title: Human interleukin-6 receptor super-antagonists with high potency and wide spectrum on multiple myeloma cells.
abstract: Interleukin-6 (IL-6) is the major growth factor for myeloma cells and is believed to participate in the pathogenesis of chronic autoimmune diseases and postmenopausal osteoporosis. IL-6 has been recently shown to possess three topologically distinct receptor binding sites: site 1 for binding to the subunit specific chain IL-6R alpha and sites 2 and 3 for the interaction with two subunits of the signaling chain gp130. We have generated a set of IL-6 variants that behave as potent cytokine receptor super-antagonists carrying substitutions that abolish interaction with gp130 at either site 2 alone (site 2 antagonist) or at both sites 2 and 3 (site 2 + 3 antagonist). In addition, substitutions have been introduced in site 1 that lead to variable increases in binding for IL-6R alpha up to 70-fold. IL-6 super-antagonists inhibit wild-type cytokine activity with efficacy proportional to the increase in receptor binding on a variety of human call lines of different origin, and the most potent molecules display full antagonism at low molar excess to wild-type IL-6. When tested on a representative set of IL-6-dependent human myeloma cell lines, although site 2 super-antagonists were in general quite effective, only the site 2 + 3 antagonist Sant7 showed antagonism on the full spectrum of cells tested. In conclusion, IL-6 super-antagonists are a useful tool for the study of myeloma in vitro and might constitute, in particular Sant7, effective IL-6 blocking agents in vivo.
authors.affiliation: Istituto di Richerche di Biologia Molecolare (IRBM)- P. Angeletti, Pomezia, Rome, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Sporeno
authors.forename: R
authors.initials: R
authors.lastname: Savino
authors.forename: L
authors.initials: L
authors.lastname: Ciapponi
authors.forename: G
authors.initials: G
authors.lastname: Paonessa
authors.forename: A
authors.initials: A
authors.lastname: Cabibbo
authors.forename: A
authors.initials: A
authors.lastname: Lahm
authors.forename: K
authors.initials: K
authors.lastname: Pulkki
authors.forename: R X
authors.initials: RX
authors.lastname: Sun
authors.forename: C
authors.initials: C
authors.lastname: Toniatti
authors.forename: B
authors.initials: B
authors.lastname: Klein
authors.forename: G
authors.initials: G
authors.lastname: Ciliberto
mesh_terms: D015703:Antigens, CD / Q000737:chemistry*; D006528:Carcinoma, Hepatocellular / Q000473:pathology; D006131:Growth Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D006801:Humans; D015850:Interleukin-6 / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology*; D008113:Liver Neoplasms / Q000473:pathology; D008545:Melanoma / Q000473:pathology; D008958:Models, Molecular; D009025:Morpholines / Q000378:metabolism; D009101:Multiple Myeloma / Q000473:pathology*; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors; D010446:Peptide Fragments / Q000737:chemistry / Q000494:pharmacology*; D016133:Polymerase Chain Reaction; D011487:Protein Conformation; D018123:Receptors, Interleukin / Q000737:chemistry*; D019947:Receptors, Interleukin-6; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000494:pharmacology; D013329:Structure-Activity Relationship; D014407:Tumor Cells, Cultured / Q000187:drug effects
chemical_list: D015703:Antigens, CD; D006131:Growth Inhibitors; D015850:Interleukin-6; D009025:Morpholines; D009363:Neoplasm Proteins; D010446:Peptide Fragments; D018123:Receptors, Interleukin; D019947:Receptors, Interleukin-6; D011993:Recombinant Fusion Proteins; C005759:2-phenyl-5,5-dimethyltetrahydro-1,4-oxazine