The role of the nuclear Akt activation and Akt inhibitors in all-trans-retinoic acid-differentiated HL-60 cells.
The pharmacological inhibitors of phosphoinositide 3-kinase (PI3K)/Akt pathway have been proposed in the treatment of leukemia based on their antiproliferative effects. However, several studies demonstrated the activation of PI3K in the nuclei of all-trans-retinoic acid (ATRA) - differentiated HL-60 cells, raising the possibility that PI3K/Akt-inhibitors may block antitumor properties of retinoids. The aim of the present study was to investigate the possible activation of nuclear Akt in ATRA-treated cells and to test the effects of Akt-inhibitors on ATRA-mediated differentiation. The Akt-activity was found to be increased in the nuclei and lysates of ATRA-differentiated HL-60 and NB4 cells. The down-modulation of the expression of Akt protein in HL-60 cells using siRNA reduces the CD11b expression in ATRA-treated cells. The treatment of both cell lines with the commercially available Akt inhibitors inhibited the growth of both control and ATRA-treated cells. Akt-inhibitors had no inhibitory effects on ATRA-mediated growth arrest and the expression of CD11b in HL-60 cells, but increased the percentage of control cells expressing CD11b. In contrast, the presence of Akt inhibitors reduced the expression of CD11b in ATRA-treated NB4 cells.
Matkovic
K
K
Department of Physiology and Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb, Croatia.
Brugnoli
F
F
Bertagnolo
V
V
Banfic
H
H
Visnjic
D
D
D039481:CD11b Antigen / Q000096:biosynthesis / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism*; D049109:Cell Proliferation / Q000187:drug effects; D002867:Chromones / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D005419:Flavonoids / Q000494:pharmacology; D005434:Flow Cytometry; D018922:HL-60 Cells; D006801:Humans; D009025:Morpholines / Q000494:pharmacology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000494:pharmacology; D012680:Sensitivity and Specificity; D014212:Tretinoin / Q000037:antagonists & inhibitors / Q000494:pharmacology*
D039481:CD11b Antigen; D002867:Chromones; D005419:Flavonoids; D009025:Morpholines; D047428:Protein Kinase Inhibitors; D034741:RNA, Small Interfering; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D014212:Tretinoin; D051057:Proto-Oncogene Proteins c-akt; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one