메뉴 건너뛰기




Volumn 79, Issue 3, 2010, Pages 321-329

Inhibition of PDE3, PDE4 and PDE7 potentiates glucocorticoid-induced apoptosis and overcomes glucocorticoid resistance in CEM T leukemic cells

Author keywords

cAMP; Glucocorticoids; Leukemia; Phosphodiesterase

Indexed keywords

8' CHLORO 6' [4 [(4 METHYLPIPERAZIN 1 YL)CARBONYL]PHENYL] 1'H SPIRO[CYCLOHEXANE 1,4' QUINAZOLIN] 2'(3'H) ONE; DIPYRIDAMOLE; GLUCOCORTICOID; HYDROCORTISONE; ISOBUTYLMETHYLXANTHINE; MILRINONE; MOTAPIZONE; PHOSPHODIESTERASE III; PHOSPHODIESTERASE III INHIBITOR; PHOSPHODIESTERASE IIIB; PHOSPHODIESTERASE INHIBITOR; PHOSPHODIESTERASE IV; PHOSPHODIESTERASE IV INHIBITOR; PHOSPHODIESTERASE IVA; PHOSPHODIESTERASE IVD; PHOSPHODIESTERASE VII; PHOSPHODIESTERASE VII INHIBITOR; PHOSPHODIESTERASE VIIA; PHOSPHODIESTERASE VIIIA; PICLAMILAST; ROLIPRAM; SPIROQUINAZOLINONE; UNCLASSIFIED DRUG; ZARDAVERINE;

EID: 70449656971     PISSN: 00062952     EISSN: None     Source Type: Journal    
DOI: 10.1016/j.bcp.2009.09.001     Document Type: Article
Times cited : (40)

References (44)
  • 1
    • 30044446499 scopus 로고    scopus 로고
    • Cyclic nucleotide phosphodiesterases as targets for treatment of haematological malignancies
    • Lerner A., and Epstein P.M. Cyclic nucleotide phosphodiesterases as targets for treatment of haematological malignancies. Biochem J 393 (2006) 21-41
    • (2006) Biochem J , vol.393 , pp. 21-41
    • Lerner, A.1    Epstein, P.M.2
  • 2
    • 0036566204 scopus 로고    scopus 로고
    • Inhibition of PDE4 phosphodiesterase activity induces growth suppression, apoptosis, glucocorticoid sensitivity, p53, and p21(WAF1/CIP1) proteins in human acute lymphoblastic leukemia cells
    • Ogawa R., Streiff M.B., Bugayenko A., and Kato G.J. Inhibition of PDE4 phosphodiesterase activity induces growth suppression, apoptosis, glucocorticoid sensitivity, p53, and p21(WAF1/CIP1) proteins in human acute lymphoblastic leukemia cells. Blood 99 (2002) 3390-3397
    • (2002) Blood , vol.99 , pp. 3390-3397
    • Ogawa, R.1    Streiff, M.B.2    Bugayenko, A.3    Kato, G.J.4
  • 3
    • 11844288967 scopus 로고    scopus 로고
    • Type 4 cAMP phosphodiesterase (PDE4) inhibitors augment glucocorticoid-mediated apoptosis in B cell chronic lymphocytic leukemia (B-CLL) in the absence of exogenous adenylyl cyclase stimulation
    • Tiwari S., Dong H., Kim E.J., Weintraub L., Epstein P.M., and Lerner A. Type 4 cAMP phosphodiesterase (PDE4) inhibitors augment glucocorticoid-mediated apoptosis in B cell chronic lymphocytic leukemia (B-CLL) in the absence of exogenous adenylyl cyclase stimulation. Biochem Pharmacol 69 (2005) 473-483
    • (2005) Biochem Pharmacol , vol.69 , pp. 473-483
    • Tiwari, S.1    Dong, H.2    Kim, E.J.3    Weintraub, L.4    Epstein, P.M.5    Lerner, A.6
  • 6
    • 0029833842 scopus 로고    scopus 로고
    • Identification of cyclic AMP phosphodiesterases 3, 4 and 7 in human CD4+ and CD8+ T-lymphocytes: role in regulating proliferation and the biosynthesis of interleukin-2
    • Giembycz M.A., Corrigan C.J., Seybold J., Newton R., and Barnes P.J. Identification of cyclic AMP phosphodiesterases 3, 4 and 7 in human CD4+ and CD8+ T-lymphocytes: role in regulating proliferation and the biosynthesis of interleukin-2. Br J Pharmacol 118 (1996) 1945-1958
    • (1996) Br J Pharmacol , vol.118 , pp. 1945-1958
