Mechanism of tumor cell killing by HO-221, a novel antitumor compound
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The mechanism of tumor cell killing by HO-221, a novel benzoylphenylurea derivative that shows broad-spectrum antitumor activities, was studied. HO-221 strongly inhibited the activity of mammalian DNA polymerase α but not that of DNA polymerases β or γ. The inhibition was equivalent to that induced by aphidicolin and ara-CTP, which were selective inhibitors of the enzyme. Furthermore, the inhibition by HO-221 of DNA polymerase α was found to be non-competitive with respect to dCTP as a substrate, unlike that induced by aphidicolin and ara-CTP. The inhibition was reduced the addition of an excess of DNA polymerase α but not by excess amounts of activated DNA as a template primer. These results suggest that HO-221 inhibits the activity of DNA polymerase α by direct interaction with the enzyme in contrast to the impairment of template activity through intercalation into DNA induced by anthracycline compounds. On the other hand, HO-221 showed almost no effect on RNA polymerase activity, the reverse transcriptase activity of avian myeloblastosis virus or protein synthesis in a cell-free system. The flow-cytometry analysis revealed that HO-221 accumulated HL-60 cells in G1-S phases at a low concentration but increased the number of cells in the G1 phase at a higher concentration, stopping cell-cycle progression. The results suggest a correlation between cell-cycle progression and inhibition by HO-221 of DNA polymerase α, which plays a role in DNA replication during the S phase in living cells.
KeywordsAnthracycline Polymerase Activity Tumor Cell Killing Aphidicolin Reverse Transcriptase Activity
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- 1.Geran RI, Greenberg NH, MacDonald MM (1972) Protocols for screening chemical agents and natural products against animal tumors and other biological systems. Cancer Chemother Rep 3(3): 1Google Scholar
- 2.Krishan A (1975) A rapid flow cytofluorometric analysis of mammalian cell cycle by propidium iodine staining. J Cell Biol 66: 188Google Scholar
- 3.Nakajima T, Masuda H, Okamoto T, Watanabe M, Yokoyama K, Yamada N, Tsukagoshi S, Taguchi T (1990) Antitumor activity on murine tumors of a novel antitumor benzoylphenylurea derivative, HO-221. Cancer Chemotehr Pharmacol (in press)Google Scholar
- 4.Nishio M, Kuroda A, Suzuki M, Ishimaru K, Nakamura S, Nomi R (1983) Retrostatin, a new specific enzyme inhibitor against avian myeloblastosis virus reverse transcriptase. J Antibiot 36:761Google Scholar
- 5.Ikegami S, Taguchi T, Ohashi M, Oguro M, Nagano H, Mano Y (1978) Aphidicolin prevents mitotic cells division by interfering with the activity of DNA polymerase α. Nature 275: 458Google Scholar
- 6.Pelham HRB, Jackson RJ (1976) An efficient mRNA-dependent translation system from reticulocyte lysates. Eur J Biochem 67: 247Google Scholar
- 7.Wang LH, Duesberg P, Beemon K, Vogt PK (1975) Mapping RNase T1-resistant oligonucleotides of avian tumor virus RNAs. J Virol 16: 1051Google Scholar
- 8.Yoshida S, Yamada M, Masaki S (1977) Inhibition of DNA polymerase α and β of calf thymus by 1-β-arabinofuranosylcytosine-5′-triphosphate. Biochim Biophys Acta 477: 144Google Scholar
- 9.Oguro M, Suzuki-Hori C, Nabano H, Mano Y, Ikegami S (1979) The mode of inhibitory action by aphidicolin on eukaryotic DNA polymerase α. Eur J Biochem 97:603Google Scholar