Hydroxycamptothecin inhibits proliferation of human lung carcinoma cell line A549 and down-regulates its Bcl-2 gene expression in vitro

Objective To investigate the effect of hydroxycamptothecin(HCPT) on the proliferation,cell cycle and apoptosis of human lung carcinoma cell line A549.Methods The growth of A549 cells exposed to HCPT was observed by staining with acridine orange/ethidium bromide dye.Agarose gel electrophoresis was performed to detect DNA fragmentation of the apoptotic cells.The cell cycle distribution of the exposed cells was analyzed using flow cytometry,and cell apoptosis was examined with annexin V-FITC/PI staining.RT-PCR was used to investigate Bcl-2 gene expression changes in the exposed cells.Results Agarose gel electrophoresis of the DNA from HCPT-treated cells showed a DNA ladder,and typical apoptotic appearance of the exposed cells was observed under fluorescence microscope.Treatment of A549 cells with 1 μmol/L HCPT for 24 h resulted in a cell apoptosis rate of 18.11%,significantly higher than the rate in control cells(0.09%,P0.05).The treatment also caused a significant reduction of Bcl-2 mRNA expression by 70%(P0.05).Conclusion HCPT can significantly inhibit the proliferation,induce apoptosis,and down-regulate Bcl-2 gene expression in human lung carcinoma cell line A549,suggesting the involvement of Bcl-2 gene in the inhibitory effect of HCPT on A549 cells.