    • Giembycz, M.A.1    Corrigan, C.J.2    Seybold, J.3    Newton, R.4    Barnes, P.J.5
  • 7
    • 0003226768 scopus 로고    scopus 로고
    • Type 4 cyclic adenosine monophosphate phosphodiesterase as a therapeutic target in chronic lymphocytic leukemia
    • Kim D.H., and Lerner A. Type 4 cyclic adenosine monophosphate phosphodiesterase as a therapeutic target in chronic lymphocytic leukemia. Blood 92 (1998) 2484-2494
    • (1998) Blood , vol.92 , pp. 2484-2494
    • Kim, D.H.1    Lerner, A.2
  • 8
    • 0034777884 scopus 로고    scopus 로고
    • Phosphodiesterase type 4 inhibitor suppresses expression of anti-apoptotic members of the Bcl-2 family in B-CLL cells and induces caspase-dependent apoptosis
    • Siegmund B., Welsch J., Loher F., Meinhardt G., Emmerich B., Endres S., et al. Phosphodiesterase type 4 inhibitor suppresses expression of anti-apoptotic members of the Bcl-2 family in B-CLL cells and induces caspase-dependent apoptosis. Leukemia 15 (2001) 1564-1571
    • (2001) Leukemia , vol.15 , pp. 1564-1571
    • Siegmund, B.1    Welsch, J.2    Loher, F.3    Meinhardt, G.4    Emmerich, B.5    Endres, S.6
  • 9
    • 0036188156 scopus 로고    scopus 로고
    • Inhibition of PDE3B augments PDE4 inhibitor-induced apoptosis in a subset of patients with chronic lymphocytic leukemia
    • Moon E., Lee R., Near R., Weintraub L., Wolda S., and Lerner A. Inhibition of PDE3B augments PDE4 inhibitor-induced apoptosis in a subset of patients with chronic lymphocytic leukemia. Clin Cancer Res 8 (2002) 589-595
    • (2002) Clin Cancer Res , vol.8 , pp. 589-595
    • Moon, E.1    Lee, R.2    Near, R.3    Weintraub, L.4    Wolda, S.5    Lerner, A.6
  • 10
    • 0036151438 scopus 로고    scopus 로고
    • PDE7A is expressed in human B-lymphocytes and is up-regulated by elevation of intracellular cAMP
    • Lee R., Wolda S., Moon E., Esselstyn J., Hertel C., and Lerner A. PDE7A is expressed in human B-lymphocytes and is up-regulated by elevation of intracellular cAMP. Cell Signal 14 (2002) 277-284
    • (2002) Cell Signal , vol.14 , pp. 277-284
    • Lee, R.1    Wolda, S.2    Moon, E.3    Esselstyn, J.4    Hertel, C.5    Lerner, A.6
  • 11
    • 0033524977 scopus 로고    scopus 로고
    • CD3- and CD28-dependent induction of PDE7 required for T cell activation
    • Li L., Yee C., and Beavo J.A. CD3- and CD28-dependent induction of PDE7 required for T cell activation. Science 283 (1999) 848-851
    • (1999) Science , vol.283 , pp. 848-851
    • Li, L.1    Yee, C.2    Beavo, J.A.3
  • 13
    • 33845445704 scopus 로고    scopus 로고
    • Phosphodiesterase 7A1 is expressed in human CD4+ naive T cells at higher levels than in CD4+ memory cells and is not required during their CD3/CD28-dependent activation
    • Nueda A., Garcia-Roger N., Domenech T., Godessart N., Cardenas A., Santamaria-Babi L.F., et al. Phosphodiesterase 7A1 is expressed in human CD4+ naive T cells at higher levels than in CD4+ memory cells and is not required during their CD3/CD28-dependent activation. Cell Immunol 242 (2006) 31-38
    • (2006) Cell Immunol , vol.242 , pp. 31-38
    • Nueda, A.1    Garcia-Roger, N.2    Domenech, T.3    Godessart, N.4    Cardenas, A.5    Santamaria-Babi, L.F.6
  • 14
    • 9444228283 scopus 로고    scopus 로고
    • Discovery of BRL 50481 [3-(N,N-dimethylsulfonamido)-4-methyl-nitrobenzene], a selective inhibitor of phosphodiesterase 7: in vitro studies in human monocytes, lung macrophages, and CD8+ T-lymphocytes
