TPGS修饰脂质体对阿霉素抗肿瘤活性的增敏作用

目的制备聚乙二醇1000维生素E琥珀酸酯(TPGS)修饰的阿霉素脂质体并考察其对阿霉素抗肿瘤活性的增敏作用。方法用阳离子树脂吸附法测定阿霉素脂质体的包封率;MTT法测定对MCF-7和MCF-7/ADR的毒性;用荧光显微镜观察阿霉素的细胞摄取,并用HPLC测定细胞内的阿霉素含量。结果 TPGS修饰的阿霉素脂质体增加了MCF-7/ADR对阿霉素的摄取,并增强了对MCF-7和MCF-7/ADR细胞的毒性。结论 TPGS修饰脂质体能显著增强MCF-7和MCF-7/ADR对阿霉素的敏感性。     

两种RGD肽修饰的新型阿霉素脂质体的体外表征

目的作为配体,肽对于多种受体显示出良好的靶向性,例如在肿瘤表面过度表达的整合素家族受体。本文主要研究和表征分别用精氨酸-甘氨酸-天冬氨酸(RGD)三肽和甘氨酸-精氨酸-甘氨酸-天冬氨酸-丝氨酸(GRGDS)五肽修饰的载药脂质体。方法分别采用RGD和GRGDS对包载阿霉素的立体稳定脂质体(SSL-doxorubicin)进行修饰,以制备RGD-SSL-doxorubicin和GRGDS-SSL-doxorubicin。在体外表征试验中,测定了各种脂质体的包封率、粒径、Zeta电位和释放率,采用SRB试验研究了各脂质体对卵巢癌细胞的细胞毒作用,并应用流式细胞仪和共聚焦显微镜考察了肿瘤细胞对各脂质体包封的阿霉素的摄取情况。结果所有脂质体的包封率均在95%以上,采用RGD或GRGDS进行的修饰并未影响长循环脂质体的包封率。各种脂质体的平均粒径在105.7±3.5nm和130.5±3.0nm之间,Zeta电位在–3.3±0.3和–6.1±0.3mV之间,在模仿体内环境的释放介质(含胎牛血清)中,12小时内约有2/5的阿霉素从脂质体中释放。与游离阿霉素相比,修饰后的脂质体对肿瘤细胞的抑制率略有下降;在研究对阿霉素摄取的流式细胞试验和共聚焦试验中,也有类似现象出现。将各种脂质体分别加入肿瘤细胞后,阿霉素主要分布于SKOV-3的细胞核。结论本研究成功制备了两种分别用精氨酸-甘氨酸-天冬氨酸(RGD)三肽和甘氨酸-精氨酸-甘氨酸-天冬氨酸-丝氨酸(GRGDS)五肽修饰的阿霉素脂质体。体外表征结果显示,该修饰不会显著改变立体稳定脂质体的性质。     

NGR多肽修饰的9-硝基喜树碱隐形脂质体药剂学性质与抗肿瘤作用研究

目的 考察NGR修饰前后9-硝基喜树碱(9-nitrocamptothecin,9-NC)隐形脂质体的药剂学性质与抗肿瘤作用。方法 采用薄膜-超声化法制备NGR修饰9-NC隐形脂质体,以未经NGR修饰的隐形脂质体作对照,考察包封率、体外释放度、内酯稳定性等药剂学性质;以HT1080为细胞模型,MTT法考察NGR修饰与未修饰9-NC隐形脂质体对细胞生长的影响,流式细胞实验比较NGR修饰与未修饰组的入胞效率。结果 NGR修饰对9-NC隐形脂质体的药剂学性质没有显著影响。修饰后的9-NC隐形脂质体对HT1080细胞的抑制率明显高于未修饰组(P<0.05),流式细胞实验显示修饰后的脂质体入胞效率显著提高。结论 NGR修饰能够显著提高9-NC隐形脂质体的抗肿瘤效果和入胞效率。     

