formazans and Glioma

Cellular reduction of tetrazolium salts to their respective formazans is frequently used to determine the metabolic activity of cultured cells as an indicator of cell viability. For membrane-impermeable tetrazolium salts such as WST1 the application of a membrane-permeable electron cycler is usually required to mediate the transfer of intracellular electrons for extracellular WST1 reduction. Here we demonstrate that in addition to the commonly used electron cycler M-PMS, menadione can also serve as an efficient electron cycler for extracellular WST1 reduction in cultured neural cells. The increase in formazan absorbance in glial cell cultures for the WST1 reduction by menadione involves enzymatic menadione reduction and was twice that recorded for the cytosolic enzyme-independent WST1 reduction in the presence of M-PMS. The optimized WST1 reduction assay allowed within 30 min of incubation a highly reliable detection of compromised cell metabolism caused by 3-bromopyruvate and impaired membrane integrity caused by Triton X-100, with a sensitivity as good as that of spectrophotometric assays which determine cellular MTT reduction or lactate dehydrogenase release. The short incubation period of 30 min and the observed good sensitivity make this optimized menadione-mediated WST1 reduction assay a quick and reliable alternative to other viability and toxicity assays.

Topics: Animals; Astrocytes; Cell Survival; Cells, Cultured; Formazans; Glioma; Humans; Methylphenazonium Methosulfate; Neurons; Octoxynol; Oxidation-Reduction; Pyruvates; Rats; Rats, Wistar; Spectrophotometry; Vitamin K 3

CD133 (Prominin-1/AC133) is generally treated as a cell surface marker found on multipotent stem cells and tumor stem-like cells, and its biological function remains debated. Genetically modified rat glioma cell lines were generated by lentiviral gene delivery of human CD133 into rat C6 glioma cells (hCD133(+) -C6) or by infection of C6 cells with control lentivirus (mock-C6). Stable hCD133 expression promoted the self-renewal ability of C6-formed spheres with an increase in the expression of the stemness markers, Bmi-1 and SOX2. Akt phosphorylation, Notch-1 activation, and Notch-1 target gene expression (Hes-1, Hey1 and Hey2) were increased in hCD133(+) -C6 when compared to mock-C6. The inhibition of Akt phosphorylation, Notch-1 activation, and Hes-1 in hCD133(+) -C6 cells effectively suppressed their clonogenic ability, indicating that these factors are involved in expanding the growth of hCD133(+) -C6. An elevated expression of GTPase-activating protein 27 (Arhgap27) was detected in hCD133(+) -C6. A decline in the invasion of hCD133(+) -C6 by knockdown of Arhgap27 expression indicated the critical role of Arhgap27 in promoting cell migration of hCD133(+) -C6. In vivo study further showed that hCD133(+) -C6 formed aggressive tumors in vivo compared to mock-C6. Exposure of hCD133(+) -C6 to arsenic trioxide not only reduced Akt phosphorylation, Notch-1 activation and Hes-1 expression in vitro, but also inhibited their tumorigenicity in vivo. The results show that C6 glioma cells with stable hCD133 expression enhanced their stemness properties with increased Notch-1/Hes-1 signaling, Akt activation, and Arhgap27 action, which contribute to increased cell proliferation and migration of hCD133(+) -C6 in vitro, as well as progressive tumor formation in vivo.

Topics: AC133 Antigen; Animals; Antigens, CD; Antineoplastic Agents; Arsenic Trioxide; Arsenicals; Basic Helix-Loop-Helix Transcription Factors; Brain Neoplasms; Cell Line, Tumor; Cell Movement; Cell Proliferation; Cell Transformation, Neoplastic; Cerebral Cortex; Disease Models, Animal; Dose-Response Relationship, Drug; Enzyme Inhibitors; Female; Formazans; Gene Expression Regulation, Neoplastic; Glioma; Glycoproteins; GTPase-Activating Proteins; Homeodomain Proteins; Humans; Intercellular Signaling Peptides and Proteins; Lentivirus; Oncogene Protein v-akt; Oxides; Peptides; Rats; Rats, Sprague-Dawley; Receptor, Notch1; RNA, Messenger; RNA, Small Interfering; Tetrazolium Salts; Time Factors; Transcription Factor HES-1; Transfection; Tumor Stem Cell Assay

