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.
Department of Cardiovascular Biology, Faculty of Medicine, University of Tokyo, Japan.
J
J
Abe
W
W
Zhou
N
N
Takuwa
J
J
Taguchi
K
K
Kurokawa
M
M
Kumada
Y
Y
Takuwa
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