Effects of up and down-regulation of Cox-2 expression on radiation sensitivity of human esophageal cancer EC9706 xenograft in nude mice / 中华放射医学与防护杂志

ABSTRACT

Objective To explore the effects of up-and down-regulation of Cox-2 expression on the growth and radiation sensitivity of human esophageal cancer EC9706 xenograft in nude mice.Methods Cox-2 specific siRNA and Cox-2 gene eukaryotic expression vector were constructed and transfected to esophageal cancer cells EC9706, and the stable transfected cell lines were obtained by the method of G418 screening.The expressions of Cox-2 mRNA and its protein were detected by RT-PCR and Western blot, respectively.The inhibitory effects of Cox-2 regulation combined with X-ray irradiation on cancer cell growth were detected by the nude mouse xenograft assay.Results Cox-2 gene expression was significantly decreased in the Cox-2 down-regulated group and increased in the Cox-2 up-regulated group.Compared with the control group without gene transfer, the average volumes of EC9706 xenograft tumor in the Cox-2 up-and down-regulated group significantly decreased (F =34.26, P ＜ 0.05) and increased (F =26.38, P ＜ 0.05) , respectively.After 20 Gy X-ray irradiation, the average volume of xenograft was significantly reduced in the Cox-2 down-regulated group (F =16.35, P ＜ 0.05) , but it had no significantly changes in the Cox-2 up-regulated group.Conclusions Down-regulation of Cox-2 expression inhibits the growth of human esophageal cancer EC9706 xenograft in a nude mice and increases cell radiation sensitivity, but upregulation of Cox-2 expression makes tumor cells to become radioresistant.