Benzamide riboside induces apoptosis independent of Cdc25A expression in human ovarian carcinoma N.1 cells.
One of the mechanisms of action of a new oncolytic agent, benzamide riboside (BR) is by inhibiting inosine 5'-monophosphate dehydrogenase (IMPDH) which catalyzes the formation of xanthine 5'-monophosphate from inosine 5'-monophosphate and nicotinamide adenine dinucleotide, thereby restricting the biosynthesis of guanylates. In the present study BR (10 - 20 microM) induced apoptosis in a human ovarian carcinoma N.1 cell line (a monoclonal derivative of its heterogenous parent line HOC-7). This was ascertained by DNA fragmentation, TUNEL assay, [poly(ADP)ribose polymerase]-cleavage and alteration in cell morphology. Apoptosis was accompanied by sustained c-Myc expression, concurrent down-regulation of cdc25A mRNA and protein, and by inhibition of Cdk2 activity. Both Cdk2 and cdc25A are G1 phase specific genes and Cdk2 is the target of Cdc25A. These studies demonstrate that BR exhibits dual mechanisms of action, first by inhibiting IMPDH, and second by inducing apoptosis, which is associated with repression of components of the cell cycle that are downstream of constitutive c-Myc expression.
Grusch
M
M
Institute of Clinical Pathology, University of Vienna, Währinger Gürtel 18-20, A-1090 Vienna, Austria.
Rosenberger
G
G
Fuhrmann
G
G
Braun
K
K
Titscher
B
B
Szekeres
T
T
Fritzer-Skekeres
M
M
Oberhuber
G
G
Krohn
K
K
Hengstschlaeger
M
M
Krupitza
G
G
Jayaram
H N
HN
D000230:Adenocarcinoma; D017209:Apoptosis / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000378:metabolism* / Q000494:pharmacology; D005260:Female; D006801:Humans; D007168:IMP Dehydrogenase / Q000037:antagonists & inhibitors*; D009705:Nucleosides / Q000378:metabolism* / Q000494:pharmacology; D010051:Ovarian Neoplasms; D014407:Tumor Cells, Cultured; D020687:cdc25 Phosphatases / Q000096:biosynthesis* / Q000235:genetics
D004791:Enzyme Inhibitors; D009705:Nucleosides; C076145:3-(1-deoxyribofuranosyl)benzamide; D007168:IMP Dehydrogenase; C517004:CDC25A protein, human; D020687:cdc25 Phosphatases