Quercetin-Induced Cell Apoptosis in GLC-82 Human Lung Cancer Cells

Objective:To study the effects of quercetin on growth inhibition and apoptosis of GLC-82 human lung cancer cells. Methods: GLC-82 cells were cultured with different concentrations of quercetin. Growth inhibition of quercetin on GLC-82 cells was evaluated by MTT assay. Morphologic changes of quercetin-treated cells were observed by light microscope, and the nuclei stained with Hoechst33258 were visualized by fluorescence. Nuclei area and apoptotic rate were measured with QWin image processing and analysis system. The protein expressions of Mdm2, p53 , Bax, Bcl-2 and caspase-3 were analyzed by fluorescence immunocytochemical method ( SABC-Cy3 ) , and the fluorescent intensity was measured with QWin. Results: 48h after quercetin treatment, apoptotic cells increased dose-dependently. Morphological changes of GLC-82 cells showed features typical of apoptosis, including karyopyknosis, and patchy aggregation of the chromatin. The growth inhibition of GLC-82 cells was concentration-dependent. Quercetin increased the levels of Mdm2 and Bcl-2 proteins, reduced the levels of Bax and caspase-3 proteins, and had no significant effect on p53 protein. In addition, the positive rates of Mdm2, Bcl-2, Bax and p53 were elevated and that of caspase-3 was lowered. Conclusion: Quercetin may inhibit the growth and induce apoptosis of lung cancer GLC-82 cells. Upregulated expression of Mdm2 protein inhibited the pro-apoptotic effect of p53, which appeared to be responsible for reduced cell death.