Decline in Exogenous Gene Expression in Primate Brain Following Intravenous Administration Is Due to Plasmid Degradation

Purpose Nonviral gene transfer to the brain of adult Rhesus monkeys is possible with a single intravenous administration of plasmid DNA that is encapsulated in the interior of pegylated immunoliposomes, which are targeted across membrane barriers in vivo with a monoclonal antibody to the human insulin receptor. Methods The present studies measure the rate of decay of luciferase gene expression in the Rhesus monkey with luciferase enzyme assays, Southern blotting, and real-time polymerase chain reaction. Results Luciferase enzyme activity in frontal cortex, cerebellum, and liver decays with a t_1/2 of 2.1 ± 0.1, 2.6 ± 0.2, and 1.7 ± 0.01 days, respectively. Luciferase plasmid in brain and liver was detectable by Southern blotting at 2 days, but not at 7 or 14 days. The concentration of luciferase plasmid DNA in brain and liver was measured by real-time polymerase chain reaction, and decayed with t_1/2 of 1.3 ± 0.3 and 2.7 ± 0.5 days, respectively. Conclusions The maximal concentration of luciferase plasmid DNA in Rhesus monkey brain was 3–4 molecules/cell following an i.v. administration of 12 μg/kg pegylated immunoliposome encapsulated plasmid DNA. These results demonstrate that the rate of loss of exogenous gene expression in the primate in vivo correlates with the rate of DNA degradation of the exogenous plasmid DNA.     

In Vivo Disposition Characteristics of Plasmid DNA Complexed with Cationic Liposomes

To control disposition and hence gene expression, we investigated the disposition characteristics of plasmid DNA complexed with the cationic liposomes Lipofectin_® and LipofectACE_® after intravenous injection in mice via the tail vein. The optimum ratios of DNA and liposome complexes were selected through in vitro cytotoxicity and transfection studies. The highest transfection was found at the DNA:liposome ratio of 1:5 w/w. Hence, this ratio was used for in vivo disposition studies, and the distribution patterns were compared with that of naked pCAT. Following intravenous injection of [₃₂P] pCAT, radioactivity was rapidly eliminated from plasma and approximately 60% of the dose was taken up by the liver within 1.5 min. In the case of LipofectACE_® samples, radioactivity elimination from plasma was equally rapid, but its accumulation was observed in both the liver (35%) and the lung (45%). For Lipofectin_® samples, radioactivity was initially accumulated in both the liver (55%) and the lung (25%), but lung accumulation was not sustained beyond 5 min after administration. Both liposomal samples showed in vivo gene expression in the lung, heart, kidney and spleen, but not in the liver. Thus, the present study demonstrated the disposition and gene expression of pCAT can be controlled by complex formation with liposomes.     

Ultrasound Enhancement of In Vitro Transfection of Plasmid DNA by a Cationized Gelatin

In vitro transfection efficiency of a plasmid DNA for rat gastric mucosal (RGM)-1 cells was enhanced by ultrasound (US) irradiation. Ethylenediamine was introduced to the carboxyl groups of gelatin to prepare a cationized gelatin as the vector of plasmid DNA encoding luciferase. An electrophoresis experiment revealed that the cationized gelatin was mixed with plasmid DNA at the weight ratio of 5.0 to form a cationized gelatin-plasmid DNA complex. The complex obtained was about 200 nm in diameter with a positive charge. When incubated with the cationized gelatin-plasmid DNA complex and subsequently exposed to US, RGM-1 cells exhibited a significantly enhanced luciferase activity although the extent increased with an increase in the DNA concentration, in contrast to the cationized gelatin alone with or without US irradiation and US irradiation alone. US irradiation was also effective in enhancing the activity by free plasmid DNA although the extent was less than that of the complex. The US-induced enhancement of luciferase activity was influenced by the exposure time period, frequency, and intensity of US. The activity enhancement became higher to be significant at the irradiation time period of 60 s and thereafter decreased. A series of cytotoxicity experiments revealed that an increase in the irradiation time period and intensity of US decreased the viability of cells themselves. It is possible that US irradiation under an appropriate condition enables cells to accelerate the permeation of the cationized gelatin-plasmid DNA complex through the cell membrane, resulted in enhanced transfection efficiency of plasmid DNA. These findings clearly indicate that US exposure is a simple and promising method to enhance the gene expression of plasmid DNA.     

