[CD133 promotes the invasion and metastasis of gastric cancer via epithelial-mesenchymal transition].

Objective To examine the association between CD133 expression and invasion of gastric cancer,and to elucidate whether CD133 can promote the invasion and metastasis of gastric cancer via epithelial-mesenchymal transition (EMT).Methods The CD133+ and CD133-KATO-Ⅲ cells were sorted by magnetic activated cell sorting (MACS).The invasion ability was detected by Transwell method.RT-PCR and Western blot were used to detect the expression of EMT-related factors in KATO-Ⅲ cells before and after CD133 was knocked out by siRNA method.The expressions of CD133 and EMT-related proteins of cancer and adjacent normal tissues in 50 patients with gastric cancer were detected by Western blot,and correlations among protein expressions were also analyzed.Results As compared to CD133-cells,the number of broken-membrane cells was significantly higher (67.7±10.5 vs.13.3±6.8,P=0.001) and the invasion ability was stronger (P＜0.05) in CD133+ cells,while the mRNA expression levels of Snail and N-cadherin were significantly higher in CD133+ cells (0.311±0.015 vs.0.223±0.016,P=0.040; 0.581±0.020 vs.0.270 ±0.018,P=0.004),and the protein expression levels of Snail and N-cadherin were significantly higher in CD133+ cells as well (0.513±0.015 vs.0.179±0.023,P=0.030; 0.538±0.028 vs.0.202±0.032,P=0.020),but E-cadherin mRNA and protein levels were significantly lower in CD133+ cells (0.231±0.009 vs.0.460±0.015,P=0.040; 0.426±0.030 vs.0.748±0.027,P=0.040).After CD133 knock-out,the expressions of Snail and N-cadherin were down-regulated (P＜0.05) and the expression of E-cadherin was up-regulated (P＜0.05).As compared to normal mucosal tissues,the protein expression levels of Snail,N-cadherin and CD133 in gastric cancer tissues were significantly higher (0.635±0.119 vs.0.485±0.116,P=0.029; 0.599±0.114 vs.0.259±0.108,P=0.020;0.754±0.154 vs.0.329±0.134,P=0.001),while the protein expression of E-cadherin in gastric cancer tissues was lower (0.378±0.123 vs.0.752±0.156,P=0.003).The protein expressions of Snail and N-cadherin were positively correlated with CD133 expression (r=0.278,P=0.048 ; r=0.406,P=0.003) and the protein expression of E-cadherin was negatively correlated with CD133 expression(r=-0.504,P=0.000).Conclusion CD133 + cells in primary lesion of gastric cancer have relatively higher invasion ability,which may promote the metastasis of gastric cancer via up-regulation of EMT-related factors. Key words: Stomach neoplasms;  CD133;  Epithelial-mesenchymal transition;  Invasion; Metastasis