bims-stacyt Biomed news on
Starvation pathways leading to cytokine regulation
Issue of 2018‒01‒21
four papers selected by
Cristina Muñoz Pinedo
L’Institut d’Investigació Biomèdica de Bellvitge

  1. Neuropharmacology. 2018 Jan 10. doi: 10.1016/j.neuropharm.2018.01.012131
    Abstract:  The inflammatory response of glial cells contributes to neuronal damage or repair after brain ischemia/reperfusion insult. We previously demonstrated a protective role of TP53-induced glycolysis and apoptosis regulator (TIGAR) in ischemic neuronal injury through increasing the flow of pentose phosphate pathway (PPP). The present study investigated the possible role of TIGAR in ischemia/reperfusion-induced inflammatory response of astrocytes. Male ICR mice were subjected to middle cerebral artery occlusion for 2 h followed by 24 h reperfusion and cultured primary astrocytes were subjected to oxygen glucose deprivation for 9 h followed by 24 h reoxygenation (OGD/R). Adenoviral vectors were used to alter the levels of TIGAR protein in brain and in culture primary astrocytes. We showed that during the OGD/R insult the protein levels of TIGAR were rapidly increased in astrocytes. Overexpression of TIGAR mediated increased the viability, levels of NADPH and rGSH, and reduced intracellular reactive oxygen species (ROS) in cultured primary astrocytes. Overexpression of TIGAR not only significantly reduced infarct volume after stroke insult but also markedly reduced long-term mortality and improved recovery of neurological functions. Overexpression of TIGAR tempered OGD/R- or ischemia/reperfusion-induced the upregulation of inducible nitric oxide synthase (iNOS), cyclooxygenases COX2 and the release of pro-inflammatory cytokines interleukin 1 beta (IL-1β) and tumor necrosis factor-α (TNF-α), while TIGAR knockdown produced opposite effects on these parameters. Moreover, Overexpression of TIGAR suppressed OGD/R-induced degradation of IκBα and NF-κB nuclear translocation in cultured primary astrocytes. The present study elucidates a novel mechanism by which TIGAR protects neurons against ischemia/reperfusion injury.
    Keywords:  Astrocytes; Inflammation; NADPH; NF-κB; Stroke; TIGAR
  2. Cancer Lett. 2018 Jan 10. doi: 10.1016/j.canlet.2018.01.028
    Abstract:  Since disturbed metabolic conditions such as obesity and diabetes can be critical determinants of breast cancer progression and therapeutic failure, we aimed to determine the mechanism responsible for their pro-oncogenic effects. Using non-invasive, epithelial-like ERα-positive MCF-7 and T47D human breast cancer cells we found that hyperglycaemia induced epithelial to mesenchymal transition (EMT), a key programme responsible for the development of metastatic disease. This was demonstrated by loss of the epithelial marker E-cadherin together with increases in mesenchymal markers such as vimentin, fibronectin and the transcription factor SLUG, together with an enhancement of cell growth and invasion. These phenotypic changes were only observed with cells grown on fibronectin and not with those plated on collagen. Analyzing metabolic parameters, we found that hyperglycaemia-induced, matrix-specific EMT promoted the Warburg effect by upregulating glucose uptake, lactate release and specific glycolytic enzymes and transporters. We showed that silencing of fatty acid synthase (FASN) and the downstream ERα, which we showed previously to mediate hyperglycaemia-induced chemoresistance in these cells, resulted in suppression of cell growth: however, this also resulted in a dramatic enhancement of cell invasion and SLUG mRNA levels via a novel caveolin-1-dependent mechanism.
    Keywords:  Breast cancer; Epithelial to mesenchymal transition; Fibronectin; Hyperglycaemia; Warburg effect
  3. Angiogenesis. 2018 Jan 13. doi: 10.1007/s10456-018-9594-9
    Abstract:  Corneal neovascularization is a sight-threatening condition caused by angiogenesis in the normally avascular cornea. Neovascularization of the cornea is often associated with an inflammatory response, thus targeting VEGF-A alone yields only a limited efficacy. The NF-κB signaling pathway plays important roles in inflammation and angiogenesis. Here, we study consequences of the inhibition of NF-κB activation through selective blockade of the IKK complex IκB kinase β (IKK2) using the compound IMD0354, focusing on the effects of inflammation and pathological angiogenesis in the cornea. In vitro, IMD0354 treatment diminished HUVEC migration and tube formation without an increase in cell death and arrested rat aortic ring sprouting. In HUVEC, the IMD0354 treatment caused a dose-dependent reduction in VEGF-A expression, suppressed TNFα-stimulated expression of chemokines CCL2 and CXCL5, and diminished actin filament fibers and cell filopodia formation. In developing zebrafish embryos, IMD0354 treatment reduced expression of Vegf-a and disrupted retinal angiogenesis. In inflammation-induced angiogenesis in the rat cornea, systemic selective IKK2 inhibition decreased inflammatory cell invasion, suppressed CCL2, CXCL5, Cxcr2, and TNF-α expression and exhibited anti-angiogenic effects such as reduced limbal vessel dilation, reduced VEGF-A expression and reduced angiogenic sprouting, without noticeable toxic effect. In summary, targeting NF-κB by selective IKK2 inhibition dampened the inflammatory and angiogenic responses in vivo by modulating the endothelial cell expression profile and motility, thus indicating an important role of NF-κB signaling in the development of pathologic corneal neovascularization.
    Keywords:  Cornea; IKK2; IMD0354; NF-κB; Neovascularization; VEGF
  4. Matrix Biol. 2018 Jan 10. doi: 10.1016/j.matbio.2017.12.015
    Abstract:  Increased uptake of glucose, a general hallmark of malignant tumors, leads to an accumulation of intermediate metabolites of glycolysis. We investigated whether the high supply of these intermediates promotes their flow into UDP-sugars, and consequently into hyaluronan, a tumor-promoting matrix molecule. We quantified UDP-N-Acetylglucosamine (UDP-GlcNAc) and UDP-glucuronic acid (UDP-GlcUA) in human breast cancer biopsies, the levels of enzymes contributing to their synthesis, and their association with the hyaluronan accumulation in the tumor. The content of UDP-GlcUA was 4 times, and that of UDP-GlcNAc 12 times higher in the tumors as compared to normal glandular tissue obtained from breast reductions. The surge of UDP-GlcNAc correlated with an elevated mRNA expression of glutamine-fructose-6-phosphate aminotransferase 2 (GFAT2), one of the key enzymes in the biosynthesis of UDP-GlcNAc, and the expression of GFAT1 was also elevated. The contents of both UDP-sugars strongly correlated with tumor hyaluronan levels. Interestingly, hyaluronan content did not correlate with the mRNA levels of the hyaluronan synthases (HAS1-3), thus emphasizing the role of the UDP-sugar substrates of these enzymes. The UDP-sugars showed a trend to higher levels in ductal vs. lobular cancer subtypes. The results reveal for the first time a dramatic increase of UDP-sugars in breast cancer, and suggest that their high supply drives the accumulation of hyaluronan, a known promoter of breast cancer and other malignancies. In general, the study shows how the disturbed glucose metabolism typical for malignant tumors can influence cancer microenvironment through UDP-sugars and hyaluronan.
    Keywords:  Breast cancer; Hyaluronan; UDP-N-Acetylglucosamine; UDP-sugar; Warburg effect