Two new complexes [(Etdpa)MnCl(2)] and [(Adpa)Mn(Cl)(H(2)O)] (Etdpa = ethyl bis(2-pyridylmethyl)amino-2-propionate; Adpa = bis(2-pyridylmethyl)amino-2-propionic acid) were synthesized and characterized by spectral methods. The crystal structure of [(Etdpa)MnCl(2)] shows that the Mn(II) atom is coordinated by three N atoms (N1, N2, N3), one oxygen atom (O1) of the ligand (Etdpa) and two chloride atoms (Cl1, Cl2), forming a distorted octahedral geometry. The binding interaction between ct-DNA and the synthesized complexes was relatively weak, but they can inhibit the induced swelling of Ca(2+)-loaded mitochondria in a dose-dependent manner. The [(Adpa)Mn(Cl)(H(2)O)] can cause the obvious decrease of mitochondria membrane potential. The MTT (3-[4,5-Dimethylthiazol-2-yl]-2,5-diphenpyltetra-zolium bromide) assay shows that the two Mn(II) complexes are more active against cancer cells. Especially [(Adpa)Mn(Cl)(H(2)O)] can inhibit the proliferation of glioma cells with IC(50) 9.5 μM. Experimental results indicate that the [(Adpa)Mn(Cl)(H(2)O)] could be a new potential antitumor complex to target the mitochondria.

Topics: Animals; Antineoplastic Agents; Brain Neoplasms; Breast Neoplasms; Cell Line, Tumor; Cell Survival; Coordination Complexes; DNA; Drug Evaluation, Preclinical; Drug Interactions; Esophageal Neoplasms; Female; Formazans; Glioma; HeLa Cells; Humans; Inhibitory Concentration 50; Manganese; Membrane Potential, Mitochondrial; Mitochondria, Liver; Molecular Structure; Oxygen; Rats; Reference Standards; Tetrazolium Salts

We have shown previously that human glioblastoma multiforme cells vary in their ability to survive under hypoxic conditions. Under oxygen limiting conditions, hypoxia-tolerant cells decrease their oxygen consumption rate whereas hypoxia-sensitive cells continue to consume oxygen at a relatively steady rate until the oxygen supply becomes exhausted. We now show that hypoxia-tolerant and hypoxia-sensitive cells exhibit distinct patterns of mitochondrial function in response to hypoxic challenge. Hypoxia-tolerant cell lines retain stable mitochondrial membrane potential and ATP concentration when incubated under oxygen limiting conditions. In addition, hypoxia-tolerant cell lines are consistently more sensitive to a wide spectrum of inhibitors of mitochondrial function than are hypoxia-sensitive cells. In contrast, the hypoxia-sensitive cells are unable to maintain stable mitochondrial membrane potential and ATP levels when incubated at reduced oxygen tension. These results demonstrate significant differences in the mitochondrial function between these two phenotypes and reinforce previous data that suggest a regulatory role for mitochondria in the development of hypoxia tolerance.

Topics: Adenosine Triphosphate; Brain Neoplasms; Cell Hypoxia; Cell Membrane; Cell Survival; Flow Cytometry; Formazans; Gene Expression Regulation; Glioma; Humans; Hypoxia; Ion Channels; Membrane Potentials; Mitochondria; Oxygen; Sensitivity and Specificity; Tetrazolium Salts; Tumor Cells, Cultured; Uncoupling Agents

This assay is based on morphological changes of rat glioma cells treated with db-cAMP. The db-cAMP treatment induces a tubulin-dependent change causing the cells to acquire a spherical shape. Pretreatment with tubulin inhibitors brings about the disintegration of tubulin polymer and/or prevents its polymerization. Cells with inhibited tubulin fail to respond to db-cAMP treatment. Cells treated with inhibitors of tubulin polymerization are then separated from the spherical cells by aspiration. A semiautomated scanning procedure evaluates the final culture density and yields graphical data.

Topics: Animals; Brain Neoplasms; Bucladesine; Cell Differentiation; Drug Screening Assays, Antitumor; Formazans; Glioma; Rats; Tubulin; Tumor Cells, Cultured