Treatment of lung cancer via telomerase inhibition: self-assembled nanoplexes versus polymeric nanoparticles as vectors for 2'-O-Methyl-RNA

Antisense oligonucleotide, 2'-O-Methyl-RNA (OMR), is known as potent telomerase inhibitor for the treatment of lung cancer but limited by poor intracellular uptake. Chitosan-coated polymeric nanoparticles were compared to chitosan solution as non-viral vectors for OMR. The study investigated the role of chitosan properties and concentration in improving the efficiency of the nanocarriers in terms of loading, viability, cellular uptake, and telomerase inhibition in human lung cancer cell lines. Certain concentration of chitosan on nanoparticle surface is necessary to significantly increase the cellular uptake. However, excessive chitosan negatively affected the transfection efficiency. Self-assembled nanoplexes with chitosan polymer are preferentially adsorbed to the cell membrane rather than being internalized. Thus, polymeric nanoparticles proved to be superior to cationic polymers as carrier for antisense oligonucleotides. Charge cannot be considered the principle factor behind improved transfection. Uptake studies carried out on air-interface cell cultures to mimic in vivo conditions supported the results on normal cultures showing enhanced uptake of nanoplexes over naked oligonucleotides. OMR nanoplexes reduced telomerase activity by ～50% in A549 cells concluding the potential of the system as a safe, non-invasive, and efficient treatment for lung carcinoma. These data are prerequisites for the ongoing studies on lung perfusion model and in vivo experiments.     

The influence of chitosan content in cationic chitosan/PLGA nanoparticles on the delivery efficiency of antisense 2′-O-methyl-RNA directed against telomerase in lung cancer cells

Tailorable cationic chitosan/PLGA nanoparticles (CPNP) were used for the delivery of an antisense 2′-O-methyl-RNA (2OMR) directed against RNA template of human telomerase. Here, we describe the influence of the chitosan content on binding efficiency, complex stability, uptake in different human lung cell types and finally demonstrate the efficacy of this nanoplex system.CPNPs were prepared by the emulsion-solvent evaporation method using different amounts of chitosan and purified by preparative size exclusion chromatography. The characterization by photon correlation spectroscopy and zeta potential measurements showed a small increase in size and an increase of zeta potential with increasing amounts of chitosan. Binding efficiency and complex stability with 2OMR was high in water and correlated well with the chitosan content of particles but was weak in physiologically relevant media (PBS and RPMI cell culture medium). However, flow cytometry analysis showed that the uptake of 2OMR into A549 lung cancer cells was considerably higher in combination with nanoparticles and dependent on the amount of chitosan when compared to 2OMR alone. Confocal laser scanning microscopy revealed that the uptake into A549 cells is mediated via complexes of 2OMR and chitosan/PLGA nanoparticles despite the weak binding in cell culture medium. The nanoparticles were well tolerated and efficient in inhibiting telomerase activity.     

Targeting human telomerase by antisense oligonucleotides and ribozymes

Human telomerase is a ribonucleoprotein enzyme complex that enables cells to maintain telomere length, allowing indefinite replicative capacity. The notion that telomerase is reactivated in 80-90% of human cancers has led to the proposal of telomerase as a promising therapeutic target for novel anticancer interventions. Due to its inherent accessibility to nucleic acids, telomerase appears an ideal target for strategies based on the use of antisense oligonucleotides and ribozymes that target its RNA template. In this review a summary of the different antisense- and ribozyme-based approaches used thus far to inhibit telomerase activity in human cancer cells is provided. All these strategies significantly inhibited the enzyme's catalytic activity in in vitro and in vivo tumor models. However, while in some studies tumor cell growth arrest was observed as a consequence of telomere shortening after prolonged telomerase inhibition, other studies have shown that antisense- and ribozyme-based treatments targeting telomerase induced rapid loss (i.e. within a few days) of tumor cell viability with concomitant apoptosis. In the latter case it is unlikely that cell death was related to telomere erosion since the cells would not have undergone enough divisions to significantly shorten their telomeres. A possible explanation is that telomerase inhibitors may induce apoptosis in cancer cells directly by interfering with the capping function of the enzyme. Overall, the available results indicate antisense oligonucleotides and ribozymes as good tools to inhibit telomerase and suggest that abrogation of telomerase activity may affect tumor cell proliferation also through pathways that are not dependent on telomere erosion.     