Peptide-mediated Gene Transfer of Cationic Lipid/Plasmid DNA Complexes to Endothelial Cells

The purpose of this research is to develop ligand-targeted plasmid based gene delivery systems for gene transfer to tumor endothelium. Cell adhesion assays were used to test the peptide inhibition of human endothelial cell adsorption to vitronectin-treated tissue culture plates. A series of RGD containing peptides were tested in linear form and with one and two disulfide bonds. The linear and two disulfide bond peptides yielded similar IC₅₀ (≈1 × 10^-7 M). Substitution of two methionines for cysteines yielded a single disulfide bond that increased the IC₅₀ by 10-fold. The single and double disulfide peptides were derivatized to N-succinyl-dioleoylphopsphatidylethanolamine and incorporated into 100 nm liposomes radiolabeled with ³H-cholesterylhexadecylether. Liposome uptake by human umbilical vein endothelial cells was tested as a function of lipopeptide surface density. Increase in membrane surface density from 5 to 20 mol% increased human umbilical derived endothelial cell (HUVEC) uptake of the liposomes for both the single and double disulfide peptides. Liposome uptake by HUVECs was 3-fold greater for the double disulfide compared to the single disulfide. The single and double disulfide lipopeptides were then tested for gene transfer to HUVECs using DOTMA:Cholesterol cationic liposomes. The polyplexes were formed by rapidly mixing plasmid DNA with DOTMA:CHOL liposomes at a 3:1 charge ratio in 2% ethanol, 10% lactose. The ethanol was removed by lyophilization and upon rehydration, the lipoplexes had a mean diameter of approximately 100 nm. HUVEC transfection studies showed that increasing the mol% of the single disulfide RGD lipopeptide to 20 mol% increased gene transfer by 10-fold. This increase in transfection could be reduced to that obtained in the absence of lipopeptide by co-incubating the HUVECs with a 100-fold excess of the single disulfide RGD peptide, thus demonstrating lipopeptide mediated gene transfer to endothelial cells.     

抗血小板单克隆抗体重组质粒的构建及其在大肠杆菌中的表达

目的:在原核细胞中表达抗血小板Fab抗体,为研制治疗性抗血小板抗体奠定基础.方法:从含有抗血小板抗体轻链基因和重链Fd段基因的克隆载体pGEM T-Easy上经双酶切获得抗体轻链基因和重链Fd段基因片段,将其以特定位点分别插入噬菌体抗体表达载体p3MH上,构建原核表达重组质粒p3MH/P140κ-Fd.转化E. coli XLI-Blu感受态细胞,并进行诱导表达,用ELISA方法进行鉴定.结果:血小板抗体轻链基因和重链Fd段基因片段准确插入p3MH载体,重组质粒在大肠杆菌表达的上清中含有与血小板特异性结合的Fab抗体.结论:在原核细胞中成功克隆并高效表达了可溶性的抗血小板Fab抗体.     

Development of the Liver- and Lobe-Selective Nonviral Gene Transfer Following the Instillation of Naked Plasmid DNA Using Catheter on the Liver Surface in Mice

Purpose. The present study has undertaken the liver- and lobe-selective nonviral gene transfer following the instillation of naked plasmid DNA (pDNA) using catheter on the liver surface in mice. Methods. The polyethernylon catheter was inserted intraperitoneally through the abdominal wall and was retained on the surface of the liver right and left medial lobes. pDNA was administered through the catheter to the liver right and left medial lobes. Results. The luciferase levels produced in the applied liver lobes at 6 h after liver surface instillation of pDNA were significantly higher than those produced in other liver lobes and other tissues assayed, and ranged from approximately 5 folds higher in other lobes to 20-30 folds higher in other tissues. Following liver surface instillation of pDNA at a time from 2 to 24 h or at a volume from 15 to 60 l, the gene expressions of the applied liver lobes were always significantly higher than those of other liver lobes and other tissues. Conclusion. We have demonstrated the liver- and lobe-selective gene transfection following the instillation of naked pDNA using catheter on the liver surface in mice.     

