Sun Xiaoyi,Chen Jinliang,Chen Hailiang,Liang Wenquan
The transfection agent polycation polyethylenimine (PEI) has been rarely used to construct liposomes for chemical antitumor drugs. In this study, it was introduced into cisplatin (CDDP) encapsulated neutral liposomes (CDDP-NL) by amphiphilic PEI-cholesterol (PEI-Chol) to investigate
its effect on the antitumor activity in A549 cells. The IC50 was 0.65 ± 0.02, 2.94 ± 0.21 and 2.03 ± 0.15 g/ml for CDDP-cationic liposomes (CDDP-CL), CDDP-NL and free CDDP, respectively. The enhanced anticancer activity was attributed to the addition of PEI-Chol
which influenced cellular processing of CDDP. With the help of inhibitors, we found that besides clathrin dependent and actin dependent uptake pathways, caveolae-mediated endocytosis was involved in the internalization of CDDP-CL. Improved internalization of CDDP was observed. Intracellular
Pt accumulations were 6.5 times and 3 times of those in CDDP-NL and free CDDP groups, respectively. The differences of intracellular location caused by endocytosis routes and lysosomes escape capacity of PEI-Chol was observed by fluorescence colocalization studies. PEI-Chol also decreased
the Pt fraction exported out of cells and extended the cellular Pt retention of CDDP liposomes. In conclusion, cationic modification of liposomes with PEI is a potential and promising way for antitumor drug delivery.
Novel polysaccharide-platinum conjugated polymers bearing alendronate on Portulaca oleracea polysaccharides (PPS) were designed and synthesized. Their chemical structures and properties were characterized by Fourier transform infrared spectroscopy (FT-IR), 1 H NMR and 31 P NMR spectroscopy, Thermogravimetric analysis (TGA), X-ray powder diffraction (XRD), UV–vis spectrophotometer (UV–vis) and other analysis methods. The results demonstrated that alendronate can be used as the linker of Portulaca oleracea polysaccharides and platinum compounds. Portulaca oleracea polysaccharides-alendronate (PPS-ALN) conjugates exhibited stronger antioxidant ability than PPS. The cytotoxicity assay to cancer cells was tested in vitro, and the Portulaca oleracea polysaccharides-alendronate-platinum (PPS-ALN-Pt) conjugates strongly inhibited the proliferation of cancer cells than PPS and PPS-ALN. The evaluation of complexes affinity toward supercoiled plasmid DNA, displayed a high DNA interaction. Interestingly, the platinum conjugates displayed immunological competence in HeLa cells by cellular immunofluorescence assay. Besides, the cellular platinum accumulation of PPS-ALN-Pt conjugates was higher than that of cisplatin in HeLa cells, implying that the polysaccharide-platinum conjugated polymers might have a synergistically therapeutic application in metal anticancer drug delivery.
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