| Background: Anaplastic thyroid carcinoma(ATC)accounts for 2% of all thyroid cancers.However,its 5-year survival rate was less than 10% due to its strong aggressiveness and non-iodine-concentrating characteristic.Mesoporous silica nanoparticles(MSNs)drug delivery system can enhance the targeting of anti-tumor drugs and delay the release of drugs,thereby has been widely used in the targeted therapy of cancer.By reviewing the literature,we found that VEGF(vascular endothelial growth factor)expression is closely related to tumorigenesis.Additionally,VEGF receptor(VEGFR)was overexpressed in ATC and anti-VEGFR targeted drugs can prolong the survival time of cancers,including ATC.At present,however,in the treatment of ATC,the reports on dual-targeted therapy(internal irradiation and anti-tumor drugs)to ATC via 131I-labeled and drug loaded nanoparticles are rare.Objective: To observe the radioactive distribution of 131I-labeled anti-VEGFR2-targeted multi-functional MSNs(131I-BSA-MSNs-anti-VEGFR2)in a ATC tumor-bearing nude mouse model and explore its antitumor efficacy when loading 17-AAG and Torin2.Methods:(1)The corresponding nanoparticles were constructed,including MSNs,BSA-MSN,BSA-MSNs-anti-VEGFR2 and BSA-MSN(17-AAG+Torin2).The size and morphology of the nanoparticles was determined by dynamic light scattering(DLS)and transmission electron microscope(TEM),respectively.The standard curves of 17-AAG and Torin2 were established.The drug loading efficiency(DLE)and drug entrapment efficiency(DEE)of MSNs were obtained by fitting equation.Additionally,BSA-MSNs was radiolabeled with 131 I by the Chloramine-T method.(2)The interaction between 17-AAG and Torin2 was analyzed by MTS experiments.The targeted binding of MSN and MSNs-anti-VEGFR2 in ARO and FRO cells of the two ATC cell lines were observed using fluorescence confocal microscopy.The cellular uptake of Na131 I,131I-BSA-MSN or 131I-BSA-MSNs-anti-VEGFR2 was determined by 131 I cell-ingested experiment to observe the nanoparticles in the intracellular retention time.(3)In vivo experiments,FRO tumor xenografts were induced in the right shoulder of the mice.131I-BSA-MSNs(17-AAG+Torin2)-anti-VEGFR2(targeted +drug-loaded group),131I-BSA-MSNs-anti-VEGFR2(targeted group),131I-BSA-MSN(non-targeted group),Na131 I group and normal saline(control group)were administrated via intratumoral injection.The scintigraphic imaging was performed to observe the radioactivity distribution at different time by SPECT/CT.Percent injected dose per gram of tissue(% ID/g)in the normal organs and tumor of Na131 I,targeted,and non-targeted groups were recorded at 24 h and 72 h after injection.Using body weight and tumor volume before injection as a reference,the changes of body weight and tumor volume during the observation period(30 days)in each group were also recorded.Survival analysis was calculated using Kaplan-Meier curves.At the end of the experiment,the histopathological examination was performed on the major organs and tumor in nude mice.In addition,VEGFR2 expression of the tumor in the control group was detected by immunohistochemistry.Results:(1)MSNs,BSA-MSNs,BSA-MSNs-anti-VEGFR2 and BSA-MSNs(17-AAG+Torin2)-anti-VEGFR2 were successfully constructed.The nanoparticles were spherical,and all have a regular shape.The particle size distribution was narrow,the average particle size of the nanoparticles was 108,139,163 and 159 nm,respectively,and the average zeta potential was-23.91,45.53,28.45 and-1.83 m V,respectively.The DLE of BSA-MSNs-anti-VEGFR2 to 17-AAG and Torin2 was 7% and 6%,respectively,and the DEE was 87% and 85%,respectively.The rate of 131 I labeling was approximately 50%–75%,and radiochemical purity 95%-98%.(2)In vitro experiments,Cytotoxicity assay showed that the inhibitory rate of ATC cells increased with the increasing of concentration of 17-AAG and Torin2(0.1-5μM).However,the inhibitory rate tended to be gentle when the concentration was higher than 1μM.When 17-AAG and Torin2 were incubated with cells for 48 hours and the ratio of two drugs was 1: 1 or 2: 1,the cytotoxicity to ATC cells was similar(IC50 was 0.33 μM and 0.26 μM,respectively).Fluorescence confocal microscopy results showed that both MSNs-anti-VEGFR2 and MSNs were significantly phagocytosed by FRO and ARO tumor cells.The uptakes of FRO and ARO cells to 131I-labeled nanoparticles showed a dynamic change via 131 I cell-ingested quantitative experiment.After 3 hours of incubation,the radioactive uptake in the targeted group was higher than that in non-targeted one(all P<0.01).(3)In vivo experiments,SPECT/CT revealed that the radioactivity of the tumor in the targeted group was stronger than that in the non-targeted group at 1-3 weeks after injection(t values were 8.81,7.06 and 12.78,respectively,P<0.05).Tissue distribution experiments showed that the uptake rates at 24 h and 72 h(32.2 ± 2.8% ID/g,23.0 ± 1.8% ID/g)were significantly higher than those in the non-target group(26.1 ± 2.5% ID / g,12.3 ± 1.2 % ID/g)(t = 2.81,8.57,P = 0.04 and 0.001 respectively).At 30 days of the treatment,(1)The tumor volumes of Na131 I,control and non-targeted groups increased to 395.0±22.5%,405.0± 24.1% and 198.7±13.2%,compared with the baseline,respectively.No significant change was observed in the targeted group(101.1 ± 2.4%),whereas the volume of tumor in the targeted +drug-loaded group decreased to 94.1 ± 8.2%;(2)The body weight of nude mice in the Na131 I and control groups decreased to 88.6 ± 3.0% and 86.2 ± 3.1%,respectively,and no change was observed in the non-targeted group(102.1 ± 3.1%).Moreover,the body weight of nude mice in the targeted and the targeted +drug-loaded groups increased to 116.2±3.4% and 123.1±3.2% compared with the baseline;(3)Survival analysis showed that median survival time was 27,25,34,38,and 46 days for the above groups,respectively,and log-rank analysis showed that the median survival time was longer in the drug-loaded and targeted groups than that in the non-targeted group(P <0.001,0.0047,respectively),and which was longer in the drug-loaded group than that in the targeted group(P <0.001);(4)Pathological HE staining showed no significant abnormality was found in the main organs(heart,liver,spleen,kidney and lung)of nude mice after treatment;while the tumor tissues in the non-targeted,targeted and drug-loaded groups showed degeneration and massive necrosis,which was more obvious in the targeted and drug-loaded groups.Immunohistochemistry confirmed a high expression of VEGFR2 in the tumor cells.Conclusion: The 131I-BSA-MSNs-anti-VEGFR2 and 131I-BSA-MSNs can inhibit ATC tumor growth,and 131I-BSA-MSNs(17-AAG+Torin2)-anti-VEGFR2 can prolong the survival of tumor-bearing nude mice more effectively and such an approach may represent a novel therapeutic option for ATC. |
PDF Full Text Request