| Objective Recently, a lot of quinolone compounds has been reported that the compounds possessed potential anticancer activity. The mechanisms of these cytotoxic agents are not fully understood, as with many other agents, are likely to be inhibition of cell proliferation, cell cycle arrest, interfere with normal microtubule dynamics or induction of tumor cells apoptosis. In the present study, a series of quinolone derivatives was designed and synthesized by Dr Hu Guoqiang. Human hepatocarcinoma SMMC-7721 cells were tested for its sensitivity to the quinolone derivatives in order to explore the anticancer mechanism of triazole derivatives and to select new anti-cancer drugs. The results provide data support for the development of the chemical which has the function of antineoplastic.Methods The proliferation of the cells and the inhibition effect of Quinolone derivatives on the cell proliferation were examined by MTT assay. PI fluorescence staining with flow cytometric analysis was used to analysis cell cycle. Cell apoptosis was observed by fluorescence microscope techniques with Hoechst 33258 associated with propidium iodide (PI) staining and TUNEL assay. DNA ladder bands were observed through agarose gel electrophoresis. Mitochondrial membrane potential(△ψm) was measured by High content screening. Western blot was used to assay changes of the proteins correlated cell apoptosis.Results The results of drug screening indicated that ten kind of quinolone derivatives possessed inhibiting activity to proliferation of SMMC-7721 cells. QNT4 possessed high inhibiting activity to proliferation of SMMC-7721 cells. The cells proliferation was inhibited by QNT4 at 0.625μmol·L-110μmol·L-1 in dose and time dependent manners. The approximate the concentration of 50% growth inhibition (IC50) values of QNT4 for 24h was 2.411μmol·L-1. QNT4 treated the cells for 24 hours , the number of the treated group cells compared with Control group cells decreased in G0/G1 phase , increased in S phase and G2 / M phase . The result of Hoechst 33258 staining cells showed that the number of apoptosic cells was increased significantly .These cells all had typical apoptosis feature: chromatin condensation, nuclear fragmentation .The typical DNA ladder bands were shown by agarose gel electrophoresis .The Tunnel result showed that the ratio of apoptosic cells increased and in dose-dependent manner .Compared with control group ,the apoptosis ratio had significant difference(p<0.05) . The result of mitochondrial membrane potential(△ψm)by High Content Screening testing revealed that it decreased(8.74±3.62)%, (39.64±4.52)%and(46.90±3.29)% respectively in different QNT4 treated groups compared with contol group . The mitochondrial membrane potential had significant difference(p<0.05) between QNT4 treated groups and control group .The result of Western-blot appeared that P53 expression increased significantly and in dose-dependent manner; Bax expression increased, Bcl-2 expression decreased ;Caspase-9 expression increased ,both Caspase-9 and Caspase-3 active fragment expression increased; but Caspase-8 expression did not change significantly .Conclusions:1. QNT4 possess high inhibiting effect to proliferation of SMMC-7721 cells and can induce the cell cycle arrest. The cell proliferation was inhibited by QNT4 in dose and time dependent manners.2. At the approximate the concentration of IC50 values, QNT4 can induce apoptosis of human hepatocarcinoma SMMC-7721 cells significantly.3. QNT4 can induce apoptosis of human hepatocarcinoma SMMC-7721 cells, via mitochondrial-dependent pathways.
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