Alteration of the phosphorylation state of p34cdc2 kinase by the flavone L86-8275 in breast carcinoma cells. Correlation with decreased H1 kinase activity.
The flavone L86-8275 [(-)cis-5,7-dihydroxy-2-(2-chlorophenyl)-8-[4-(3-hydroxy-1-methyl)- piperidinyl]-4H-1-benzopyran-4-one] delayed the progression of aphidicolin-synchronized MDA-468 breast carcinoma cells through S phase and prevented progression through G2. L86-8275 prevented the G2-related increase in histone H1 kinase activity mediated by cyclin-dependent kinase-1 (p34cdc2 kinase). L86-8275 inhibited [32P]orthophosphate labeling of p34cdc2 threonine and tyrosine residues and decreased the phosphotyrosine content of p34cdc2. Diminution of p34cdc2 phosphotyrosine appeared selective, as a general depletion of cellular phosphotyrosine was not observed. The mass of p34cdc2 in L86-8275-exposed cells was not decreased during the period over which these effects occurred. [35S]Methionine labeling of p34cdc2 or other cellular proteins was not inhibited at concentrations that were effective for complete cellular growth inhibition. We hypothesize that L86-8275 interferes with the normal cell cycle-dependent phosphorylation of p34cdc2, resulting in decreased kinase activity and cell cycle arrest.
Worland
P J
PJ
Laboratory of Biological Chemistry, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892.
Kaur
G
G
Stetler-Stevenson
M
M
Sebers
S
S
Sartor
O
O
Sausville
E A
EA
D000595:Amino Acid Sequence; D016590:Aphidicolin; D001943:Breast Neoplasms / Q000201:enzymology*; D016203:CDC2 Protein Kinase / Q000378:metabolism*; D016213:Cyclins / Q000096:biosynthesis; D003513:Cycloheximide / Q000494:pharmacology; D015536:Down-Regulation; D004640:Emetine / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D005419:Flavonoids / Q000494:pharmacology*; D006801:Humans; D016200:Maturation-Promoting Factor / Q000378:metabolism*; D008938:Mitosis / Q000187:drug effects; D008969:Molecular Sequence Data; D010766:Phosphorylation / Q000187:drug effects; D010880:Piperidines / Q000494:pharmacology*; D011233:Precipitin Tests; D016196:S Phase; D014407:Tumor Cells, Cultured / Q000187:drug effects
D016213:Cyclins; D005419:Flavonoids; D010880:Piperidines; D016590:Aphidicolin; C077990:alvocidib; D003513:Cycloheximide; D016203:CDC2 Protein Kinase; D016200:Maturation-Promoting Factor; D004640:Emetine