Dual-pH-Sensitive Micelle Co-delivering Paclitaxel And Calcitriol For Triple-Negative Breast Cancer Therapy

The therapy of triple-negative breast cancer(TNBC)relies on chemotherapy basing on cytotoxic agents,including paclitaxel(PTX).Unfortunately,PTX will facilitate the invasion of cancer cells and the formation of metastases.To counteracts pro-metastasis of PTX in TNBC therapy,in this work,calcitriol(CTL)is delivered along with PTX by a dual-pH-sensitive micelle.The PTX/CTL-co-loaded dual-pH-sensitive micelle(PCDM)can switch its surface charge from negative to positive at the tumor tissue and release PTX and CTL inside the lysosomes because of the structure change of the polymers composing PCDM under the acidic condition.This property makes PCDM able to escape from mononuclear-phagocyte system clearance and easy to enter tumor cells.This research mainly includes the following four parts:1.Synthesis and characterization of materialsTwo kinds of materials BD-PEG and BD-PEI-DMA were synthesized by Michael addition.The structure of the product was confirmed by NMR and the molecular weight of the two materials was confirmed by MALDI-TOF and GPC.The molecular weights of the two materials were 3.35KDa and 8.355KDa.2.Synthesis and characterization of PCDMThe PCDM was obtained by the method of film hydration.The particle size and the potential change under different pH of the PCDM was measured,and the shape of micelle was observed by transmission electron microscope.The result of the release experiment showed the good stability of the micelle.3.The anti-tumor experiment of PCDM in vitroThe model of 4T1 cells was constructed,and the coumarin(C6)was used instead of drugs to test the cellular uptake efficiency.The result of cell migration,invasion and wound healing experiments showed the inhibition of the invasion,migration and wound healing ability of 4T1 cells treated with miceclles.Meanwhile,the result of cytotoxicity indicated that the drug-loaded BD-PEI-DMA/BD-PEG micelles had more efficient anti-proliferation effect on cancer cells due to mediating higher intracellular drug concentrations under acidic environment.4.The anti-tumor and anti-metastasis experiment of PCDM in vivoIn this part,we first proved that PCDM can effectively improve the circulation time in blood and drug accumulation of tumor tissue through the pharmacokinetics experiment of rats and the distribution experiment of 4T1 tumor bearing nude mice.Compared with the free PTX and CTL group and the saline group,PCDM which co-load PTX and CTL drugs can effectively inhibit proliferation of tumor,and the effect of PCDM is better than any single drug group and the group of micelles without BD-PEI-DMA.The result of Immunofluorescence and the measurement of the number of Ly6C~+monocytes in lung tissue indicated that PCDM efficiently suppresses the 4T1 primary tumor growth in mice and inhibits lung metastasis,due to down-regulation of matrix metalloproteinase-9(MMP-9)and BCL-2 levels,up-regulation of E-cadherin level,and counteracting the PTX-induced elevated C-C motif chemokine ligand 2(CCL2)and Ly6C~+monocytes levels by CTL.PCDM shows good biocompatibility without promoting the serum calcium level.Therefore,the combination of PTX and CTL based on this pH-sensitive micelle is promising for the TNBC treatment.