新型阿霉素隐形阳离子脂质体的制备及体外细胞实验

目的制备阿霉素隐形阳离子脂质体(DOX-SCL),并与中性脂质体(DOX-SNL)比较在体外小鼠乳腺癌4T1细胞实验上的差异。方法采用薄膜超声法制备空白脂质体,硫酸铵梯度法包载盐酸阿霉素(DOX);引入赖氨酸-胆固醇酯(Chol-lys)制成阳离子脂质体(CL),同时引入聚乙二醇-胆固醇琥珀酸酯(CHEMS-PEG)制成隐形阳离子脂质体(SCL);采用凝胶柱-UV法测定包封率;采用MTT法测定细胞毒性及体外抗肿瘤活性;通过流式细胞试验考察4T1细胞对脂质体的摄取情况。结果 SCL粒径约为100 nm,Zeta电位约为15.2 mV,对DOX的包封率大于95%;CHEMS-PEG的引入可以有效地降低CL的细胞毒性;与DOX-SNL相比,4T1细胞对DOX-SCL的摄取有所增加,DOX-SCL对4T1细胞的抑制率也更高。结论 SCL作为新型药物载体,可有效地促进DOX在肿瘤细胞中的传递。     

靶向肿瘤新生血管的阿霉素阳离子脂质体的体外研究

本研究采用3β-［N-(N′,N′-二甲基胺乙基)胺基甲酰胺基］胆固醇(DC-Chol)和二棕榈酰磷脂酰胆碱为脂材制备了各种DC-Chol含量不同的阿霉素阳离子脂质体，考察了阿霉素阳离子脂质体的体外性质，同时以大鼠主动脉内皮细胞为模型，考察它们对不同阳离子脂质体的摄取情况，并采用静脉注射FITC-Dextran(M_r 500 000)标记体内肿瘤新生血管，为体内靶向肿瘤血管提供依据。结果表明阿霉素阳离子脂质体包封率均在90%以上，粒径在100~200 nm。随着DC-Chol含量的增加，zeta电位升高，但PEG的加入会降低zeta电位。DC-Chol含量的增加会增大阿霉素的释放量，同时也促进脂质体被内皮细胞的摄取，加快摄取速度。因此在进行体内靶向肿瘤血管考察时应充分关注这些体外实验结果。FITC-Dextran标记法可以显影体内新生血管，为体内肿瘤血管靶向实验提供直观的观察方法。     

新型阿霉素抗耐药性隐形脂质体的体外细胞毒和体内毒性研究

目的多药耐药(multidrug resistance,MDR)是目前临床肿瘤治疗的主要障碍。本文研制了新型阿霉素抗耐药性隐形脂质体(DARSLs)，并对其体外细胞毒和体内毒性进行评价。方法采用硫酸铵梯度法将阿霉素(DOX)和维拉帕米(VER)药物同时包载到隐形脂质体内，制备成DARSLs；采用耐药性鼠前列腺肿瘤细胞株MLLB2和人子宫肉瘤细胞株MES-SA/DX5进行体外细胞毒性评价；采用SD大鼠对阿霉素抗耐药性隐形脂质体进行体内毒性评价。结果在药脂比(DOX/VER/Lipid，w/w/w)为1∶0.11∶10时，阿霉素包封率大于90%，维拉帕米包封率约为70%。平均粒径为(118.1±22.3) nm。体外细胞毒性实验证实该脂质体能够在体外有效地逆转肿瘤细胞耐药性，并导致耐药肿瘤细胞生长抑制。体内系统毒性及心脏毒性实验结果显示，该脂质体能够明显改善游离阿霉素单独使用或与维拉帕米联合使用时产生的全身毒性，尤其是心脏毒性。结论DARSLs具有相对较低的毒性，且能有效抑制耐药肿瘤的生长。     

