In vivo SILAC-based Proteomics Reveals Phosphoproteome Changes during Skin Carcinogenesis

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Sara Zanivan, Group Leader, Beatson Institute for Cancer Research

Abstract
Mouse models of cancer are a resource of great potential in cancer research and they have provided important insights into tumour biology. We addressed one of the major challenges in cancer proteomics and performed a functional proteomic study to investigate the stepwise development of tumour in vivo. We applied an advanced proteomic workflow employing high resolution mass spectrometry in combination with the SILAC mouse technology to the well-established DMBA-TPA two-stage mouse model of skin carcinogenesis. We profiled the phosphoproteome of i) normal skin, ii) epidermal hyperplasia, iii) pre-malignant lesion and iv) invasive squamous cell carcinoma. The more than 6,000 proteins and 12,000 phosphorylation sites identified recapitulate general alteration in tumour cells, such as cell proliferation and metabolic switch to anaerobic glycolysis, but also specific for cutaneous carcinoma, such as the loss of keratinocyte differentiation. Additionally, our unbiased overview provides clear evidence that distinct parts of the proteome and phosphoproteome are regulated during the different steps of carcinogenesis and identifies the specific deregulated processes. Beyond providing a novel approach to discover molecules and mechanisms in carcinoma development and the first in depth functional portrait of skin carcinogenesis, we illustrate the relevance of this approach to human and validated some of the stage specific candidates in human tumour tissues.