Study Of Docetaxel-loaded Copolymer Micelles With Treatment Of Prostate Cancer On Nude Mice

Objective:To prepare Docetaxel-PEG-PCL block copolymer micelles and study the drug loading (DL) and encapsulation efficiency(EE) of micelles, long-circulating effection in vivo, toxic and side-effects and increasing effect of LNCaP-C4-2B cells. We established nude mouse model of prostate cancer, did in vivo treatment and observed the changes of weight and tumor growth. We explored a new formulation of docetaxela and a new strategy for the treatment of prostate cancer.Method:1. We prepared Docetaxel-PEG-PCL block copolymer micelles. The micelles were prepared by solvent evaporation with hydrophobic anticancer drug docetaxel as a model drug and observed the shape of the micelles before and after prepared by transmission electron microscopy morphology. We studied the micelle's size, potential, drug loading, encapsulation efficiency by laser particle size analyzer and high performance liquid chromatography. Determined pharmacokinetic parameters of DTX and PEG-PCL-DTX micelles in rats, compare half-time period and blood concentrations; and determined hemolytic reaction of DTX and PEG-PCL-DTX micelles with blood of guinea pig.2. In vitro test:human prostate cancer cell line LNCaP-C4-2B was treated with 0.01,0.1,1,10,100,200μmol/L concentrations of of docetaxel and Docetaxel-PEG-PCL micelles respectively for 24 and 48 hour, and used MTT assay to evaluated inhibition rates. We also used window chamber model to observed LNCaP-C4-2B's growth in nude mouse.3. In vivo test: after establishment of tumor-bearing nude mice model, intravenous injected the same dose of docetaxel, Docetaxel-PEG-PCL micelles and NS, and regularly observed changes of the tumor size,48 hour after the last administration, abstracted eye blood, and measured plasma prostate-specific antigen (PSA) levels. All of the tumors were taken out, fixed with formalin and evaluated with HE stain and immunol histochemistry.Results:The drug loading and encapsulation efficiency were (8.72±0.24)% and (98.1±1.6)%, average particle size of 25.1nm and zeta potential of 2.19mV. The results of pharmacokinetic parameters indicated that the half-time life and mean residence time in vivo of PEG-PCL-DTX micelles were prolonged than DTX group; PEG-PCL-DTX micelles's hemolytic reactions were improved than DTX group. The result of MTT assay indicated that PEG-PCL-DTX could inhibit the growth of LNCaP-C4-2B cells. The results of in vivo test indicated that after the treatment of DTX, PEG-PCL-DTX and notmal saline, tumors in PEG-PCL-DTX groups had grown slowly, the tumor volumes were smaller than DTX groups, and it had statistical significance (P＜0.05). The results of the PSA tests indicated that PEG-PCL-DTX group' s PSA level were lower than DTX group' s. Immunohistochemistry results indicated that the positive rate levels of VEGF, COX-2, bcl-2 and P53 in PEG-PCL-DTX micelle groups were lower than DTX group and model group.Conclusion:PEG-PCL-DTX micelles can increase water-solubility of docetaxel, and have better delayed release effect so as to inhibit the growth of prostate cancer tumor.