SLC2A5 overexpression in childhood philadelphia chromosome-positive acute lymphoblastic leukaemia.

To study glycolysis/glycogenesis-related genes expression in childhood B-cell acute lymphoblastic leukaemia (B-ALL), we performed a microarray-based analysis using published gene expression profiles. We found that SLC2A5, which encodes solute carrier family 2 member 5 (SLC2A5, previously termed GLUT5) that facilitates cell fructose uptake, was up-regulated in Philadelphia chromosome-positive ALL (Ph+ALL). Microarray-based analyses also suggested that SLC2A5 expression was significantly down-regulated in childhood B-ALL with t(1;19) or 11q23 mutation. High SLC2A5 expression was found in patients who had disease recurrence within 3 years, early relapse, shortened complete remission duration and positive minimal residue disease (MRD) status after treatment. SLC2A5 overexpression at both the mRNA and protein level in Ph+ALL was confirmed in a validation cohort of childhood B-ALL. We also validated the correlation of SLC2A5 expression and MRD status. A mechanistic study using a human Ph+ALL cell line showed that BCR-ABL1 kinase might regulate SLC2A5 expression via MYC. The tyrosine kinase inhibitors (TKIs) imatinib and dasatinib repressed SLC2A5 expression and the cell uptake of fructose. Fructose protected the tumour cells from nutrition deficiency and drug-induced cell death. Overall, our findings showed that SLC2A5 was up-regulated in childhood Ph+ALL. SLC2A5 expression correlated with childhood B-ALL clinical factors, such as MRD status. Given that TKIs could inhibit SLC2A5 expression, repression of fructose utility after TKI treatment contributes to TKI-induced Ph+ALL cytotoxicity. Targeting SLC2A5 might be promising in B-ALL treatment, especially for Ph+ALL patients with high SLC2A5 expression.

Allopurinol decreases serum uric acid level and intestinal glucose transporter-5 expression in rats with fructose-induced hyperuricemia.

BACKGROUND: High fructose consumption is considered to be related to the increasing prevalence of hyperuricemia (HUA). Glucose transporters (GLUT) 2 and 5 are crucial for fructose absorption and transporter. Effects of anti-HUA drugs, allopurinol (API) and benzbromarone (BBR), on expressions of GLUT5 and GLUT2 are not evaluated. METHOD: Wistar rats were given 10% fructose in drinking water for 60 days to induce HUA, and 5mg/kg API and 10mg/kg BBR were intragastricly treated for 30 days. Serum level of uric acid and xanthine oxidase (XOD) activity in liver were determined. Expressions of GLUT2 and GLUT5 in intestine were analyzed by immunohistochemistry staining assay and Western blot assay. RESULTS: Treatment with API or BBR significantly decreased the serum level of uric acid in HUA rats induced by fructose. Meanwhile, API treatment significantly reduced the XOD activity in liver and GLUT5 expression in intestine. However, BBR treatment did not show inhibitory effects on hepatic XOD activity and intestinal GLUT5 expression. In addition, treatment with API or BBR did not show any effect on GLUT2 expression in intestine. CONCLUSION: API decreases serum level of uric acid in fructose-induced HUA rats. The mechanisms are associated with suppressing XOD activity in liver to reduce uric acid production, and inhibiting GLUT5 expression in intestine to reduce fructose absorption.

Changes in glucose and carnitine levels and their transporters in utero-tubal junction in relation to sperm storage in the vespertilionid bat, Scotophilus heathi.

Prolonged sperm storage over winter is a common feature of reproduction in some bats. In order to understand how sperm storage in the female genital tract of the vespertilionid bat, Scotophilus heathi (Greater yellow bat), is controlled, we compared concentrations of glucose and the fatty-acid carrier carnitine in the blood, and carnitine concentrations and levels of expression of the glucose transporters (GLUTs) and the carnitine transporter OCTN2 in the utero-tubal junction of females during non-storage (early winter) and sperm-storage periods (late winter-early spring). During the sperm-storage period (December-January) blood glucose concentrations declined, as did the expression of GLUT3 and GLUT5 in the utero-tubal junction. At the same time there were increases in the concentration of carnitine, and expression of OCTN2 and hormone-sensitive lipase (HSL) in the utero-tubal junction. These results suggest that prolonged sperm storage is enhanced by decreased glucose availability but increased free fatty acid availability at the site of sperm storage. Increases in expression of GLUT4 and GLUT8 in late winter suggest a role for these GLUTs in increasing sperm motility prior to fertilization.

