Study Of Nanoparticles Loaded Taxol Inhibition Of Gastric Cancer Cell Proliferation And The Related Mechanism

BackgroundTumor is a serious threat to human being’s life and health. It is the primaryleading cause for death in the developed countries and the second leading cause in thedeveloping countries. In recent years, with the rapid population growth and theincreasing of aging, as well as people’s little attention to the healthy lifestyles, theincidence of tumor has been increasing day by day.Paclitaxol is recognized as the most effective anti-tumor drug, the effect onbreast cancer、ovarian cancer、lung cancer and so on is obvious. But there is a seriousshortage, that is the polyoxyethylene castor oil-ethanol, using as the solube toovercome the low solubility of paclitaxol, often causes severe allergic reactions tobodies. PTX-NPs is a new taxol pharmaceutical form, used the amphiphilic blockpolymeric as the carrier, which is consisted of hydrophilic and hydrophobic segmentsin aqueous. Due to the obvious advantage of the carrier, the solubility of the toxol hasbeen greatly increased, enhancing the anti-tumor function.As to the mechanism of taxol anti-tumor, it is almost about the role of damagethe dynamic balance of microtubule’s polymerization and depolymerization, leadingto cell cycle arrest and finally cell apoptosis. While whether the mechanism ofanti-tumor is relative with the inducing DNA damage、activating the cell cyclecheckpoints or not has not been reported until now.PurposeTo research whether the PTX-NPs is more effective than PTX in inhibitioncancer cell proliferation; research the relative mechanism of anti-tumor role of thePTX-NPs and PTX. MethodsChoose the HepG2、Hela、A549、SGC-7901cell as experiment subjects, usingMTT assay detect the inhibition rate of the cancer cell proliferation; select SGC-7901as experiment subject, using the flow cytometry to detect the role in gastric cancercell cycle distribution of the PTX-NPs and PTX; using the immunofluorescentstaining assay to detect the phospho-ATM foci and the rH2AX foci; using westernblotting to detect the expression of the ATM and p-ATM, H2AX and rH2AX,p-Cdc25C, p-cdc2, CyclinB1, Chk2and p-Chk2, p53and p-p53, after disposed byPTX-NPs and PTX.ResultsMTT assay results showed that PTX—NPs and PTX have strong inhibitory ratefor cancer cell of HepG2、Hela、A549、SGC-7901, the inhibitory rate is a kind ofconcentration-dependent manner. Under the same concentration, the inhibitory effectof PTX-NPs is stronger than PTX. Flow cytometry assay results showed that bothPTX-NPs and PTX have the role of leading the cell cycle arrest in the G2/M phase,the percentage of G2/M phase distribution increases with the drug concentration. Andthe effect of PTX-NPs in cell cycle arrest is greater than PTX. Immunofluorescentstaining assay results showed that PTX-NPs and PTX can lead the generation ofphospho-ATM foci and rH2AX foci in a concentration-dependent manner. Under thesame concentration, the capacity of PTX-NPs about leading the generation of foci isstronger than PTX. The effect of changing the expression of cell cycle related proteinof PTX-NPs and PTX was detected by the western blotting. The result indicated thatthe PTX-NPs and PTX have the capability of activating ATM and H2AX byphosphorylating them; they can increase the amount of expression of p-Cdc25C andp-cdc2; increase the amount of phospho-Chk2and p-p53, while has little function ofaffecting the expression of CylinB1. Furthermore, the impact of PTX-NPs aboutchanging the amount of expression of the cell cycle related protein is stronger thanthat of PTX.ConclusionsThe function of inhibiting tumor cell proliferation of PTX-NPs is greater thanPTX, and both of them can induce DNA damage、active the cell cycle checkpoint andfinally arrest the cell cycle in G2/M phase, suppressing the cell proliferation and leading tumor cell apoptosis.