The Effect Of Quercetin From Sophora Japonica Buds On Cell Proliferation And Apoptosis In Nasopharyngeal Carcinoma Cell Line

Objective:To study the effects of quercetin from Sophora japonica buds on the proliferation and apoptosis of Nasopharyngeal carcinoma cell line CNE2 and to observe this tumor cell proliferation, apoptosis, cell cycle and the expression of protein Bcl-2. To investigate the potential mechanisms of antitumor activity by quercetin and provide a new experimental evidence for the clinical treatment of Nasopharyngeal carcinoma.Methods:1. Using trypan blue exclusive assay , cell proliferation which were affected by different concentrations of quercetin were valuated after 24h,48h,72h.2. The morphological changes were observed under an inverted microscope after different concentrations of quercetin affected 48h. At the same time, apoptotic cell were detected by immunofluorescence techniques with Hoechst33342 staining after different concentrations of quercetin affecting 48h;.3. Cell cycle and the percentage of apoptotic cell were detected by FCM.4. The expression of protein Bcl-2 was analyzed by western blot.Results:1. Growth rate of the Nasopharyngeal cancer cell was obviously decreased along with increase of the quercetin concentration,the effect is also showed in time course.2. The pictures of inverted microscope showed that with the increasing of drug concentration, cells were decreased, cell outlines were not clear and burr-like was visible, cell volume was variable small, the division of cytoplasm was uneven, and cell debris increased gradually. Hoechst33342 staining revealed, with the concentration increased, the rate of apoptotic cells raised after 48h. When the concentration of quercetin over 60μmol/L, complete nucleus was seldomly seen under Fluorescence microscope instead of a large number of incomplete cell nucleus, nucleus debris and apoptotic body .3. Flow cytometry study revealed, with the concentration increased, especially the concentration reached 40μmol/L, the percentage of apoptotic cells raised (P<0.01)and cell cycle progression delayed at G1 phase while S phase decreased after 48h.4. The expression of protein Bcl-2 was down-regulated along with increase of the quercetin concentration. When the concentration over 40μmol/L, the number was significantly different compared with the control group.Conclusion:The quercetin can effectively inhibit tumor cell growth and induce tumor cells into apoptosis, which may be associated with the low expression of protein Bcl-2 in Nasopharyngeal carcinoma cell line CNE2. So quercetin is a potential chemopreventive and chemotherapeutic agent for Nasopharyngeal carcinoma. This provides a new way for the clinical treatment of Nasopharyngeal carcinoma.