紫杉醇隐形脂质体的制备及在小鼠体内的组织分布

目的　研究紫杉醇隐形脂质体的制备方法并考察其在小鼠体内的组织分布。方法　采用共沉淀和微流态化两步法制备紫杉醇隐形脂质体,用两亲性聚乙二醇-二硬脂酰磷脂酰乙醇胺(PEG-DSPE)修饰脂质体膜。以RP-HPLC法测定小鼠组织内紫杉醇药物浓度。结果　隐形脂质体粒径≤100 nm,药物包封率≥98%。均以5 mg.kg^-1经iv脂质体紫杉醇和游离紫杉醇,24 h后紫杉醇隐形脂质体在血液中驻留35%以上,在肝脾组织中摄取不足10%。而膜材中不含PEG-DSPE的紫杉醇传统脂质体在血液中驻留10%,被单核吞噬细胞系统(mononuclear phagocyte system, MPS)捕获了50%以上。证明紫杉醇隐形脂质体延长了在血循环中的时间并减少了MPS的吞噬。血液AUC隐形脂质体约为传统脂质体的2.0倍。结论　采用共沉淀和微流态化法可制得包封率高、粒径小的脂质体,用PEG-DSPE修饰磷脂膜可以增加隐形脂质体的AUC,并延长其在血循环中的时间。     

双配体修饰的阿霉素脂质体靶向于脑胶质瘤的体外研究

目的筛选和优化转铁蛋白、叶酸共同修饰的阿霉素脂质体的处方及制备工艺,以期得到具有良好的脑胶质瘤靶向治疗作用的给药系统。方法采用薄膜分散和硫酸铵梯度法制备阿霉素脂质体。将叶酸连接至二硬脂酸磷脂酰乙醇胺-聚乙二醇2000(DSPE-PEG2000-NH2)得到DSPE-PEG2000-Folic,考察不同磷脂种类、药脂比、水化介质和载药时间,对脂质体粒径、包封率和稳定性的影响,确定脂质体的处方工艺。以大鼠的脑毛细血管内皮细胞(bEnd3)和星形胶质细胞组成体外血脑屏障(blood-brain barrier,BBB),并结合大鼠胶质瘤C6细胞,构建体外模拟胶质瘤靶向治疗的复合BBB模型。考察阿霉素脂质体在bEnd3细胞中的摄取机制和透过BBB的转运速率及对C6细胞的毒性。结果确定了DSPC作为主要磷脂组分,并以120 mmol.L 1的硫酸铵作为水化介质,药脂比为1∶1 5,载药时间选择60 min,成功制备了高包封率和稳定性的双配体脂质体。其在bEnd3细胞中摄取远大于普通脂质体(P<0.05),摄取过程受网格蛋白和小窝内陷介导的细胞内吞作用,并受转铁蛋白和叶酸的影响;同时其在BBB模型中的药物透过速率、及其进一步透过BBB后对下层C6细胞的毒性,均显著高于其他脂质体组。结论转铁蛋白和叶酸共同修饰的阿霉素脂质体具有较好的体外脑胶质瘤靶向治疗作用。     

LHRHa与八聚精氨酸共修饰载氟尿嘧啶靶向脂质体的构建及其抗前列腺癌作用

目的 构建促黄体激素释放激素类似物(LHRHa)与八聚精氨酸(R8)共修饰载氟尿嘧啶(5-FU)脂质体(LHRHa/R8-LP-5-FU),对其前列腺癌靶向性以及治疗效果进行初步研究.方法 采用薄膜分散法制备LHRHa/R8-LP-5-FU,考察其形态、粒径、电位,并通过PC-3前列腺癌细胞定性和定量摄取实验考察其前列腺癌细胞靶向性.采用噻唑蓝(MTT)实验以及肿瘤球实验考察LHRHa/R8-LP-5-FU对PC-3细胞增殖抑制率.结果 所制备LHRHa/R8-LP-5-FU粒径为(115.0±15.2) nm,电位为(11.00±2.15) mV,5-FU的包封率(84.5±5.1)％.体外细胞摄取实验表明,PC-3细胞对LHRHa/R8-LP摄取效率分别是R8修饰脂质体(R8-LP)和LHRHa修饰脂质体(LHRHa-LP) 2.8和3.2倍(P＜0.01).细胞毒性实验结果显示,以0.9％氯化钠溶液为对照,LP-5-FU、R8-LP-5-FU、LHRHa-LP-5-FU和LHRHa/R8-LP-5-FU对PC-3细胞的增殖抑制率分别为(26.4±4.5)％,(39.5±4.2)％,(48.6±3.5)％和(82.5±4.3)％(P＜0.01).LHRHa/R8-LP-5-FU对肿瘤球的生长抑制作用明显高于其他脂质体.细胞毒性实验结果与细胞摄取实验结果一致.结论 LHRHa与细胞穿膜肽共修饰载5-FU脂质体具有良好的前列腺肿瘤细胞靶向性和抗肿瘤作用,是一种潜在的治疗前列腺癌的高效给药系统.     

