O209: Stress-induced extracellular vesicles promote EGFR-ERK dependent growth and cetuximab resistance in colorectal cancer

Abstract

Abstract Introduction Extracellular vesicles (EVs) are nanoized vesicles, which deliver bioactive cargoes to target cells. Our lab has shown that metabolic stress leads to changes in the trafficking and also the cargo and functions of EVs secreted from colorectal cancer (CRC) cells: a so-called “EV switch”. Proteomic analysis revealed that switched EVs carry increased levels of the EGFR-ligand Amphiregulin (AREG). The aim of this work was to investigate the pro-tumorigenic properties of switched EVs in vitro and in vivo. Methods Size exclusion chromatography was used to isolate EVs from HCT116 and Caco-2 CRC cells grown under glutamine-replete and -depleted conditions, and their effect on recipient cell growth measured using the IncuCyte Live Cell Imager. Co-incubation assays with an AREG-neutralising antibody were undertaken to test the role of switched EVs. The in vivo role of switched EVs were investigated using a novel chick embryo model. In addition, we tested whether the growth inhibitory effects of cetuximab could be reversed by co-treatment with switched EVs. Results Switched EVs from HCT116 and Caco-2 cells contain increased levels of AREG and promote EGFR-ERK dependent growth in recipient cells in vitro and in vivo. These effects were inhibited by co-treatment with an AREG neutralising antibody. Caco-2 (KRAS-wild type), but not HCT116 (KRAS-mutant), cell growth was inhibited by cetuximab, which was partially reversed by co-treatment with switched EVs. AREG neutralisation reversed this EV-induced cetuximab rescue. Conclusion Switched EVs mediate CRC cell growth and cetuximab resistance, and could serve as novel biomarkers to predict treatment response.