Intracellular Gene Transfer in Rats by Tail Vein Injection of Plasmid DNA

In this study, we examined the effect of various factors on gene delivery efficiency of tail vein injection of plasmid DNA into rats. We measured the level of reporter gene expression in the internal organs including the lung, heart, spleen, kidney, and liver as function of injection volume, injection time, and DNA dose. Persistency of reporter gene expression in transfected animals was also examined. We demonstrated that plasmid delivery to rats by the tail vein is effective as long as the volume of injected DNA solution is adjusted to 7–8% of body weight with an injection time of less than 10 s. With the exception of a short-term increase in serum concentration of alanine aminotransferase and transient irregularity in cardiac function during and soon after the injection, the procedure is well tolerated. Lac Z staining of the liver from transfected animals showed approximately 5–10% positive cells. Persistency test for transgene expression in animals using plasmid carrying cDNA of human alpha 1 antitrypsin gene driven by chicken beta actin gene promoter with CMV enhancers showed peak level of transgene product 1 day after the injection followed by a gradual decline with time. Peak level was regained by a second injection performed on day 38 after the first injection. These results show that tail vein injection is an effective means for introducing plasmid DNA into liver cells in rats. We believe that this procedure will be extremely useful for gene function studies in the context of whole animal in rats.Key words: gene delivery, gene therapy, hydrodynamic gene delivery, nonviral vectors, siRNA delivery     

逆转录病毒介导耐药基因的高效表达

目的　建立多药耐药基因MDR1的逆转录病毒转移系统。方法　脂质体转染法将携带MDR1基因的逆转录病毒载体HaMDR导入单向型包装细胞GP E86 ;用获得的单向型病毒重复转导双嗜型包装细胞GP envAm12 ,经秋水仙碱加压选择获得高滴度的病毒生产细胞Am12 /HaM DR ;MDR1基因的转移和表达用聚合酶链反应 (PCR)、MTT比色法和流式细胞术 (FCM )分析。结果　单向型与双嗜型病毒生产细胞的滴度分别为 6 2× 10 5和 9 0× 10 5CFU/ml;PCR分析证实生产细胞有MDR1基因整合并稳定表达 ,但同时存在异常剪接的转录本 ;MTT比色法和FCM分析显示MDR1基因转移细胞的耐药程度提高 12～ 2 6 7倍 ,P 糖蛋白表达率达 97%～ 99%。结论　逆转录病毒可有效介导MDR1基因转移和表达 ,为导入造血干 /祖细胞后进行根治性化疗奠定基础。     

Significant Role of Liver Sinusoidal Endothelial Cells in Hepatic Uptake and Degradation of Naked Plasmid DNA After Intravenous Injection

Purpose. Uptake and degradation of naked plasmid DNA (pDNA) by liver sinusoidal endothelial cells (LSECs) were investigated. Methods. Tissue distribution and intrahepatic localization were determined after an intravenous injection of ¹¹¹In- or ³²P-labeled pDNA into rats. Cellular uptake and degradation of fluorescein- or ³²P-labeled pDNA were evaluated using primary cultures of rat LSECs. Results. Following intravenous injection, pDNA was rapidly eliminated from the circulation and taken up by the liver. Fractionation of liver-constituting cells by centrifugal elutriation revealed a major contribution of LSECs to the overall hepatic uptake of pDNA. Confocal microscopic study confirmed intracellular uptake of pDNA in cultured LSECs. Apparent cellular association of pDNA was similar at 37°C and 4°C. However, trichloroacetic acid (TCA) precipitation experiments showed the TCA-soluble radioactivity in the culture medium increased in an accumulative manner at 37°C. Involvement of a specific mechanism was demonstrated, as the uptake of pDNA was significantly inhibited by excess unlabeled pDNA and some polyanions (polyinosinic acid, dextran sulfate, heparin) but not by others (polycytidylic acid, dextran). These inhibitors also reduced the amount of TCA-soluble radioactivity in the culture medium. Conclusion. These results suggest that LSECs efficiently ingested and rapidly degraded naked pDNA in vivo and in vitro and released the degradation products into the extracellular space.     

