Antitumor efficiency of the cytosine deaminase/5-fluorocytosine suicide gene therapy system on malignant gliomas: an in vivo study.

BACKGROUND: Suicide gene therapy, particularly that utilizing the cytosine deaminase/5-fluorocytosine (CD/5-FC) system, represents a novel and attractive methodology of cancer research. Mechanistically, the CD enzyme can convert the antifungal agent 5-FC into the antimetabolite agent 5-fluorouracil (5-FU), thereby killing tumor cells. The purpose of this study was to investigate the antitumor efficiency of the CD/5-FC system in malignant gliomas using a nude mouse model. MATERIAL/METHODS: The eukaryotic expression plasmid pCMV-CD was transfected into U251 malignant glioma cells. Resistant clones (labeled U251/CD cells) were subsequently isolated and further confirmed by reverse transcription polymerase chain reaction (RT-PCR), immunofluoroscence, and immunoblot. Then U251/CD cells were incubated with 5-FC at various concentrations to measure viability ratios as determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. 5-FU concentrations in the media were measured by high-performance liquid chromatography (HPLC). Finally, the volumes and weights of tumors from glioma-bearing nude mice after 5-FC intervention were evaluated. RESULTS: The results revealed that the untreated U251 cells were insensitive to 5-FC whereas the U251/CD cells were highly sensitive. Apoptosis and cell death were observed on the U251/CD cells after 5-FC administration. HPLC analysis showed that 5-FU was detected in the U251/CD cell media. These in vivo animal data showed that the volumes and weights of the implanted tumors were dramatically decreased due to cell apoptosis and tumor necrosis. CONCLUSIONS: The in vivo results encourage a further investigation in a controlled trial on the treatment of malignant gliomas via the CD/5-FC gene therapy system.

Selenium inhibits high glucose- and high insulin-induced adhesion molecule expression in vascular endothelial cells.

BACKGROUND: Initiation of an atherosclerotic lesion requires endothelial expression of adhesion molecules. Selenium (Se), a biologically essential trace element, can inhibit cytokine (e.g., TNF-alpha)-induced expression of adhesion molecules. Atherosclerosis is accelerated in diabetic patients. This is at least partially caused by hyperglycemia and hyperinsulinemia increasing adhesion molecule expression. These experiments tested whether Se can also alter high glucose- and high insulin-induced expression of adhesion molecules. METHODS: Human umbilical vein endothelial cells (HUVECs) were pretreated with Se and stimulated by high glucose or high insulin. Expression of adhesion molecules was measured by Western blot. RESULTS: Se (100 nmol/L) significantly inhibited glucose (25 mmol/L)-induced expression of vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), and E-selectin. Moreover, Se significantly inhibited insulin (100 nmol/L)-induced VCAM-1 and ICAM-1 expression, whereas high insulin had no inducing effect on E-selectin. Se also inhibited high glucose- and high insulin-induced activation of p38 mitogen-activated protein kinase (p38), which indicated that the preventive effects of Se on adhesion molecules may be associated with p38. The important role of p38 in Se effects was further confirmed using p38 inhibitor SB203580. CONCLUSIONS: These results suggest that Se can inhibit high glucose- and high insulin-induced expression of adhesion molecules. Such antagonism is at least partially mediated through the modulation of p38 pathway. Therefore, Se may be considered as a potential preventive intervention for diabetes-accelerated atherosclerosis.

[The mechanism and implication of costimulatory molecules in dendritic cells in the development of asthma].

OBJECTIVE: To exploring the role of costimulatory molecules in the development of asthma and its mechanisms. METHODS: Murine asthma model was established with ovalbumin (OVA) sensitization and challenge, and the model was confirmed by histological analysis of lung tissues, cell numbers and differentiations of bronchoalveolar lavage, serum OVA-specific IgE level and interleukin (IL)-4 and IL-5 production by splenic T cells. The purity of spleen-derived dendritic cells was assayed with fluorescein-actived cell sorter (FACS) by analyzing CD(11c) molecule. FACS was also used to measure the expression of CD(80) and CD(86) on spleen-derived dendritic cell (DC) from OVA-sensitized and challenged mice. Finally, the production of IL-4 and IL-5 in naive T cells after stimulation with spleen-derived DC from OVA-sensitized and challenged mice were determined with ELISA. RESULTS: Histological analysis of lung tissues, components of broncho-alveolar fluid, the level of serum OVA-specific IgE, and the production of IL-4 and IL-5 were all consistent with the characteristic of a murine asthma model. The expression of CD(80) on spleen-derived DC from OVA-sensitized and challenged mice was increased significantly compared with that from PBS-treated mice, while there was no difference in CD(86) expression. On the other hand, DC from OVA-sensitized and challenged mice stimulated the production of IL-4 and IL-5 by naïve T cells. CONCLUSION: Our results suggest that DC, via upregulation of CD(80), might play a pivotal role in the maintenance and amplification of allergic immune response, namely the Th2 immune response.