Radiosensitising effect of retinoblastoma gene (Rb94) on human lung adenocarcinoma cell line A549 / 中华放射肿瘤学杂志

ABSTRACT

Objective To construct an eukaryotic expression vector of retinoblastoma gene (pIRES-Rb94), and investigate the radiosensitising effect of Rb94 on lung adenocarcinoma cell line A549 and the mechanism. Methods Recombinant expression plasmid pIRES-Rb94 was constructed and then transfected into A549 cells using lipofectamine 2000. Steadily transfected cells were obtained using G418 se-lecting system. Cell counting method was used to produce the growth curve and the population doubling time was then calculated. The radiosensitivity of A549 cells was assessed by clonogenic assay. The expression of bTERT and Bcl-2 mRNA was detected by real-time RT-PCR. Cell cycle distribution was measured by flow cytometry. Results Steadily transfected cell line pIRES-Rb94-A549 was aquired. Compared with A549 cells, the population doubling time of pIRES-Rb94-A549 cells was increased from 31.5 h to 39.5 h (t=5.15, P<0.01). The expression of hTERT and Bcl-2 mRNA was both down-regulated (0.021.00, t= 18.99,P<0.01,0.011.00,t=13.73,P<0.01). The number of cells was increased in G2/M phases (35.91%4.53%, t =36.78,P=0.00), whereas decreased in G0/G1 and S phases (47.02%74.07%, t =11.71,P=0.00;17.07%22.32%, t =2.30,P<0.05). The sensitizing enhancement ratio was 1.30. Conclusions Rb94 has marked radiosensitizing effect on A549 cells by G2/M phase blockage and down-regulation of hTERT and Bcl-2 mRNA expression. Rb94 may also inhibit the ability of cell proliferation by regulating cell cycle distribution.