Functionalized Mesoporous Polymer Nanospheres Loaded With SiRNA And Paclitaxel For The Treatment Of Tumors

Cancer has always been one of the difficult medical problems for human beings to overcome,and it is also one of the hotspots of medical research.Because of the drug resistance of breast cancer cells,it is difficult to deal with breast cancer.At present,the combination therapy of siRNA and drugs has become one of the most effective treatments for cancer.However,because of the negative electricity of siRNA and the hydrophobicity of most drugs,it is a difficult problem to use the same carrier to load siRNA and drug simultaneously for combined therapy.In this study,the ordered mesoporous polymer nanospheres(MPNs)prepared by previous work were grafted with polyethyleneimine(PEI),cucurbituril [7] and folic acid(FA)in turn to achieve the modification and functionalization of ordered mesoporous polymer nanospheres.The modified and functionalized nanospheres could simultaneously load c-Myc siRNA and paclitaxel,thus forming a therapeutic system to achieve the purpose of combined therapy.In this study,modified MPNs(MPNs-PEI)were obtained by grafting PEI through MPNs.The positively charged MPNs-PEI could adsorb negatively charged c-Myc siRNA more effectively,and the c-Myc siRNA could be more inserted into the pores of mesoporous polymer nanospheres.And then MPNs-PCF was obtained by grafting both cucurbituril [7](CB[7])and a targeting molecule folic acid(FA)on MPNs-PEI.The hydrophobic drug paclitaxel could effectively enter the CB[7] cavity after grafting CB[7],thus realizing the loading of both c-Myc siRNA and paclitaxel.After grafting FA,the MPNs-PCF had a targeting function,and enabled it to actively target cancer cells.The degradability of MPNs-PCF in the presence or absence of enzymes and in different pH PBS buffers,and the ability to load siRNA and paclitaxel were investigated.The release ability of MPNs-PCF@siRNA/PTX in different pH PBS buffers was investigated.At the cytological level,the biocompatibility of MPNs-PCF@siRNA/PTX was qualitatively and quantitatively investigated by fluorescence microscopy and MTT assay;The cytotoxicity of MPNs-PCF@siRNA/PTX was investigated by MTT assay;The endocytosis and apoptosis effects of MPNs-PCF@siRNA/PTX were investigated by fluorescence microscopy and flow cytometry;The inhibition of mRNA and protein expression of MCF-7 breast cancer cells by MPNs-PCF@siRNA/PTX were investigated byRT-PCR and WB.In in vivo study,the MCF-7 tumor model was constructed,and the therapeutic effect of MPNs-PCF@siRNA/PTX was examined by both tumor inhibition assay and histopathological examination.The experimental results showed that the prepared MPNs-PEI has the advantages of uniform size,complete spherical shape and good dispersibility.The good biodegradability of MPNs-PCF proved that when it is applied to the body,it does not have a negative impact on the organism due to accumulation in the body.The results of release experiments showed that MPNs-PCF had high coverage and loading rate,and the coverage of siRNA and paclitaxel was as high as 94.38% and 92.07%.When the ratio of carrier to paclitaxel or siRNA was 1: 1,the loading rate of paclitaxel reached 49.51% while that of siRNA reached 44.51%,and the sustained release effect was good.The results of cell experiments showed that MPNs-PCF@siRNA/PTX had good biocompatibility,and MPNs-PCF could significantly reduce the IC50 value of the drug;The results of endocytosis experiments showed that MPNs-PCF@siRNA/PTX endocytosis was the most obvious;The apoptosis experiments showed that the apoptotic rates of MCF-7 cells,when MPNs-PC@siRNA/PTX and MPNs-PCF@siRNA/PTX were used,were 63.5% and83.5%,respectively.The results of RT-PCR and WB showed that the gene inhibition rate of MCF-7 cells,when MPNs-PC@siRNA/PTX was used,was as high as 82%,and the protein expression inhibition rate was 61%,much higher than that of the control group and showing good therapeutic effects.The animal experiments indicated that the tumor inhibition rate of MPNs-PC@siRNA/PTX experimental group was as high as 76.3%.Compared with the control group,the MPNs-PCF@siRNA/PTX experimental group prolonged the survival cycle of the nude mice,the body weight increased,and the tumor growth rate was slow.Histopathological results showed that the MPNs-PCF@siRNA/PTX experimental group had the least damage to the organs of the nude mice,and the tumor treatment effect was good.In summary,the targeted dual-load treatment system(MPNs-PCF@siRNA/PTX)that we constructed had an excellent therapeutic effect in the treatment of tumors.