Sulfhydryl Based Cationic Surfactants and the Impact of Polyanions on Disulfide Bond Formation: Implications for Gene Transfer Vectors

Compacting plasmid DNA (pDNA) into a small size is a fundamental necessity for the efficient in vivo transfer of nucleic acids to somatic cells. An approach for accomplishing this is to condense pDNA using cationic detergents with sulfhydryl groups, near their critical micelle concentration. In this study, a model surfactant was used to study how the rate of disulfide bond formation relates to environmental factors. It was shown that the thiol detergent had the ability to form a disulfide bond when oxidized and the presence of polyanions was significantly increased. The addition of a reducing agent disrupted the disulfide bonds initially, but this was followed by disulfide bond reformation in a short time period.     

Cationic Lipid Structure and Formulation Considerations for Optimal Gene Transfection of the Lung

Abstract

Enhanced gene transduction to the lung using cationic lipids could be attained through optimization of the structure of the lipids and the formulation of the cationic lipid : plasmid DN A (pDNA) complexes. We have expanded on our earlier observation of the importance of the structural orientation of the cationic lipid headgroup. Through the synthesis of a number of matched pairs of cationic lipids differing only in the configuration of their headgroup, we confirmed that those harboring a T-shape headgroup are more active than their linear counterparts, at least when tested in the lungs of BALB/c mice. Additionally, we demonstrated that not only are the structural considerations of these cationic lipids important, but also their protonation state, the free base being invariably more active than its salt counterpart. The salt forms of cationic lipids bound pDNA with greater avidity, which may have affected their subsequent intracellular dissolution and transit of the pDNA to the nucleus. Inclusion of a number of frequently used solutes in the vehicle severely inhibited the gene transfection activity of the cationic lipids. The selection of neutral co-lipids was also an important factor for overall transfection activity of the formulation, with significant gains in transfection activity realized when diphytanoylphosphatidylethanol-amine or dilinoleoylphosphatidylethanolamine were used in lieu of dioleoylphosphati-dylethanolamine. Finally, we showed that a transacylation reaction could occur between the cationic lipid and neutral co-lipid which reduced the transfection activity of the complexes. It is the hope that as our understanding of the many factors that influence the activity of these cationic lipid: pDNA complexes improves, formulations with much greater potency can be realized for use in the treatment of pulmonary diseases.     

Enhanced Gene Transfection in Macrophages Using Mannosylated Cationic Liposome-Polyethylenimine-Plasmid DNA Complexes

We have previously reported that plasmid DNA and cholesten-5-yloxy-N-{4-[(1-imino-2-β-D-tWomannosylethyl)amino]butyl}forrnarnide(Man-C4-Chol)/dioleoylphosphatidylethanolamine(DOPE)(6:4) liposome complexes (DNA/Man-complexes) exhibit efficient gene transfection in macrophages via mannose receptor-mediated endocytosis. To further enhance gene transfetion, polyethylenimine (PEI) was incorporated into this liposome complex (DNA/Man-PEI-complexes), noticing a pH-buffering capacity in endosomes and DNA-condensing activity of PEI. In mouse peritoneal macrophages, the uptake and transfection activity of DNA/Man-PEI-complexes were 2-times and 6-times higher than those of DNA/Man-complexes, respectively. Furthermore, the presence of 1 mg/ml mannan significantly inhibited both the uptake and transfection efficiency of DNA/Man-PEI-complexes. These results suggested that the newly developed multifunctional DNA/Man-PEI-complexes exhibit highly improved gene transfection in macrophages via mannose receptor-mediated endocytosis.     

Improvement of In Vivo Transfer of Plasmid DNA in Muscle: Comparison of Electroporation versus Ultrasound

Plasmid-based gene delivery to muscle is a treatment strategy for many diseases with potential advantages above viral-based gene delivery methods, however, with a relative low transfection efficiency. We compared two physical methods—electroporation and ultrasound—that facilitate DNA uptake into cells. Mice (C57Bl/6) were injected intramuscular using plasmid DNA encoding an intracellular protein (p53) followed by electroporation or ultrasound. Then 48 hr after the injections the mice were sacrificed. The parameter for transfection efficiency was the area of muscle expressing the transgene. The p53 expression plasmid showed a 36-fold increase (p = 0.015) in transfection efficiency with electroporation compared to ultrasound. Compared with ultrasound, electroporation significantly improves transfection efficiency of naked plasmid DNA transfer into skeletal muscle.     

