Role of caspases and CD95/Fas in the apoptotic effects of a nucleotide analog PMEG in CCRF-CEM cells.
OBJECTIVE
9-[2-(phosphonomethoxy)ethyl] guanine (PMEG) is a guanine acyclic nucleotide analog whose targeted prodrugs are being investigated for chemotherapy of lymphomas. Its antiproliferative effects have been attributed to cell cycle arrest and induction of apoptosis, however, the underlying mechanisms remain poorly understood. The objective of this study was to determine the requirements for caspase and CD95/Fas activation in PMEG-induced apoptosis. Additionally, the influence of PMEG on cell cycle regulatory proteins was explored.


METHODS
CCRF-CEM cells were exposed to PMEG with/without caspase inhibitor or anti-Fas blocking antibody and assayed for phosphatidyl serine externalization, mitochondrial depolarization and the cleavage of procaspase 3 and the nuclear protein poly (ADP-ribose) polymerase (PARP).


RESULTS
Despite an observed increase of caspase 3, 8 and 9 proteolytic activity, neither pretreatment of the cells with cell-permeable caspase inhibitors nor blocking the death receptor with anti-Fas antibody did prevent apoptosis induced by PMEG.


CONCLUSIONS
PMEG-induced apoptosis is caspase- and CD95/Fas-independent.
Mertlíková-Kaiserová
Helena
H
Institute of Organic Chemistry and Biochemistry AS CR, Flemingovo nám. 2, 166 10 Prague 6, Czech Republic.
Votruba
Ivan
I
Matousová
Marika
M
Holy
Antonín
A
Hájek
Miroslav
M
D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D020169:Caspases / Q000378:metabolism*; D002453:Cell Cycle / Q000187:drug effects / Q000502:physiology; D045744:Cell Line, Tumor; D019927:Cyclin E / Q000096:biosynthesis / Q000235:genetics; D050756:Cyclin-Dependent Kinase Inhibitor Proteins / Q000096:biosynthesis / Q000378:metabolism; D018844:Cyclin-Dependent Kinases / Q000096:biosynthesis / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D006147:Guanine / Q000031:analogs & derivatives* / Q000494:pharmacology; D006801:Humans; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000502:physiology; D015513:Oncogene Proteins / Q000096:biosynthesis / Q000235:genetics; D009943:Organophosphorus Compounds / Q000494:pharmacology*; D016196:S Phase / Q000187:drug effects; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D019014:fas Receptor / Q000378:metabolism*
C475820:CCNE1 protein, human; D019927:Cyclin E; D050756:Cyclin-Dependent Kinase Inhibitor Proteins; C491901:FAS protein, human; D015513:Oncogene Proteins; D009943:Organophosphorus Compounds; D019014:fas Receptor; C063380:9-((2-phosphonylmethoxy)ethyl)guanine; D006147:Guanine; D018844:Cyclin-Dependent Kinases; D020169:Caspases