Focal DNA copy number changes in neuroblastoma target MYCN regulated genes

Neuroblastoma is an embryonic tumor arising from immature sympathetic nervous system cells. Recurrent genomic alterations include MYCN and ALK amplification as well as recurrent patterns of gains and losses of whole or large partial chromosome segments. A recent whole genome sequencing effort yielded no frequently recurring mutations in genes other than those affecting ALK. However, the study further stresses the importance of DNA copy number alterations in this disease, in particular for genes implicated in neuritogenesis. Here we provide additional evidence for the importance of focal DNA copy number gains and losses, which are predominantly observed in MYCN amplified tumors. A focal 5 kb gain encompassing the MYCN regulated miR-17,92 cluster as sole gene was detected in a neuroblastoma cell line and further analyses of the array CGH data set demonstrated enrichment for other MYCN target genes in focal gains and amplifications. Next we applied an integrated genomics analysis to prioritize MYCN down regulated genes mediated by MYCN driven miRNAs within regions of focal heterozygous or homozygous deletion. We identified RGS5, a negative regulator of G-protein signaling implicated in vascular normalization, invasion and metastasis, targeted by a focal homozygous deletion, as a new MYCN target gene, down regulated through MYCN activated miRNAs. In addition, we expand the miR-17,92 regulatory network controlling TGFß signaling in neuroblastoma with the ring finger protein 11 encoding gene RNF11, which was previously shown to be targeted by the miR-17,92 member miR-19b. Taken together, our data indicate that focal DNA copy number imbalances in neuroblastoma (1) target genes that are implicated in MYCN signaling, possibly selected to reinforce MYCN oncogene addiction and (2) serve as a resource for identifying new molecular targets for treatment

Rare mutations in SQSTM1 modify susceptibility to frontotemporal lobar degeneration

Mutations in the gene coding for Sequestosome 1 (SQSTM1) have been genetically associated with amyotrophic lateral sclerosis (ALS) and Paget disease of bone. In the present study, we analyzed the SQSTM1 coding sequence for mutations in an extended cohort of 1,808 patients with frontotemporal lobar degeneration (FTLD), ascertained within the European Early-Onset Dementia consortium. As control dataset, we sequenced 1,625 European control individuals and analyzed whole-exome sequence data of 2,274 German individuals (total n = 3,899). Association of rare SQSTM1 mutations was calculated in a meta-analysis of 4,332 FTLD and 10,240 control alleles. We identified 25 coding variants in FTLD patients of which 10 have not been described. Fifteen mutations were absent in the control individuals (carrier frequency < 0.00026) whilst the others were rare in both patients and control individuals. When pooling all variants with a minor allele frequency < 0.01, an overall frequency of 3.2 % was calculated in patients. Rare variant association analysis between patients and controls showed no difference over the whole protein, but suggested that rare mutations clustering in the UBA domain of SQSTM1 may influence disease susceptibility by doubling the risk for FTLD (RR = 2.18 [95 % CI 1.24-3.85]; corrected p value = 0.042). Detailed histopathology demonstrated that mutations in SQSTM1 associate with widespread neuronal and glial phospho-TDP-43 pathology. With this study, we provide further evidence for a putative role of rare mutations in SQSTM1 in the genetic etiology of FTLD and showed that, comparable to other FTLD/ALS genes, SQSTM1 mutations are associated with TDP-43 pathology

MIBG scans in patients with stage 4 neuroblastoma reveal two metastatic patterns, one is associated with MYCN amplification and in MYCN-amplified tumours correlates with a better prognosis

Methods: Diagnostic 123I-MIBG scans from 249 patients (123 from a European and 126 from the COG cohort) were assessed for metastatic spread in 14 body segments and the form of the lesions: “focal” (clear margins distinguishable from adjacent background) or “diffuse” (indistinct margins, dispersed throughout the body segment). The total numbers of diffuse and focal lesions were recorded. Patients were then categorized as having lesions exclusively focal, lesions more focal than diffuse, lesions more diffuse than focal, or lesions exclusively diffuse.Results: Diffuse lesions affected a median of seven body segments and focal lesions a median of two body segments (P < 0.001, both cohorts). Patients with a focal pattern had a median of 2 affected body segments and those with a diffuse pattern a median of 11 affected body segments (P < 0.001, both cohorts). Thus, two MIBG-avid metastatic patterns emerged: “limited-focal” and “extensive-diffuse”. The median numbers of affected body segments in MYCN-amplified (MNA) tumours were 5 (European cohort) and 4 (COG cohort) compared to 9 and 11, respectively, in single-copy MYCN (MYCNsc) tumours (P < 0.001). Patients with exclusively focal metastases were more likely to have a MNA tumour (60 % and 70 %, respectively) than patients with the other types of metastases (23 % and 28 %, respectively; P < 0.001). In a multivariate Cox regression analysis, focal metastases were associated with a better event-free and overall survival than the other types of metastases in patients with MNA tumours in the COG cohort (P < 0.01).Conclusion: Two metastatic patterns were found: a “limited and focal” pattern found mainly in patients with MNA neuroblastoma that correlated with prognosis, and an “extensive and diffuse” pattern found mainly in patients with MYCNsc neuroblastoma.Purpose: The aim of this study was to find clinically relevant MIBG-avid metastatic patterns in patients with newly diagnosed stage 4 neuroblastoma

