RNA interference remarkably suppresses bcl-2 gene expression in cancer cells in vitro and in vivo

Abstract

Bcl-2 is an anti-apoptotic protein. If the level of Bcl-2 protein can be reduced sufficiently in tumors using RNA interference (RNAi) to target the gene message, the apoptosis of tumor cells may be promoted. In this study, we synthesized 19 nucleotides (nts) small interference RNA (siRNA) constructs suppressing bcl-2 gene expression in human tumor cells (HeLaB2 and BGC-823 cell lines) in vitro. The bcl-2 gene expression levels were significantly reduced when these siRNA were transfected into experimental two tumor cells for 72 hours. The apoptosis process was also examined in the tumor cells. Here we synthesized siRNA from a DNA template under the control of the RNA polymerase III promoter in transfected tumor cells. Using this DNA vector-based approach, we found that the siRNA efficiently and specifically inhibited the synthesis of protein encoded by the bcl-2 gene in HeLaB2 and BGC-823 tumor cells. Tumor growth was inhibited by 66.5% with 2mg/kg pSilencer 3.1H1-bcl-2 in mouse liver tumor-bearing BALB/c mice. This approach may prove to be a valuable clinical technique for the analysis of specific gene functions and gene therapy of malignant tumors that utilize the bcl-2 gene via RNA interference.

RNA Interference as a Plausible Anticancer Therapeutic Tool

“…A study by Fu et al (2005) demonstrated that siRNA targeting Bcl-2 induced apoptosis in 50% of the cells in vitro and shRNAs against Bcl-2 suppressed tumour growth by 60% in mice with xenograft tumour.…”

RNA interference: A new therapeutic strategy of cancer

“…Their results indicated that silencing of Bcl-2 led to the inhibition of in vivo tumor growth in mice. 13 This provides feasibility for using RNAi as in vivo therapeutic strategy of cancer.…”

“…Furthermore, it is evidenced that human cancer cells preserve RNAi machinery and that chemically synthesized and vector-driven siRNAs can be incorporated into intrinsic RNAi system for silencing target mRNA molecules, which forms reliable basis for using RNAi as therapeutic strategy of cancer. 12 In this issue of Cancer Biology & Therapy, Fu et al 13 described several approaches to achieve downregulation of Bcl-2 protein utilizing RNAi in human tumor cells and in tumor-bearing mouse models. They directly transfected synthesized siRNA targeting bcl-2 into tumor cells such as HeLaB2 and BGC-823 cell line in vitro.…”

“…Collectively, the study of Fu et al 13 in this issue of Cancer Biology & Therapy is an excellent example of the possibility of utilizing RNAi as a new therapeutic strategy of cancer. In fact, combined siRNAs targeting several cancer-associated genes may achieve favourable therapeutic effects.…”

Asymmetric siRNA: New Strategy to Improve Specificity and Reduce Off-Target Gene Expression

“…In recent years, many siRNAs have been investigated for their clinical potential, and some have demonstrated their potential therapeutic value for various diseases, including the infection of human immunodeficiency virus type 1 (HIV-1) (Capodici et al, 2002;Coburn and Cullen, 2002;Novina et al, 2002;Soutschek et al, 2004;Chang et al, 2005;Fu et al, 2005;Kim and Rossi, 2007). One of the main obstacles for the clinical use of siRNA is unintended off-target effects (Castanotto and Rossi, 2009), i.e., the down-regulation or up-regulation of genes other than the target.…”