RESUMO
The miR-34 family plays an important role in gastric cancer, and the inactivation or reduced expression of the miR-34 family is detected in gastric cancer cell lines and gastric cancer tissues compared with normal gastric mucosa tissues, indicating it is associated with the occurrence and development of gastric cancer. Studies have shown that miR-34 plays a key role in inhibiting gastric cancer progression by regulating IGF2BP3, survivin, Bcl-2 and epithelial-mesenchymal transition-related pathway, indicating that miR-34 is an important target for gastric cancer treatment. In terms of clinical treatment, miR-34 has not only been proved to have radiochemotherapy sensitization, but also achieved good curative effect in tumor clinical trials. With the emergence of miR-34 vectors targeting gastric cancer, it is possible to use it for gastric cancer treatment. Deep understanding of the molecular basis and clinical efficacy of miR-34 for gastric cancer treatment can help to evaluate the potential of the miR-34 family as a new therapeutic target for gastric cancer.
RESUMO
Objective:To investigate the effects of programmed death-ligand 1 (PD-L1) expression on the biological behaviors of gastric cancer cell line MKN45.Methods:The PD-L1 gene of gastric cancer cell line MKN45 was silenced by RNA interference technique. MKN45 cells were divided into blank control group, si-NC group (transfected with siRNA-NC) and si-PD-L1 group (transfected with siRNA-PD-L1). Quantitative real-time PCR was used to detect the mRNA expressions of PD-L1 and epithelial-mesenchymal transformation (EMT)-related proteins E-cadherin, Vimentin and Snail in MKN45 cells, and Western blotting was used to detect the expression levels of PD-L1 protein in MKN45 cells of each group. Transwell migration test, Transwell invasion test and MTT test were used to detect the migration, invasion and adhesion abilities of MKN45 cells.Results:The relative expression levels of PD-L1 mRNA in the blank control group, si-NC group and si-PD-L1 group were 1.002±0.092, 1.005±0.121 and 0.237±0.017, respectively, with a statistically significant difference ( F=75.61, P<0.001). The protein expression levels of PD-L1 in the three groups were 0.944±0.028, 1.008±0.088 and 0.269±0.015, respectively, with a statistically significant difference ( F=172.99, P<0.001). The mRNA and protein expression levels of PD-L1 in the si-PD-L1 group were lower than those in the other two groups (all P<0.001), but there were no statistically significant differences between the blank control group and si-NC group (all P>0.05). The cell migration rates of the blank control group, si-NC group and si-PD-L1 group were (1.000±0.020)%, (1.012±0.084)% and (0.488±0.050)%, respectively, with a statistically significant difference ( F=80.73, P<0.001). The cell invasion rates of the three groups were (0.929±0.087)%, (0.924±0.208)% and (0.300±0.100)%, respectively, with a statistically significant difference ( F=19.37, P<0.001), and the cell adhesion rates of the three groups were (100.000±5.407)%, (99.280±4.845)% and (59.723±2.674)%, respectively, with a statistically significant difference ( F=79.87, P<0.001). Compared with the blank control group and si-NC group, the migration, invasion and adhesion abilities of MKN45 cells in the si-PD-L1 group decreased significantly (all P<0.001). The expression levels of E-cadherin mRNA of the three groups were 1.000±0.023, 0.981±0.051, 3.618±0.201, the expression levels of Vimentin mRNA were 1.000±0.043, 1.108±0.150, 0.328±0.011, the expression levels of Snail mRNA were 1.061±0.103, 1.090±0.110, 0.304±0.043, respectively, with statistically significant differences ( F=477.17, P<0.001; F=65.97, P<0.001; F=72.70, P<0.001). Compared with the blank control group and si-NC group, the mRNA expression levels of Vimentin and Snail of MKN45 cells in the si-PD-L1 group decreased, while the expression level of E-cadherin mRNA increased, with statistically significant differences (all P<0.001). Conclusion:Silencing the expression of PD-L1 can reduce the migration, invasion and adhesion abilities of MKN45 cells, and the mechanism may be related to the effect of PD-L1 on the EMT pathway of gastric cancer.