    • Smith S.J., Cieslinski L.B., Newton R., Donnelly L.E., Fenwick P.S., Nicholson A.G., et al. Discovery of BRL 50481 [3-(N,N-dimethylsulfonamido)-4-methyl-nitrobenzene], a selective inhibitor of phosphodiesterase 7: in vitro studies in human monocytes, lung macrophages, and CD8+ T-lymphocytes. Mol Pharmacol 66 (2004) 1679-1689
    • (2004) Mol Pharmacol , vol.66 , pp. 1679-1689
    • Smith, S.J.1    Cieslinski, L.B.2    Newton, R.3    Donnelly, L.E.4    Fenwick, P.S.5    Nicholson, A.G.6
  • 15
    • 0030459832 scopus 로고    scopus 로고
    • Identification and tissue-specific expression of PDE7 phosphodiesterase splice variants
    • Bloom T.J., and Beavo J.A. Identification and tissue-specific expression of PDE7 phosphodiesterase splice variants. Proc Natl Acad Sci USA 93 (1996) 14188-14192
    • (1996) Proc Natl Acad Sci USA , vol.93 , pp. 14188-14192
    • Bloom, T.J.1    Beavo, J.A.2
  • 17
  • 18
    • 0034720463 scopus 로고    scopus 로고
    • Cloning and characterization of the human and mouse PDE7B, a novel cAMP-specific cyclic nucleotide phosphodiesterase
    • Gardner C., Robas N., Cawkill D., and Fidock M. Cloning and characterization of the human and mouse PDE7B, a novel cAMP-specific cyclic nucleotide phosphodiesterase. Biochem Biophys Res Commun 272 (2000) 186-192
    • (2000) Biochem Biophys Res Commun , vol.272 , pp. 186-192
    • Gardner, C.1    Robas, N.2    Cawkill, D.3    Fidock, M.4
  • 19
    • 58049194092 scopus 로고    scopus 로고
    • Cyclic nucleotide phosphodiesterase profiling reveals increased expression of phosphodiesterase 7B in chronic lymphocytic leukaemia
    • Zhang L., Murray F., Zahno A., Kanter J.R., Chou D., Suda R., et al. Cyclic nucleotide phosphodiesterase profiling reveals increased expression of phosphodiesterase 7B in chronic lymphocytic leukaemia. Proc Natl Acad Sci USA 105 (2008) 19532-19537
    • (2008) Proc Natl Acad Sci USA , vol.105 , pp. 19532-19537
    • Zhang, L.1    Murray, F.2    Zahno, A.3    Kanter, J.R.4    Chou, D.5    Suda, R.6
  • 20
    • 20944438000 scopus 로고    scopus 로고
    • Tumor necrosis factor-alpha-dependent expression of phosphodiesterase 2: role in endothelial hyperpermeability
    • Seybold J., Thomas D., Witzenrath M., Boral S., Hocke A.C., Burger A., et al. Tumor necrosis factor-alpha-dependent expression of phosphodiesterase 2: role in endothelial hyperpermeability. Blood 105 (2005) 3569-3576
    • (2005) Blood , vol.105 , pp. 3569-3576
    • Seybold, J.1    Thomas, D.2    Witzenrath, M.3    Boral, S.4    Hocke, A.C.5    Burger, A.6
  • 22
    • 0036177992 scopus 로고    scopus 로고
    • Phosphodiesterase isoenzyme families in human osteoarthritis chondrocytes-functional importance of phosphodiesterase 4
    • Tenor H., Hedbom E., Hauselmann H.J., Schudt C., and Hatzelmann A. Phosphodiesterase isoenzyme families in human osteoarthritis chondrocytes-functional importance of phosphodiesterase 4. Br J Pharmacol 135 (2002) 609-618
    • (2002) Br J Pharmacol , vol.135 , pp. 609-618
    • Tenor, H.1    Hedbom, E.2    Hauselmann, H.J.3    Schudt, C.4    Hatzelmann, A.5
  • 23
    • 0032555138 scopus 로고    scopus 로고
    • Cloning and characterization of a cAMP-specific cyclic nucleotide phosphodiesterase