DNA/Lipid complex incorporated with fibronectin to cell adhesion enhances transfection efficiency in prostate cancer cells and xenografts

Previously we have described the development and applications of lipid-based nanoparticles for gene delivery vector. In an attempt to improve transfection efficiency using the cell adhesion of extracellular matrix (ECM) to DNA/lipid complex (nanoplex), the mRNA expression of integrin alpha2beta1 and CD44 in prostate cancer cells was detected as adhesion molecules for fibronectin (Fn), collagen I (Col) and laminin (Lam) using a commercially available cDNA array (GEArray) system. These ECM proteins could enhance DNA transfection activity in cells when coated on the nanoplex. Among the ECM proteins, Fn-coating nanoplexes significantly increased transfection activity 2-fold in prostate cancer PC-3 cells, and exhibited higher DNA transfection activities to PC-3 xenografts, compared with commercially available cationic polymer in vivo jetPEI. These results indicated that Fn-coating nanoplexes could facilitate efficient transfection of prostate tumor cells.     

Efficient telomerase inhibition in human non-small cell lung cancer cells by liposomal delivery of 2'-O-methyl-RNA

The antisense oligonucleotide 2'-O-methyl-RNA is a selective telomerase inhibitor targeting the telomerase RNA component and represents a potential candidate for anticancer therapy. The poor cellular uptake of 2'-O-methyl-RNA is a limiting factor that may contribute to the lack of functional efficacy. To improve delivery of 2'-O-methyl-RNA and consequently antitumoral efficiency in human lung cancer cells, we have investigated several transfection reagents. The transfection reagents DOTAP, MegaFectin 60, SuperFect, FuGENE 6 and MATra-A were tested for intracellular delivery. A FAM-labeled 2'-O-methyl-RNA was used to assess the intracellular distribution by confocal laser scanning microscopy in A549 human non-small cell lung cancer cells. Telomerase activity was measured using the telomeric repeat amplification protocol. Cell viability after transfection was quantified by the MTT assay. All transfection reagents enhanced 2'-O-methyl-RNA uptake in A549 cells but the cationic lipid reagents DOTAP and MegaFectin 60 were most efficient in the delivery of 2'-O-methyl-RNA resulting in telomerase inhibition. Among both DOTAP exhibited the lowest cytotoxicity. Our experiments show that DOTAP is the most suitable transfection reagent for the delivery of 2'-O-methyl-RNA in human lung cancer cells according to its relatively low cytotoxicity and its ability to promote efficient uptake leading to the inhibition of telomerase.     

Delivery of nanoparticulate drug delivery systems via the intravenous route for cancer gene therapy

While the systemic route of administration enables therapeutic genes to spread through the bloodstream and access target cells, it is a challenge to achieve this. Several studies demonstrate that systemic administration of therapeutic genes or other nucleic acid-based constructs such as siRNA to solid tumors as well as cancer metastases are better with nanoparticulate systems compared to administration of free (uncomplexed) nucleic acids. Nanoparticle-based nucleic acid delivery systems might be more pertinent, due to the several privileges in terms of enhanced tissue penetrability, improved cellular uptake and to a lesser extent, targeted gene delivery to the cells of interest provided targeting ligands are used. Systemic delivery of nanoplexes has already been reported with different nanoparticles containing DNA via various routes of administration. The goal of the present article is to review the current state of intravenous delivery of nanoparticles for gene therapy of cancer.     

