Hannah L. F. Swa1, Asfa Alli Shaik1, Lina H. K. Lim2 and Jayantha Gunaratne1,3
1 Quantitative Proteomics Group, Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Singapore
2 Department of Physiology and 3 Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
Published in Proteomics on 13 Aug 2014.
Annexin-1 (ANXA1) is known to be involved in important cellular processes and implicated in cancer. Our previous study showed its roles in cell migration and DNA-damage response processes in breast cancer initiation. In order to understand its roles in tumorigenesis, we extended our studies to analyze tumors derived from Polyomavirus Middle T-Antigen (PyMT) ANXA1-heterozygous (ANXA1+/- ) and null (ANXA1-/- ) mice. We performed quantitative comparison of ANXA1+/- and ANXA1-/- tumors employing reductive dimethyl labelling quantitative proteomics. We observed 253 differentially-expressed proteins (DEPs) with high statistical significance among over 5000 quantified proteins. Combinatorial use of pathway and network-based computational analyses of the DEPs revealed that ANXA1 primarily modulates processes related to cytoskeletal remodelling and immune responses in these mammary tumors. Of particular note, ANXA1-/- tumor showed reduced expression of a known epithelial-mesenchymal transition (EMT) marker Vimentin (VIM), as well as myosin light chain kinase (MLCK), which has been reported to induce Rho-kinase mediated assembly of stress fibres known to be implicated in EMT. Integrative network analysis of established interactome of ANXA1 alongside with DEPs further highlights the involvement of ANXA1 in EMT. Functional role of ANXA1 in tumorigenesis was established in invasion assay where knocking down ANXA1 in murine mammary tumor cell line 168FARN showed lower invasive capability. Altogether, this study emphasizes that ANXA1 plays modulating roles contributing to invasion-metastasis in mammary tumorigenesis, distinctive to its roles in cancer initiation.
Comprehensive network mapping of the ANXA1-regulated proteins. Functional interactions among the down-regulated proteins alongside with the downstream interactors of ANXA1 are represented. The reconstructed network combines individual protein-protein interactions obtained from STRING and those pathway-informed interactions obtained from MetaCore. Individual functional clusters identified based on biological process enrichment are shown in the dotted circles. The nodes and edges are differently colored according to the function of protein and type of interactions involved.
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