| A key challenge of tumor in clinical chemotherapy is multidrug resistance(MDR).Studies have shown that orphan nuclear receptor-derived peptide-NuBCP-9(e.g.,N9)can induce cell apoptosis by targeting mitochondria to induce conformational changes of the drug resistance-related protein Bcl-2,so it has a promising application in the treatment of drug-resistant tumor.However,N9 has defects such as easy inactivation and difficulty in penetrating cell membrane.In addition,related studies have reported that celastrol has various pharmacological activities such as anti-inflammatory,anti-cancer and antirheumatic activities,but it has problems in the anti-cancer applications such as poor water solubility and serious toxic side effects.Therefore,it is of great significance to design the nanocarriers targeting tumor microenvironment for intracellular delivery and targeted release of N9,and to use low-dose celastrol as a curative sensitizer for treating drugresistant tumors.This project aims to construct a silicon-based nanocarrier suitable for intracellular delivery and controlled release of N9,and at the same time explore the potential of combined application with low-dose celastrol in drug-resistant tumors,so as to achieve the safe and efficient treatment.For this purpose,sol-gel method was firstly used to prepare mesoporous and hollow-structured silicon-based nanoparticles,and MTT,flow cytometry and western blotting experiments were performed to evaluate the difference between the above two nanocarriers in cellular delivery of N9 for anti-cancer therapy.Given that,macroporous silicon-based nanoparticles(MSNs)with a particle size of～60 nm(pore size～10 nm)were preliminarily decided as the bare carriers.A peptide-loaded macroporous silica delivery system with multi-arm polyethylene glycol(e.g.,mPEG)as gating switch was followed by being constructed and physicochemically characterized using transmission/scanning electron microscope,dynamic light scattering instrument and Fourier infrared spectrometer techniques.The controlled drug release was also verified by simulated pH environments inside and outside the cell.Finally,HeLa-Bcl2 and LS174T cell lines were used as drug-resistant cancer cell models,and a variety of technical methods were taken to comprehensively study the anti-cancer effects of the controlled release silicapeptide delivery system in combination with celasrtol both in vivo and in vitro.Our results showed that combination of the prepared silica-peptide drug delivery system(～8 μM N9)had good acid responsive drug release characteristics,and could induce about 75%of LS174T cells to apoptosis in combination with celastrol at a dose of 0.5 μg/mL,which was about 3 times that of free celastrol.In vivo anticancer studies indicated that mPEGblocked silicon nanosystem had good tumor targeting and retention capabilities in the MC38 tumor-bearing mice model,and there was still a strong fluorescent signal at the tumor site at 48 h.Combined use of silica-peptide nano-drug delivery system and celastrol(0.4 mg/kg)had an anti-tumor rate of 83%,which was 3.2 times than free drug groups,confirming their prominent capability against multidrug resistant tumors.In summary,we have successfully constructed a silicon nano-drug carrier system with acid-sensitive drug release characteristics and suitable for the delivery of biomacromolecule anti-cancer peptide,and further confirmed its potential application with low-dose celastrol in the safe and efficient treatment of drug-resistant cancers.This research not only provides a new idea for drug treatment of drug-resistant tumors,but a feasible nanotechnology strategy for the combination of other peptide protein drugs and chemotherapeutics in clinical cancer treatment. |
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