Drug action on poly(A) polymerase activity and isoforms during U937 cell apoptosis.
The enzyme poly(A) polymerase (PAP; EC 2.7.7.19) catalyzes the polyadenylation of mRNAs. It's activity levels and isoforms vary within the cell cycle (31) and apoptosis (34). The direct effect of most anticancer drugs is cell damage (DNA and RNA synthesis inhibition, DNA breaks and/or cell cycle aberrations), which then triggers signaling pathways that activate apoptosis and eventually lead to regulated cell death. The experiments described here concern the chemotherapeutic agents, interferon (IFN) and 5-fluorouracil (5-FU), and their action on U937 cells, alone or in various combinations, resulting in the commitment of cell apoptosis, as observed by the appearance of DNA fragmentation. Furthermore, examination of U937 cell apoptotic trend in parallel with PAP activity measurements and isoforms detection by immunoblotting, revealed both partial enzyme inactivation and dephosphorylation, in particular after the combined drug action of 5-FU and IFN on U937 cells. Our work on chemotherapeutic drug action at the level of mRNA polyadenylation may contribute to new insights into the mechanism of cell apoptosis, as well as provide information on mRNA poly(A) tail formation, removal and function.
Balatsos
N A
NA
Dept of Biochemistry and Molecular Biology, Papanikolaou Research Centre of Oncology, Saint Savvas Anticancer Hospital, Athens, Greece.
Lallas
G
G
Havredaki
M
M
Tsiapalis
C M
CM
D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D003593:Cytoplasm / Q000201:enzymology; D053938:DNA Fragmentation / Q000187:drug effects; D005472:Fluorouracil / Q000494:pharmacology*; D006801:Humans; D016898:Interferon-alpha / Q000494:pharmacology*; D007527:Isoenzymes / Q000187:drug effects / Q000302:isolation & purification / Q000378:metabolism; D007700:Kinetics; D011062:Polynucleotide Adenylyltransferase / Q000187:drug effects / Q000302:isolation & purification / Q000378:metabolism*; D020298:U937 Cells
D016898:Interferon-alpha; D007527:Isoenzymes; D011062:Polynucleotide Adenylyltransferase; D005472:Fluorouracil