RIPK2 promotes colorectal cancer metastasis by protecting YAP degradation from ITCH-mediated ubiquitination.

Colorectal cancer (CRC) is the second leading cause of cancer-related death worldwide, making the exploration of metastatic mechanisms crucial for therapeutic advancements. In this study, we identified receptor-interacting protein kinase 2 (RIPK2) as an independent risk factor for poor CRC prognosis. Single-cell RNA sequencing and spatial transcriptomics revealed that a tumor cell cluster with high RIPK2 expression exhibited enhanced metastatic potential, closely linked to bacterial invasion. In vitro and in vivo experiments confirmed that RIPK2 specifically promotes tumor cell migration and invasion, rather than proliferation. Proteomic analysis indicated that RIPK2 knockdown leads to increased proteolysis mediated by ubiquitin, particularly affecting the oncoprotein YAP. Additionally, bacterial invasion of epithelial cells was significantly suppressed in RIPK2 knockdown cells, suggesting a connection to the NOD2-RIPK2 pathway, stimulated by bacterial muramyl dipeptide (MDP). We demonstrated that MDP levels are significantly higher in CRC tissues compared to adjacent non-cancerous tissues, correlating with RIPK2 activation. This activation triggers K63-linked ubiquitination of RIPK2, essential for NF-κB and MAPK pathway activation. Mechanistic studies identified the E3 ubiquitin ligase ITCH as a critical mediator, balancing K63-linked ubiquitination of RIPK2 and K48-linked ubiquitination of YAP, leading to YAP degradation and suppressed CRC metastasis. The stability of YAP could also be disrupted by GSK583, a pharmacological inhibitor of RIPK2, effectively suppressing CRC metastasis. Our findings provide deep insights into RIPK2's role in CRC progression and present a promising target for future therapeutic strategies.