OBJECTIVETo study the effects of antisense Bmi-1 (B cell-specific moloney murine leukemia virus insertion site 1) RNA on the growth, cell cycle and apoptosis of lung cancer cell line A549.

METHODSRecombinant plasmids carrying antisense Bmi-1 RNA were transfected into A549 cells, which expressed a high level of endogenous Bmi-1. The mRNA level of A549 cell was analyzed by real time quantitative RT-PCR and the protein level was determined using Western blot. MTT growth curve and plate colony forming assay were used to measure the effect of antisense Bmi-1 RNA expression on the growth of A549. Flow cytometry was used to analyze cell cycle and apoptosis.

RESULTSAntisense Bmi-1 RNA reduced the Bmi-1 expression at the protein level, but did not alter the mRNA level in A549 cells. Compared with the control cells, A549 cells transfected with antisense Bmi-1 RNA showed a strong inhibition of the cell growth. The number of plate colony formation of the antisense Bmi-1 transfected cells (0.67 +/- 0.50) was less than those of the control (73.0 +/- 4.1) and cells transfected with empty vector (67.0 +/- 4.0, P < 0.01). Transfection of antisense Bmi-1 RNA arrested the A549 cells at G₀/G₁ phase of the cell cycle and did not increase the apoptosis.

CONCLUSIONAntisense Bmi-1 RNA expression inhibits A549 cells proliferation, likely through the interference of Bmi-1 leading to an arrest of the proliferating cells at the G₀/G₁ phase.