title: Induction of G1 Arrest by SB265610 Involves Cyclin D3 Down-regulation and Suppression of CDK2 (Thr160) Phosphorylation.
abstract: OBJECTIVE
  The current study investigated the mechanisms underlying the antitumor activity of SB265610, a cysteine-amino acid-cysteine (CXC) chemokines receptor 2 (CXCR2) antagonist.
  
  
  METHODS
  Cell-cycle progression and regulatory molecules were assessed by flow cytometry, immunoblotting, real-time PCR and immunoprecipitation. Target validation was achieved via RNA interference.
  
  
  RESULTS
  G1 arrest induced by SB265610 occurred at concentrations lacking CXCR2 selectivity, persisted upon interleukin 8 (IL8) challenge, and did not affect IL8 downstream target expression. Profiling of G1 regulators revealed cyclin-dependent kinase 2 (CDK2) (Thr160) hypophosphorylation, cyclin D3 gene down-regulation, and p21 post-translational induction. However, only cyclin D3 and CDK2 contributed towards G1 arrest. Furthermore, SB265610 induced a sustained phosphorylation of the p38MAPK. Pharmacological interference with p38MAPK significantly abrogated SB265610-induced G1 arrest and normalized the expression of cyclin D3, with restoration of its exclusive binding to CDK6, but with weak recovery of CDK2 (Thr160) hypo-phosphorylation.
  
  
  CONCLUSIONS
  The present study described the mechanisms for the anti-proliferative activity of SB265610 which may be of value in IL8-rich tumor microenvironments.
authors.affiliation: World Class Institute, Incurable Diseases Therapeutics Research Center, Korea Research Institute of Bioscience and Biotechnology, Ochang, Cheongwon, Republic of Korea Department of Pharmacology and Toxicology, Faculty of Pharmacy, Tanta University, Tanta, Egypt.
authors.forename: Ahmed E
authors.initials: AE
authors.lastname: Goda
authors.affiliation: World Class Institute, Incurable Diseases Therapeutics Research Center, Korea Research Institute of Bioscience and Biotechnology, Ochang, Cheongwon, Republic of Korea Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, U.S.A.
authors.forename: Raymond L
authors.initials: RL
authors.lastname: Erikson
authors.affiliation: Chemical Biology Research Center, Korea Research Institute of Bioscience and Biotechnology, Ochang, Cheongwon, Republic of Korea.
authors.forename: Jong-Seog
authors.initials: JS
authors.lastname: Ahn
authors.affiliation: World Class Institute, Incurable Diseases Therapeutics Research Center, Korea Research Institute of Bioscience and Biotechnology, Ochang, Cheongwon, Republic of Korea bykim@kribb.re.kr.
authors.forename: Bo-Yeon
authors.initials: BY
authors.lastname: Kim
mesh_terms: D059447:Cell Cycle Checkpoints / Q000187:drug effects; D056743:Cyclin D3 / Q000096:biosynthesis* / Q000235:genetics; D051357:Cyclin-Dependent Kinase 2 / Q000096:biosynthesis* / Q000235:genetics; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000235:genetics; D016193:G1 Phase / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D016209:Interleukin-8 / Q000235:genetics; D008297:Male; D010671:Phenylurea Compounds / Q000008:administration & dosage*; D010766:Phosphorylation; D011471:Prostatic Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D023063:Receptors, Interleukin-8B / Q000096:biosynthesis* / Q000235:genetics; D014230:Triazoles / Q000008:administration & dosage*; D059016:Tumor Microenvironment / Q000187:drug effects; D048051:p38 Mitogen-Activated Protein Kinases / Q000235:genetics
chemical_list: C549500:1-(2-bromophenyl)-3-(7-cyano-3H-benzotriazol-4-yl)urea; C534696:CCND3 protein, human; C508606:CXCL8 protein, human; D056743:Cyclin D3; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016209:Interleukin-8; D010671:Phenylurea Compounds; D023063:Receptors, Interleukin-8B; D014230:Triazoles; C495894:CDK2 protein, human; D051357:Cyclin-Dependent Kinase 2; D048051:p38 Mitogen-Activated Protein Kinases
keywords: G1 arrest; SB265610; cyclin D3; p21; p38MAPK; phospho(Thr160)-CDK2