PO-271 Rise of the machines: probing intercellular crosstalk with mass spectrometry

Abstract

IntroductionThe whole of signalling consequences in the tumour micro-environment tremendously exceeds the sum of its parts. Complex responses orchestrated by different cell types, and in response to each other, are also thought to be a major driver of chemo-resistance. Signalling in the tissue milieu could require secreted factors, physical contacts between cells, or interactions with structural components in the extracellular matrix, all of which are difficult to study with classical methods in cell biology.Material and methodsHere we apply cutting-edge mass spectrometry (MS) techniques to interrogate extracellular signalling events, and mine for key mediators of intercellular crosstalk. Using a panel of >10 breast fibroblast and cancer cell lines, we profiled secretions (and vesicles), extracellular matrix deposition and plasma membrane components, with diverse preparative and analytical methodologies. Using a membrane crosslinking approach, we provide, in addition, structural information on plasma membrane docking sites that potentially mediate contact-dependent signalling between cells.Results and discussionsWe report a novel pair of cancer-associated fibroblast activators of (breast) tumour origin, and show that (phospho)protein contents of extracellular vesicles clearly distinguish triple negative and Her2-positive breast cancers with diagnostic significance. In addition, we observe differential deposition of extracellular matrix between different breast cancer subtypes, in combination with a plethora of associated post-translational modifications on matrix components. Collectively, these data indicate that breast cancer cells invest specifically and heavily in modifying the extracellular environment, and imply that some of these processes could be drug-able for improved treatment response.ConclusionWe describe here a complementary and transferrable MS-based tool package to study tumour micro-environmental crosstalk. Given the extreme sensitivity and hypothesis-free nature of MS identifications, novel mediators of intercellular signalling identified in this manner are expected to fuel further investigations in uncharted territories of the tumour micro-environment.