ABSTRACT
<p><b>OBJECTIVE</b>To evaluate the inhibitory effects of survivin antisense oligonucleotide (survivin-ASODN) mediated by polyamidoamine dendrimer (PAMAM) against the growth of subcutaneously transplanted colorectal cancer in nude mice.</p><p><b>METHODS</b>Nude mouse models bearing colorectal cancer was established by subcutaneous injection of SW620 cells. Survivin- OSADN (300 microg/L) was mixed with 4.06 microg/L PAMAM or liposome to prepare two transfection complexes, and their morphologies were observed by transmission electron microscope. The particle size of the prepared complexes was determined by laser particle size analyzer, and the zeta potential was measured. The encapsulation efficiency and the DNA release rate in vitro were determined by ultraviolet spectrophotometer. The transfection complexes were then directly injected into the xenografts of the tumor-bearing nude mice. The tumor volume changes were observed, and the expression of survivin in the transplanted tumor was measured by Western blotting.</p><p><b>RESULTS</b>The PAMAM-survivin-ASODN complex had a significantly smaller diameter and greater zeta potential than liposome-survivin-ASODN (P<0.01 and 0.05, respectively). The encapsulation efficiency was comparable between the two complexes. In in vitro condition, PAMAM-survivin-ASODN allowed sustained survivin-ASODN release for as long as 14 days, as compared with the 5 days for the liposome complex. After injection into the tumor xenografts, PAMAM-survivin- ASODN resulted in significantly lower expression of survivin protein in the transplanted tumors (P<0.05), and also in significantly greater reduction of the tumor volume than the liposome complex (P<0.05).</p><p><b>CONCLUSION</b>PAMAM can effectively deliver survivin-ASODN into transplanted colorectal tumor cells to reduce the expression of survivin and inhibit the tumor growth.</p>
Subject(s)
Animals , Humans , Mice , Cell Proliferation , Colorectal Neoplasms , Pathology , Dendrimers , Inhibitor of Apoptosis Proteins , Mice, Inbred BALB C , Mice, Nude , Microtubule-Associated Proteins , Genetics , Pharmacology , Neoplasm Transplantation , Oligonucleotides, Antisense , Pharmacology , Polyamines , Pharmacology , Repressor Proteins , Tumor Cells, CulturedABSTRACT
Objective:To use polyamidoamine(PAMAM)dendrimer as gene delivery system for survivin gene anti- sense oligodeoxynucleotide(asODN)transfection for inhibition of HepG2 cancer cell growth.Methods:The first to the fifth generation of PAMAM and asODN were used to prepare a complex:PAMAM-asODN.The morphology of PAMAM- asODN was observed using agrose electrophoresis and atomic force microscope(AFM).PAMAM-asODN was then used to transfect HepG2 cells and cells transfected with asODN served as control.The transfection efficacy of PAMAM-asODN into HepG2 cells was observed under confocol microscope,the surviving mRNA expression was analyzed by RT-PCR,and the inhibition of HepG2 cell growth was determined by MTT assay.Results:Agrose electrophoresis showed strong complexing action between PAMAM and asODN and they formed a complex with a diameter of 25 nm.Confocol microscope showed the transfection efficacy of PAMAM-asODN was higher than that of asODN.RT-PCR showed a decreased expression of sur- vivin mRNA in PAMAM-asODN transfected cells.MTF results demonstrated that the growth of HepG2 cell was obviously inhibited after transfection of PAMAM-asODN and the inhibition rate increased with culture time,concentration of com- plex,the generation of PAMAM.PAMAM-asODN at 6.0?mol/L G4.0 resulted in a 55% inhibition of HepG2 cells 96 h after culture.Conclusion:PAMAM dendrimers can efficiently mediate the entry of survivin asODN into HepG2 cells,re- sulting in inhibition of HepG2 cells.PAMAM might be a promising gene carrier for potential molecular therapy of cancer.