    • Soderling S.H., Bayuga S.J., and Beavo J.A. Cloning and characterization of a cAMP-specific cyclic nucleotide phosphodiesterase. Proc Natl Acad Sci USA 95 (1998) 8991-8996
    • (1998) Proc Natl Acad Sci USA , vol.95 , pp. 8991-8996
    • Soderling, S.H.1    Bayuga, S.J.2    Beavo, J.A.3
  • 25
    • 0037409401 scopus 로고    scopus 로고
    • Comparison of enzymatic characterization and gene organization of cyclic nucleotide phosphodiesterase 8 family in humans
    • Gamanuma M., Yuasa K., Sasaki T., Sakurai N., Kotera J., and Omori K. Comparison of enzymatic characterization and gene organization of cyclic nucleotide phosphodiesterase 8 family in humans. Cell Signal 15 (2003) 565-574
    • (2003) Cell Signal , vol.15 , pp. 565-574
    • Gamanuma, M.1    Yuasa, K.2    Sasaki, T.3    Sakurai, N.4    Kotera, J.5    Omori, K.6
  • 26
    • 0032127768 scopus 로고    scopus 로고
    • cAMP-specific phosphodiesterase HSPDE4D3 mutants which mimic activation and changes in rolipram inhibition triggered by protein kinase A phosphorylation of Ser-54: generation of a molecular model
    • Hoffmann R., Wilkinson I.R., McCallum J.F., Engels P., and Houslay M.D. cAMP-specific phosphodiesterase HSPDE4D3 mutants which mimic activation and changes in rolipram inhibition triggered by protein kinase A phosphorylation of Ser-54: generation of a molecular model. Biochem J 333 Pt 1 (1998) 139-149
    • (1998) Biochem J , vol.333 , Issue.PART 1 , pp. 139-149
    • Hoffmann, R.1    Wilkinson, I.R.2    McCallum, J.F.3    Engels, P.4    Houslay, M.D.5
  • 27
    • 0031887507 scopus 로고    scopus 로고
    • Phosphodiesterase profile of human B lymphocytes from normal and atopic donors and the effects of PDE inhibition on B cell proliferation
    • Gantner F., Gotz C., Gekeler V., Schudt C., Wendel A., and Hatzelmann A. Phosphodiesterase profile of human B lymphocytes from normal and atopic donors and the effects of PDE inhibition on B cell proliferation. Br J Pharmacol 123 (1998) 1031-1038
    • (1998) Br J Pharmacol , vol.123 , pp. 1031-1038
    • Gantner, F.1    Gotz, C.2    Gekeler, V.3    Schudt, C.4    Wendel, A.5    Hatzelmann, A.6
  • 29
    • 33646855087 scopus 로고    scopus 로고
    • Phosphodiesterase 8 (PDE8) regulates chemotaxis of activated lymphocytes
    • Dong H., Osmanova V., Epstein P.M., and Brocke S. Phosphodiesterase 8 (PDE8) regulates chemotaxis of activated lymphocytes. Biochem Biophys Res Commun 345 (2006) 713-719
    • (2006) Biochem Biophys Res Commun , vol.345 , pp. 713-719
    • Dong, H.1    Osmanova, V.2    Epstein, P.M.3    Brocke, S.4
  • 30
    • 0031611368 scopus 로고    scopus 로고
    • Expression and regulation of mRNA for distinct isoforms of cAMP-specific PDE-4 in mitogen-stimulated and leukemic human lymphocytes
    • Jiang X., Paskind M., Weltzien R., and Epstein P.M. Expression and regulation of mRNA for distinct isoforms of cAMP-specific PDE-4 in mitogen-stimulated and leukemic human lymphocytes. Cell Biochem Biophys 28 (1998) 135-160
    • (1998) Cell Biochem Biophys , vol.28 , pp. 135-160
    • Jiang, X.1    Paskind, M.2    Weltzien, R.3    Epstein, P.M.4
  • 31
    • 0030876492 scopus 로고    scopus 로고
    • Phosphodiesterase profiles of highly purified human peripheral blood leukocyte populations from normal and atopic individuals: a comparative study
