叶酸修饰的G5-PAMAM-D介导HSV-TK/GCV自杀基因系统治疗前列腺癌的体外实验研究

Prostate Cancer Treatment with HSV-TK/GCV Suicide Gene System Mediated by Folate-Modified G5-PAMAM-D: an Experimental Study in vitro

目的:探讨叶酸修饰的第五代聚酰胺-胺型树枝状聚合物(G5-PAMAM-D-fol)作为基因载体进行前列腺癌自杀基因治疗的可行性。方法:以GS-PAMAM-D-fol为基因载体将含有自杀基因HSV-TK的重组质粒pcDNA3-tk转染至前列腺癌细胞系PC-3和LNCaP,24h后以RT-PCR法检测HSV-TK基因在两种前列腺癌细胞系中的mRNA表达;再次转染后24h,对转染的两种细胞分别给予不同浓度的前体药物更昔洛韦(GCV),48h后采用四甲基偶氮唑盐比色法(MTT法)检测细胞抑制率。结果:RT-PCR结果证明G5-PAMAM-D-fol可将重组质粒pcDNA3-tk转染2种前列腺癌细胞并转录HSV-TK基因。MTT实验反映出A组(G5-PAMAM-D-fol/pcDNA3-tk)对PC-3和LNCaP细胞有明显的杀伤作用,并且比B组(G5-PAMAM-D/pcDNA3-tk)的细胞抑制率更高。C组(G5-PAMAM-D-fol)和D组(GS-PAMAM-D)随着GCV浓度的增加细胞生长并未受到明显的抑制,而且前者并未表现出比后者更明显的细胞杀伤作用。结论:G5-PAMAM-D-fol能够在体外将自杀基因重组质粒成功转入前列腺癌细胞并表达HSV-TK基因,其靶向性强且细胞毒性低。

Objective： To investigate the feasibility of the folate-modified fifth generation polyamido-amine dendrimer （G5-PAMAM-D-fol） as a gene vector in the suicide gene therapy of prostate cancer. Methods： G5-PAMAM-D-fol was used as the gene vector to transfect the recombinant plasmid pcDNA3-tk containing the HSV-TK suicide gene into the prostate cancer cell lines PC-3 and LNCaP. RT-PCR assay was used to detect HSV-TK mRNA expression in the two cells lines 24 hours after transfection. After another 24 hours, the prodrug ganciclovir （GCV） was given to the transfected PC-3 and LNCaP cells at different concentrations. MTT assay was carried out to determine the cell suppression rate 48 hours after GCV was introduced. Results： The RT-PCR and DNA ladder assays confirmed that as a genetic carrier, G5-PAMAM-D-fol could transfect the recombinant plasmid pcDNA3-tk into the two prostate cancer cells lines, PC-3 and LNCaP, and transcribe the HSV-TK gene. MTT assay showed that the two cell lines were significantly inhibited in group A （G5-PAMAM-D-fol/pcD- NA3-tk）, and the cell-inhibition rate was higher in group A than in group B （G5-PAMAM-D/pcDNA3-tk）. MTT assay also indi- cated that with an increase of the prodrug concentration, cell growth was not obviously suppressed in group C （G5-PAMAM-D-fol） nor in group D （G5-PAMAM-D） and the exterminating effect was not significantly greater in group C than in group D. Conclusions： G5-PAMAM-D-fol can efficiently transfect the recombinant plasmid containing the suicide gene into the prostate cancer cells and express the HSV-TK gene in vitro, with a high targeting success and a low cytotoxicity to the tumor cells.