Tissue-Specific Characteristics of <Emphasis Type="Italic">in Vivo</Emphasis> Electric Gene: Transfer by Tissue and Intravenous Injection of Plasmid DNA

Purpose To evaluate the tissue-specific characteristics of electric gene transfer after tissue and intravenous injection of naked plasmid DNA (pDNA).Methods pDNA encoding firefly luciferase was injected directly into the liver, kidney, spleen, skin and muscle, or into the tail vein of mice, and electric pulses were then applied to one of these organs. The distribution of transgene expressing cells was evaluated using pDNA encoding -galactosidase.Results Tissue injection of pDNA produced a significant degree of transgene expression in any tissue with the greatest amount in the liver, followed by kidney and spleen. The expression in these organs decreased quickly with time, and muscle showed the greatest expression at 7 days. Electroporation significantly increased the expression, and the expression level was comparable among the organs. Intravenous injection of pDNA followed by electroporation resulted in a significant expression in the liver, spleen, and kidney but not in the skin or muscle.Conclusions Electric gene transfer to the liver, kidney, and spleen can be an effective approach to obtain significant amounts of transgene expression by either tissue or intravenous injection of pDNA, whereas it is only effective after tissue injection as far as skin- or muscle-targeted gene transfer is concerned.     

Improved stomach selectivity of gene expression following microinstillation of plasmid DNA onto the gastric serosal surface in mice

Stomach-selective gene transfer is a promising approach as a therapeutic strategy for refractory gastric diseases. In this study, we improved the stomach selectivity of gene expression following microinstillation of naked plasmid DNA (pDNA) onto the gastric serosal surface in mice. pDNA encoding firefly luciferase was used as a reporter gene. It was confirmed that the gene expression level in the stomach 6h after gastric serosal surface microinstillation of pDNA was significantly higher than after intragastric, intraperitoneal and intravenous administration. Regarding selectivity of gene expression, the gene expression level in the stomach after gastric serosal surface microinstillation of 1 microg/1 microL (dose/volume) pDNA was 5.7 times higher than that in the spleen. In our previous study (30 microg/30 microL), the expression level in the stomach was 2.7 times higher than that in the spleen; therefore, the selectivity was 2.1 times higher in this study. When we investigated gene expression at various pDNA solution concentrations, the ratio of the gene expression level in the stomach to that in the spleen was the highest as 1 microg/1 microL of pDNA, which was considered the optimal concentration. Information in this study is useful for further development of target organ-selective gene delivery systems.     

Cancer Pharmacogenomics: DNA Genotyping and Gene Expression Profiling to Identify Molecular Determinants of Chemosensitivity

Cancer patients exhibit a wide heterogeneity in their responses to chemotherapy. Improvement in chemotherapeutic responses could be achieved by gaining more detailed information on the molecular determinants (i.e., DNA, RNA or protein) underlying this heterogeneity. Pharmacogenomics approaches can be used to integrate information on drug responsiveness with alterations in molecular entities, often on a genome-wide scale. By using information gleaned from pharmacogenomics studies, it is anticipated that cancer chemotherapy can be tailored to the individual patient or tumor phenotype. This review focuses on pharmacogenomics studies conducted to gain insight into the molecular determinants of chemosensitivity to cancer chemotherapeutics.     

sTRAIL基因的克隆及其在大肠杆菌中的表达

克隆TRAIL基因的95-281位(sTRAIL)，构建表达载体，建立原核表达体系，优化诱导表达的条件。分离人外周血淋巴细胞，提取总RNA，RT-PCR，克隆sTRAIL的cDNA，构建原核表达载体，优化IPIG诱导的条件。结果：(1)克隆了TRAIL基因95-281位的cDNA，DNA测序结果与报道的一致。(2)构建了sTRAIL基因的原核表达载体，酶切结果与预期的一致。(3)转化宿主菌，优化IPIG诱导条件，发现3mmol/L，诱导3～4h表达最好。sTRAIL基因的克隆及表达为下游中试发酵及纯化奠定了上游的基础，也为研究TRAIL抗肿瘤的机制提供了可能。     

