FBX8 promotes metastatic dormancy of colorectal cancer in liver.

Patients with colorectal cancer (CRC) often develop malignant regrowth of metastatic dormant tumor cells in liver years after primary treatment. FBX8 is involved in suppressing tumor metastasis. Short-term chemotherapy experiments and liver metastasis mice model of orthotopic injection into the cecum were performed to construct the dormant models. GST-pull-down assay, Co-IP and immunofluorescence were used to confirm the bindings among FBX8 and its substrates. FBX8 upregulated the expression of epithelial and stemness markers, while downregulated the expression of mesenchymal and proliferative markers associated with tumor cell dormancy. FBX8 promoted the maintenance of metastatic dormancy of CRC cells. Mechanistically, FBX8 directly bound to HIF-1α, CDK4 and C-myc through its Sec7 domain and led to the ubiquitin degradation of these proteins, thereby inhibiting cell cycle progression, proliferation, angiogenesis, and metastasis. Clinically, FBX8 expression was negatively correlated with the HIF-1α, CDK4, and c-Myc in CRC tissues. Our study reveals a novel mechanism of FBX8 in regulating tumor metastatic dormancy in liver and provides new strategies for the treatment of CRC metastasis.

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