Abstract

Biguanides (i.e. metformin, phenformin and buformin) are antidiabetic drugs with potential antitumor effects. Herein, a polycationic polymer, N,N′-bis(cystamine)acrylamide-buformin (CBA-Bu), containing multiple biodegradable disulphide bonds and buformin-mimicking side chains was synthesised. CBA-Bu was equipped with high efficiency and safety profile for gene delivery, meanwhile exhibiting potential antitumor efficacy. As a gene vector, CBA-Bu was able to condense plasmid DNA (pDNA) into nano-sized (<200 nm), positively-charged (>30 mV) uniform polyplexes that were well resistant to heparin and DNase I. Due to the reduction responsiveness of the disulphide bonds, CBA-Bu/pDNA polyplexes could release the loaded pDNA in the presence of dithiothreitol, and induce extremely low cytotoxicity in NIH/3T3 and U87 MG cells. The transfection results showed that CBA-Bu had a cellular uptake efficiency comparable to 25 kDa PEI, while a significantly higher gene expression level. Additionally, CBA-Bu had a lower IC50 value than its non-biguanide counterpart in two cancer cell lines. Furthermore, CBA-Bu could activate AMPK and inhibit mTOR pathways in U87 MG cells, a mechanism involved in the antitumor effect of biguanides. Taken together, CBA-Bu represented an advanced gene vector combining desirable gene delivery capability with potential antitumor activity, which was promising to achieve enhanced therapeutic efficacy in antitumor gene therapy.

摘要

双胍类（即二甲双胍、苯乙双胍和丁福明）是具有潜在抗肿瘤作用的抗糖尿病药物。在此，聚阳离子聚合物，N , N'-双（胱胺）丙烯酰胺-丁福明（CBA-Bu），包含多个可生物降解的二硫键和丁福明模拟侧链被合成。CBA-Bu 具有高效和安全的基因传递特性，同时表现出潜在的抗肿瘤功效。作为基因载体，CBA-Bu 能够将质粒 DNA (pDNA) 浓缩成纳米级 (<200 nm)、带正电 (>30 mV) 的均匀复合物，对肝素和 DNase I 具有良好的耐受性。 由于由于二硫键的还原反应性，CBA-Bu/pDNA 复合物可以在二硫苏糖醇存在下释放负载的 pDNA，并在 NIH/3T3 和 U87 MG 细胞中诱导极低的细胞毒性。转染结果表明，CBA-Bu 具有与 25 kDa PEI 相当的细胞摄取效率，同时具有显着更高的基因表达水平。此外，在两种癌细胞系中，CBA-Bu 的 IC50 值低于其非双胍对应物。此外，CBA-Bu 可以激活 AMPK 并抑制 U87 MG 细胞中的 mTOR 通路，这是一种参与双胍抗肿瘤作用的机制。总之，CBA-Bu 代表了一种先进的基因载体，结合了理想的基因传递能力和潜在的抗肿瘤活性，有望在抗肿瘤基因治疗中实现更高的治疗效果。