抑癌基因PTEN在大肠癌中的表达及意义

目的探讨大肠癌组织中抑癌基因PTEN蛋白的表达及其临床意义。方法应用免疫组织化学SP法,检测53例大肠癌组织中PTEN蛋白的表达水平。结果53例大肠癌中PTEN蛋白阳性率52.8%,阳性强度明显低于癌旁组织(100%)(P<0.01,P<0.05);大肠癌组织中PTEN蛋白的表达与大肠癌的分化程度密切相关(P<0.05),即癌组织分化愈差,PTEN蛋白表达愈弱;PTEN蛋白表达还与淋巴结转移、Dukes分期密切相关(P<0.01,P<0.05)。结论PTEN的异常表达在大肠癌发生、发展过程中可能起重要作用,其表达水平有可能作为反映大肠癌进展和预后的生物学指标。     

新疆地区原发性肝癌肿瘤同时性转移基因差异表达

目的：研究新疆地区原发性肝癌肿瘤同时性转移原发灶和转移灶的基因差异表达。方法：选取新疆医科大学第一附属医院2018年1月 ~ 2021年5月收治的首次出现同时性转移的原发性肝癌患者21例,采用下一代测序技术（NGS）研究其原发灶和转移灶中突变基因的表达,以及所涉及的通路和药物作用靶点,分析其突变基因与临床特征的关系;并用Kaplan-Meier单因素生存分析统计患者基因突变与临床特征及总生存期间的相关性。结果：原发性肝癌标本中原发灶和转移灶共同显示出突变率最高的10种基因：MUC16（43%）、TTN（36%）、ZAN（29%）、MYO18B（29%）、DNAH7（29%）、DNAH10（29%）、DMLX2（29%）、DCC（29%）、CSMD1（29%）、CDLSR2（29%）,转移灶和原发灶突变基因差异无统计学意义（P ＞ 0.05）,且基因变异的分类主要为错义突变,以单核苷酸多态性（SNP）最多见。在碱基突变的统计中,C ＞ A替换发生率最高,C ＞ T替换的发生频率次之。原发性肝癌患者TTN基因突变与性别、族别、分化程度有关（P ＜ 0.05）;MYO18B基因突变与族别有关（P ＜ 0.05）;TTN基因突变是原发性肝癌患者预后的独立预测基因;共筛选出10个原发灶和转移灶中突变基因的共同药物作用靶点,分别为可成药基因组、丝氨酸/苏氨酸激酶、离子通道、肿瘤抑制因子、酪氨酸激酶、DNA修复因子、复杂转录因子、转录因子结合位点、肿瘤治疗靶点基因组、ABC转运体。结论：原发性肝癌同时性转移异质性不明显。本研究筛选出原发性肝癌少见基因突变、与临床预后相关的基因突变以及药物作用靶点和基因突变所涉及的通路,为原发性肝癌的诊断、潜在的治疗靶点及相关的分子机制研究提供参考。     

乳腺癌p16基因甲基化和蛋白表达的检测及其临床意义

目的:探讨p16基因在乳腺癌中甲基化状态、表达情况及其与临床的关系.方法:应用甲基化特异性的聚合酶链反应(methylation specific PCR,MSP)检测48例乳腺癌中p16基因甲基化状态,应用免疫组化检测p16基因的蛋白表达情况.结果:p16基因在乳腺癌中甲基化率为27.1%(13/48),有淋巴结及远处转移的甲基化率(52.6%,10/19)高于无转移的甲基化率(10.3%,3/29)(P＜0.05);13例甲基化病例中P16蛋白失表达率(76.9%,10/13)高于非甲基化病例(8.6%,3/35)(P＜0.05).结论:p16基因高甲基化是乳腺癌中常见的分子生物学改变之一,p16基因高甲基化和乳腺癌浸润及转移有相关性;P16蛋白表达和其高甲基化呈负相关,甲基化是p16抑癌基因失活的主要方式之一.