Effects of down-regulateUBE2T on proliferation, apoptosis and epithelial-mesenchymal transitionof breast cancer cells

Objective To investigate the expression of ubiquitin binding enzyme E2T (UBE2T) in breast cancer (BRCA) and its role and mechanism in proliferation, migration, invasion and apoptosis of BRCA cells. Methods The Tumor Genome Atlas (TCGA) database was used to analyze UBE2T expression in BRCA tissues, and the effects of UBE2T expression on disease-free survival (DFS) and overall survival (OS) were analyzed by Kaplan-Meier survival curve. In vitro, MCF-7, BT-474 and MDA-MB-231 BRCA cell lines were subjected to shRNA to down-regulat UBE2T. Real-time quantitative PCR and Western blot were used to confirm the knock-down efficiency, and the effects of UBE2T on tumor cell proliferation, apoptosis, migration and invasion were analyzed. The effect of UBE2T on cell epithelial-mesenchymal transition (EMT) was studied by Western blot. A xenograft tumor model was established to verify the effect of UBE2T knockdown on the growth of BRCA cells in vivo. Results The results of bioinformatics analysis showed that UBE2T expression level in breast cancer tissues and adjacent tissues was statistically different (P<0.001), and the expression was increased in tissues with distant metastasis or late stage (all P<0.05). The results of KM curve indicated that DFS and OS were decreased in UBE2T high level group (both P<0.05). Western blot confirmed that UBE2T was highly expressed in MCF-7, BT-474 and MDA-MB-231 cells (all P<0.01). After UBE2T silenced by shRNA, the proliferation ability of tumor cells was significantly decreased (all P<0.05). Flow cytometry showed that the apoptosis rates of MCF-7, BT-474 and MDA-MB-231 cells in the silent groups were significantly higher than shNC groups (all P<0.001). The results of scratch test indicated that the mobility of MCF-7 and BT-474 cells in knockdown groups were significantly lower than that shNC groups (both P<0.01). Transwell results showed that the migration cells and invasion cells of MCF-7, BT-474 and MDA-MB-231 in shUBE2T groups were all lower than those in shNC groups (all P<0.01). In addition, down-regulation of UBE2T decreased the expression of EMT-related proteins N-cadherin, Snail and Vimentin (all P<0.05), and increased E-cadherin (all P<0.01). However, the TIMER results showed that UBE2T was positively correlated with E-cadherin (P<0.001), N-cadherin (P=0.013) and Snail (P<0.001), and negatively correlated with Vimentin (P<0.001). In vivo experiments showed that down-regulation UBE2T slowed down the growth of transplanted tumors. Conclusion UBE2T is highly expressed in BRCA tissues and may affect the prognosis. Silencing UBE2T can inhibit the proliferation and induce apoptosis of BRCA cells, and reduce the migration and invasion ability by altering the expression of EMT-related proteins.