TY - JOUR
T1 - Inhibitory mechanisms of 1-(3-C-ethynyl-β-D-ribo-pentofuranosyl)uracil (EUrd) on RNA synthesis
AU - Yokogawa, Tatsushi
AU - Naito, Tomoharu
AU - Kanda, Hiroshi
AU - Takatori, Satoshi
AU - Takenaka, Kiyoko
AU - Sasaki, Takuma
AU - Matsuda, Akira
AU - Fukushima, Masakazu
AU - Kim, Hye Sook
AU - Wataya, Yusuke
N1 - Funding Information:
This work was supported in part by Grants-in-Aid for Scientific Research on Priority Areas (13218082) from the Ministry of Education, Culture, Sports, Science and Technology of Japan.
PY - 2005
Y1 - 2005
N2 - 1-(3-C-ethynyl-β-D-ribo-pentofuranosyl)uracil (EUrd) is an antimetabolite that strongly inhibits RNA synthesis and shows a broad antitumor activity in vitro and in vivo. In mouse mammary tumor FM3A cells, EUrd is sequentially phosphorylated to its 5′-triphosphate, EUTP, a major metabolite, and the RNA synthesis is inhibited proportionally to its intracellular accumulation. To study the inhibitory mechanisms of EUrd on RNA synthesis, we have performed the kinetic analysis of EUTP on RNA polymerization using isolated nuclei RNA synthesis was inhibited competitively by EUTP. The inhibition constant, Ki was much lower than the Km value of UTP (Ki value of EUTP, 84 nM; Km value of UTP, 13 μM), indicating that the high affinity of EUTP could contribute to the specific inhibition of RNA synthesis. As a result of RNA synthesis inhibition, EUrd, but not ara-C, induced shrinkage of nucleoli, which are the main sites for RNA synthesis in FM3A cells. Thus, the strong affinity of EUTP to RNA polymerase and specific inhibition of RNA synthesis could contribute to its antitumor effect. EUrd is expected to be a new antitumor drug, possessing a strong inhibitory effect on the synthesis of RNA.
AB - 1-(3-C-ethynyl-β-D-ribo-pentofuranosyl)uracil (EUrd) is an antimetabolite that strongly inhibits RNA synthesis and shows a broad antitumor activity in vitro and in vivo. In mouse mammary tumor FM3A cells, EUrd is sequentially phosphorylated to its 5′-triphosphate, EUTP, a major metabolite, and the RNA synthesis is inhibited proportionally to its intracellular accumulation. To study the inhibitory mechanisms of EUrd on RNA synthesis, we have performed the kinetic analysis of EUTP on RNA polymerization using isolated nuclei RNA synthesis was inhibited competitively by EUTP. The inhibition constant, Ki was much lower than the Km value of UTP (Ki value of EUTP, 84 nM; Km value of UTP, 13 μM), indicating that the high affinity of EUTP could contribute to the specific inhibition of RNA synthesis. As a result of RNA synthesis inhibition, EUrd, but not ara-C, induced shrinkage of nucleoli, which are the main sites for RNA synthesis in FM3A cells. Thus, the strong affinity of EUTP to RNA polymerase and specific inhibition of RNA synthesis could contribute to its antitumor effect. EUrd is expected to be a new antitumor drug, possessing a strong inhibitory effect on the synthesis of RNA.
KW - EUrd
KW - Inhibitor of RNA Synthesis
KW - Nucleolus
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U2 - 10.1081/NCN-200055727
DO - 10.1081/NCN-200055727
M3 - Article
C2 - 15892261
AN - SCOPUS:20944437995
VL - 24
SP - 227
EP - 232
JO - Nucleosides, Nucleotides and Nucleic Acids
JF - Nucleosides, Nucleotides and Nucleic Acids
SN - 1525-7770
IS - 3
ER -