limited. Here, we have identified the herpesvirus-associated ubiquitin-specific protease (HAUSP or USP75-7) as a regulator of N-Myc in neuroblastoma. HAUSP interacts with N-Myc, and HAUSP expression induces deubiquitination and subsequent stabilization of N-Myc. Conversely, RNAi-mediated knockdown of HAUSP in neuroblastoma cancer cell lines, or genetic ablation of Hausp in the mouse brain destabilizes N-Myc, which leads to inhibition of N-Myc function. Notably, HAUSP is more abundant in neuroblastoma patients with poorer prognosis and HAUSP expression significantly correlates with N-Myc transcriptional activity. Furthermore, small molecule inhibitors against HAUSP deubiquitinase activity significantly suppress the growth of MYCN-amplified human neuroblastoma cell lines in xenograft mouse models. Together, our findings demonstrate a crucial role of HAUSP in regulating N-Myc function in vivo and suggest that HAUSP inhibition is a potential therapy for MYCN-amplified tumors.

BackgroundMolecular characterization has the potential to advance the management of pediatric cancer and high-risk hematologic disease. The clinical integration of genome sequencing into standard clinical practice has been limited and the potential utility of genome sequencing to identify clinically impactful information beyond targetable alterations has been underestimated.MethodsThe Precision in Pediatric Sequencing (PIPseq) Program at Columbia University Medical Center instituted prospective clinical next generation sequencing (NGS) for pediatric cancer and hematologic disorders at risk for treatment failure. We performed cancer whole exome sequencing (WES) of patient-matched tumor-normal samples and RNA sequencing (RNA-seq) of tumor to identify sequence variants, fusion transcripts, relative gene expression, and copy number variation (CNV). A directed cancer gene panel assay was used when sample adequacy was a concern. Constitutional WES of patients and parents was performed when a constitutionally encoded disease was suspected. Results were initially reviewed by a molecular pathologist and subsequently by a multi-disciplinary molecular tumor board. Clinical reports were issued to the ordering physician and posted to the patient’s electronic medical record.ResultsNGS was performed on tumor and/or normal tissue from 101 high-risk pediatric patients. Potentially actionable alterations were identified in 38% of patients, of which only 16% subsequently received matched therapy. In an additional 38% of patients, the genomic data provided clinically relevant information of diagnostic, prognostic, or pharmacogenomic significance. RNA-seq was clinically impactful in 37/65 patients (57%) providing diagnostic and/or prognostic information for 17 patients (26%) and identified therapeutic targets in 15 patients (23%). Known or likely pathogenic germline alterations were discovered in 18/90 patients (20%) with 14% having germline alternations in cancer predisposition genes. American College of Medical Genetics (ACMG) secondary findings were identified in six patients.ConclusionsOur results demonstrate the feasibility of incorporating clinical NGS into pediatric hematology-oncology practice. Beyond the identification of actionable alterations, the ability to avoid ineffective/inappropriate therapies, make a definitive diagnosis, and identify pharmacogenomic modifiers is clinically impactful. Taking a more inclusive view of potential clinical utility, 66% of cases tested through our program had clinically impactful findings and samples interrogated with both WES and RNA-seq resulted in data that impacted clinical decisions in 75% of cases.Electronic supplementary materialThe online version of this article (doi:10.1186/s13073-016-0389-6) contains supplementary material, which is available to authorized users.