Aim: To explore the possibility of RNA interference (RNAi)-based gene therapy against HER2-overexpressing tumors using adenovirus-mediated vector.
Methods: A plasmid named pHER2-GFP containing HER2 and green fluorescent protein (GFP) fusion was constructed and cotransfected into CHO-K1 cells respectively with nine small interference RNA (siRNA)-expressing plasmids targeting different regions of HER2. The siRNA-expressing plasmids with best interference effect were screened out and then used to identify the gene silence effect in HER2-overexpressing SKBR3 breast cancer cells. Subsequently, the siRNA-expressing cassettes were subcloned into adenoviral vectors. Downregulation of HER2 by adenovirus-mediated RNAi and its effect on SKBR3 cell proliferation were identified again.
Results: Two siRNA-expressing plasmids with best interference effect were screened out and HER2 was also efficiently downregulated in SKBR3 cells infected with the adenovirus containing these siRNA-expressing cassettes. Downregulation of HER2 resulted in the increase of cells in G1 phase and the induction of apoptosis. Furthermore, infection of adenovirus inhibited SKBR3 cell growth, which was confirmed by MTT and cell long-term proliferation assays.
Conclusion: The adenovirus-mediated RNAi could downregulate the HER2 expression efficiently and exert an inhibitory effect on growth of HER2-overexpressing breast cancer cell.