TRIM25 ubiquitinates IGF2BP3 and inhibits viability of esophageal carcinoma EC109 cells

AIM: To investigate the relationship among tripartite motif-containing protein 25 (TRIM25), insulin-like growth factor 2 mRNA-binding protein 3 (IGF2BP3) and viability of human esophageal carcinoma EC109 cells. METHODS: The EC109 cells were divided into TRIM25 over-expression group, IGF2BP3 over-expression group, TRIM25 knock-down group, and IGF2BP3 knock-down and TRIM25 over-expression group. The viability of EC109 cells was mea-sured by MTT assay and CCK-8 assay. The stability of IGF2BP3 was detected by Western blot. The interaction between TRIM25 and IGF2BP3 was evaluated by immunoprecipitation, and the TRIM25 vector or empty vector was transfected to detect the ubiquitination of IGF2BP3 by immunoprecipitation. RESULTS: Over-expression of TRIM25 inhibited, but over-expression of IGF2BP3 promoted the viability of EC109 cells. However, the viability of the cells with knock-down of IGF2BP3 and over-expression of TRIM25 was lower than that of the cells with knock-down of IGF2BP3 only. Over-expression of TRIM25 resulted in reducing the expression level of IGF2BP3, which was recovered if the cells were treated with MG132, a proteasome inhibitor. When TRIM25 expression was knocked down, the viability of EC109 cells was significantly promoted on days 2, 3 and 4. The interaction between TRIM25 and IGF2BP3 was confirmed. At the same time, over-expression of TRIM25 increased the ubiquitination degree of IGF2BP3 in the EC109 cells. CONCLUSION: TRIM25 ubi-quitinates IGF2BP3, resulting in degradation of IGF2BP3 by proteasomes, thereby inhibiting the viability of esophageal carcinoma cells.