Quantitative proteomic and cell biological analysis of TGF driven tumour promotion in melanoma and squamous cell cancers

We have recently discovered that mutant BRAFV600E confers an intrinsic dependence on TGF/TGF type 1 receptor (TGFBR1) signalling for clonogenicity, anchorage independent growth and cell proliferation under stress conditions of human melanoma cells in vitro, for tumour growth in-vivo and metastasis in xenografted zebrafish. Importantly, vemurafenib-resistant patient derived melanoma cells retained sensitivity to TGFBR1 inhibition, suggesting that TGFBR1 could be targeted therapeutically to combat the development of vemurafenib drug-resistance (1). We have also recently demonstrated that mutational inactivation of TGF receptors in skin stem cells can drive cutaneous squamous cell cancer (cSCC) formation (2). Analysis of primary human cSCC, head and neck SCC and oesophageal SCC cell lines surprisingly reveals that TGFR1 signalling can also promote clonogenicity, proliferation and cell migration independently of activation of canonical SMAD signalling. Our data in both melanoma and SCC indicates that the TGFR1 kinase can regulate yet to be identified substrates that can promote disease progression. We will seek to identify these substrates using state of the art quantitative proteomics (3) coupled with transcriptomics. Novel candidate mediators of tumour progression will be interrogated for biological activity using real-time imaging, cell biological and biochemical assays coupled with interrogation of primary human tumour material. These studies will identify novel mediators of TGF signalling, biomarkers for the use of TGF targeted therapeutics and new targets for therapeutic intervention.