葡萄糖受体靶向的钆喷酸葡胺长循环脂质体的肿瘤细胞靶向研究

目的：制备葡萄糖受体靶向的钆喷酸葡胺（GdDTPA）长循环脂质体，并研究其对高表达葡萄糖受体肿瘤细胞的靶向性。方法：合成新型含葡萄糖表面活性剂（N-棕榈酰葡萄糖胺），利用逆向蒸发法制备Gd—DTPA脂质体、PEG修饰Gd—DTPA脂质体、葡萄糖修饰Gd-DTPA脂质体以及葡萄糖PEG修饰GdDTPA脂质体。将4种脂质体分别与前列腺癌细胞一起培养，用MRI检测前列腺癌细胞摄取的Gd-DTPA浓度。结果：成功合成新型含葡萄糖表面活性荆（N棕榈酰葡萄糖胺），以及制备4种Gd-DTPA脂质体。前列腺癌细胞对4种脂质体都有摄取，每种脂质体MRI检测的SBTIW信号值分别为Gd-DTPA脂质体362、PEG修饰Gd-DTPA脂质体299、葡萄糖修饰GdDTPA脂质体397、葡萄糖PEG修饰GdDTPA脂质体377。结论：葡萄糖的修饰有利于脂质体对肿瘤细胞的靶向。     

Enhanced Intracellular Uptake of Sterically Stabilized Liposomal Doxorubicin <Emphasis Type="Italic">in Vitro</Emphasis> Resulting in Improved Antitumor Activity <Emphasis Type="Italic">in Vivo</Emphasis>

Purpose To investigate the correlation between the in vitro intracellular uptake and the in vivo antitumor activity of anticancer drugs delivered by sterically stabilized liposomes (SSL).Methods Arginine-glycine-aspartic acid (RGD) peptide or RGD mimetic (RGDm) was coupled onto the surface of SSL to obtain the cell-binding carrier to facilitate the intracellular delivery of the encapsulated drugs. DOX-loaded SSL (SSL-DOX), DOX-loaded RGD-modified SSL (RGD-SSL-DOX) and DOX-loaded RGDm-modified SSL (RGDm-SSL-DOX) were prepared by lipid film dispersion followed by remote loading of DOX. The intracellular uptake of DOX from the various liposomal formulations was evaluated in vitro with melanoma B16 cells, and the pharmacokinetics, biodistribution, and antitumor activity were compared in C57BL/6 mice carrying melanoma B16 tumors.Results In vitro intracellular uptake of DOX by B16 cells and in vivo antitumor activity in terms of tumor growth inhibition and mice survival time prolongation for various liposomal DOX were in the following order: RGD-SSL-DOX > RGDm-SSL-DOX > SSL-DOX. The mean survival time of the mice treated with RGD-SSL-DOX, RGDm-SSL-DOX, and SSL-DOX was 55, 49, and 44 days, respectively. The three liposomal DOX formulations produced very close DOX accumulation in tumor, which is significantly higher than that of free DOX. RGD- or RGDm-SSL-DOX demonstrated prolonged circulation time similar to that of SSL-DOX, whereas they showed significantly lower DOX level in blood and remarkably higher uptake by spleen than SSL-DOX.Conclusions Enhanced intracellular uptake of DOX encapsulated in SSL could produce an improved therapeutic effect for the melanoma B16 tumors. Enhancing intracellular delivery of the anticancer drugs encapsulated in SSL may be a promising strategy to improve their therapeutic efficacy for solid tumors.     

