Human Runt related transcription factor 3 suppresses the metastasis of salivary adenoid cystic carcinoma through transcriptional inhibition of epithelial-mesenchymal transition

Objective To investigate the effect of expression of human Runt related transcription factor 3 (RUNX3) on epithelial mesenchymal transition (EMT) in adenoid cystic carcinoma cells. Methods Lentivirus vector was transfected into MDA-MB-231 cells to obtain the RUNX3-overexpressed cell line (RUNX3 overexpression group), and the cell line with blank lentivirus vector infection served as negative control group. After the wild-type RUNX3 was overexpressed in SACC-83 and SACC-LM cells, RUNX3 protein was detected by Western blotting, and the effect of RUNX3 on the expression of E-cadherin, Vimentin, N-cadherin, Fibronectin and Snail at mRNA and protein levels was investigated using Western blotting and real-time quantitative reverse transcriptase-polymerase chain reaction (RT-qPCR) analysis respectively. Matrix metalloproteinase (MMP)-2 and MMP-9 proteins were also detected by Western blotting. The effect of RUNX3 on the migration of SACC cells was measured by cell scratch assay. Results After SACC-83 and SACC-LM cells were treated with lentivirus-RUNX3, the expression of RUNX3 protein [(0.968±0.035) and (0.956±0.037)] was significantly up-regulated as compared with negative control group [(0.425±0.031) and (0.196±0.028)] with the difference being statistically significant (P=0.002 and P=0.000). The mRNA expression levels of Vimentin, Fibronectin and Snail decreased from 34.2% to 61.9%, and the protein expression decreased from 31.8% to 71.8%. However, the expression levels of E-cadherin mRNA and protein in SACC-83 cells were up-regulated 2.671 fold and 2.237 fold respectively. The expression levels of E-cadherin mRNA and protein in SACC-LM cells were up-regulated 3.687 fold and 5.454 fold respectively as compared with negative control group. MMP-2 and MMP-9 protein expression levels were significantly down-regulated by RUNX3 overexpression (P=0. 005 and P=0.004). The migration of SACC-83 and SACC-LM cells was significantly inhibited by RUNX3 overexpression. Conclusion RUNX3 suppresses the invasion and metastasis of SACC cells through transcriptional inhibition of EMT, which is one of the possible mechanisms of RUNX3 in the adenoid cystic carcinoma. Key words: Salivary adenoid cystic carcinoma; Runt related transcription factor 3; Epithelial-mesenchymal transition; Metastasis