Objective  To investigate the inhibitory effect of lentivirus-mediated Bmi1-shRNA on transplanted human non-small cell lung cancer (NSCLC) by intratumoral injection.    Methods  Recombinant lentivirus containing Bmi1-shRNA was constructed. A model of subcutaneous implanted tumor was generated through injecting human lung cancer cell A549 (10

7

) into the NOD/SCID mice. The 27 established mice with a mass at a diameter of 4 to 5 mm were divided

into 3 groups randomly and equally. Recombinant lentivirus containing Bmi1-shRNA (5×10

8

TU/ml

0.1 ml)

lentivirus containing NC-shRNA (5×10

8

TU/ml

0.1 ml

as negative controls) and PBS (0.1 ml

as blank control) was given the mice of the 3 groups respectively

once per 3 d

for 4 weeks. The size of the tumor mass were measured every 3 d. The mice were sacrificed in the end of 4 weeks’ treatment. The expression of GFP in the xenografts was detected through laser scanning confocal microscope. RT-PCR and Western blot analysis were used to test the mRNA and protein expressions of Bmi1 in the xenografts.    Results  GFP was expressed in the tumor mass of the recombinant lentivirus groups

but not in the blank control. The average tumor volume in Bmi1-shRNA lentivirus group was significantly lower than that in the negative control and blank control groups (P0.05) with an inhibitory rate of 52.9 % and 57.9% respectively. RT-PCR and Western blotting showed that the mRNA and protein expression of Bmi1 was decreased in the Bmi1-shRNA lentivirus group (P0.05).    Conclusion  Intratumoral injection of recombinant Bmi1-shRNA Lentivirus inhibits the growth and proliferation of A549 xenografts in the NOD/SCID mice

suggesting that Bmi1 might represent a therapeutic target in the genotherapies of non-small cell lung cancer.