The Study Of Molecular Mechanism Of Synergistic Antitumor Action And Induced Apoptosis Of Zoledronic Acid And Paclitaxel

In the early experiment of this study, The breast cancer cell line MCF-7 and lung cancer cell line A-549 were devided into 15 groups which were treated with increasing concentrations of the zoledronic acid or paclitaxel. The results of MTT showed us that zoledronic acid and paclitaxel could inhibit the growth of breast cancer cell line MCF-7 and lung cancer cell line A-549 alone; zoledronic acid and paclitaxel caused a dose-dependent inhibition in cell growth; combining clinically achievable concentrations and drug concentrations described in literature, we chosed the 100uM as the appropriate concentrations of zoledronic acid in this experiment; the proper concentration of paclitaxel is 2nM. We combined zoledronic acid with paclitaxel to deal with both cell lines in sequential or simultaneous. At the same time, we set up a control group which wasn't given any treatment.In the experiment, we assessed the inhibition rate, apoptosis rate and the changes of cell cycle by MTT and flow cytometer. There are synergistic effects for the combined treatment with zoledronic acid and paclitaxel. The levels of apoptosis are dependent on drug sequencing, with the greatest effect achieved when paclitaxel is administered prior to zoledronic acid. Additionally, when paclitaxel is administered prior to zoledronic acid, it could induce an accumulation of cells in S phase and inhibit the cells division.Objective:In this part of the study, we analyze the inhibitory action of zoledronic acid and paclitaxel to breast cancer cell line MCF-7 and lung cancer cell line A-549, observing the changes of the related markers in PI3K/Akt and Raf/Mek/Erk signaling pathway, to explore the probable mechanism of synergistic antitumor effects on the combined use for zoledronic acid and paclitaxel.Methods:The breast cancer cell line MCF-7 and lung cancer cell line A-549 were devided into 4 groups:blank contract; paclitaxel and zoledronic alone; paclitaxel then zoledronic acid, the expressions of Akt, phospho-Akt, Erk, phospho-Erk, Bcl-2 were detected by Western blot and the Akt and Erk gene expression were detected by Real time PCR. Results:1,The best planting density of the cell lines MCF-7 and A549 for the 24 well plate was 4x104/ml. The best planting density of the cell lines MCF-7 for the 6 well plate was 2x 105/ml, The best planting density of the cell lines A549 for the 6 well plate was 3x105/ml.2,When the planting density was identical, MCF-7 cells grew faster than A549cells, and the growth tendency of the two cell lines coincided with the S growth curve.3,The Real-time PCR results demonstrated that the Erk and Akt mRNA of the group of paclitaxel then zoledronic acid were lower than others in the two cell lines.4,The Western blot results demonstrated that the Erk and Akt level of the four group were parallel in the two cell lines. however, the phospho-Erk, phospho-Akt and phosphor-Bcl-2 level of the group of paclitaxel then zoledronic acid were lowest, then paclitaxel alone, and the third was zoledronic acid alone, the control was greatest.Conclusions:The combination of paclitaxel and zoledronic acid induce the down-regulation of phospho-Erk, phospho-Akt and phospho-Bcl-2 protein expression in PI3k/Akt and Raf/Mek/Erk signaling pathway, which could be the one of the synergistic antitumor mechanisms of the two drugs.