Ultrasound Targeted Microbubble Destruction for Novel Dual Targeting of HSP72 and HSC70 in Prostate Cancer

The aim was to determine whether ultrasound targeted microbubble destruction (UTMD) promotes dualtargeting of HSP72 and HSC70 for therapy of castration-resistant prostate cancer (CRPC), to improve thespecific and efficient delivery of siRNA, to induce tumor cell specific apoptosis, and to find new therapeutictargets specific of CRPC.VCaP cells were transfected with siRNA oligonucleotides. HSP70, HSP90 and cleavedcaspase-3 expression were determined by real-time quantitative polymerase chain reaction and Western blotting.Apoptosis and transfection efficiency were assessed by flow cytometry. Cell viability assays were used to evaluatesafety. We found HSP72, HSC70 and HSP90 expression to be absent or weak in normal prostate epithelial cells(RWPE-1), but uniformly strong in prostate cancerous cells (VCaP). UTMD combined with dual targeting ofHSP72 and HSC70 siRNA improve the efficiency of transfection, cell uptake of siRNA, downregulation of HSP70and HSP90 expression in VCaP cells at the mRNA and protein level, and induction of extensive tumor-specificapoptosis. Cell counting kit-8 assays showed decreased cellular viability in the HSP72/HSC70-siRNA silencedgroup. These results suggest that the combination of UTMD with dual targeting HSP70 therapy for PCa maybe most efficacious, providng a novel, reliable, non-invasive, safe targeted approach to improve the specific andefficient delivery of siRNA, and achieve maximal effects.