SCF‐FBXL8 contributes to liver metastasis and stem‐cell‐like features in colorectal cancer cells by mediating ubiquitination and degradation of TP53

Abstract

Abstract Background FBXL8 is a conserved F‐box protein, belonging to the ubiquitin ligase complex, which promotes the development and progression of tumours. However, the regulation function and mechanism of FBXL8's involvement in colorectal cancer (CRC) remain unclear. Methods RT–PCR is used to detect gene expression levels. Protein levels were determined by western blotting and flow cytometry. The bindings of FBXL8 and p53 and ubiquitination levels were detected by cell transfection and immunoprecipitation. The transwell assay was used to measure the ability of cells to migrate and invade. Animal studies were used to verify the function of FBXL8 in vivo. Results The expression of FBXL8 was up‐regulated in CRC tissues, and its overexpression was associated with poor prognosis in CRC patients. The up‐regulation of FBXL8 promoted the proliferation, invasion and migration of CRC tumour cells and maintained the stem‐cell characteristics of colorectal tumour cells. Further analysis demonstrated that FBXL8 targeted p53 and reduced its stability through ubiquitination. Knockout of FBXL8 down‐regulated the proliferation, migration and stem‐like properties of tumour cells. CRC mouse xenograft tumour model confirmed that FBXL8 gene knockout inhibited tumour formation and liver metastasis. Conclusion FBXL8 was highly expressed in CRC. Mechanism studies have shown that FBXL8 degraded tumour suppressor gene p53 by ubiquitination. FBXL8 knockout inhibited the proliferation and stem characteristics of CRC cells, so SCF‐FBXL8‐TP53 has potential to be used as a therapeutic target for CRC in subsequent studies.

Keywords

• colorectal cancer
• FBXL8
• P53
• stem‐cell
• ubiquitination