A fumagillin derivative angiogenesis inhibitor, AGM-1470, inhibits activation of cyclin-dependent kinases and phosphorylation of retinoblastoma gene product but not protein tyrosyl phosphorylation or protooncogene expression in vascular endothelial cells.
Fumagillin analogue AGM-1470 potently inhibits angiogenesis with a minimal toxicity in vivo and is expected to be of therapeutic use as a powerful antitumor agent (Ingber et al., Nature, 348:555-557, 1990). In the present study, we have investigated the effects and the mechanism of action of AGM-1470 on cultured human umbilical vein endothelial cells. AGM-1470 acts directly on endothelial cells to inhibit growth factor-induced DNA synthesis, with half maximal and maximal effects obtained at approximately 2 x 10(-10) and 5 x 10(-9) M, respectively. AGM-1470 does not inhibit early G1 mitogenic events, such as cellular protein tyrosyl phosphorylation or the expression of immediate early genes c-fos and c-myc, but potently inhibits phosphorylation of RB protein, a tumor suppressor retinoblastoma gene product. The later addition of AGM-1470 up to 3 h after the growth factor stimulation still exerts full inhibitory effects on both DNA synthesis and RB phosphorylation, suggesting that the major site of action of AGM-1470 is located relatively late in the G1 phase. AGM-1470 inhibits growth factor-induced activation of candidate RB kinases cdc2 and cdk2 but fails to inhibit them directly in vitro. AGM-1470 completely abolishes the growth factor-induced mRNA expression of cdc2 and cyclin A and partially inhibits that of cyclin E but has little effect on the mRNA level of cdk2, cdk4, or cyclin D1. These results indicate that angioinhibitory action of AGM-1470 involves suppression of mRNA expression of specific members of cdks and cyclins and of activation of both cdc2 and cdk2 kinases in endothelial cells.
Abe
J
J
Department of Cardiovascular Biology, Faculty of Medicine, University of Tokyo, Japan.
Zhou
W
W
Takuwa
N
N
Taguchi
J
J
Kurokawa
K
K
Kumada
M
M
Takuwa
Y
Y
D016203:CDC2 Protein Kinase / Q000378:metabolism*; D042846:CDC2-CDC28 Kinases; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases; D003510:Cyclohexanes; D004247:DNA / Q000096:biosynthesis*; D004305:Dose-Response Relationship, Drug; D016193:G1 Phase / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D006801:Humans; D000077609:O-(Chloroacetylcarbamoyl)fumagillol; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D012333:RNA, Messenger / Q000378:metabolism; D016160:Retinoblastoma Protein / Q000378:metabolism*; D012717:Sesquiterpenes / Q000008:administration & dosage / Q000494:pharmacology*; D013997:Time Factors
D003510:Cyclohexanes; D012333:RNA, Messenger; D016160:Retinoblastoma Protein; D012717:Sesquiterpenes; D004247:DNA; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D016203:CDC2 Protein Kinase; D042846:CDC2-CDC28 Kinases; C495894:CDK2 protein, human; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases; D000077609:O-(Chloroacetylcarbamoyl)fumagillol