Effects of Leptin gene down-regulation by RNA interference on xenograft of human lung adenocarcinoma A549 cell line in nude mice

Objective To investigate the inhibitory effect of Leptin gene in vivo silencing by RNA interference on xenograft of human lung adenocarcinoma A549 cell line in nude mice. Methods The Leptin gene and plasmid carrying siRNA were transfected into A549 cells by lentivirus.Three different BALB/C nude mice models were established through subcutaneous injection of A549 cells into three nude mice groups: the blank group was inculated with blank A549 cells, while the negative group was inoculated with cells transfected with empty plasmid, the RNA inteference group was inoculated with cells transfected with Leptin-siRNA.The growth of tumors was observed, and the volume and weight of the tumors were measured at different time points.The curve of tumor growth was described, and the inhibition rate was calculated.Leptin gene expression in tumor tissues was determined by inmunohistochemistry and Western blot.Cell apoptosis of tumor was detected by terminal-deoxynucle oitidyl tramsferase mediated nick end labeling. Results Smaller volume and lighter tumor weight were observed in the interference group compared to the blank and negative groups (F=9.118, 9.121, both P<0.05). The inhibition rate of tumor volume was (59.3±3.1) %, and the inhibition rate of tumor weight was (64.5±4.8) %.Leptin protein expression level was also significantly lower than the blank and negative groups (F=13.784, P<0.05). The apoptosis rate in the interference group was higher than in the blank and negtive groups [(47.3±4.1) %, (5.6±1.5), (7.2±2.8) %, F=14.537, P<0.05]. Conclusions Silencing the expression of Leptin gene can inhibit the growth of subcutaneous xenograft tumor effectively.It is expected that Leptin gene would be a new target for gene therapy in lung adenocarcinoma. Key words: Leptin; RNA interference; A549 cells; Transplantation tumor