Effect of different expression levels of USP28 on apoptosis and related protein expression in esophageal cancer cell ECA109 after irradiation / 中华放射肿瘤学杂志

ABSTRACT

Objective@#To observe the effect of different expression levels of USP28 on the radiosensitivity of ECA109 cells by gene transfection method, aiming to provide theoretical basis for comprehensive treatment of esophageal cancer.@*Methods@#The expression levels of USP28 and c-Myc in the esophageal epithelial cells Het-1A, ECA109 and ECA109R were quantitatively measured by qRT-PCR. The specific siRNA sequences were designed according to the USP28 and c-Myc genes. The pcDNA-USP28 and pcDNA-c-Myc plasmids were constructed. The esophageal cancer cell ECA109 was transfected with Lipofectamine 2000 to observe the transfection effect and related protein expression. ECA109 and ECA109R cells were exposed to 6 Gy X-ray radiation. The cell apoptosis in each group was detected by flow cytometry. The radiosensitivity was evaluated by clone formation assay.@*Results@#The expression levels of USP28 and c-Myc in ECA109 were significantly higher than those in Het-1A (both P<0.05), and the expression levels of USP28 and c-Myc in ECA109R were remarkably higher than those in ECA109(both P<0.05). The pcDNA-USP28 and pcDNA-c-Myc recombinant plasmids were successfully constructed. Compared with the negative control group, the expression of USP28 at the protein and mRNA levels in the si-USP28 group was significantly down-regulated, whereas those in the pcDNA-USP28 group were remarkably up-regulated. Similar results were obtained in terms of c-Myc. Compared with the control group, the expression level of c-Myc protein was significantly up-regulated in the pcDNA-USP28 group, whereas considerably down-regulated in the si-USP28 group. After 6 Gy irradiation, the apoptosis rate and radiosensitivity of ECA109 cells were significantly declined. The apoptosis rate and radiosensitivity of ECA109R cells were increased in the si-USP28 group.@*Conclusions@#The expression of USP28 protein is closely correlated with the radiosensitivity of esophageal cancer cells. The underlying mechanism may be related to the regulation of c-Myc expression by USP28.