RAB22A triggers intercellular chemoresistance transmission in colorectal cancer by promoting exosome release via the PKM2-pSNAP23 axis.

Abstract

Chemoresistance is not only related to tumor cells themselves, but also regulated by the interaction between cells in the tumor microenvironment (TME). However, the underlying mechanisms are not well understood. RAB22A, a member of the RAB family of small GTPases that was identified by our group previously as an oncogene in colorectal cancer (CRC). In this study, we demonstrated that elevated expression of RAB22A in CRC cells, particularly in chemoresistant CRC cells, is associated with increased exosome secretion and enhanced chemoresistance. Mechanistically, RAB22A augments exosome secretion by inhibiting the ubiquitination and degradation of pyruvate kinase type M2 (PKM2), then promoting the phosphorylation of synaptosome-associated protein 23 (SNAP-23). Furthermore, RAB22A not only directly promotes chemoresistance in CRC cells but also indirectly induces acquired drug resistance of other CRC cells in the TME by promoting the secretion of RAB22A-PKM2-rich exosomes, thereby triggering intercellular chemoresistance transmission. Together, we reveal an essential role of RAB22A-PKM2-SNAP-23 signaling cascade in exosome induction in chemoresistant CRC cells and intercellular chemoresistance transmission, highlighting that targeting the RAB22A/PKM2/pSNAP axis is a potential novel strategy to reverse chemoresistance, and suggest circulating exosomal RAB22A and PKM2 as markers to predict the efficacy of chemotherapy in CRC.