ascorbic-acid and Leukemia-Lymphoma--Adult-T-Cell

Clear therapeutic guidelines for HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) are missing due to the lack of randomized double-blind controlled clinical trials. Moderate yet similar clinical benefit has been demonstrated for IFN-α and high-dose ascorbic acid (AA) monotherapy in a large open clinical trial. However, there is a lack of in vivo and in vitro studies exploring and comparing the effects of high-dose AA and IFN-α treatment in the context of HAM/TSP. Therefore, we performed the first comparative analysis of the ex vivo and in vitro molecular and cellular mechanisms of action of IFN-α and high-dose AA in HAM/TSP.. Through thymidine incorporation and quantification of Th1/Th2/Th17 cytokines, we demonstrate that high-dose AA displays differential and superior antiproliferative and immunomodulatory effects over IFN-α in HAM/TSP PBMCs ex vivo. In addition, high-dose AA, but not IFN-α, induced cell death in both HAM/TSP PBMCs and HTLV-1-infected T-cell lines MT-2 and MT-4. Microarray data combined with pathway analysis of MT-2 cells revealed AA-induced regulation of genes associated with cell death, including miR-155. Since miR-155 has recently been demonstrated to up-regulate IFN-γ, this microRNA might represent a novel therapeutic target in HAM/TSP, as recently demonstrated in multiple sclerosis, another neuroinflammatory disease. On the other hand, IFN-α selectively up-regulated antiviral and immune-related genes.. In comparison to IFN-α, high-dose AA treatment has superior ex vivo and in vitro cell death-inducing, antiproliferative and immunomodulatory anti-HTLV-1 effects. Differential pathway activation by both drugs opens up avenues for targeted treatment in specific patient subsets.

Topics: Adult; Aged; Antineoplastic Agents; Ascorbic Acid; Cell Death; Cells, Cultured; Female; Gene Expression Profiling; Humans; Immunologic Factors; Interferon-alpha; Leukemia-Lymphoma, Adult T-Cell; Male; Microarray Analysis; Middle Aged; Organ Culture Techniques; Spinal Cord Diseases; Young Adult

Dihydroorotate dehydrogenase (DHODH) catalyzes the oxidation of dihydroorotate to orotate in the pyrimidine biosynthesis pathway. It is functionally connected to the respiratory chain, delivering electrons to ubiquinone. We report here that inhibition of cytochrome c oxidase by nitric oxide (NO) indirectly inhibits DHODH activity. In digitonin-permeabilized cells, DEA/NO, a chemical NO donor, induced a dramatic decrease in DHO-dependent O(2) consumption. The inhibition was reversible and more pronounced at low O(2) concentration; it was correlated with a decrease in orotate synthesis. Since orotate is the precursor of all pyrimidine nucleotides, indirect inhibition of DHODH by NO may significantly contribute to NO-dependent cytotoxicity.

Topics: Animals; Antioxidants; Ascorbic Acid; Digitonin; Dihydroorotate Dehydrogenase; Electron Transport; Electron Transport Complex IV; Enzyme Inhibitors; Humans; Hydrazines; K562 Cells; Leukemia L1210; Leukemia-Lymphoma, Adult T-Cell; Macrophages; Mice; Mitochondria; Nitric Oxide; Nitric Oxide Donors; Nitrogen Oxides; Orotic Acid; Oxidation-Reduction; Oxidoreductases; Oxidoreductases Acting on CH-CH Group Donors; Oxygen; Rats; Recombinant Proteins; Tumor Cells, Cultured