Targeted delivery of antisense oligodeoxynucleotide and small interference RNA into lung cancer cells

Selective gene inhibition by antisense oligodeoxynucleotide (AS-ODN) or by small interference RNA (siRNA) therapeutics promises the treatment of diseases that cannot be cured by conventional drugs. However, antisense therapy is hindered due to poor stability in physiological fluids and limited intracellular uptake. To address these problems, a ligand targeted and sterically stabilized nanoparticle formulation has been developed in our lab. Human lung cancer cells often overexpress the sigma receptor and, thus, can be targeted with a specific ligand such as anisamide. AS-ODN or siRNA against human survivin was mixed with a carrier DNA, calf thymus DNA, before complexing with protamine, a highly positively charged peptide. The resulting particles were coated with cationic liposomes consisting of DOTAP and cholesterol (1:1, molar ratio) to obtain LPD (liposome-polycation-DNA) nanoparticles. Ligand targeting and steric stabilization were then introduced by incubating preformed LPD nanoparticles with DSPE-PEG-anisamide, a PEGylated ligand lipid developed earlier in our lab, by the postinsertion method. Nontargeted nanoparticles coated with DSPE-PEG were also prepared as a control. Antisense activities of nanoparticles were determined by survivin mRNA down-regulation, survivin protein down-regulation, ability to trigger apoptosis in tumor cells, tumor cell growth inhibition, and chemosensitization of the treated tumor cells to anticancer drugs. We found that tumor cell delivery and antisense activity of PEGylated nanoparticles were sequence dependent and rely on the presence of anisamide ligand. The uptake of oligonucleotide in targeted, PEGylated nanoparticles could be competed by excess free ligand. Our results suggest that the ligand targeted and sterically stabilized nanoparticles can provide a selective delivery of AS-ODN and siRNA into lung cancer cells for therapy.     

Chitosan-coated PLGA nanoparticles for DNA/RNA delivery: effect of the formulation parameters on complexation and transfection of antisense oligonucleotides

Cationically modified poly(D,L-lactide-co-glycolide) (PLGA) nanoparticles have recently been introduced as novel carriers for DNA/RNA delivery. The colloidal characteristics of the nanoparticles--particle size and surface charge--are considered the most significant determinants in the cellular uptake and trafficking of the nanoparticles. Therefore, our aim was to introduce chitosan-coated PLGA nanoparticles, whose size and charge are tunable to adapt for a specific task. The results showed that biodegradable nanoparticles as small as 130 nm and adjustable surface charge can be tailored controlling the process parameters. As a proof of concept, the overall potential of these particulate carriers to bind the antisense oligonucleotides, 2'-O-methyl-RNA, and improve their cellular uptake was demonstrated. The study proved the efficacy of chitosan-coated PLGA nanoparticles as a flexible and efficient delivery system for antisense oligonucleotides to lung cancer cells.     

Targeted delivery of antisense inhibitor of miRNA for antiangiogenesis therapy using cRGD-functionalized nanoparticles

MiRNAs are viable therapeutic targets for cancer therapy, but the targeted delivery of miRNA or its anti-miRNA antisense oligonucleotides (AMOs) remains a challenge. We report here a PEGylated LPH (liposome-polycation-hyaluronic acid) nanoparticle formulation modified with cyclic RGD peptide (cRGD) for specific and efficient delivery of AMO into endothelial cells, targeting α(v)β? integrin present on the tumor neovasculature. The nanoparticles effectively delivered anti-miR-296 AMO to the cytoplasm and downregulated the target miRNA in human umbilical vein endothelial cells (HUVECs), which further efficiently suppressed blood tube formulation and endothelial cell migration, owing to significant upregulation of hepatocyte growth factor-regulated tyrosine kinase substrate (HGS), whereas nanoparticles without cRGD modification showed only little AMO uptake and miRNA silencing activity. In vivo assessment of angiogenesis using Matrigel plug assay also demonstrated that cRGD modified LPH nanoparticles have potential for antiangiogenesis in miRNA therapeutics. With the delivery of anti-miR-296 AMO by targeted nanoparticles, significant decrease in microvessel formulation within Matrigel was achieved through suppressing the invasion of CD31-positive cells into Matrigel and prompting HGS expression in angiogenic endothelial cells.     

