ABSTRACT
A novel class of pyrazolopyrimidine-sulfonamides was discovered as selective dual inhibitors of aurora kinase A (AKA) and cyclin-dependent kinase 1 (CDK1). These inhibitors were originally designed based on an early lead (compound I). SAR development has led to the discovery of potent inhibitors with single digit nM IC(50)s towards both AKA and CDK1. An exemplary compound 1a has demonstrated good efficacy in an HCT116 colon cancer xenograft model.
Subject(s)
Antineoplastic Agents/pharmacology , CDC2 Protein Kinase/antagonists & inhibitors , Colonic Neoplasms/drug therapy , Protein Kinase Inhibitors/pharmacology , Protein Serine-Threonine Kinases/antagonists & inhibitors , Pyrimidines/pharmacology , Sulfonamides/pharmacology , Animals , Antineoplastic Agents/chemical synthesis , Antineoplastic Agents/chemistry , Aurora Kinase A , Aurora Kinases , CDC2 Protein Kinase/metabolism , Cell Line, Tumor , Cell Proliferation/drug effects , Chemistry Techniques, Synthetic , Colonic Neoplasms/pathology , Crystallography, X-Ray , Dose-Response Relationship, Drug , Drug Design , Ether-A-Go-Go Potassium Channels/antagonists & inhibitors , Humans , Mice , Mice, Nude , Models, Molecular , Molecular Structure , Neoplasms, Experimental/drug therapy , Neoplasms, Experimental/pathology , Protein Kinase Inhibitors/chemical synthesis , Protein Kinase Inhibitors/chemistry , Protein Serine-Threonine Kinases/metabolism , Pyrimidines/chemical synthesis , Pyrimidines/chemistry , Stereoisomerism , Structure-Activity Relationship , Sulfonamides/chemical synthesis , Sulfonamides/chemistry , Xenograft Model Antitumor AssaysABSTRACT
Integrin alpha6beta4-mediated adhesion interactions play key roles in keratinocyte and epithelial tumor cell biology. In order to evaluate how alpha6beta4 adhesion interactions contribute to these important cellular processes, the authors generated soluble versions of the integrin by recombinant expression of the subunit ectodomains fused to a human immunoglobulin G (IgG) Fc constant domain. Coexpression of the appropriate subunits enabled dimerization, secretion and purification of stable Fc-containing alpha6beta4 heterodimers. The soluble proteins exhibited the same metal ion and ligand dependency in their binding characteristics as intact alpha6beta4. Using these reagents in combination with anti-beta4 antibodies, the authors identified two distinct functional epitopes on the beta4 subunit. They demonstrated the involvement of one epitope in adhesion interactions and the other in regulating adhesion-independent growth in alpha6beta4-expressing tumor cell lines. The availability of these soluble integrin reagents and the data provided herein help to further delineate the structure-function relationships regulating alpha6beta4 signaling biology.
Subject(s)
Integrin alpha6beta4/physiology , Integrin beta4/chemistry , Animals , Antibodies/metabolism , CHO Cells , Cell Adhesion , Cell Communication , Cell Line, Tumor , Cricetinae , Cricetulus , Dimerization , Humans , Integrin beta4/immunology , Integrin beta4/physiology , K562 Cells , Keratinocytes/cytology , Keratinocytes/metabolism , Recombinant Fusion Proteins/biosynthesis , Recombinant Fusion Proteins/metabolism , Signal Transduction , Structure-Activity RelationshipABSTRACT
The primary limitation of IgG antibodies for radioimmunotherapy of solid tumors is their prolonged serum half-life, leading to dose-limiting bone marrow toxicity at doses providing inadequate radiation to the tumor. A humanized C(H)2 domain-deleted variant of the anti-TAG-72 antibody CC49 (HuCC49DeltaC(H)2) has faster blood clearance, compared to the IgG, while retaining tumor targeting. We compared the pharmacokinetics and tumor uptake of (111)In-HuCC49DeltaC(H)2 in BALB/c mice and a colon carcinoma (LS-174T) mouse xenograft with that of (111)In-labeled chimeric CC49 (cCC49), an antibody with pharmacokinetics similar to the humanized CC49 parent. Immuno-conjugates of HuCC49DeltaC(H)2 and cCC49 prepared with the (111)In chelator Mx-DTPA (1-isothiocyantobenzyl-3-methyldiethylenetriaminepentaacetic acid) retained low nM affinity and radiolabeling protocols provided greater than 95% radio-incorporation with (111)In while retaining greater than 80% immunoreactivity. Blood clearance of (111)In-HuCC49DeltaC(H)2 in BALB/c mice was monoexponential (t(1/2) 5.4 hours) and faster than (111)In-cCC49 (biexponential clearance; t1/2Delta 1.5 hours; t1/2beta 162 hours). The (111)In-HuCC49DeltaC(H)2 also cleared more rapidly from the blood in the murine xenograft. At 1 hour postinjection, blood concentrations for (111)In-HuCC49DeltaC(H)2 and (111)In-cCC49 were comparable (25.5 injected dose per g [%ID/g] and 21.3 %ID/g, respectively); tumor uptake for (111)In- HuCC49DeltaC(H)2 was 7.9 %ID/g, compared to 7.5 %ID/g for (111)In-cCC49. However, at 24 hours, blood concentration for (111)In-HuCC49DeltaC(H)2 was less than (111)In-cCC49 (0.9 %ID/g versus 5.2 %ID/g, respectively) with comparable tumor retention (14.4 %ID/g versus 19.0 %ID/g, respectively). Faster blood clearance of (111)In-HuCC49DeltaC(H)2 and tumor localization comparable to that of (111)In-cCC49 provided a fourfold improved tumor-to-blood ratio for (111)In-HuCC49DeltaC(H)2 at 24 hours postinjection.
