| BACKGROUNDChemotherapy and incretion treatment play a key role in the treatment of breast cancer. Although there are negative reports, NSABP B-16 and NSABP B-20 investigation all confirmed the advantage of regimen of AC, CMF combined with Tamoxifen. Paclitaxol and Cisplatin were used as the second line chemotherapy in breast cancer. There were few reports about the synergistic effect between Tamoxifen and Paclitaxol, Cisplatin. The influence on drug sensitivity in individual after long time usage of Tamoxifen was not known clearly. All of these should be investigated further.OBJECTIVESTo evaluate the synergistic effect of chemotherapy using Paclitaxol or Cisplatin combined with Tamoxifen and to study the influence on drug sensitivity in MCF-7 cell line when using Tamoxifen for a long time.METHODS1, The value of IC50, IC30 and 1C 10 of Paclitaxol and Cisplatin were determined by MTT method. And also the cell double proliferation time.2, MCF-7 cell line was treated by different dose delivery of Paclitaxol and Cisplatin, alone or combined or combined with 2x10~8mol/l of Tamoxifen 3 cycles. Flow cytometer was used to detect theinfluence on cell cycle, and also the expression of C-myc , caspase-3, MT, GST-pi, p170> Bcl-2, Bax, E-cadherin, VEGF. Cell apoptosis were detected by Annexin V/PI assay.3, After 8 and 16 weeks of coculture of 1 x10-7 mol/l TAM with MCF-7 cell line, flow cytometer was used to detect the expression of ER/PR/EGFR/C-erbB-2. Western blot was used to determine the protein of EGFR/C-erbB-2. EGFR/C-erbB-2 mRNA were detected by RT-PCR.4, After 16 weeks of coculture of 1x10-7 mol/1 TAM and MCF-7 cell line, MTT method was used to detect the difference of drug sensitivity of Cisplatin and Paclitaxol, and also the effect on cell growth of E2, EGF, Insulin. The in vitro adenosine triphosphate tumor chemosensitivity assay(ATP-TCA) was used to define the difference of drug sensitivity of Adriamycin. Flow cytometer was used to detect the expression of p170 , Bcl-2, Bax protein. Flow cytometer was used to detect intracellular flurescence intensity of Epirubincin and the influence of Glivec on the flurescence intensity.RESULTS1, After the treatment of the different dose delivery of Paclitaxol and Cisplatin, alone or combined or combined with 2x10-8mol/l of Tamoxifen (D-10,T-10,L2-10,L3-10, D-30,T-30,L2-30,L3-30), the ratio of cells in S phase of MCF-7 cell line was decreased, the proportion of cells in GO/G1 increased, and the time of cellular double proliferation prolonged evidently (P<0.05). 2X10-8mol/l TAM combined with 1C 10 dose density of Paclitaxol plus Cisplatin (Group L3-10) and 1C 10 dose density of Paclitaxol plus Cisplatin (Group L2-10) were used to treat MCF-7 cell line and the results were compared. After three cycles of treatment, the proportion of cells in S phase in group L3-10 and L2-10 was 5.8 % ,7 % respectively, and the time of cellular double proliferation was 59+6 and 55+8 hours respectively. 2x10-8 mol/1 TAM combined with IC30 dose density of Paclitaxol plus Cisplatin (Group L3-30) and1C 10 dose density of Paclitaxol plus Cisplatin (Group L2-30) were used to treat MCF-7 cell line and the results were compared.After three cycles of treatment, the proportion of cells in S phase in group L3-30 and L2-30 was 5.3%, 4.6%respectively, and the time of cellular double proliferation was 82+12 and 80+16 hours respectively.2,The expression of pertinent protein to cell growth, cell apoptosis, drug anti-sensitivity, metastasis, and angiogenesis after three cycles treatment of IC 10 and IC 30 dose density of L2 and L3 was as following (Table 1,2).3 ,After three cycles treatment of IC 10 dose density of L2-10 and L3-10, the proportion of apoptosis cells and death cells was 22% and 23% respectively. In the two groups treated by IC30 dose density, the pertinent data was 40% and 37% respectively, and it increased significantly compared with 2% of the control group (p<0.05) . There was no statistical significance in the comparison between L2...
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