Small Interfering RNA Targeting bcl-2 Sensitizes Malignant Melanoma

Oligonucleotides. 2003;13(5):393-400. doi: 10.1089/154545703322617078.

Abstract

Malignant melanoma is a prime example of a treatment-resistant tumor with poor prognosis. Even with innovative treatment regimens, response rates remain low, and the duration of responses is short. More than 90% of all melanomas express the antiapoptotic protein Bcl-2, shown to contribute to a chemoresistant phenotype in melanoma. We previously demonstrated that antisense-mediated inhibition of Bcl-2 sensitizes malignant melanoma to apoptosis-inducing treatment modalities. In the present study, we evaluated synthetic small interfering RNA (siRNA) compounds targeting Bcl-2 as a novel approach to downregulate Bcl-2 expression in melanoma cells. siRNA treatment led up to a 19-fold reduction of bcl-2 mRNA levels and only barely detectable Bcl-2 protein expression at low nanomolar concentrations. Silencing of Bcl-2 in melanoma cells by specific siRNA led to a moderate increase in apoptotic cell death and inhibition of cell growth. However, if siRNA compounds targeting Bcl-2 were combined with the apoptosis-inducing chemotherapeutic agent cisplatin, a massive increase in apoptotic cell death compared with controls was observed. Notably, the combination of Bcl2 siRNA and low-dose cisplatin resulted in a supra-additive effect, with nearly complete suppression of cell growth, whereas cell growth in cisplatin-only-treated cells was only moderately affected (96% vs. 25%, p < 0.001). These findings underline a key role for Bcl-2 in conferring chemoresistance to melanoma and highlight Bcl-2 siRNA strategies as novel and highly effective tools, with the potential for future targeted therapy of malignant melanoma.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis / genetics
  • Biological Transport
  • Cell Division
  • Cell Line, Tumor
  • Gene Silencing
  • Humans
  • Kinetics
  • Melanoma / genetics*
  • Melanoma / pathology
  • Polymerase Chain Reaction
  • Proto-Oncogene Proteins c-bcl-2 / genetics
  • RNA, Small Interfering / genetics*
  • RNA, Small Interfering / pharmacokinetics

Substances

  • Proto-Oncogene Proteins c-bcl-2
  • RNA, Small Interfering