title: Monensin-mediated growth inhibition in NCI-H929 myeloma cells via cell cycle arrest and apoptosis.
abstract: Previously, we showed that monensin, Na+ ionophore, potently inhibited the growth of acute myelogenous leukemia and lymphoma cells. Here, we investigated the antiproliferative effect of monensin on human myeloma cell lines. Monensin significantly inhibited the proliferation of myeloma cell lines examined with IC50 of about 1 micro M. Cell cycle analysis indicated that monensin induced a G1 and/or a G2-M phase arrest in these cell lines. To address the mechanism of the antiproliferative effect of monensin, we examined the effect of this drug on cell cycle-related proteins in NCI-H929 cells. Monensin decreased the levels of CDK2, CDK6, cdc2, cyclin A, cyclin B1, cyclin D1 and cyclin E proteins but did not alter CDK4 protein. While p21 was increased by monensin, p27 was not. In addition, monensin markedly enhanced the binding of p21 with CDK6 and cdc2. Furthermore, the activities of CDK2- and CDK6-associated kinases were reduced in association with hypophosphorylation of Rb protein. The activity of cdc2-associated kinase was decreased, which was accompanied by reduction of cdc25C phosphatase. Also, monensin induced apoptosis in myeloma cells, as evidenced by annexin V binding assay and flow cytometric detection of sub-G1 DNA content. This apoptotic process was associated with down-regulation of Bcl-2, loss of mitochondria transmembrane potential (Deltapsim) and an increase of caspase-3 activity. In addition, monensin caused the up-regulation of ERK and p38 kinase activities. Taken together, these results have demonstrated for the first time that monensin potently inhibited the proliferation of human myeloma cell lines, especially NCI-H929 cells, via cell cycle arrest in association with p21 and apoptosis.
authors.affiliation: Cancer Research Institute, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Woo Hyun
authors.initials: WH
authors.lastname: Park
authors.forename: Eun Shil
authors.initials: ES
authors.lastname: Kim
authors.forename: Byoung Kook
authors.initials: BK
authors.lastname: Kim
authors.forename: Young Yiul
authors.initials: YY
authors.lastname: Lee
mesh_terms: D000935:Antifungal Agents / Q000494:pharmacology*; D017209:Apoptosis; D015153:Blotting, Western; D016203:CDC2 Protein Kinase / Q000378:metabolism; D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000378:metabolism; D002455:Cell Division; D045744:Cell Line, Tumor; D002469:Cell Separation; D019938:Cyclin D1 / Q000378:metabolism; D051361:Cyclin-Dependent Kinase 6; D050759:Cyclin-Dependent Kinase Inhibitor p21; D018844:Cyclin-Dependent Kinases / Q000378:metabolism; D016213:Cyclins / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D004591:Electrophoresis, Polyacrylamide Gel; D005434:Flow Cytometry; D016195:G2 Phase; D006801:Humans; D020128:Inhibitory Concentration 50; D008564:Membrane Potentials; D008840:Microfilament Proteins / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism; D008938:Mitosis; D008956:Models, Chemical; D008985:Monensin / Q000494:pharmacology*; D009101:Multiple Myeloma / Q000188:drug therapy* / Q000378:metabolism*; D009124:Muscle Proteins; D011233:Precipitin Tests; D011485:Protein Binding; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D013997:Time Factors; D020687:cdc25 Phosphatases / Q000378:metabolism
chemical_list: D000935:Antifungal Agents; C493956:CDKN1A protein, human; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D008840:Microfilament Proteins; D009124:Muscle Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; C058992:Tagln protein, mouse; D019938:Cyclin D1; D008985:Monensin; D016203:CDC2 Protein Kinase; C495911:CDK6 protein, human; D051361:Cyclin-Dependent Kinase 6; D018844:Cyclin-Dependent Kinases; C517009:CDC25C protein, human; C517010:Cdc25c protein, mouse; D020687:cdc25 Phosphatases