title: The mechanism of transglutaminase 2 inhibition with glucosamine: implications of a possible anti-inflammatory effect through transglutaminase inhibition.
abstract: OBJECTIVE
  Although many efforts on revealing mechanism of the constitutive activation of NF-κB in cancer cells contributed to understanding canonical pathways, largely it remains to be determined for therapeutic approaches. Recently, we found that increased expression of transglutaminase 2 (TGase 2) appears to be responsible for constitutive activation of NF-κB in certain types of cancer cells. In previous studies, we demonstrated that TGase 2 inhibition markedly increases anti-cancer drug sensitivity in drug resistance cancer cells. Therefore, we develop safe and effective TGase 2 inhibitors for therapeutic approach.
  
  
  METHODS
  We screened a chemical library of natural compounds using in vitro TGase 2 activity assay. The salient discovery was that glucosamine (GlcN), a known anti-inflammatory substance, inhibited the cross-linking activity of TGase 2. We tested, through a biochemical analysis including kinetics, whether the GlcN and GlcN analogs specifically inhibit TGase 2. We also determined the inhibitory mechanism using conformational change of TGase 2.
  
  
  RESULTS
  We found that the primary amine of GlcN plays a key role in TGase 2 inhibition. We also demonstrated that GlcN reversed TGase 2-mediated I-κBα polymerization in vitro. Interestingly, the metabolite of GlcN, glucosamine-6-phosphate (GlcN6P), inhibited TGase 2 activity via binding to the GTP-binding site with better efficiency than GlcN. In the native gel electrophoresis, it was clearly observed that GlcN6P binds to TGase 2 directly as an allosteric inhibitor.
  
  
  CONCLUSIONS
  We concluded that GlcN inhibits TGase 2 activity by direct contact. GlcN and its metabolite GlcN6P can down-regulate constitutive activation of NF-κB in vivo via inhibition of TGase 2.
authors: Cancer Cell and Molecular Biology Branch, Division of Cancer Biology, Research Institute, National Cancer Center, 111 Jungbalsan-ro, Ilsandong-gu, Goyang, Gyeonggi-do, 410-769, Republic of Korea.
authors: Kyung-Chae
authors: KC
authors: Jeong
authors: Kyung-Ohk
authors: KO
authors: Ahn
authors: Byung Il
authors: BI
authors: Lee
authors: Chang-Hoon
authors: CH
authors: Lee
authors: Soo-Youl
authors: SY
authors: Kim
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000378:metabolism / Q000494:pharmacology; D001665:Binding Sites; D055162:Biocatalysis / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D019204:GTP-Binding Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D005944:Glucosamine / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology*; D019298:Glucose-6-Phosphate / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D006160:Guanosine Triphosphate / Q000378:metabolism; D006168:Guinea Pigs; D006801:Humans; D051550:I-kappa B Kinase / Q000378:metabolism; D007700:Kinetics; D009154:Mutation; D016328:NF-kappa B / Q000378:metabolism; D011485:Protein Binding; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011503:Transglutaminases / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism
chemical_list: D000893:Anti-Inflammatory Agents; D016328:NF-kappa B; C001293:glucosamine 6-phosphate; D019298:Glucose-6-Phosphate; D006160:Guanosine Triphosphate; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011503:Transglutaminases; D051550:I-kappa B Kinase; D019204:GTP-Binding Proteins; D005944:Glucosamine