Differential expression of Glut 1 mRNA and protein levels correlates with increased sensitivity to the glyco-conjugated nitric oxide donor (2-glu-SNAP) in different tumor cell types.

Nitric Oxide (NO) releasing agents can serve as potent cytotoxic agents. However at present there are no effective ways to target delivery of NO donors like S-nitroso-N-acetyl-penicillamine (SNAP). SNAP conjugated to glucose (2-gluSNAP) can be readily transported across the membrane by GLUT 1 transporters. Therefore, sensitivity of cells to 2-gluSNAP may depend on glucose-transporter GLUT 1. We evaluated the cytotoxicity of SNAP and 2-gluSNAP on a GLUT 1 rich glioblastoma cell line T98G and GLUT 1 deficient osteoblastoma cell line 143B and its mitochondria-deficient variant rhoo (cell line 206). The cytotoxity of SNAP and 2-gluSNAP was assessed by clonogenic assay performed in the above cell lines in vitro. Immunoblotting and semi-quantitative real-time PCR assays were used to evaluate the expression of GLUT 1 transporter at protein and mRNA levels. The glioblastoma cell line T98G was more sensitive to 2-gluSNAP than unconjugated SNAP. SNAP and 2-gluSNAP affected the osteosarcoma cell lines 143B and rhoo poorly. Immunoblot analysis detected GLUT 1 protein in T98G cells and not in 143B or rhoo. There was about a 10-fold difference in GLUT 1 mRNA level in T98G cells compared to 143B and rhoo cell lines. This is consistent with our cytotoxicity studies and immunoblot analysis. Our results give credence to our hypothesis that the sensitivity to NO donors can be increased by glyco-conjugation and the cytotoxicity of the glyco-conjugated NO donors depends on the expression of GLUT 1 mRNA and protein.

Controlled photoinitiated release of nitric oxide from polymer films containing S-nitroso-N-acetyl-DL-penicillamine derivatized fumed silica filler.

This report describes the first hydrophobic nitric oxide (NO)-releasing material that utilizes light as an external on/off trigger to control the flux of NO generated from cured polymer films. Fumed silica polymer filler particles were derivatized with S-nitroso-N-acetyl-dl-penicillamine and blended into the center layer of trilayer silicone rubber films. Nitric oxide is generated upon irradiation with light, and fluxes increase with increasing power of incident light. The ability to precisely control NO generation from this material has the potential to answer fundamental questions about the levels of NO needed to achieve desired therapeutic affects in different biomedical applications.

The influence of glyco-nitric oxide conjugate on proliferation of breast cancer cells in vitro.

The aim of the study was to evaluate the influence of a nitric oxide donor: Glyco-2-SNAP on the proliferation status of two breast cancer cell lines: MDA-MB-231 and MCF-7. The study was performed by the thymidine incorporation method as well as by the immunocytochemical detection of the Ki-67 antigen. We found that the donor significantly inhibits the process of proliferation. The effect of the Glyco-2-SNAP is significant in both lines, however stronger in MDA -MB-231 cells where the donor at 100 microM inhibited DNA synthesis from 70462.000 dpi (SD +/-2066.175, n=4) for control to about 3120.250 dpi (SD +/-971.689 n=4). In UCF-7 cells the control gave 31142.500 dpi (SD +/-712.9214, n=4) and the treatment with 100 microM of Glyco-2 SNAP resulted in 4095.50 dpi. (SD +/-315.723, n=4). In both lines SNAP, classical NO donor also had an inhibitory effect but much higher concentrations. Ki-67 protein expression was significantly influenced by Glyco-2-SNAP at 100 microM (42.5% +/-6.45) concentrations in MDA-MB 231. No effect of G-SNAP was seen in MCF-7 cells. The control staining for both lines was about 90%. Our results presesent the possibility of exploiting a novel kind of NO donor as a potential mode of treatment that may be an alternative to classical therapeutic strategies in breast cancer.