    • Gantner F., Tenor H., Gekeler V., Schudt C., Wendel A., and Hatzelmann A. Phosphodiesterase profiles of highly purified human peripheral blood leukocyte populations from normal and atopic individuals: a comparative study. J Allergy Clin Immunol 100 (1997) 527-535
    • (1997) J Allergy Clin Immunol , vol.100 , pp. 527-535
    • Gantner, F.1    Tenor, H.2    Gekeler, V.3    Schudt, C.4    Wendel, A.5    Hatzelmann, A.6
  • 32
    • 34247139844 scopus 로고    scopus 로고
    • Differential expression and function of phosphodiesterase 4 (PDE4) subtypes in human primary CD4+ T cells: predominant role of PDE4D
    • Peter D., Jin S.L., Conti M., Hatzelmann A., and Zitt C. Differential expression and function of phosphodiesterase 4 (PDE4) subtypes in human primary CD4+ T cells: predominant role of PDE4D. J Immunol 178 (2007) 4820-4831
    • (2007) J Immunol , vol.178 , pp. 4820-4831
    • Peter, D.1    Jin, S.L.2    Conti, M.3    Hatzelmann, A.4    Zitt, C.5
  • 33
    • 0031028090 scopus 로고    scopus 로고
    • Challenge of human Jurkat T-cells with the adenylate cyclase activator forskolin elicits major changes in cAMP phosphodiesterase (PDE) expression by up-regulating PDE3 and inducing PDE4D1 and PDE4D2 splice variants as well as down-regulating a novel PDE4A splice variant
    • Erdogan S., and Houslay M.D. Challenge of human Jurkat T-cells with the adenylate cyclase activator forskolin elicits major changes in cAMP phosphodiesterase (PDE) expression by up-regulating PDE3 and inducing PDE4D1 and PDE4D2 splice variants as well as down-regulating a novel PDE4A splice variant. Biochem J 321 Pt 1 (1997) 165-175
    • (1997) Biochem J , vol.321 , Issue.PART 1 , pp. 165-175
    • Erdogan, S.1    Houslay, M.D.2
  • 34
    • 0032493818 scopus 로고    scopus 로고
    • Induction of phosphodiesterases 3B, 4A4, 4D1, 4D2, and 4D3 in Jurkat T-cells and in human peripheral blood T-lymphocytes by 8-bromo-cAMP and Gs-coupled receptor agonists. Potential role in beta2-adrenoreceptor desensitization
    • Seybold J., Newton R., Wright L., Finney P.A., Suttorp N., Barnes P.J., et al. Induction of phosphodiesterases 3B, 4A4, 4D1, 4D2, and 4D3 in Jurkat T-cells and in human peripheral blood T-lymphocytes by 8-bromo-cAMP and Gs-coupled receptor agonists. Potential role in beta2-adrenoreceptor desensitization. J Biol Chem 273 (1998) 20575-20588
    • (1998) J Biol Chem , vol.273 , pp. 20575-20588
    • Seybold, J.1    Newton, R.2    Wright, L.3    Finney, P.A.4    Suttorp, N.5    Barnes, P.J.6
  • 35
    • 33646798806 scopus 로고    scopus 로고
    • Phosphodiesterase 7 (PDE7) as a therapeutic target
    • Giembycz M.A., and Smith S.J. Phosphodiesterase 7 (PDE7) as a therapeutic target. Drugs Future 31 (2006) 207-229
    • (2006) Drugs Future , vol.31 , pp. 207-229
    • Giembycz, M.A.1    Smith, S.J.2
  • 36
    • 0036277784 scopus 로고    scopus 로고
    • Potential role of phosphodiesterase 7 in human T cell function: comparative effects of two phosphodiesterase inhibitors
    • Nakata A., Ogawa K., Sasaki T., Koyama N., Wada K., Kotera J., et al. Potential role of phosphodiesterase 7 in human T cell function: comparative effects of two phosphodiesterase inhibitors. Clin Exp Immunol 128 (2002) 460-466
    • (2002) Clin Exp Immunol , vol.128 , pp. 460-466
    • Nakata, A.1    Ogawa, K.2    Sasaki, T.3    Koyama, N.4    Wada, K.5    Kotera, J.6
  • 37
    • 61849162798 scopus 로고    scopus 로고