汉黄芩素对人卵巢癌细胞株SKOV3裸鼠移植瘤生长及端粒酶活性的抑制作用

目的端粒酶在多种肿瘤细胞中高表达,可能是肿瘤分子靶向治疗的一个理想靶点。已有的研究表明,汉黄芩素体外具有抑制肿瘤细胞端粒酶活性和肿瘤细胞增殖的作用。该研究旨在评价汉黄芩素对人卵巢癌SKOV3细胞裸鼠移植瘤生长及端粒酶活性是否具有抑制作用。方法将移植人卵巢癌SKOV3细胞的裸鼠随机分为5组:汉黄芩素高剂量组(600mg·kg-1)、汉黄芩素低剂量组(300mg·kg-1)、空白对照组、顺铂治疗组(3mg·kg-1)和联合用药(顺铂+汉黄芩素)组,定期检测裸鼠的体重及肿瘤体积,裸鼠移植瘤组织分别提取DNA、RNA和蛋白质,用Southern印迹杂交法测定端粒长度、RT-PCR扩增观察端粒酶基因hTERT的表达、TRAP-PCR-银染法测定端粒酶活性。结果动物实验表明,汉黄芩素对SKOV3移植瘤有明显的抑瘤作用,高剂量组抑瘤率达56.67%(与对照组比较,P=0.002);低剂量组抑瘤率达38.10%(P=0.019),化疗组抑瘤率达50.83%(P=0.004),联合用药(顺铂+汉黄芩素)组的抑瘤率为66.9%,优于单独使用组(P=0.002);不同浓度汉黄芩素组肿瘤组织的端粒长度与空白对照组比较差异无显著性,汉黄芩素对瘤体端粒酶基因hTERT表达、端粒酶活性均有抑制作用,而且作用强度与剂量有关。结论汉黄芩素在体内具有抗肿瘤和抑制端粒酶活性的作用,抑制强度与剂量成正比,抑瘤率与顺铂合用有相加的作用。     

端粒酶反义hTR和反义hTERT合用对宫颈癌HeLa细胞凋亡的影响

目的探讨端粒酶反义hTR和反义hTERT联合作用于宫颈癌HeLa细胞,对HeLa细胞凋亡的影响。方法实验分空白对照组、脂质体对照组、正义hTR组、正义hTERT组、反义hTR组、反义hTERT组及反义hTR+反义hTERT组。分别采用四甲基偶氮唑蓝法(MTT)、逆转录聚合酶链反应技术-端粒重复序列扩增(TRAP)酶联免疫法(ELISA)、吖啶橙染色法、流式细胞术检测宫颈癌HeLa细胞转染反义hTR和反义hTERT后细胞的端粒酶活性、形态学、凋亡和周期的改变。结果宫颈癌HeLa细胞转染端粒酶反义核酸后,出现明显的细胞凋亡形态学改变,端粒酶活性抑制率、凋亡率增高及细胞周期阻滞,与空白对照组、脂质体对照组及正义核酸组比较,统计学上差异有显著性(P<0.01)。HeLa细胞转染0.2μmol·L-1反义hTR+反义hTERT72h后,端粒酶活性抑制率、细胞凋亡率分别为80.5%、28.6%,与反义hTR组和反义hTERT组比较(端粒酶活性抑制率、细胞凋亡率分别为hTR:62.7%、13.2%;hTERT:66.5%、13.7%),差异有显著性(P<0.01,q值分别为0.919、1.075)。反义hTR+反义hTERT组比反义hTR组和反义hTERT组细胞凋亡的形态学改变更明显,反义hTR+反义hTERT组G0/G1期细胞比例增加(G1期细胞比例为57.8%,空白对照组G1期细胞比例为50.7%)。结论端粒酶反义核酸能通过抑制端粒酶活性诱导细胞凋亡,端粒酶反义hTERT和反义hTR有协同效应。     

Transferrin targeted core-shell nanomedicine for combinatorial delivery of doxorubicin and sorafenib against hepatocellular carcinoma

