title: Calmodulin antagonists induce cell cycle arrest and apoptosis in vitro and inhibit tumor growth in vivo in human multiple myeloma.
abstract: BACKGROUND
  Human multiple myeloma (MM) is an incurable hematological malignancy for which novel therapeutic agents are needed. Calmodulin (CaM) antagonists have been reported to induce apoptosis and inhibit tumor cell invasion and metastasis in various tumor models. However, the antitumor effects of CaM antagonists on MM are poorly understood. In this study, we investigated the antitumor effects of naphthalenesulfonamide derivative selective CaM antagonists W-7 and W-13 on MM cell lines both in vitro and in vivo.
  
  
  METHODS
  The proliferative ability was analyzed by the WST-8 assay. Cell cycle was evaluated by flow cytometry after staining of cells with PI. Apoptosis was quantified by flow cytometry after double-staining of cells by Annexin-V/PI. Molecular changes of cell cycle and apoptosis were determined by Western blot. Intracellular calcium levels and mitochondrial membrane potentials were determined using Fluo-4/AM dye and JC-10 dye, respectively. Moreover, we examined the in vivo anti-MM effects of CaM antagonists using a murine xenograft model of the human MM cell line.
  
  
  RESULTS
  Treatment with W-7 and W-13 resulted in the dose-dependent inhibition of cell proliferation in various MM cell lines. W-7 and W-13 induced G1 phase cell cycle arrest by downregulating cyclins and upregulating p21cip1. In addition, W-7 and W-13 induced apoptosis via caspase activation; this occurred partly through the elevation of intracellular calcium levels and mitochondrial membrane potential depolarization and through inhibition of the STAT3 phosphorylation and subsequent downregulation of Mcl-1 protein. In tumor xenograft mouse models, tumor growth rates in CaM antagonist-treated groups were significantly reduced compared with those in the vehicle-treated groups.
  
  
  CONCLUSIONS
  Our results demonstrate that CaM antagonists induce cell cycle arrest, induce apoptosis via caspase activation, and inhibit tumor growth in a murine MM model and raise the possibility that inhibition of CaM might be a useful therapeutic strategy for the treatment of MM.
authors.affiliation: Department of Internal Medicine, Division of Hematology, Rheumatology and Respiratory Medicine, Faculty of Medicine, Kagawa University, 1750-1 Ikenobe, Miki-cho, Kita-gun, Kagawa 761-0793, Japan. yokokura@med.kagawa-u.ac.jp.
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Yokokura
authors.forename: Saki
authors.initials: S
authors.lastname: Yurimoto
authors.forename: Akihito
authors.initials: A
authors.lastname: Matsuoka
authors.forename: Osamu
authors.initials: O
authors.lastname: Imataki
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Dobashi
authors.forename: Shuji
authors.initials: S
authors.lastname: Bandoh
authors.forename: Takuya
authors.initials: T
authors.lastname: Matsunaga
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D020013:Calcium Signaling / Q000187:drug effects; D002147:Calmodulin / Q000037:antagonists & inhibitors*; D059447:Cell Cycle Checkpoints / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D005260:Female; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D009101:Multiple Myeloma / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology*; D023041:Xenograft Model Antitumor Assays
chemical_list: D000970:Antineoplastic Agents; D002147:Calmodulin