Project description:Therapeutic approaches to treat melanoma include small molecule drugs that target activating protein mutations in pro-growth signaling pathways like the MAPK pathway. While beneficial to the approximately 50% of patients with activating BRAFV600 mutation, mono- and combination therapy with MAPK inhibitors is ultimately associated with acquired resistance. To better characterize the mechanisms of MAPK inhibitor resistance in melanoma, we utilize patient-derived xenografts and apply proteogenomic approaches leveraging genomic, transcriptomic, and proteomic technologies that permit the identification of resistance-specific alterations and therapeutic vulnerabilities. A specific challenge for proteogenomic applications comes at the level of data curation to enable multi-omics data integration. Here, we present a proteogenomic approach that uses custom curated databases to identify unique resistance-specific alternations in melanoma PDX models of acquired MAPK inhibitor resistance. We demonstrate this approach with a NRASQ61L melanoma PDX model from which resistant tumors were developed following treatment with a MEK inhibitor. Our multi-omics strategy addresses current challenges in bioinformatics by leveraging development of custom curated proteogenomics databases derived from individual resistant melanoma that evolves following MEK inhibitor treatment and is scalable to comprehensively characterize acquired MAPK inhibitor resistance across patient-specific models and genomic subtypes of melanoma.
Project description:Metastatic melanoma is either intrinsically resistant or rapidly acquires resistance to targeted therapy treatments, such as MAPK inhibitors. A leading cause of resistance to targeted therapy is a dynamic transition of melanoma cells from a proliferative to a highly invasive state, a phenomenon called phenotype switching. Mechanisms regulating phenotype switching represent potential targets for improving treatment of melanoma patients. Using a drug screen targeting chromatin regulators in patient-derived 3D MAPK inhibitor-resistant melanoma cell cultures, we discovered that PARP inhibitors restore sensitivity to MAPK inhibitors, independent of DNA damage repair pathways. Integrated transcriptomic, proteomic, and epigenomic analyses demonstrated that PARP inhibitors induce lysosomal autophagic cell death, accompanied by enhanced mitochondrial lipid metabolism that ultimately increases antigen presentation and sensitivity to T-cell cytotoxicity. Moreover, transcriptomic and epigenetic rearrangements induced by PARP inhibition reversed EMT-like phenotype switching, which redirected melanoma cells toward a proliferative and MAPK inhibitor-sensitive state. The combination of PARP and MAPK inhibitors synergistically induced cancer cell death both in vitro and in vivo in patient-derived xenograft models. Therefore, this study provides a scientific rationale for treating melanoma patients with PARP inhibitors in combination with MAPK inhibitors to abrogate acquired therapy resistance.
Project description:Rapid resistance to BRAF inhibitors in BRAFV600-mutant metastatic melanoma has produced an urgent need for new treatment options. BRAF inhibitor resistance commonly involves reactivation of mitogen-activated protein kinase (MAPK) signaling and yet inhibition of downstream kinases has not circumvented resistance, partly because MAPK is regulated via a complex network of feedback mechanisms that influence pathway rebound. To examine the transcriptome responses of melanoma cells to MAPK inhibition, a panel of 11 BRAFV600-mutant melanoma cell lines were treated with control (DMSO), 100nM dabrafenib alone (i.e BRAF inhibitor monotherapy) or 100nM dabrafenib + 10nM trametinib (i.e combination BRAF + MEK inhibition) for 24h.
