glutaminase and thiazolyl-blue

Microglia represent the main cellular targets of HIV-1 in the brain. Infected and/or activated microglia play a pathogenic role in HIV-associated neurocognitive disorders (HAND) by instigating primary dysfunction and subsequent death of neurons. Although microglia are known to secrete neurotoxins when infected with HIV-1, the detailed mechanism of neurotoxicity remains unclear. Using a human microglia primary culture system and macrophage-tropic HIV-1 strains, we have now demonstrated that HIV-1 infection of microglia resulted in a significant increase in extracellular glutamate concentrations and elevated levels of neurotoxicity. RNA and protein analysis revealed upregulation of the glutamate-generating enzyme glutaminase isoform glutaminase C in HIV-1-infected microglia. The clinical relevance of these findings was further corroborated with investigation of postmortem brain tissues. The glutaminase C levels in the brain tissues of HIV dementia individuals were significantly higher than HIV serum-negative control and correlated with elevated concentrations of glutamate. When glutaminase was subsequently inhibited by siRNA or by a small molecular inhibitor, the HIV-induced glutamate production and the neuronal loss was diminished. In conclusion, these findings support glutaminase as a potential component of the HAND pathogenic process as well as a novel therapeutic target in their treatment.

Topics: Analysis of Variance; Antigens, CD; Antigens, Differentiation, Myelomonocytic; Brain; Caspase 3; Cells, Cultured; Chromatography, High Pressure Liquid; Disintegrins; Dizocilpine Maleate; Enzyme-Linked Immunosorbent Assay; Excitatory Amino Acid Antagonists; Fetus; Gene Expression Regulation, Viral; Glutamic Acid; Glutaminase; Glutamine; HIV Infections; HIV-1; Humans; Microglia; Microtubule-Associated Proteins; Receptors, Cell Surface; RNA, Small Interfering; Tetrazolium Salts; Thiazoles; Time Factors

Tumor cells intensely utilize glutamine as the major source of respiratory fuel. Glutamine-analogue acivicin inhibits tumor growth and tumor-induced angiogenesis in Ehrlich ascites carcinoma. In the present study, antitumor properties of acivicin in combination with glutaminase enzyme is reported. Acivicin along with E. coli glutaminase synergistically reduced in vitro proliferation and matrigel invasion of human MCF-7 and OAW-42 cells. Effects of single and combined treatments with acivicin and glutaminase on angiogenic factors were also analyzed in these cell lines. Co-administration of the treatment agents inhibits the release of VEGF and MMP-9 by cells in culture supernatant significantly than single agent treatments. The result suggests that combination of acivicin with glutaminase may provide a better therapeutic option than either of them given separately for treating human breast and ovarian cancer. However, further studies are required to be conducted in vivo for its confirmation.

Topics: Antimetabolites, Antineoplastic; Breast Neoplasms; Cell Line, Tumor; Cell Proliferation; Collagen; Drug Combinations; Female; Glutaminase; Glutamine; Humans; In Vitro Techniques; Isoxazoles; Laminin; Matrix Metalloproteinase 9; Neoplasm Invasiveness; Ovarian Neoplasms; Proteoglycans; Tetrazolium Salts; Thiazoles; Vascular Endothelial Growth Factor A