Combinatorial drug delivery is an attractive, but challenging requirement of next generation cancer nanomedicines. Here, we report a transferrin-targeted core-shell nanomedicine formed by encapsulating two clinically used single-agent drugs, doxorubicin and sorafenib against liver cancer. Doxorubicin was loaded in poly(vinyl alcohol) nano-core and sorafenib in albumin nano-shell, both formed by a sequential freeze-thaw/coacervation method. While sorafenib from the nano-shell inhibited aberrant oncogenic signaling involved in cell proliferation, doxorubicin from the nano-core evoked DNA intercalation thereby killing > 75% of cancer cells. Upon targeting using transferrin ligands, the nanoparticles showed enhanced cellular uptake and synergistic cytotoxicity in ~ 92% of cells, particularly in iron-deficient microenvironment. Studies using 3D spheroids of liver tumor indicated efficient penetration of targeted core-shell nanoparticles throughout the tissue causing uniform cell killing. Thus, we show that rationally designed core-shell nanoparticles can effectively combine clinically relevant single-agent drugs for exerting synergistic activity against liver cancer.From the Clinical EditorTransferrin-targeted core-shell nanomedicine encapsulating doxorubicin and sorafenib was studied as a drug delivery system against hepatocellular carcinoma, resulting in enhanced and synergistic therapeutic effects, paving the way towards potential future clinical applications of similar techniques.     

Nanoparticles in cancer therapy and diagnosis

Numerous investigations have shown that both tissue and cell distribution profiles of anticancer drugs can be controlled by their entrapment in submicronic colloidal systems (nanoparticles). The rationale behind this approach is to increase antitumor efficacy, while reducing systemic side-effects. This review provides an update of tumor targeting with conventional or long-circulating nanoparticles. The in vivo fate of these systems, after intravascular or tumoral administration, is discussed, as well as the mechanism involved in tumor regression. Nanoparticles are also of benefit for the selective delivery of oligonucleotides to tumor cells. Moreover, certain types of nanoparticles showed some interesting capacity to reverse MDR resistance, which is a major problem in chemotherapy. The first experiments, aiming to decorate nanoparticles with molecular ligand for 'active' targeting of cancerous cells, are also discussed here. The last part of this review focus on the application of nanoparticles in imaging for cancer diagnosis.     

Nanoparticles in cancer therapy and diagnosis

Numerous investigations have shown that both tissue and cell distribution profiles of anticancer drugs can be controlled by their entrapment in submicronic colloidal systems (nanoparticles). The rationale behind this approach is to increase antitumor efficacy, while reducing systemic side-effects. This review provides an update of tumor targeting with conventional or long-circulating nanoparticles. The in vivo fate of these systems, after intravascular or tumoral administration, is discussed, as well as the mechanism involved in tumor regression. Nanoparticles are also of benefit for the selective delivery of oligonucleotides to tumor cells. Moreover, certain types of nanoparticles showed some interesting capacity to reverse MDR resistance, which is a major problem in chemotherapy. The first experiments, aiming to decorate nanoparticles with molecular ligand for ‘active’ targeting of cancerous cells, are also discussed here. The last part of this review focus on the application of nanoparticles in imaging for cancer diagnosis.     

荷包牡丹碱对人肺癌A549细胞生长及端粒酶活性的抑制作用

目的探讨荷包牡丹碱对人肺癌A549细胞生长的抑制作用及其作用机制。方法 A549细胞加入荷包牡丹碱0～200μmol.L-1分别作用24,48和72 h,MTT法测定A549细胞的生长抑制作用。荷包牡丹碱0～20μmol.L-1作用72 h,端粒重复序列扩增(TRAP)法测定端粒酶活性。变温紫外法检测荷包牡丹碱9μmol.L-1对端粒酶G-四链体的稳定作用。结果荷包牡丹碱25,50,100和200μmol.L-1作用细胞72 h后的抑制率分别为33.4%,88.2%,88.6%和89.4%,明显高于正常对照组细胞(P<0.05),并具有量效(r=0.906,P<0.05)和时效(r=0.949,P<0.05)性。与正常对照组相比,荷包牡丹碱5,10,15和25μmol.L-1可有效抑制A549细胞端粒酶的活性(P<0.05),相对TRAP端粒酶活性从正常对照组的1.471±0.102分别降低为1.093±0.054,1.013±0.016,0.554±0.034,0.365±0.081(P<0.05)。荷包牡丹碱9μmol.L-1使G-四链体的熔点值从正常对照组的48℃提高到54℃。结论荷包牡丹碱可以通过稳定G-四链体结构,抑制端粒酶活性,有效抑制人肺腺癌细胞A549的生长。     

