Synergistic Suppression of Prostatic Cancer Cells by Coexpression of BothMurine Double Minute 2Small Interfering RNA and Wild-Typep53Gene In Vitro and In Vivo

Abstract

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 1␣ 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 1␣ 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.

Tumor suppressor gene RBM5 delivered by attenuated Salmonella inhibits lung adenocarcinoma through diverse apoptotic signaling pathways

“…Typhimurium, which could selectively target tumors and deliver the therapeutic agents into tumors while reducing the damage to normal tissue [23,33,34]. More recently, these bacteria have been engineered to express numerous genes, including survivin [35], MDM2 [36], Neu3 [37] and STAT3 siRNA [25] against prostate cancer in our laboratory. So this time, we first employed the attenuated S. enterica ser.…”

Knockdown of HIF-1α by siRNA-expressing plasmid delivered by attenuated Salmonella enhances the antitumor effects of cisplatin on prostate cancer

“…The transfection reagent used was Lipofectamine 2000 (Invitrogen, CA, USA). Approximately 6 × 10 3 cells per well were transfected with the plasmids with or without DDP for 48 h, then cell viability was determined by (3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT, Sigma-Aldrich) assay following standard protocols as previously described 25 .…”

“…Genetically attenuated bacteria such as attenuated Salmonella offers promise as an anticancer vector and has been widely used as a tool to deliver plasmids that express siRNA in vivo 16–21 . Our previous studies have demonstrated that a combination of low-dose DDP with gene therapy expressing tumor protein p53 (p53) and mouse double minute 2 homolog (MDM2) siRNA, delivered by attenuated Salmonella enterica serovar Typhi vaccine strain Ty21a ( Salmonella Typhi Ty21a ), synergistically inhibited ovarian cancer and PCa growth without damaging normal tissues 22–25 . Here, we tested our hypothesis that knockdown of HIF-1α by siRNA gene therapy delivered by the attenuated Salmonella Typhi Ty21a is a promising strategy to increase the sensitivity of PCa to DDP from the perspective of targeting cancer-specific metabolism.…”

Exposure to low dose cadmium enhances FL83B cells proliferation through down-regulation of caspase-8 by DNA hypermethylation

“…[26][27][28] Statistical analysis After washing with PBS, the samples were TUNEL stained according to the manufacturer's instructions (Promega).…”