PT - JOURNAL ARTICLE AU - Kun Ji AU - Bo Wang AU - Yue-ting Shao AU - Ling Zhang AU - Ya-nan Liu AU - Chen Shao AU - Xiao-jie Li AU - Xin Li AU - Jia-di Hu AU - Xue-jian Zhao AU - De-qi Xu AU - Yang Li AU - Lu Cai TI - Synergistic Suppression of Prostatic Cancer Cells by Coexpression of Both <em>Murine Double Minute 2</em> Small Interfering RNA and Wild-Type <em>p53</em> Gene In Vitro and In Vivo AID - 10.1124/jpet.111.180364 DP - 2011 Jul 01 TA - Journal of Pharmacology and Experimental Therapeutics PG - 173--183 VI - 338 IP - 1 4099 - http://jpet.aspetjournals.org/content/338/1/173.short 4100 - http://jpet.aspetjournals.org/content/338/1/173.full SO - J Pharmacol Exp Ther2011 Jul 01; 338 AB - Our objective was to evaluate cell growth and death effects by inhibiting Murine Double Minute 2 (MDM2) expression in human prostate cancer cells overexpressing the wild-type (WT) p53 gene. Prostate PC-3 tumor cells were transfected with a plasmid containing either mdm2 small interfering (Si-mdm2) or the WT p53 gene (Pp53) alone, or both (Pmp53), using Lipofectamine in vitro and attenuated Salmonella enterica serovar Typhi vaccine strain Ty21a (Salmonella Typhi Ty21a) in vivo. Cell growth, apoptosis, and the expression of related genes and proteins were examined in vitro and in vivo by flow cytometry and Western blot assays. We demonstrated that human prostate tumors had increased expression of MDM2 and mutant p53 proteins. Transfection of the PC-3 cells with the Pmp53 plasmid in vitro offered significant inhibition of cell growth and an increase in apoptotic cell death compared with that of the Si-mdm2 or Pp53 group. These effects were associated with up-regulation of p21 and down-regulation of hypoxia-inducible factor 1α expression in Pmp53-transfected cells. To validate the in vitro findings, the nude mice implanted with PC-3 cells were treated with attenuated Salmonella Typhi Ty21a carrying the plasmids, which showed that the Pmp53 plasmid significantly inhibited the tumor growth rate in vivo compared with that of the Si-mdm2 or Pp53 plasmid alone. Tumor tissues from mice treated with the Pmp53 plasmid showed increased expression of p21 and decreased expression of hypoxia-inducible factor 1α proteins, with an increased apoptotic effect. These results suggest that knockdown of mdm2 expression by its specific small interfering RNA with overexpression of the WT p53 gene offers synergistic inhibition of prostate cancer cell growth in vitro and in vivo.