TNFα regulates sugar transporters in the human intestinal epithelial cell line Caco-2.

PURPOSE: During intestinal inflammation TNFα levels are increased and as a consequence malabsorption of nutrients may occur. We have previously demonstrated that TNFα inhibits galactose, fructose and leucine intestinal absorption in animal models. In continuation with our work, the purpose of the present study was to investigate in the human intestinal epithelial cell line Caco-2, the effect of TNFα on sugar transport and to identify the intracellular mechanisms involved. METHODS: Caco-2 cells were grown on culture plates and pre-incubated during different periods with various TNFα concentrations before measuring the apical uptake of galactose, α-methyl-glucoside (MG) or fructose for 15 min. To elucidate the signaling pathway implicated, cells were pre-incubated for 30min with the PKA inhibitor H-89 or the PKC inhibitor chelerythrine, before measuring the sugar uptake. The expression in the apical membrane of the transporters implicated in the sugars uptake process (SGLT1 and GLUT5) was determined by Western blot. RESULTS: TNFα inhibited 0.1mM MG uptake after pre-incubation of the cells for 6-48h with the cytokine and in the absence of cytokine pre-incubation. In contrast, 5mM fructose uptake was stimulated by TNFα only after long pre-incubation times (24 and 48 h). These effects were mediated by the binding of the cytokine to its specific receptor TNFR1, present in the apical membrane of the Caco-2 cells. Analysis of the expression of the MG and fructose transporters at the brush border membrane of the cells, after 24h pre-incubation with the cytokine, revealed decrease on the amount of SGLT1 and increase on the amount of GLUT5 proteins. Short-term inhibition of MG transport by TNFα was not modified by H-89 but was blocked by chelerythrine. CONCLUSIONS: SGLT1 and GLUT5 expression in the plasma membrane is regulated by TNFα in the human epithelial cell line Caco-2 cells, leading to alteration on sugars transport, suggesting that TNFα could be considered as a physiological local regulator of nutrients absorption in response to an intestinal inflammatory status.

Clinical and immunopathologic alterations in rhesus macaques affected with globoid cell leukodystrophy.

Globoid cell leukodystrophy, or Krabbe's disease, is a severe disorder of the central and peripheral nervous system caused by the absence of galactocerebrosidase (GALC) activity. Herein, we describe the clinical, neuropathological, histochemical, and immunohistological features observed in rhesus macaques affected with Krabbe's disease. Clinical signs included pronounced muscle tremors of head and limbs, difficulty ambulating, ataxia, hypermetria, proprioceptive deficits, and respiratory abnormalities. Histopathologically, all animals presented with evidence of demyelination in the peripheral and central nervous systems and accumulation of mononuclear and multinuclear globoid cells in the cerebral and cerebellar white matter associated with severe gliosis. Using immunohistochemistry and multi-label confocal microscopy, it was determined that globoid cells were CD68+, HAM56+, LN5+, CD163+, IBA-1+, and Glut-5+, suggesting that both peripheral blood-derived monocytes/macrophages and resident parenchymal microglia gave rise to globoid cells. Interestingly, many of the globoid cells and parenchymal microglia with a more ameboid morphology expressed HLA-DR, indicating immune activation. Increased expression of iNOS, TNF-alpha, and IL-1 beta were observed in the affected white matter, colocalizing with globoid cells, activated microglia, and astrocytes. Cytokine mRNA levels revealed markedly increased gene expression of CCL2 in the brain of affected macaques. CCL2-expressing cells were detected throughout the affected white matter, colocalizing with GFAP+ cells and astrocytes. Collectively, these data suggest that dysregulation of monocyte/macrophage/microglia and up-regulation of certain cytokines may contribute to the pathogenesis of Krabbe's disease.

Retinoic acid improves a hybridoma culture in a fructose-based medium by up-regulation of fructose incorporation via retinoid nuclear receptors.

Fructose was focused on as an alternative sugar source to glucose in a hybridoma culture medium because it decreases lactate production during cultivation, leading to cell and product stability. But, not all human hybridoma cell lines grew well in a fructose-based serum-free medium. We found that the addition of all-trans-retinoic acid to the fructose-based medium improved the growth and monoclonal antibody production of hybridoma cell lines by up-regulation of fructose incorporation that represented increased expression of the fructose transporter, GLUT5. Selective activation of retinoid nuclear receptor by synthetic ligands showed that both retinoic acid receptors and retinoid X receptors might be related to the improvement of the fructose-based hybridoma culture. This study might be applicable to cell cultures susceptible to lactate and pH changes as well as hybridoma cultures.