Intracellular delivery of doxorubicin with RGD-modified sterically stabilized liposomes for an improved antitumor efficacy: in vitro and in vivo

Passive targeting by sterically stabilized liposomes (SSL), once combined with efficient intracellular delivery, may be a very useful strategy to improve the antitumor efficacy for the anticancer agents. The arginine-glycine-aspartic acid tripeptide (RGD) is known to serve as a recognition motif for several different integrins located on cell surface. In this study, the RGD tripeptide was coupled to the distal end of the poly (ethylene glycol)-coated liposomes (RGD-SSL) aimed to achieve increased tumor accumulation and enhanced intracellular uptake. DOX-loaded RGD-SSL (RGD-SSL-DOX), DOX-loaded SSL (SSL-DOX), and free DOX were compared with respect to their in vitro uptake and cytotoxicity and their in vivo biodistribution and therapeutic efficacy in tumor-bearing mice. Flow cytometry and confocal microscopy studies revealed that RGD-SSL could facilitate the DOX uptake into melanoma cells by integrin-mediated endocytosis. RGD-SSL-DOX displayed higher cytotoxicity on melanoma cells than SSL-DOX. While RGD-SSL-DOX demonstrated prolonged circulation time and increased tumor accumulation as SSL-DOX did, it showed remarkably higher splenic uptake than SSL-DOX. Mice receiving RGD-SSL-DOX (5 mg DOX/kg) showed effective retardation in tumor growth compared with those receiving same dose of SSL-DOX, free DOX solution, or saline. These results suggest that RGD-modified SSL may be a feasible intracellular targeting carrier for efficient delivery of chemotherapeutic agents into tumor cells.     

RGD-modified polymeric micelles as potential carriers for targeted delivery to integrin-overexpressing tumor vasculature and tumor cells

Integrins αvβ3 and αvβ5 are overexpressed in angiogenic tumor endothelial cells and malignant tumor cells, making them attractive targets for cancer therapy. In this study, an integrin αvβ3 and αvβ5 binding tripeptide, RGD (Arg-Gly-Asp), was conjugated with the surface of poly(ethylene glycol)–block–poly(d,l-lactide) (PEG–PLA) micelles. A lipophilic fluorescent probe, DiI, was loaded into both the nontargeted methoxy PEG–PLA (mPEG–PLA) micelles and the targeted RGD-modified PEG–PLA micelles. The DiI-loaded targeted micelles had a size of 24.2?nm. The targeted micelles were stable in phosphate buffered saline and exhibited a negligible leakage in culture medium. Transmission electron microscopy analysis showed that targeted micelles were spherical in shape. Cell uptake of DiI-labeled targeted micelles by human umbilical vein endothelial cells and melanoma B16 cells was investigated by spectrophotofluorometry and confocal microscopy techniques. Results revealed that RGD-modified micelles significantly facilitated the intracellular delivery of the encapsulated agents via integrin-mediated endocytosis. This study suggests that RGD-modified PEG–PLA micelles are promising drug carriers for targeted delivery to both angiogenic tumor endothelial cells and tumor cells and that the targeted micelles may be attractive carriers for combination cancer therapy against both targets.     

Antitumor activity of new liposomal prodrug of mitomycin C in multidrug resistant solid tumor: insights of the mechanism of action

The antitumor activity of a novel thiolytically cleavable lipid-based prodrug of mitomycin C (MMC) delivered by STEALTH liposomes (SL) was studied in drug resistant human ovarian carcinoma A2780/AD model and compared with free MMC and both free and SL forms of an established anticancer drug--doxorubicin (DOX). It was found that SL-prodrug (SL-pMMC) possessed enhanced antitumor activity when compared with the parent MMC, free DOX, and SL-DOX. An observance of the high antitumor efficiency of SL-pMMC was a result of its preferential accumulation in the tumor by the enhanced permeability and retention (EPR) effect, suppression of multidrug resistance (MDR) associated with P-glycoprotein and MRP drug efflux pumps, activation of caspase-dependent apoptosis signaling pathways and suppression of antiapoptotic cellular defense by increasing the BAX/BCL2 ratio. Consequently, the described SL-pMMC formulations can be considered good candidates for the chemotherapy of multidrug resistant tumors.     

