Project description:Widespread monoallelic methylation of colorectal cancer associated tumour suppressor genes, including multiple Wnt pathway inhibitors, in Hyperplastic Polyposis Syndrome.
Project description:Cancers harbouring loss-of-function (LOF) alterations in tumour suppressor genes lack targeted therapies, thus alternative means to characterise gene function and identify vulnerabilities in these cancer cells are required. Here, we map the in silico genetic networks of KMT2D, a frequently mutated tumour suppressor gene, to demonstrate its utility in uncovering novel functional associations and vulnerabilities in cancer cells with tumour suppressor gene LOF alterations. In silico KMT2D networks revealed associated with histone modification, DNA replication, metabolism, and immune response. We identified synthetic lethal (SL) candidates encoding exising therapeutic targets. Analysing patient data from The Cancer Genome Atlas (TCGA) and the Personalized OncoGenomics Project (NCT021556210), we showed dysregulated pathways associated with SL candidates and elevated immune checkpoint response markers in KMT2DLOF cases, bringing forth evidence supporting KMT2D as a biomarker for immune checkpoint inhibitors. Our study presents a framework for identifying targetable vulnerabilities in cancers with tumour suppressor gene alterations.
Project description:LMTK3 is an oncogenic receptor tyrosine kinase (RTK) implicated in various types of cancer including breast, lung, gastric and colorectal. It is localized in different cellular compartments but its nuclear function has not been investigated thus far. We have mapped LMTK3 binding across the genome using ChIP-seq and found that LMTK3 binding events are correlated with repressive chromatin markers. We further identified KRAB associated protein-1 (KAP1) as a binding partner of LMTK3. The LMTK3/KAP1 interaction is stabilized by PP1α, which suppresses KAP1 phosphorylation specifically at LMTK3-associated chromatin regions, inducing chromatin condensation and resulting in transcriptional repression of LMTK3-bound tumour suppressor-like genes. Furthermore, LMTK3 functions at enhancer regions in tethering the chromatin to the nuclear periphery, resulting in H3K9me3 modification and gene silencing. In summary, we propose a model where a scaffolding function of nuclear LMTK3 promotes cancer progression through chromatin remodeling, revealing a previously undescribed mechanism of RTK activity.