| Triple negative breast cancer(TNBC)is a subtype of breast cancer with a specific pathology and a high recurrence and mortality rate.Currently,due to the lack of effective targets for TNBC,the clinical treatment strategy for TNBC is still mainly based on chemotherapy,but patients have serious toxic reactions during chemotherapy,and some of them cannot even tolerate it at all,and once patients develop resistance to chemotherapy drugs,tumors will rapidly recur and metastasize.In recent years,there is increasing evidence that the metabolism of glutamine is closely related to the growth and metastasis of TNBC,and limiting glutamine uptake can inhibit the growth of TNBC cells to a certain extent.However,the compensatory non-regenerative mechanism of glutamine catalyzed by the highly expressed pyruvate carboxylase(PC)in TNBC can limit the effectiveness of this therapeutic strategy.Based on the above research status,this study constructed a co-delivery system based on amphiphilic block copolymer micelles of siRNA and the chemotherapeutic drug paclitaxel(PTX),using siRNA to silence pyruvate carboxylase(PC)highly expressed in TNBC as a way to block glutamine metabolism in non-exogenous glutamine-dependent TNBC cells while enhancing the sensitivity of tumor cells to PTX.In addition,the fluorescent group Cy5 on the copolymer micelles can be used to track the uptake of drugs by TNBC in real time,thus enabling the integration of diagnosis and treatment.The main research results achieved are as follows.1.We successfully synthesized PMMA-PLys polymer micelles and characterized their physicochemical characteristics.The successful polymerization of hydrophilic blocks and hydrophobic blocks with Cy5 fluorescent groups was demonstrated by NMR,fluorescence spectroscopy,Fourier transform infrared spectroscopy,and gel permeation chromatography,The PMMA-PLys polymer micelles were characterized by cytotoxicity and hemolysis experiments.Through cytotoxicity and hemolysis experiments,we successfully demonstrated that the polymer micelles have low toxicity and low hemolysis rate,and have good biosafety.2.We investigated the drug loading capacity of PMMA-PLys polymer micelles and proved that the micelles have excellent loading capacity of small molecule drugs and siRNAs.The loading rate of PMMA-PLys polymer micelles on PTX was determined by HPLC method to be 16.63±0.56%,and the maximum loading mass ratio of polymer micelles to PC siRNA was determined by agarose gel electrophoresis experiments to be 1/24,the silencing efficiency of PMMA-PLys@si PC on PC was76.25% as demonstrated by immunoblotting experiments.In simulated drug release studies of PMMA-PLys polymer micelles,the experimental results showed that PMMA-PLys polymer micelles have some retarding ability for drug release,with45.81±2.07% drug release at comparative p H=7.3 and 76.34±1.67% drug release at p H=5.5,demonstrating that in the acidic microenvironment of tumor PMMAPLys@PTX showed more excellent drug release in the acidic tumor microenvironment.3.A synergistic effect of PTX combined with siRNA targeting was demonstrated at the cellular level for the treatment of non-glutamine-dependent triple-negative breast cancer.The results of cell proliferation assay,flow cytometry(FCM),Hoechst 33342-stained cells nuclear apoptosis assay and mitochondrial transmembrane potential assay showed that PMMA-PLys@PTX@si PC could more effectively inhibit the proliferation of breast cancer MDA-MB 231 cells and induced apoptosis in triple-negative breast cancer cells.In summary,a PMMA-PLys polymeric micelle was constructed as a paclitaxel and siRNA co-delivery vehicle in this study,and in vitro antitumor experiments showed that this nano-delivery system could inhibit the proliferation of MDA-MB-231 cells and induce apoptosis,demonstrating a synergistic therapeutic effect compared with paclitaxel administration alone.At the same time,the nano-delivery system is capable of real-time tracking using fluorescence signals,which also shows potential for future therapeutic integration of TNBC. |
PDF Full Text Request