Variants of bcl-2 specific siRNA for silencing antiapoptotic bcl-2 in pancreatic cancer

BACKGROUND AND AIMS: Pancreatic cancer remains a devastating diagnosis with only limited therapeutic options. Specific inhibition of expression of target genes has become possible using small interfering (si) RNAs. We therefore investigated how far siRNA specific for bcl-2 may serve as a therapeutic option for pancreatic cancer in vitro and in vivo. METHODS: siRNAs targeting two different regions in the bcl-2 gene were transfected to YAP C and DAN G pancreatic carcinoma cells and human foreskin fibroblasts. Permutations were generated by changing 3' and 5' overhangs and varying the length of the paired RNA duplex. Transfection efficacy was determined using FITC labelled siRNAs and fluorescence microscopy. Cell survival and apoptosis were quantified at 24-120 hours. Pancreatic cancer xenografts in male nude mice were treated intraperitoneally with siRNAs daily for 24 days. siRNA pharmacokinetics in vivo were assessed using radioactively labelled siRNAs. Total protein and RNA were extracted for western Blot analysis and quantitative polymerase chain reaction. RESULTS AND CONCLUSIONS: Bcl-2 specific siRNAs specifically inhibited expression of the target gene in vitro and in vivo. Antiproliferative and proapoptotic effects were observed in tumour cells but not in fibroblasts or non-malignant tissues. siRNA permutations and diverse overhangs influenced gene silencing efficacy. siRNA was quickly distributed to all organs and excreted via the kidney and liver. Bcl-2 specific siRNA is a promising adjunctive treatment for pancreatic carcinoma.