| dc.description.abstract | Centrosome amplification is associated with worse cancer prognosis, and it was found to induce spontaneous tumorigenesis and invasion contributing to malignant progression. Pancreatic Ductal Adenocarcinoma (PDAC) tumours which are characterised by extensive fibrous stromal compartments often harbour cells with extra centrosomes, however it is not well understood how cells with centrosome amplification contribute to tumour progression. Here we found that PDAC cells with extra centrosomes secrete increased numbers of small extracellular vesicles (SEVs), but not large extracellular vesicles. The secreted SEVs were readily internalised by pancreatic stellate cells (PSCs) which are key stromal mediators in PDAC. Furthermore, upon uptake, SEVs induced a myofibroblastic-like activation in a subset of PSCs, and this phenotypic change is characterised by increased α-SMA fibre formation, and extracellular matrix protein expression such as collagens and fibronectin. Although this phenotype is similar to the phenotype of TGF-β treated PSCs, we did not detect TGF-β in the activating SEVs through proteomic analysis, nor did we observe the canonical downstream effector SMAD2 enriched in the nucleus of PSCs. This suggests that PSC activation through SEVs from cells with extra centrosomes is not directly reliant on the canonical TGF-β pathway. However, we identified three candidate activating proteins within SEVs through proteomic analysis and siRNA silencing experiments that were not previously implicated in the activation of stellate cells. Furthermore, through RNA sequencing we investigated the phenotypic changes within the PSC population treated with SEVs on a single cell level. We propose that an alternative cellular signalling cascade is mediating the activation of stellate cells by SEVs, which we intend to further dissect in the future. In summary, cells with extra centrosomes contribute to the tumour-stromal crosstalk in PDAC through the increased secretion of SEVs, with biologically distinct cargoes. | en_US |