Antitumor activity of new liposomal prodrug of mitomycin C in multidrug resistant solid tumor: Insights of the mechanism of action

The antitumor activity of a novel thiolytically cleavable lipid-based prodrug of mitomycin C (MMC) delivered by STEALTH® liposomes (SL) was studied in drug resistant human ovarian carcinoma A2780/AD model and compared with free MMC and both free and SL forms of an established anticancer drug—doxorubicin (DOX). It was found that SL-prodrug (SL-pMMC) possessed enhanced antitumor activity when compared with the parent MMC, free DOX, and SL-DOX. An observance of the high antitumor efficiency of SL-pMMC was a result of its preferential accumulation in the tumor by the enhanced permeability and retention (EPR) effect, suppression of multidrug resistance (MDR) associated with P-glycoprotein and MRP drug efflux pumps, activation of caspase-dependent apoptosis signaling pathways and suppression of antiapoptotic cellular defense by increasing the BAX/BCL2 ratio. Consequently, the described SL-pMMC formulations can be considered good candidates for the chemotherapy of multidrug resistant tumors.     

RGD-modified PEG–PAMAM–DOX conjugates: In vitro and in vivo studies for glioma

This work was based on our recent studies that a promising conjugate, RGD-modified PEGylated polyamidoamine (PAMAM) dendrimer with doxorubicin (DOX) conjugated by acid-sensitive cis-aconityl linkage (RGD-PPCD), could increase tumor targeting by binding with the integrin receptors overexpressed on tumor cells and control release of free DOX in weakly acidic lysosomes. To explore the application of RGD-PPCD to glioma therapy, the effects of the conjugate were further evaluated in glioma model. For comparative studies, DOX was also conjugated to PEG–PAMAM by acid-insensitive succinic linkage to produce the PPSD conjugates, which was further modified by RGD to form RGD-PPSD. In vitro cytotoxicity of the acid-sensitive conjugates against C6 cells was higher than that of the acid-insensitive ones, and further the modification of RGD enhanced the cytotoxicity of the DOX-polymer conjugates as a result of the increased cellular uptake of the RGD-modified conjugates by C6 cells. In vivo pharmacokinetics, biodistribution and antitumor activity were investigated in an orthotopic murine model of C6 glioma by i.v. administration of DOX-polymer conjugates. In comparison with DOX solution, all the conjugates showed significantly prolonged half-life and increased AUC and exhibited higher accumulation in brain tumor than normal brain tissue. Although RGD-PPCD was more than 2-fold lower tumor accumulation than RGD-PPSD, it exhibited the longest survival times among all treatment groups, and therefore, RGD-PPCD conjugate provide a desirable candidate for targeted therapy of glioma.     

Comparing cellular uptake and cytotoxicity of targeted drug carriers in cancer cell lines with different drug resistance mechanisms

The purpose of this study was to compare the cellular uptake and cytotoxicity of targeted and nontargeted doxorubicin (DOX)-loaded poly(d,l-lactide co-glycolide) (PLGA) nanoparticle (NP) drug delivery systems in drug-resistant ovarian (SKOV-3) and uterine (MES-SA/Dx5) cancer cell lines. The cellular uptakes of DOX from nonconjugated DOX-loaded NPs (DNPs) and from HER-2 antibody-conjugated DOX-loaded NPs (ADNPs) in MES-SA/Dx5 cancer cells were higher compared to free DOX. Results also showed higher uptake of DOX from ADNPs in SKOV-3 cells compared with both free DOX and DNPs treatment. Cytotoxicity results at 10 μM extracellular DOX concentration were consistent with the cellular uptake results. Our study concludes that cellular uptake and cytotoxicity of DOX can be improved in MES-SA/Dx5 cells by loading DOX into PLGA NPs. DNPs targeted to membrane receptors may enhance cellular uptake and cytotoxicity in SKOV-3 cells. FROM THE CLINICAL EDITOR: The authors of this study compare the cellular uptake and cytotoxicity of targeted and nontargeted doxorubicin loaded PLGA nanoparticle delivery systems in drug-resistant ovarian and uterine cancer cell lines, concluding that cellular uptake and cytotoxicity of doxorubicin can be improved by the proposed methods.     

