Project description:Somatic mutations in various epigenetic regulators, including histone methyltransferases KMT2C and KMT2D, have emerged as important cancer-driving events. However, the mechanism of action and therapeutic vulnerability imparted by these mutations remain poorly understood. We identified KMT2D and 8 other epigenetic regulators as potential suppressors to melanoma initiation through an in vivo pooled epigenome-focused RNAi screen. Loss of KMT2D, which exhibits somatic mutations in human melanoma and other cancers, drastically enhanced melanoma progression in xenograft models and a BRAFV600E-driven genetically engineered mouse model of melanoma. Epigenome profiling of 6 histone marks and chromatin state alterations showed substantial reprogramming of H3K4me1- and H3K27ac-marked active enhancer states in KMT2D mutant tumors. Energy metabolic pathways such as glycolysis, OxPhos and TCA/electron transport showed high degree of deregulation which was confirmed with metabolic profiling. Pharmacological abrogation of glycolysis led to reduced proliferation and tumorigenesis preferentially in KMT2D mutant cells. Mechanistically, we find that enhancer loss at IGFBPs increases IGF signaling and downstream AKT phosphorylation that leads to upregulation of metabolic pathways rendering KMT2D mutant cells dependent on these energy metabolism pathways for their higher growth potential. Overall, we present evidence that KMT2D mutations promote tumorigenesis by reprogramming energy metabolism pathways through enhancer reprogramming.
Project description:Somatic mutations in various epigenetic regulators, including histone methyltransferases KMT2C and KMT2D, have emerged as important cancer-driving events. However, the mechanism of action and therapeutic vulnerability imparted by these mutations remain poorly understood. We identified KMT2D and 8 other epigenetic regulators as potential suppressors to melanoma initiation through an in vivo pooled epigenome-focused RNAi screen. Loss of KMT2D, which exhibits somatic mutations in human melanoma and other cancers, drastically enhanced melanoma progression in xenograft models and a BRAFV600E-driven genetically engineered mouse model of melanoma. Epigenome profiling of 6 histone marks and chromatin state alterations showed substantial reprogramming of H3K4me1- and H3K27ac-marked active enhancer states in KMT2D mutant tumors. Energy metabolic pathways such as glycolysis, OxPhos and TCA/electron transport showed high degree of deregulation which was confirmed with metabolic profiling. Pharmacological abrogation of glycolysis led to reduced proliferation and tumorigenesis preferentially in KMT2D mutant cells. Mechanistically, we find that enhancer loss at IGFBPs increases IGF signaling and downstream AKT phosphorylation that leads to upregulation of metabolic pathways rendering KMT2D mutant cells dependent on these energy metabolism pathways for their higher growth potential. Overall, we present evidence that KMT2D mutations promote tumorigenesis by reprogramming energy metabolism pathways through enhancer reprogramming.
Project description:Purpose: Study of the mechanism trough which KTM2D regulates chromatin modification and transcription in a xenograft model of human metatstatic melanoma Methods: We generated patient derived xenografts (PDXs) from metastatic melanoma (MM) biopsies of three different patients. The MMs carry NRASQ61L, NRASQ61Q or BRAFV600 mutations. Cells from secondary PDX (PDX2) were transduced with lentiviral vectors carrying Luciferase (shLuc) and KMT2D (shKMT2D) hairpins and mRNA profiles and genome-wide chromatin-state maps were generated by deep sequencing using Illumina HiSeq2000. Results: we found that KMT2D regulates the activity of a subset of enhancers required for expression of specific genes.
Project description:Transcriptomics and phosphoproteomics were carried out in B6.Cg-Mapttm1(EGFP)Klt (mapt knockout: tau-KO) and wild-type (WT) 12-month-old mice to learn about the effects of tau ablation.