    • ASB16165, a novel inhibitor for phosphodiesterase 7A (PDE7A), suppresses IL-12-induced IFN-gamma production by mouse activated T lymphocytes
    • Kadoshima-Yamaoka K., Murakawa M., Goto M., Tanaka Y., Inoue H., Murafuji H., et al. ASB16165, a novel inhibitor for phosphodiesterase 7A (PDE7A), suppresses IL-12-induced IFN-gamma production by mouse activated T lymphocytes. Immunol Lett 122 (2009) 193-197
    • (2009) Immunol Lett , vol.122 , pp. 193-197
    • Kadoshima-Yamaoka, K.1    Murakawa, M.2    Goto, M.3    Tanaka, Y.4    Inoue, H.5    Murafuji, H.6
  • 38
    • 70249093993 scopus 로고    scopus 로고
    • A multi-target antisense approach against PDE4 and PDE7 reduces smoke-induced lung inflammation in mice
    • Fortin M., D'Anjou H., Higgins M.E., Gougeon J., Aube P., Moktefi K., et al. A multi-target antisense approach against PDE4 and PDE7 reduces smoke-induced lung inflammation in mice. Respir Res 10 (2009) 39
    • (2009) Respir Res , vol.10 , pp. 39
    • Fortin, M.1    D'Anjou, H.2    Higgins, M.E.3    Gougeon, J.4    Aube, P.5    Moktefi, K.6
  • 39
    • 52949103280 scopus 로고    scopus 로고
    • Can the anti-inflammatory potential of PDE4 inhibitors be realized: guarded optimism or wishful thinking?
    • Giembycz M.A. Can the anti-inflammatory potential of PDE4 inhibitors be realized: guarded optimism or wishful thinking?. Br J Pharmacol 155 (2008) 288-290
    • (2008) Br J Pharmacol , vol.155 , pp. 288-290
    • Giembycz, M.A.1
  • 40
    • 52949140176 scopus 로고    scopus 로고
    • PDE4 inhibitors: current status
    • Spina D. PDE4 inhibitors: current status. Br J Pharmacol 155 (2008) 308-315
    • (2008) Br J Pharmacol , vol.155 , pp. 308-315
    • Spina, D.1
  • 41
    • 0029745055 scopus 로고    scopus 로고
    • Inhibition of calmodulin-dependent phosphodiesterase induces apoptosis in human leukemic cells
    • Jiang X., Li J., Paskind M., and Epstein P.M. Inhibition of calmodulin-dependent phosphodiesterase induces apoptosis in human leukemic cells. Proc Natl Acad Sci USA 93 (1996) 11236-11241
    • (1996) Proc Natl Acad Sci USA , vol.93 , pp. 11236-11241
    • Jiang, X.1    Li, J.2    Paskind, M.3    Epstein, P.M.4
  • 42
    • 0031689426 scopus 로고    scopus 로고
    • Antisense inhibition of phosphodiesterase expression
    • Epstein P.M. Antisense inhibition of phosphodiesterase expression. Methods 14 (1998) 21-33
    • (1998) Methods , vol.14 , pp. 21-33
    • Epstein, P.M.1
  • 43
    • 66949168902 scopus 로고    scopus 로고
    • Chronic lymphocytic leukemia and B and T cells differ in their response to cyclic nucleotide phosphodiesterase inhibitors
    • Meyers J.A., Su D.W., and Lerner A. Chronic lymphocytic leukemia and B and T cells differ in their response to cyclic nucleotide phosphodiesterase inhibitors. J Immunol 182 (2009) 5400-5411
    • (2009) J Immunol , vol.182 , pp. 5400-5411
    • Meyers, J.A.1    Su, D.W.2    Lerner, A.3
  • 44
    • 0035710746 scopus 로고    scopus 로고
    • Analysis of relative gene expression data using real-time quantitative PCR and the 2(-Delta Delta C(T)) Method
    • Livak K.J., and Schmittgen T.D. Analysis of relative gene expression data using real-time quantitative PCR and the 2(-Delta Delta C(T)) Method. Methods 25 (2001) 402-408
    • (2001) Methods , vol.25 , pp. 402-408
    • Livak, K.J.1    Schmittgen, T.D.2


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.