Detection of copy number aberrations in cell free DNA from plasma of neuroblastoma patients using shallow massive parallel sequencing

Neuroblastoma (NB) is a heterogeneous disease characterized by distinct clinical and biological features. The somatic mutation burden is low in these tumors, while copy number alterations are highly recurrent. Low stage tumors usually present with numerical chromosome aberrations, while high stage tumors are characterized by the presence of segmental aberrations, the latter being associated with poor prognosis. Presently, determination of DNA copy number profiles is mandatory in most treatment protocols and determined using FISH, MLPA, array-CGH or SNP-arrays. Such analysis can be precluded through the inability to biopsy the tumor or lack of sufficient tumor material. In this study, we investigated whether cell free DNA (cfDNA) isolated from plasma samples of NB patients could offer an alternative to biopsies, and whether shallow massive parallel sequencing (MPS) could be used as a substitute for classical DNA copy number analyses. CfDNA was isolated from plasma using the QiaAmp circulating nucleic acid kit (Qiagen). Samples were preprocessed with the Ion Plus Fragment Library kit, barcoded, pooled by six and sequenced on an Ion Proton (ThermoFisher) instrument. Data analysis for CNV detection was done using the QDNAseq algorithm implemented in the online genomic data visualisation tool Vivar. The minimal number of reads per sample was set at 10 million. Comparison of the MPS data with the array-CGH profiles of the tumors from the same patient showed that all structural and numerical chromosome aberrations including MYCN amplification could be readily detected with MPS using a very low input of cfDNA (5 ng). Interestingly, MPS data show a much better signal-to-noise ratio compared with array data. In conclusion, MPS analysis of cfDNA isolated from plasma offers a cost-effective, non-invasive and rapid alternative for DNA copy number profiling in neuroblastoma

MIBG scans in patients with stage 4 neuroblastoma reveal two metastatic patterns, one is associated with MYCN amplification and in MYCN-amplified tumours correlates with a better prognosis

textabstractMethods: Diagnostic 123I-MIBG scans from 249 patients (123 from a European and 126 from the COG cohort) were assessed for metastatic spread in 14 body segments and the form of the lesions: “focal” (clear margins distinguishable from adjacent background) or “diffuse” (indistinct margins, dispersed throughout the body segment). The total numbers of diffuse and focal lesions were recorded. Patients were then categorized as having lesions exclusively focal, lesions more focal than diffuse, lesions more diffuse than focal, or lesions exclusively diffuse.Results: Diffuse lesions affected a median of seven body segments and focal lesions a median of two body segments (P < 0.001, both cohorts). Patients with a focal pattern had a median of 2 affected body segments and those with a diffuse pattern a median of 11 affected body segments (P < 0.001, both cohorts). Thus, two MIBG-avid metastatic patterns emerged: “limited-focal” and “extensive-diffuse”. The median numbers of affected body segments in MYCN-amplified (MNA) tumours were 5 (European cohort) and 4 (COG cohort) compared to 9 and 11, respectively, in single-copy MYCN (MYCNsc) tumours (P < 0.001). Patients with exclusively focal metastases were more likely to have a MNA tumour (60 % and 70 %, respectively) than patients with the other types of metastases (23 % and 28 %, respectively; P < 0.001). In a multivariate Cox regression analysis, focal metastases were associated with a better event-free and overall survival than the other types of metastases in patients with MNA tumours in the COG cohort (P < 0.01).Conclusion: Two metastatic patterns were found: a “limited and focal” pattern found mainly in patients with MNA neuroblastoma that correlated with prognosis, and an “extensive and diffuse” pattern found mainly in patients with MYCNsc neuroblastoma.Purpose: The aim of this study was to find clinically relevant MIBG-avid metastatic patterns in patients with newly diagnosed stage 4 neuroblastoma