Extracellular vesicles containing oncogenic mutant β-catenin activate Wnt signalling pathway in the recipient cells.

Mutations in beta-catenin, especially at the residues critical for its degradation, render it constitutively active. Here, we show that mutant beta-catenin can be transported via extracellular vesicles (EVs) and activate Wnt signalling pathway in the recipient cells. An integrative proteogenomic analysis identified the presence of mutated beta-catenin in EVs secreted by colorectal cancer (CRC) cells. Follow-up experiments established that EVs released from LIM1215 CRC cells stimulated Wnt signalling pathway in the recipient cells with wild-type beta-catenin. SILAC-based quantitative proteomics analysis confirmed the transfer of mutant beta-catenin to the nucleus of the recipient cells. In vivo tracking of DiR-labelled EVs in mouse implanted with RKO CRC cells revealed its bio-distribution, confirmed the activation of Wnt signalling pathway in tumour cells and increased the tumour burden. Overall, for the first time, this study reveals that EVs can transfer mutant beta-catenin to the recipient cells and promote cancer progression.