PRPF19 facilitates colorectal cancer liver metastasis through activation of the Src-YAP1 pathway via K63-linked ubiquitination of MYL9

Distant metastasis is one of the leading causes of cancer-related mortality of colorectal cancer (CRC). Dysregulation of E3 ubiquitin ligases has been implicated in acting vital roles in multiple cancers. In this study, we found that the E3 ubiquitin ligase, PRPF19 was positively correlated with liver metastasis, and predicted a worse clinical outcome in CRC. However, the biological effects and the underlying molecular mechanisms of PRPF19 in CRC remain elusive thus far. We illustrated that PRPF19 promoted the migration and invasion capability of CRC cells in both gain- and loss- of function assays. Mechanistically, we uncovered that myosin light chain 9 (MYL9) was the downstream substrate of PRPF19. PRPF19 enhanced the stability of MYL9 via K63-linked ubiquitination, and promoted the migration and invasion capability of CRC cells in an MYL9-mediated manner. Furthermore, the Src–YAP1 cascade was identified as the downstream effector mechanism by which the PRPF19/MYL9 axis promoted metastasis in CRC. Taken together, our findings highlighted that the PRPF19/MYL9 axis served as a novel mechanism in CRC metastasis, which provided an attractive therapeutic strategy for CRC treatment.