Anwer K, Kao G, Proctor B, Rolland A, Sullivan S
Valentis Inc, The Woodlands, TX 77381-4248, USA.
J Drug Target. 2000;8(2):125-35. doi: 10.3109/10611860008996858.
Intravenous (i.v.) administration of cationic lipid N-[( 1-(2-3-dioleyloxy)propyl)]-N-N-N-trimethylammonium chloride (DOTMA)-based transfection complexes in mice with subcutaneous squamous cell tumors yielded plasmid delivery and expression in tumor lesions. The efficiency of gene transfer in tumors was significantly lower than in the lung. This was consistent with low plasmid levels associated with the tumor, suggesting that plasmid delivery to the tumor site was a limiting factor. Lowering the lipid/DNA charge ratio from 5:1 to 0.8:1 (+/-) did not change DNA levels in tumor but significantly reduced DNA levels in lung. However, expression levels were significantly reduced in both tissues at lower lipid/DNA charge ratios. Complexes prepared from small unilamellar liposomes gave significantly lower expression levels in the lungs but similar expression levels in tumors when compared to complexes prepared from larger unilamellar liposomes. The small liposome complexes were better tolerated than large liposome complexes. Varying the cationic lipid to colipid (cholesterol or DOPE) molar ratio from 4: 1 to 1: 1 significantly reduced expression levels in both tumor and lung. Cationic lipid substitution, using a cholesterol cationic lipid, diethyldiamino-carbamyl-cholesterol instead of DOTMA, produced reduced expression in all other tissues except tumor. Incorporation of PEG into preformed transfection complexes reduced DNA delivery to lung, increased circulation half-life, and enhanced DNA delivery to tumor. In a lung metastatic mouse tumor model, where the accessibility of the i.v. administered transfection complexes to tumor lesions should be less challenging, DOTMA: CHOL complexes (4: 1 lipid to colipid molar ratio, 3: 1 +/- lipid to plasmid charge ratio) were preferentially localized in tumor lesions. These data demonstrate that systemic gene transfer to distal tumor sites by lipid/ DNA complexes may be limited by low plasmid delivery. Modifying the chemical surface properties of transfection complexes enhanced both DNA delivery and expression in tumor and is one approach that may overcome limitations.
在患有皮下鳞状细胞瘤的小鼠中静脉注射基于阳离子脂质N-[(1-(2,3-二油酰氧基)丙基)]-N-N-N-三甲基氯化铵（DOTMA）的转染复合物，可使质粒在肿瘤病灶中递送并表达。肿瘤中的基因转染效率显著低于肺部。这与肿瘤中质粒水平较低一致，表明质粒递送至肿瘤部位是一个限制因素。将脂质/DNA电荷比从5:1降至0.8:1（±）并未改变肿瘤中的DNA水平，但显著降低了肺部的DNA水平。然而，在较低的脂质/DNA电荷比下，两个组织中的表达水平均显著降低。与由较大单层脂质体制备的复合物相比，由小单层脂质体制备的复合物在肺部的表达水平显著降低，但在肿瘤中的表达水平相似。小脂质体复合物比大脂质体复合物耐受性更好。将阳离子脂质与共脂质（胆固醇或二油酰基磷脂酰乙醇胺（DOPE））的摩尔比从4:1改变为1:1会显著降低肿瘤和肺部的表达水平。使用胆固醇阳离子脂质二乙氨基甲酰胆固醇代替DOTMA进行阳离子脂质替代，除肿瘤外，在所有其他组织中均使表达降低。将聚乙二醇（PEG）掺入预先形成的转染复合物中可减少DNA向肺部的递送，延长循环半衰期，并增强DNA向肿瘤的递送。在肺转移小鼠肿瘤模型中，静脉注射的转染复合物进入肿瘤病灶的难度应该较小，DOTMA:CHOL复合物（脂质与共脂质摩尔比为4:1，脂质与质粒电荷比为3:1±）优先定位于肿瘤病灶中。这些数据表明，脂质/DNA复合物向远处肿瘤部位的全身基因转移可能受到低质粒递送的限制。修饰转染复合物的化学表面性质可增强肿瘤中的DNA递送和表达，这是一种可能克服限制的方法。
