Inhibitory effects on proliferation and invasion of lung cancer cells by RNAi-mediated knockdown of osteopontin

Objective To develop DNA vector-based RNA interference (RNAi) technology and block the expression of osteopontin (OPN) in lung cancer cell line A549 ,and further examine its possible effect on invasion and proliferation of lung cancer cells. Methods One double-stranded DNA vectors pEN-TRTM/U6-INF (pINF-1) targeting the mRNA of human OPN, and the control vector pENTRTM/U6-CTR (pCTR) mismatching with mRNA of OPN were constructed, and then they were transfected into human A549 cells with high metastatic potentials. Western blotting was used to quantify the protein level of OPN. The malignant phenotypes of transfected A549 cells including proliferation and invasive activities were ana-lyzed. Results As compared with control group only transfected with Lipofectamine~(TM) 2000, OPN protein lev-el in plNF-1 group could be decreased by 85% 72 h after transfection,and no significant difference was found in the group transfected with pCTR. In vitro cellular growth rate was decreased by 56% (P<0.05) in the group transfected with pINF-1 ,and migrating number of A549 cells (15.2±2.8) transfected with pINF-1 was also significantly decreased (P<0.01 ) as compared with the control group (72.4±6.5). Conclusion Se-quence-specific shRNA (pINF-1) can significantly reduce the OPN expression in A549 cell line. The sup-pression of OPN expression in A549 cells transfected with pINF-1 can induce the decline of invasive and pro-liferative ability of A549. This suggests that OPN may be an alternative target for treatment in lung cancer. Key words: Lung carcinoma; Osteopontin; RNA interference; Metastasis