Project description:Widespread monoallelic methylation of colorectal cancer associated tumour suppressor genes, including multiple Wnt pathway inhibitors, in Hyperplastic Polyposis Syndrome.
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.
Project description:A hallmark of solid tumours is the development of hypoxic regions where rapidly growing transformed cells outstrip their blood supply. Tumour cells in these starved regions sense reduced levels of oxygen and switch on genes that help them to adapt, survive and continue growing. Since hypoxia is a key physiological difference between normal and cancer tissue, an opportunity exists to selectively kill tumour cells by exploiting the differences in protein expression between normal and hypoxic tumour tissue. However, a major challenge is to identify druggable hypoxia-induced proteins critical for tumour cell survival. This is especially important in cancers of unmet need where hypoxia gene signatures correlate with poor prognosis (for example, colorectal cancers). To identify new hypoxia-induced proteins, we performed SILAC-based proteomics on colorectal cancer cells exposed to normoxia and hypoxia. In this study, we identify a new hypoxia-activated GPCR signalling axis that enables colorectal tumour cells to survive the microenvironmental stress of hypoxia. Our findings uncover a previously unappreciated role for this GPCR-axis as a key regulator of the adaptive response to hypoxia and highlght an opportunity to exploit tumour-associated hypoxia for therapy.