Innovative strategy for treatment of lung cancer: targeted nanotechnology-based inhalation co-delivery of anticancer drugs and siRNA

A tumor targeted mesoporous silica nanoparticles (MSN)-based drug delivery system (DDS) was developed for inhalation treatment of lung cancer. The system was capable of effectively delivering inside cancer cells anticancer drugs (doxorubicin and cisplatin) combined with two types of siRNA targeted to MRP1 and BCL2 mRNA for suppression of pump and nonpump cellular resistance in non-small cell lung carcinoma, respectively. Targeting of MSN to cancer cells was achieved by the conjugation of LHRH peptide on the surface of MSN via poly(ethylene glycol) spacer. The delivered anticancer drugs and siRNA preserved their specific activity leading to the cell death induction and inhibition of targeted mRNA. Suppression of cellular resistance by siRNA effectively delivered inside cancer cells and substantially enhanced the cytotoxicity of anticancer drugs. Local delivery of MSN by inhalation led to the preferential accumulation of nanoparticles in the mouse lungs, prevented the escape of MSN into the systemic circulation, and limited their accumulation in other organs. The experimental data confirm that the developed DDS satisfies the major prerequisites for effective treatment of non-small cell lung carcinoma. Therefore, the proposed cancer-targeted MSN-based system for complex delivery of drugs and siRNA has high potential in the effective treatment of lung cancer.     

叶酸受体介导的负载紫杉醇纳米药物输送系统的体外生物活性的研究

目的:叶酸受体介导的负载紫杉醇纳米药物输送系统的的体外生物活性研究。方法:应用激光共聚焦观察肝素-叶酸-紫杉醇纳米粒进入叶酸受体阳性表达KB细胞和叶酸受体阴性表达A549细胞的情况,考察纳米粒对靶细胞摄取情况;以原药紫杉醇为对照组,应用MTT法检测纳米粒子对叶酸受体阳性表达KB细胞的抗癌抑制活性;应用流式细胞仪对纳米粒子抗癌机制进行分析。结果:细胞摄取实验表明,肝素-叶酸-紫杉醇纳米药物是通过叶酸受体介导的内吞作用实现对靶细胞的特异性;与紫杉醇对比,纳米粒子的针对叶酸受体阳性细胞的抑制效果更好,半数抑制浓度(IC50)为0.06g/mL,MTT实验结果与细胞摄取实验结果一致;流式细胞仪检测表明肝素-叶酸-紫杉醇纳米药物也表现出与紫杉醇相似的抑制作用,即G2/M期均有所增长。结论:体外生物活性检测表明叶酸受体介导的负载紫杉醇的纳米药物输送系统有较好的靶向性,其应用前景值得期待。     

Transfection of 3′,3′′-bis-peptide-siRNA conjugate by cationic lipoplexes mixed with a neutral cytosin-1-yl-lipid

Cationic lipids have been applied to siRNA delivery for tumor therapeutics. However, the excess positive charges of these nanoplexes may lead to high cytotoxicity and nonnegligible immunogenicity both in vitro and in vivo, which limited the applications of gene drugs. We constructed multi-component lipoplex to delivery 3′,3′′-bis-peptide-siRNA conjugate (pp-siRNA) by the treatment of melanoma. Based on the previous studies that the gemini lipid (CLD) encapsulated pp-siRNA, a novel neutral cytosin-1-yl-lipid (DNCA) was considered to replace a certain ration of CLD by hydrogen bonds and π-π stacking for reducing the cytotoxicity. It similarly retained in both the loading efficiency and targeted mRNA inhibition when DNCA was accounted for 40% in the lipoplex, with lower toxicity. Moreover, CLD/DNCA/pp-siRNA nanoplex could be uptake in A375 cells and internalized mainly by macropinocytosis and caveolin-mediated endocytosis. Besides, 90%CLD/DNCA/pp-siRNA nanoplexes presented the highest efficient knockdown for the mutant B-RAF mRNA (~80%). All the results demonstrated that the mixed cationic and neutral lipids could efficiently realize the delivery of pp-siRNA and had potential application for cancer therapy.