| Objectives:Pancreatic cancer is characterized by significant desmoplastic response and abundant extracellular matrix.These characteristics lead to abnormal vascular function in pancreatic cancer tumors,which leads to the poor distribution and anti-tumor effect of anti-tumor drugs in pancreatic cancer.Nanomedicine is a hot issue in drug research which is expected to overcome the biological barriers and toxic side effects of drugs in the body to achieve safer and more effective cancer treatment.The hedgehog pathway is abnormally activated in pancreatic cancer and plays an important role in desmoplastic response.Blocking the hedgehog pathway can inhibit the desmoplastic response of pancreatic cancer,reduce the extracellular matrix,restore the function of blood vessels in the tumor,and promote the distribution and anti-tumor effects of drugs in pancreatic cancer.Method:Section 1:1.SN38 was used for chemical synthesis with PLA to construct SN38-PLA molecules,and prepared SN38 nanoparticles as anti-tumor drugs with PEG-PLA2.Electron microscopy,DLS,and in vitro release experiments were used to examine the characterization of SN38 nanoparticles.Section 2:1.CCK-8,colony formation assay,and flow cytometry were used to examine the effects of SN38 and SN38 nanoparticles on proliferation and apoptosis of pancreatic cancer cells.2.A specific hedgehog inhibitor,vismodegib,was selected for further study,and CCK-8,colony formation assay and flow cytometry were used to detect the role of vismodegib in pancreatic cancer cell proliferation and apoptosis,and the effects of vismodegib combined with SN38.3.The bxpc-3 subcutaneous tumor model and patient-derived tumor xenograft model was built,and the effect of vismodegib on extracellular matrix and the effect of two drugs on pancreatic cancer were observed in the cell line subcutaneous tumor model and the patient-derived tumor transplantation model.Results:Section 1:1.SN38 nanoparticles were constructed by co-assembly of SN38-PLA and PEG2k-PLA5k.The size of SN38 nanoparticles is 50.7±0.483 nm with a good spherical morphology.2.SN38 nanoparticles have good sustained release properties at 37℃ pH 7.4 or 4.6,and the drug release distribution at 72 hours is 16.77 ± 1.11%and 21.67 ± 1.01%,respectively.Section 2:1.The half maximal inhibitory concentrations(IC50)of free SN38 and SN38 nanoparticles were 0.52±0.08 and 0.47±0.06 μM in bxpc-3 cells,1.79±0.10 and 1.01±0.15 μM in PANC1 cells,4.96 ± 0.41 and 4.64 ± 0.32 μM in L3.6PL cells.Free SN38 and SN38 nanoparticles can effectively induce apoptosis of pancreatic cancer cells and expression of apoptosis-related proteins.2.In vitro,vismodegib can effectively inhibit the expression of GLI-1 mRNA and protein in Bxpc-3,L3.6PL and PANC1 cells,and vismodegib has no obvious toxic effect on pancreatic cancer cells.The combination of vismodegib and free SN38 or SN38 nanoparticles did not enhance effect of SN38 on cell proliferation and apoptosis.3.In vivo,vismodegib can effectively inhibit the expression of GLI-1 mRNA and protein in Bxpc-3 model,reduce the expression and distribution of extracellular matrix component,fibronectin,and promote the opening of blood vessels and the distribution of nanoparticles in tumor.4.Vismodegib has no obvious toxic effect on nude mice,and the combination with SN38 nanoparticles is superior to SN38 nanoparticles in the treatment of bxpc-3 subcutaneous tumor and PDX model.Conclusions:1.SN3 8 nanoparticles can be constructed based on SN38-PLA and PEG2k-PLA5k and the nanoparticles significantly improve the water solubility of SN38.2.Vismodegib can block hedgehog signaling pathway,reduce the content of extracellular matrix,promote the reopening of vessels and ultimately increase the distribution of SN38 nanoparticles in tumors.The combination of vismodegib and SN38 nanoparticles can effectively improve the therapeutic effect of SN38 nanoparticles,which provides new treatments for the clinical treatment of patients with pancreatic cancer. |
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