| The present dissertation described a research work on the evaluation of anti-proliferative effect of 128 compounds from Chinese medicinal herbs and the study on the action mechanism of two of them, DRG and HS-2. The anti-proliferative activities of 128 compounds were assessed by MTT method using human erythroleukemia K562 and human colon carcinoma HCT-15 cell lines in vitro.Among the 128 compounds tested, DRG, HS-2, Sll, S23, S31, S37, could obviously inhibit the proliferation of K562 cells and seven compounds, YIA5, YIA59, DRG, HS-2, S11, S23, S31, could obviously inhibit the proliferation of HCT-15 cells at the tested concentrations of 100, 50, 25, 12.5 g/ml, respectively. Two compounds DRG and HS-2 showed strong cytotoxicity at higher concentrations over 25 g/ml while at 12.5 g/ml they both showed apoptosis-inducing activity along with their cytotoxicity lower than that at higher concentrations. Although DRG and HS-2 are well-known compounds, no research report had so far been seen on their anticancer activity of DRG and HS-2 except for the only one publication on the apoptosis-inducing activity of HS-2 on mouse tsFT210 cells reported by our research group. Therefore, the investigation of this dissertation was focused mainly on the exploration of action mechanisms of anticancer effects of DRG and HS-2 by means of modern molecular and cellular biological techniques. The study on the anticancer activity and action mechanism of DRGIn the present work, the inhibitory effects of DRG on the proliferation of human cancer cell lines A431, A2780, A549, K562, and HCT-15 were examined by MTTmethod. The results showed that DRG respectively inhibited the proliferation of human cancer cells with the IC50 values of 9.33 0.22 M for A431, 18.7 0.16 M for A2780, 9.98?.38 uM for A549, 6.44 0.10 uM for K562, and 5.86 0.14 uM for HCT-15 and that the IC50 value of DRG is obviously less than that of the positive control cisplatin (CDDP).The apoptosis-induced effect of DRG was demonstrated by various experiments including: observing morphological feature changes of apoptotic cells with the light microscope, invert fluorescence microscope and transmission electron microscope, assessing the cell volume sizes distribution of apoptotic bodies with Coulter Multisizer II analytical instrument, determining the formation of DNA ladder with DNA agarose gel electrophoresis, measuring the Sub-G0/G1 peak percentage changes of apoptotic cells, the overturn of phospholipid phosphatidylserine(PS) and the mitochondrial transmembrane potential (m) with flow cytometry, respectively. Furthermore, the apoptotic mechanism induced by DRG was investigated with such experiments as analyzing the expression level and cleavage of pertinent proteins with Western blotting, examining in vitro the competitive binding of DRG and Bcl-2 homology domain 3(BH3) peptide to Bcl-XL protein with fluorescence spectrometer, and detecting the effects of DRG on Bcl-2 and Bax gene mRNA transcription expression level in HCT-15 cells reverse transcription-PCR (RT-PCR) assay.The data indicated that DRG obviously inhibited the proliferation of HCT-15 and K562 cells in a concentration- and time-dependent manner. Both K562 and HCT-15 cells treated with DRG exhibited typical morphological and biochemical characteristics of apoptosis which had been detected with morphological observation, Coulter Multisizer II assay, "DNA ladder" detection, flow cytometric analysis and PS overturn, etc. It was demonstrated in several aspects that DRG exerted its anticancer effect through inducing apoptosis on HCT-15 and K562 cells. The rapid decrease of m in concentration- and time-dependent manner has been found by treating HCT-15 cells with different concentrations of DRG for 24 h or with 10 uM DRG for different times, respectively. The experiments to detect the expression level and cleavage of some proteins related to death receptor pathway and mitochondria pathwayshowed that with the increase of treatment time by DRG, Cyto c was released from mitochondria into cytosol...
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