Antitumor effect of RNA interference on non-small- cell lung cancer in vivo

Objective： Lung cancer has emerged as a leading cause of cancer death in the world. Current therapies are ineffective, thus new approaches are needed to improve the therapeutic ratio. RNA interference （RNAi） has shown promise in gene silencing in vitro, the potential of which in developing new methods for the therapy of non-small-cell lung cancer （NSCLC） needs to be further tested in vivo. In this study, chemically synthesized double-stranded RNA （dsRNA） targeting epidermal growth factor receptor （EGFR） was transfected into NSCLC cell line SPC-A1 cells and established the tumor burdened athymic nude mice model to investigate whether dsRNA could induce gene silencing in NSCLC cells in vivo. Methods： SPC-A1 was transfected with EGFR sequence-specific dsRNA formulated with Lipofectamine 2000. SPC-A1 cells （1 × 107/ mL） in 200 pL were injected s.c. into the left flank area of the mice to establish the tumor burdened athymic nude mice model. Calculate the tumor growth inhibition rate by measuring the diameter and the weight of the tumor. Immunohistochemistry and Westem blot were used to monitor the reduction in the production of the EGFR protein. Realtime RT-PCR was used to detect the silencing of the EGFR mRNA level. Results： It displayed that EGFR sequence specific dsRNA （dsRNA-EGFR） significantly inhibited the tumor growth in vivo. The tumor growth inhibition rate was 75.03%. The dsRNA-EGFR sequence specifically silenced EGFR with 53.6% of down-regulation of EGFR protein production and 32.3% of silencing of EGFR mRNA level. Conclusion： DsRNA-EGFR showed a blockbuster effect in downregulation of EGFR mRNA level and protein production, and inhibition of tumor growth in vivo.