Involvement of extracellular signal-regulated kinase activation in human osteosarcoma cell resistance to the histone deacetylase inhibitor FK228 [(1S,4S,7Z,10S,16E,21R)-7-ethylidene-4,21-bis(propan-2-yl)-2-oxa-12,13-dithia-5,8,20,23-tetraazabicyclo[8.7.6]tricos-16-ene-3,6,9,19,22-pentone].
The histone deacetylase inhibitor depsipeptide [(1S,4S,7Z,10S, 16E,21R)-7-ethylidene-4,21-bis(propan-2-yl)-2-oxa-12,13-dithia-5,8,20,23-tetraazabicyclo[8.7.6]tricos-16-ene-3,6,9,19, 22-pentone] (FK228) has attracted a great deal of interest because of its antiproliferative and apoptotic properties in various malignancies. Histone deacetylase inhibitors induce the expression of the multidrug resistance transporter P-glycoprotein (P-gp), and FK228 is a known P-gp substrate. Thus, FK228 seems to induce its own mechanism of drug resistance by up-regulating P-gp. The goal of this study was to establish human FK228-resistant osteosarcoma cell lines and to investigate whether there are mechanisms of FK228 resistance in addition to P-gp up-regulation. After 72 h in culture, the 50% inhibitory concentrations (IC(50)) of FK228 were 4.8 and 991 nM in HOS and HOS/FK8 cells, respectively, and 3.6 and 1420 nM in U2OS and U2OS/FK11 cells, respectively. Increased histone H3 acetylation was observed in FK228-resistant cell lines after a 1-h treatment with 10 nM FK228. Unlike in parental cells, significant P-gp overexpression was detected in FK228-resistant cells, and 10 nM FK228 treatment activated the mitogen-activated protein kinase (MAPK) pathway but did not induce Fas ligand (FasL) up-regulation or c-FLIP down-regulation. However, treatment of FK228-resistant cells with a combination of FK228 and mitogen-activated protein kinase kinase (MEK) inhibitors induced apoptosis, up-regulated FasL, and down-regulated c-FLIP. The expression and function of P-gp were unaltered by treatment with MEK inhibitors. These results indicate that the FK228 resistance of osteosarcoma cells is related to P-gp overexpression and MAPK pathway activation by FK228. MEK or P-gp inhibitors may be useful in overcoming this resistance.
Matsubara
Hiroshi
H
Department of Pediatrics, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan.
Watanabe
Motonobu
M
Imai
Tsuyoshi
T
Yui
Yoshihiro
Y
Mizushima
Yasuhiro
Y
Hiraumi
Yoshimi
Y
Kamitsuji
Yuri
Y
Watanabe
Ken-Ichiro
K
Nishijo
Koichi
K
Toguchida
Junya
J
Nakahata
Tatsutoshi
T
Adachi
Souichi
S
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000187:drug effects / Q000235:genetics; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D001859:Bone Neoplasms / Q000188:drug therapy / Q000201:enzymology*; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D047630:Depsipeptides / Q000627:therapeutic use*; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D053222:Fas Ligand Protein / Q000187:drug effects / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D056572:Histone Deacetylase Inhibitors; D006801:Humans; D012516:Osteosarcoma / Q000188:drug therapy / Q000201:enzymology*
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000970:Antineoplastic Agents; D047630:Depsipeptides; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D056572:Histone Deacetylase Inhibitors; C087123:romidepsin; D048049:Extracellular Signal-Regulated MAP Kinases