Arsonoliposomes for the potential treatment of medulloblastoma.

PURPOSE: To investigate the arsonoliposome effect on medulloblastoma cells (VC312Rs) related to uptake, endocytotic mechanism and cell viability. METHODS: VC312R viability in presence of either arsonoliposomes or stealth liposomes was studied using MTT assay for 1-4 days. Fibroblasts (3T3) were used as control. Apoptosis was studied for 2 h, 5 h and 24 h. Bodipy-labelled arsonoliposome uptake (time- and dose-dependent) was estimated using FACS analysis. The endocytotic mechanism was investigated using inhibitors of clathrin- (chlorpromazine) and caveolae-mediated endocytosis (filipin). RESULTS: Arsonoliposomes affected significantly the VC312R viability compared to 3T3 cells and induced apoptosis to VC312Rs after 2 h of incubation. Apoptosis was not observed for 3T3 cells. Liposome uptake versus time showed a bimodal pattern. Clathrin-mediated endocytosis was the main endocytotic mechanism at low lipid concentrations and caveolae at higher ones; thus, dose-dependent uptake did not show a plateau at increased lipid concentrations. CONCLUSIONS: Arsonoliposomes showed "selective" toxicity towards medulloblastoma cells inducing apoptosis after 2 hs of incubation. Therefore, arsonoliposomes are promising anticancer vehicles for brain tumour treatment.

Penetration and intracellular uptake of poly(glycerol-adipate) nanoparticles into three-dimensional brain tumour cell culture models.

Nanoparticle (NP) drug delivery systems may potentially enhance the efficacy of therapeutic agents. It is difficult to characterize many important properties of NPs in vivo and therefore attempts have been made to use realistic in vitro multicellular spheroids instead. In this paper, we have evaluated poly(glycerol-adipate) (PGA) NPs as a potential drug carrier for local brain cancer therapy. Various three-dimensional (3-D) cell culture models have been used to investigate the delivery properties of PGA NPs. Tumour cells in 3-D culture showed a much higher level of endocytic uptake of NPs than a mixed normal neonatal brain cell population. Differences in endocytic uptake of NPs in 2-D and 3-D models strongly suggest that it is very important to use in vitro 3-D cell culture models for evaluating this parameter. Tumour penetration of NPs is another important parameter which could be studied in 3-D cell models. The penetration of PGA NPs through 3-D cell culture varied between models, which will therefore require further study to develop useful and realistic in vitro models. Further use of 3-D cell culture models will be of benefit in the future development of new drug delivery systems, particularly for brain cancers which are more difficult to study in vivo.

Methoctramine analogues inhibit responses to capsaicin and protons in rat dorsal root ganglion neurons.

We have investigated the possibility that vanilloid receptors have a binding site for polyamines and determined the consequences of binding to such a site. Whole-cell and single-channel patch-clamp recordings were used to investigate the effect of the tetraamine, methoctramine, and 16 of its analogues on capsaicin and proton induced responses of foetal rat dorsal root ganglion neurons. All but two methoctramine analogues inhibited responses to 10 microM capsaicin with IC50 values in the range of 2-70 microM at a holding potential of -100 mV. Inhibition was generally non-competitive and voltage-dependent. Methoctramine at 10 microM reduced the single channel mean open time (>3-fold), but also increased the mean closed time (1.7-fold). Sustained responses to pH 5.4 were antagonized by methoctramine with similar potency to capsaicin responses. Similar data were obtained with adult rat dorsal root ganglion neurons. These data indicate that methoctramine analogues bind to vanilloid receptors to inhibit their function.