Project description:SNP arrays were combined with next generation sequencing (NGS) to precisely define the deleted region in 17 primary 11q-loss neuroblastomas and identify allelic variants in genes relevant for neuroblastoma aetiology. We assessed PARP inhibitor olaparib in combination with other chemotherapy medications using both in vitro and in vivo models.
Project description:SNP arrays were combined with next generation sequencing (NGS) to precisely define the deleted region in 17 primary 11q-loss neuroblastomas and identify allelic variants in genes relevant for neuroblastoma aetiology. We assessed PARP inhibitor olaparib in combination with other chemotherapy medications using both in vitro and in vivo models.
Project description:Although PARP inhibitors (PARPi) now form part of the standard-of-care for the treatment of homologous recombination defective cancers, de novo and acquired resistance limits their overall effectiveness. Previously, overexpression of the BRCA1-∆11q splice variant has been shown to cause PARPi resistance. How cancer cells achieve increased BRCA1-∆11q expression has remained unclear. Using isogenic cells with different BRCA1 mutations, we show that reduction in HUWE1 leads to increased levels of BRCA1-∆11q and PARPi resistance. This effect is specific to cells able to express BRCA1-∆11q (e.g. BRCA1 exon 11 mutant cells) and is not seen in BRCA1 mutants that cannot express BRCA1-∆11q, nor in BRCA2 mutant cells. As well as increasing levels of BRCA1-∆11q protein in exon 11 mutant cells, HUWE1 silencing also restores RAD51 nuclear foci and platinum salt resistance. HUWE1 catalytic domain mutations were also seen in a case of PARPi resistant, BRCA1 exon 11 mutant, high grade serous ovarian cancer. These results suggest how elevated levels of BRCA1-∆11q and PARPi resistance can be achieved, identify HUWE1 as a candidate biomarker of PARPi resistance for assessment in future clinical trials and illustrate how some PARPi resistance mechanisms may only operate in patients with particular BRCA1 mutations.
Project description:High-risk 11q deleted neuroblastomas (NBs) typically display an undifferentiated/poorly differentiated morphology. NB is thought to develop from Schwann cell precursors (SCPs) and un-differentiated neural crest derived cells (NCC). It is therefore vital to understand the mechanisms involved in the block of differentiation. We showed that an important and novel role for oncogenic ALK-ERK1/2-SP1 signaling may be the maintenance of an undifferentiated state of transformed NC-derived progenitors that is achieved by repression of DLG2, a tumor suppressor in NB. DLG2 is expressed in the ‘bridge signature’ that represents the transcriptional transition state when neural crest cells or Schwann Cell Precursors (SCP) become chromaffin cells of the adrenal gland. The importance of SP1 and DLG2 in this process is highlighted by our findings that restoring DLG2 expression spontaneously drives NB differentiation. Further, genetic analysis of high-risk 11q deletion NB patient identified genetic lesions in the DLG2 gene, Our data also suggest that further exploration of other ‘bridge genes’ may help to better understand the mechanisms underlying the differentiation of NC-derived progenitors and their contribution to NB.
Project description:Despite recent consensus on eligibility of adjuvant systemic therapy in lymph-node negative breast cancer (NNBC) patients based on clinico-pathological criteria, specific biological markers are needed to predict sensitivity to the different therapeutic options. We examined the feasibility of developing a genomic predictor of chemotherapy response and recurrence risk in 185 patients with NNBC using assembled arrays containing 2,460 BAC clones for scanning the genome for DNA copy number changes. After surgery, 90 patients received anthracycline-based chemotherapy whereas ninety-five did not. Tamoxifen was administered to patients with hormone-receptor positive tumors. Association of genomic and clinico-pathological data and outcome was computed using Cox proportional hazard models and multiple testing adjustment procedures. Analysis of NNBC genomes revealed a common genomic signature. Specific DNA copy number aberrations were associated with hormonal receptor status, but not with other clinico-pathological parameters. In patients treated with chemotherapy, none of the genomic changes was significantly correlated with recurrence. In patients not receiving chemotherapy, deletion of eight BAC clones clustered to chromosome 11q was independently associated with relapse (DFS at 10 years±SE, 40±14% vs. 86±6%;p<00001). The 54 patients with deletion of 11q (29%) did not present more aggressive clinical-pathological features than those without 11q loss. The adverse influence of 11q deletion in clinical outcome was confirmed in an independent validation series of 88 NNBC patients. Our data suggest that NNBC patients with 11q deletion may benefit from anthracycline-based chemotherapy despite other clinical, pathological or genetic features. However, these initial findings should be evaluated in randomized clinical trials. Keywords: CGH, breast cancer