Project description:Recent trials with MAPK inhibitors have shown promising results in many patients with metastatic melanoma; however, nearly all responding patients experience disease relapse. We describe here how melanoma cells respond to MAPK inhibition in a phenotype-specific manner, suggesting that slow cycling invasive phenotype cells provide a treatment-resistant pool from which disease relapse may be derived. The implication is that while MAPK inhibition may successfully treat proliferating cells, another cell population needs to be addressed at the same time. 12 samples
Project description:Sensitive versus Resistant patient-derived colorectal cancer tumor xenografts with PIK3CA mutant against saracatinib (AZD0530) Sensitive versus Resistant patient-derived colorectal cancer tumor xenografts with PIK3CA mutant against saracatinib (AZD0530)
Project description:Focal amplifications of 3p13-3p14 occur in about 10% of melanoma and are associated with poor prognosis. The melanoma-specific oncogene MITF resides at the epicenter of this amplicon1. However, whether other loci present in this amplicon also contribute to melanomagenesis is unknown. Here we show that the recently annotated long non-coding RNA gene LINC01212 is consistently co-gained with MITF. In addition to being amplified, LINC01212 is a target of the lineage-specific transcription factor SOX10 and, consequently, it is expressed in more than 90% of human melanomas, but not in normal adult tissues. Whereas exogenous LINC01212 functions in trans to increase melanoma clonogenic potential LINC01212 knock-down dramatically decreases the viability of melanoma cells irrespective of their transcriptional cell state, BRAF, NRAS or TP53 status, diminishes melanoma growth and increases their sensitivity to MAPK-targeting therapeutics both in vitro and in patient-derived melanoma xenograft mouse models. Mechanistically, LINC01212 functions as a lineage addiction oncogene by interacting with and modulating the cellular localization and function of two proteins, XRN2 and p32, involved in nucleolar and mitochondrial rRNA processing, ribosome biogenesis and protein synthesis. LINC01212 targeting, especially in combination with BRAFV600E-inhibitors, is expected to deliver highly effective and tissue-restricted antimelanoma therapeutic responses. Five GapmeR3 treated and four control treated patient derived xenografts were analysed.
Project description:Metastatic melanoma is either intrinsically resistant or rapidly acquires resistance to targeted drugs such as MAPK inhibitors (MAPKi). Here, using a drug screen targeting chromatin regulators in patient-derived 3D melanoma cell cultures, we discovered that PARP inhibitors are capable of restoring MAPKi sensitivity. This synergy was found to be independent of DNA damage repair pathways and was effective both in vitro and in vivo in patients-derived xenografts. Strikingly, through integrated transcriptomic, proteomic and epigenomic analysis, we discovered that PARPi induces lysosomal autophagy which was accompanied by enhanced mitochondrial lipid metabolism that, ultimately, increased antigen presentation and sensitivity to T-cell cytotoxicity. Moreover, we also found that PARP inhibitors regulated EMT-like phenotype switching by dampening the mesenchymal phenotype via transcriptomic and epigenetic rearrangements. This, in turn, redirected melanoma cells towards a proliferative and, thus, MAPKi-sensitive state. Our study provides a scientific rational for treating patients with PARPi in combination with MAPKi to annihilate acquired therapy resistance.
Project description:One third of BRAF-mutant metastatic melanoma patients treated with combined BRAF and MEK inhibition progress within six months. Treatment options for these patients remain limited. Here we analyse twenty BRAFV600 mutant melanoma metastases derived from 10 patients treated with the combination of debrafenib and trametinib for resistance mechanisms and genetic correlates of response. Resistance mechanisms are identified in 9/11 progressing tumors and MAPK reactivation occurred in 9/10 tumors, commonly via BRAF amplification and mutations activating NRAS and MEK2. Our data confirming that MEK2C125S, but not the synonymous MEK1C121S protein confers resistance to combination therapy, highlight the functional differences between these kinases and the preponderance of MEK2 mutations in combination therapy-resistant melanomas. Exome sequencing did not identify additional progression-specific resistance candidates. Nevertheless, most melanomas carried additional oncogenic mutations at baseline (e.g. RCA1 and AKT3) that activate the MAPK and P13K pathways and are thus predicted to diminish response to MAPK inhibitors. Total RNA obtained from fresh frozen melanoma tumors treated with a combination of dabrafenib and trametinib