Ultrasound-targeted microbubble destruction combined with dual targeting of HSP72 and HSC70 inhibits HSP90 function and induces extensive tumor-specific apoptosis

Int J Oncol. 2014 Jul;45(1):157-64. doi: 10.3892/ijo.2014.2388. Epub 2014 Apr 14.

Abstract

The specific and efficient delivery of small interfering RNA (siRNA) into cancer cells in vivo remains a major obstacle. In this study, we investigated whether ultrasound-targeted microbubble destruction (UTMD) combined with dual targeting of HSP72 and HSC70 in prostate cancer cell lines improve the specific and efficient cell uptake of siRNA, inhibit HSP90 function and induce extensive tumor-specific apoptosis. VCaP cells were transfected with siRNA oligonucleotides. Cell viability assays were used to evaluate the safety of UTMD. The expression of HSP70, HSP90, caspase-8, caspase-3, PARP-1 and cleaved caspase-3 were determined by quantitative PCR and western blotting. Apoptosis and transfection efficiency were detected by flow cytometry. We found that HSP72, HSC70 and HSP90 expression was absent or weak in normal prostate epithelial cells (RWPE-1), and became uniformly and strongly expressed in prostate cancer cells (VCaP). VCaP and RWPE-1 cells expressed very low levels of caspase-8, caspase-3, PARP-1 and cleaved caspase-3. UTMD combined with dual targeting of HSP72 and HSC70 siRNA impoved the efficiency of transfection, cell uptake of siRNA, downregulated HSP70 and HSP90 expression in VCaP cells on the mRNA and protein levels, and upregulated major apoptotic markers (PARP-1, caspase-8, caspase-3 and cleaved caspase-3), thus, inducing extensive tumor-specific apoptosis. The Cell Counting Kit-8 assay showed decreased cellular viability in the HSP72/HSC70-siRNA silenced group. These results suggest that the combination of UTMD with dual targeting of HSP72 and HSC70 may improve the specific and efficient cell uptake of siRNA, inhibit HSP90 function and induce extensive tumor-specific apoptosis, indicating a novel, potential means for targeting therapeutic strategy to prostate cancer cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis / drug effects
  • Cell Line, Tumor
  • Combined Modality Therapy
  • Gene Expression Regulation, Neoplastic
  • HSC70 Heat-Shock Proteins / antagonists & inhibitors
  • HSC70 Heat-Shock Proteins / metabolism*
  • HSP72 Heat-Shock Proteins / antagonists & inhibitors
  • HSP72 Heat-Shock Proteins / metabolism*
  • HSP90 Heat-Shock Proteins / antagonists & inhibitors
  • HSP90 Heat-Shock Proteins / metabolism*
  • Humans
  • Male
  • Microbubbles
  • Prostatic Neoplasms / diagnostic imaging*
  • Prostatic Neoplasms / pathology*
  • RNA Interference
  • Ultrasonography

Substances

  • HSC70 Heat-Shock Proteins
  • HSP72 Heat-Shock Proteins
  • HSP90 Heat-Shock Proteins
  • HSPA8 protein, human