Treatment Of Pancreatic Cancer With Docetaxel Long-circulating Liposomes

Objective:As a new trand of anticancer drug, docetaxel belongs to inhibitor of microtubule depolymerization, acts on microtubule/mictotubule protein system, and promotes the microtubule dimer to assemble microtubule, avoids depolymerization to stabilize microtubule, blocks cells in G2 and M period and in the end inhibit cancer cell's mitosis and proliferation. During these years of clinical research, carcinoma of the pancreas has good treatment effect, effective rate of single drug is up to 29%, in our research, we produced docetaxel long-circulating liposome to studied on orthotopic model of pancreatic carcinoma.Methods:①The prupose of the study is to extend the retention of the drug in the systemic circulation by modification of the liposomes, that is to say, to increase the surface hydrophilicity of the liposomes and the stability in the circulation so as to improve the uptake by the tissue of tumor;②The construction of the model for transgenic pancreatic neoplasms loading Luc. Firstly we built the reporter genes transfection cell line, used the Luciferase tagged human bxpc PANC-1Luc and subculture.We digested cells using trypsogen with concentration of 0.25% to get cell suspension, then inoculated subcutaneous on the nape of 16 nude mice;③Establishment of orthotopic model of pancreatic carcinoma:we i.p injected with ketamine to anaesthetize nude mice, opened 1 cm's cut by the side of left upper quadrant of rectum, carefully separated stamoch and spleen and exposed pancreas, then used a 1 ml volume'injector to injected cell suspension (5x106,0.2ml) into the portal vessel near head of pancreas, after injection, brought the pancreas into abdomen and stitched skin, then the orthotopic model of pancreatic carcinoma was completed. After the operation, there was no infection and the wounds were completed healed, it meaned that the method of model had good feasibility;④A kind of ultramicroscopic sealed vesicle was prepared with egg phospholipids and cholesterol by film dispersion method, namely by enveloping docetaxel into adipoid bilayer conjugated with DSPE-PEG2000. The physicochemical properties of the vesicle were characterized by TEM, particle size analyzer and HPLC. The Entrapment rate, particle size and Zeta potential of the prepared docetaxel long-circulating liposomes was 87%,85.87nm and-0.271mV, respectively.The third part is the bioluminescence detection of the cell and gene.The first step is to inject the fireflyluciferin in the abdominal cavity and then anaesthetize the nude mice with ketamine and detecte. The growth, metastasize and the change of the tumor in situ can be detected on time by the bioluminescence, meanwhile we can measure the tumor in situ quantitativly without wound.Results:①The average encapsulation efficiency of the docetaxel long-circulating liposome was 87%,the average particle size was 85.87nm and the Zeta potential was-0.271mV;②The results indicated that 4 weeks later,there were hard lumps with distinct border and no slide;③The results of in vivo test indicated that after the treatment of DTX, DTX-Liposome and notmal saline, tumors in DTX-Liposome groups had grown slowly, the tumor volumes were smaller than DTX groups, and it had statistical significance (P<0.05).Conclusion:Study of the influence of docetaxel long-circulating liposomes on the in situ model of pancreatic cancer:liposome is a kind of microvesicle in which drug is enveloped by the adipoid bilayer. It is generally accepted that liposome can transport drug targetedly to the diseased region. In this paper, long-circulating liposomes was prepared by conjugating with DSPE-PEG2000 to phospholipids so as to extend the retention of the drug in the systemic circulation, to enhance the antitumor activity and to reduce the acute toxicity significantly. Based on the in situ model, the treatment effectiveness of the aforementioned long-circulating liposomes on the pancreatic cancer was investigated by the Xenogen in vivo imaging system.