Enhanced in vitro DNA transfection efficiency by novel folate-linked nanoparticles in human prostate cancer and oral cancer. 
Novel folate-linked, cationic nanoparticles (NPs) were developed and evaluated for potential use for gene delivery to human oral cancer (KB cells) and human prostate cancer (LNCaP cells), which abundantly expressed folate binding proteins.  Folate-polyethylenglycol-distearoylphosphatidylethanolamine conjugate (f-PEG-DSPE) was incorporated in NPs composed of 3([N-(N',N'-dimethylaminoethane)-carbamoyl] cholesterol (DC-Chol) and Tween 80.  NP-0.3FT, -1FT and -1FLT, which contain 0.3 and 1 mol% f-PEG2000-DSPE, and 1 mol% f-PEG5000-DSPE, respectively, showed about 100-200 nm in size.  The NP/plasmid DNA complex (nanoplex) remained in an injectable size (230-340 nm) and slightly increased its size in serum.  The association of NP-1FT with KB cells was enhanced by f-PEG2000-DSPE and was blocked by co-incubation with free folic acid in medium.  In transfection activity, the NP-1FT, but not NP-1FLT, showed high activity into KB and LNCaP cells in the presence of serum.  The NP-0.3FT also showed high activity into LNCaP cells, but not KB cells.  In RT-PCR analysis, KB cells strongly expressed folate receptors mRNA, but LNCaP cells did not.  In contrast, LNCaP cells expressed mRNA of prostate-specific membrane antigen (PSMA), which interacts with the folate substrate.  Uptake mechanism of folate-linked NPs in LNCaP cells may be different from that in KB cells.  This is the first report that folate-linked NPs selectively deliver the DNA to LNCaP cells, suggesting that such NPs are potentially targeted vectors to prostate cancer for gene delivery.