Estrogen-anchored pH-sensitive liposomes as nanomodule designed for site-specific delivery of doxorubicin in breast cancer therapy

The present investigation reports the development of nanoengineered estrogen receptor (ER) targeted pH-sensitive liposome for the site-specific intracellular delivery of doxorubicin (DOX) for breast cancer therapy. Estrone, a bioligand, was anchored on the surface of pH-sensitive liposome for drug targeting to ERs. The estrone-anchored pH-sensitive liposomes (ES-pH-sensitive-SL) showed fusogenic potential at acidic pH (5.5). In vitro cytotoxicity studies carried out on ER-positive MCF-7 breast carcinoma cells revealed that ES-pH-sensitive-SL formulation was more cytotoxic than non-pH-sensitive targeted liposomes (ES-SL). The flow cytometry analysis confirmed significant enhanced uptake (p < 0.05) of ES-pH-sensitive-SL by MCF-7 cells. Intracellular delivery and nuclear localization of the DOX was confirmed by fluorescence microscopy. The mechanism for higher cytotoxicity shown by estrone-anchored pH-sensitive liposomal-DOX was elucidated using reactive oxygen species (ROS) determination. The in vivo biodistribution studies and antitumor activities of formulations were evaluated on tumor bearing female Balb/c mice followed by intravenous administration. The ES-pH-sensitive-SL efficiently suppressed the breast tumor growth in comparison to both ES-SL and free DOX. Serum enzyme activities such as LDH and CPK levels were assayed for the evaluation of DOX induced cardiotoxicity. The ES-pH-sensitive-SL accelerated the intracellular trafficking of encapsulated DOX, thus increasing the therapeutic efficacy. The findings support that estrone-anchored pH-sensitive liposomes could be one of the promising nanocarriers for the targeted intracellular delivery of anticancer agents to breast cancer with reduced systemic side effects.     

A new peptide ligand for colon cancer targeted delivery of micelles

Abstract

Ligands are an imperative part of targeted drug delivery systems, and choosing a ligand with high affinity is a subject of considerable interest. In this study, we first synthesized a 12-residue peptide (TK) that interacts with integrin α₆β₁ overexpressed on colonic cancer cells. The molecular binding affinity assay indicated that TK had a high binding affinity for integrin α₆β₁. The results of cellular and tumor spheroid uptake suggested that TK peptide not only increases Caco-2 cells uptake, but also effectively increases penetration of the tumor spheroids. TK-conjugated PEG-PLA was synthesized to prepare a novel PEG-PLA micelles loading DOX or coumarin-6 (TK-MS/DOX or TK-MS/C6). The obtained TK-MS/DOX exhibited uniform, spherical shape with a size of 23.80?±?0.32?nm and zeta potential of 12.21?±?0.31 mV. The release behavior of DOX from micelles were observed no significant changes after TK modification, however, the release profile exhibited pH-sensitive properties. Compared with MS/DOX, TK-MS/DOX exhibited significantly stronger cytotoxicity for Caco-2. Confocal laser microscopy and flow cytometry data further indicated that the targeting micelles not only had higher uptake by Caco-2 cells, but also more effectively penetrated the tumor spheroids. Therefore, TK peptide appears to be suitable as a targeting ligand with potential applications in colonic targeted therapy.     

Enhanced antitumor effect of targeted nanoliposomal bleomycin

Folate receptor (FR)‐mediated drug delivery is a promising approach for active targeting of drugs to the FR‐positive tumor cells. Bleomycin (BLM) is an antitumor antibiotic with poor therapeutic activity as a result of its limited diffusion into tumor cells. The aim of this study was to investigate whether FR‐targeted PEGylated nanoliposomes (FPNL) can effectively deliver BLM to tumor cells and enhance its in vitro and in vivo efficacy. FPNL and PNL (non‐targeted) were prepared by thin film hydration method, and their physiochemical properties, cellular uptake, tissue distribution and tumor inhibitory effects were investigated. In Lewis lung cancer (LLC1) cells, FPNL containing BLM showed 2.38‐fold and 3.26‐fold higher cytotoxicity compared to PNL‐BLM and free BLM, respectively. Moreover, the uptake of FPNL by these cells was increased as compared to the PNL. Furthermore, FPNL showed significantly higher tumor distribution of BLM in the LLC1 cells and more tumor inhibition efficacy compared to free BLM and PNL. Both formulations of nanoliposomes had longer plasma half‐life than that of free BLM. Therefore, FPNL may be suitable carriers for targeted drug delivery to FR‐positive tumor cells.