Colon tumour secretopeptidome: Insights into endogenous proteolytic cleavage events in the colon tumour microenvironment

摘要: The secretopeptidome comprises endogenous peptides derived from proteins secreted into the tumour microenvironment through classical and non-classical secretion. This study characterised low-Mr (<3kDa) component of human colon (LIM1215, LIM1863) secretopeptidome, as a first step towards gaining insights extracellular proteolytic cleavage events in microenvironment. Based on two biological replicates, this isolation strategy utilised differential centrifugal ultrafiltration combination with analytical RP-HPLC nanoLC-MS/MS. Secreted were identified using Mascot post-processing analyses including MSPro re-scoring, extended feature sets Percolator, resulting 474 protein identifications 1228 (≤1% q-value, ≤5% PEP) - 36% increase peptide when compared conventional (homology ionscore thresholding). In both models, 122 41 cell surface ectodomains, 23 (12 proteins) regulated intramembrane proteolysis (RIP), 12 (9 generated intracellular domain proteolysis. Further protease/substrate database MEROPS, (http://merops.sanger.ac.uk/), revealed 335 (71%) classified originating classical/non-classical secretion, or membrane. Of these, 42 substrates MEROPS defined protease sites, while further 205 fragmented by hitherto unknown proteases. A salient finding was identification 88 implicated progression angiogenesis (FGFBP1, PLXDC2), cell-cell recognition signalling (DDR1, GPA33), invasiveness metastasis (MACC1, SMAGP); nature proteases responsible for these is unknown. To confirm reproducibility fragment abundance study, we report specific cleaved colon-specific GPA33 antigen 4/14 CRC models. improved characterisation has our understanding proteins, processing membrane RIP. novel site information provides useful detailing associated tumourigenesis environment. article part Special Issue entitled: An Updated Secretome.