title: PD98059 triggers G1 arrest and apoptosis in human leukemic U937 cells through downregulation of Akt signal pathway.
abstract: MEK/ERK pathways are frequently activated in acute myelogenous leukemia, and this signal pathway's inhibitor has made it an interesting candidate for cancer chemotherapy. Little is known, however, about the effects of cellular and molecular mechanisms on human leukemic U937 cells. In the present study, we found that treatment with PD98059 significantly arrests the G1 phase through up-regulation of cyclin-dependent kinase (Cdk) inhibitor, and produces morphological features of apoptosis in U937 cells, which were associated with poly(ADP-ribose)polymerase (PARP) cleavage and PLC-gamma1 degradation. PD98059 also decreased the Cdk-2, Cdk-4, cyclin D1, and cyclin E expression, and increased high levels of the mitotic inhibitors p16(INIa), p21(Waf1), and p27(Kip1). Also, Bcl-2's overexpression and a caspase-3 inhibitor z-DEVD-fmk significantly attenuated PD98059-induced apoptosis through the down-regulation of caspase-3 activity, but did not attenuate G1 phase arrest. Moreover, PD98059 down-regulated Akt phosphorylation and produced a synergy effect of apoptosis with LY294002 co-treatment. Thus, our results imply that PD98059-induced apoptosis is significantly involved in down-regulation of Bcl-2, caspase-3 activity, the Akt pathway, and some of the biological functions in U937 cells.
authors.affiliation: Faculty of Applied Marine Science, Cheju National University, Jeju 690-756, South Korea.
authors.forename: Dong-Oh
authors.initials: DO
authors.lastname: Moon
authors.forename: Cheol
authors.initials: C
authors.lastname: Park
authors.forename: Moon-Soo
authors.initials: MS
authors.lastname: Heo
authors.forename: Yeong-Min
authors.initials: YM
authors.lastname: Park
authors.forename: Yung Hyun
authors.initials: YH
authors.lastname: Choi
authors.forename: Gi-Young
authors.initials: GY
authors.lastname: Kim
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000378:metabolism; D061945:Caspase Inhibitors; D002470:Cell Survival / Q000187:drug effects; D002867:Chromones / Q000494:pharmacology; D019938:Cyclin D1 / Q000378:metabolism; D019927:Cyclin E / Q000378:metabolism; D051357:Cyclin-Dependent Kinase 2 / Q000378:metabolism; D051358:Cyclin-Dependent Kinase 4 / Q000378:metabolism; D015536:Down-Regulation; D005419:Flavonoids / Q000494:pharmacology*; D016193:G1 Phase / Q000187:drug effects; D006801:Humans; D020930:MAP Kinase Kinase Kinases / Q000037:antagonists & inhibitors*; D009025:Morpholines / Q000494:pharmacology; D009842:Oligopeptides / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D020298:U937 Cells
chemical_list: D053148:Caspase 3; D061945:Caspase Inhibitors; D002867:Chromones; D019938:Cyclin D1; D019927:Cyclin E; D051357:Cyclin-Dependent Kinase 2; D051358:Cyclin-Dependent Kinase 4; D005419:Flavonoids; D020930:MAP Kinase Kinase Kinases; D009025:Morpholines; D009842:Oligopeptides; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; D019253:Proto-Oncogene Proteins c-bcl-2; C110772:benzoylcarbonyl-aspartyl-glutamyl-valyl-aspartyl-fluoromethyl ketone; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one