| Firstly, MTT, SRB, cell growth curve assay, and protein content assay were used to determine the inhibitory effects of STT on the growth of Bcap-37 and BEL-7402 cell line, and then it is shown that STT has potent inhibitory effects on both Bcap-37 cell line and BEL-7402 cell line in a concentration-dependent manner.In order to evaluate the in vitro antitumor effect of STT, we used MTT assay to compare the inhibitory effect of STT on human hepatocarcinoma cells line BEL-7402 with that on human normal liver cells line L02 through MTT assay, and used the MTT and Webb coefficient assay to judge the co-effect of STT and adriamycin(ADM) on Bcap-37 and BEL-7402 cells, the results show that compared with its inhibition on the growth of BEL-7402 cell line, STT has less inhibitory effect on the proliferation of the normal liver cell line L02, and moreover the synergetic effects of STT and ADM on the two cancer cell line can be achieved at a high concentration of STT, however, when STT is at a low concentration, the antagonism of the two drugs will be produced.We applied several methods of morphological observation such as wright staining, acridine orange staining and electron microscope to observe the effect of STT on the morphological alterations of the two cancer cell line, to find that after treatment with STT, both of the two cancer cell lines will exhibit typicalmorphological alterations of apoptosis, such as rounding of cells, nucleus pyknosis, apoptotic body and so on.The flow cytometry detection with PI staining was used to detect cell cycle arrest and apoptotic peak of the two cell line after treatment with STT, and therefore it can be seen from the results that The apoptotic peaks can be induced by STT on both of the two cancer cell lines, however, STT can induce apoptosis of a large percent of BEL-7402 cell, while the apoptotic rate of Bcap-37 cell is much lower than that of BEL-7402 cell. In addition, STT has GO/G1 arrest effect on cell cycle of Bcap-37 cells.In addition, the molecular mechanism of cell cycle arrest and apoptosis induction have been studied. The immunological fluorescent assay followed by flow cytometry detection was applied to determine BCL-2 protein expression of BEL-7402 cells and cyclin Dl, cyclin E protein expression of Bcap-37 cells. The results demonstrate that STT can reduce BCL-2 protein level of BEL-7402 cell line; in addition, the cyclin E and cyclin Dl expression of Bcap-37 cell line can be down-regulated by STT.Moreover, we have quantified ROS in the two cancer cell lines after being treated by STT by using the reactive oxygen species (ROS) detection kit. The data shows that the quantity of ROS in Bcap-37 cell line, which can result in oxygenic damage, increases remarkably after treatment with STT, but there is no significant change of the ROS level in BEL-7402 cells.In summary, it can be inferred that STT has potent inhibitory effects on both Bcap-37 cell line and BEL-7402 cell line in a concentration-dependent manner, but has less inhibitory effect on the proliferation of the normal liver cell line L02. The synergetic effect on the two cell lines between STT with ADM can be seen at a high concentration of STT. The mechanism of inhibitory effect of STT on Bcap-37 cells are not only to induce apoptosis, arrest cell cycle of Bcap-37 cells at GO/G1 by decreasing the level of cyclin Dl and cyclin E, but also to give rise to oxygenic damage in cells. One of the possible causes of the anti-proliferating effect of STT on BEL-7402 cells is induces apoptosis by decreasing the level of BCL-2.After finishing those experiments mentioned above, another series of research were done to investigate the influence of flavonoids from the seed residues of Hippophae rhamnoides L. on the two cancer cell lines.In order to determinate the content of total flavonoid aglycones in the seed residues of Hippophae rhamnoides L., the HPLC followed by acid hydration was applied. The mobile phase was Methanol-H2O (60:40), the wavelength for detection was 368 nm and the flow rate was 1.0 ml/m...
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