title: Crucial roles of thymidine kinase 1 and deoxyUTPase in incorporating the antineoplastic nucleosides trifluridine and 2'-deoxy-5-fluorouridine into DNA.
abstract: Trifluridine (FTD) and 2'-deoxy-5-fluorouridine (FdUrd), a derivative of 5-fluorouracil (5-FU), are antitumor agents that inhibit thymidylate synthase activity and their nucleotides are incorporated into DNA. However, it is evident that several differences occur in the underlying antitumor mechanisms associated with these nucleoside analogues. Recently, TAS-102 (composed of FTD and tipiracil hydrochloride, TPI) was shown to prolong the survival of patients with colorectal cancer who received a median of 2 prior therapies, including 5-FU. TAS-102 was recently approved for clinical use in Japan. These data suggest that the antitumor activities of TAS-102 and 5-FU proceed via different mechanisms. Thus, we analyzed their properties in terms of thymidine salvage pathway utilization, involving membrane transporters, a nucleoside kinase, a nucleotide-dephosphorylating enzyme, and DNA polymerase α. FTD incorporated into DNA with higher efficiency than FdUrd did. Both FTD and FdUrd were transported into cells by ENT1 and ENT2 and were phosphorylated by thymidine kinase 1, which showed a higher catalytic activity for FTD than for FdUrd. deoxyUTPase (DUT) did not recognize dTTP and FTD-triphosphate (F3dTTP), whereas deoxyuridine-triphosphate (dUTP) and FdUrd-triphosphate (FdUTP) were efficiently degraded by DUT. DNA polymerase α incorporated both F3dTTP and FdUTP into DNA at sites aligned with adenine on the opposite strand. FTD-treated cells showed differing nuclear morphologies compared to FdUrd-treated cells. These findings indicate that FTD and FdUrd are incorporated into DNA with different efficiencies due to differences in the substrate specificities of TK1 and DUT, causing abundant FTD incorporation into DNA.
authors.affiliation: Drug Discovery and Development I, Discovery and Preclinical Research Division, Taiho Pharmaceutical Co., Ltd., Tsukuba, Ibaraki 300-2611, Japan.
authors.forename: Kazuki
authors.initials: K
authors.lastname: Sakamoto
authors.affiliation: Drug Discovery and Development I, Discovery and Preclinical Research Division, Taiho Pharmaceutical Co., Ltd., Tsukuba, Ibaraki 300-2611, Japan.
authors.forename: Tatsushi
authors.initials: T
authors.lastname: Yokogawa
authors.affiliation: Drug Discovery and Development I, Discovery and Preclinical Research Division, Taiho Pharmaceutical Co., Ltd., Tsukuba, Ibaraki 300-2611, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ueno
authors.affiliation: Drug Discovery and Development I, Discovery and Preclinical Research Division, Taiho Pharmaceutical Co., Ltd., Tsukuba, Ibaraki 300-2611, Japan.
authors.forename: Kei
authors.initials: K
authors.lastname: Oguchi
authors.affiliation: Drug Discovery and Development I, Discovery and Preclinical Research Division, Taiho Pharmaceutical Co., Ltd., Tsukuba, Ibaraki 300-2611, Japan.
authors.forename: Hiromi
authors.initials: H
authors.lastname: Kazuno
authors.affiliation: Drug Discovery and Development I, Discovery and Preclinical Research Division, Taiho Pharmaceutical Co., Ltd., Tsukuba, Ibaraki 300-2611, Japan.
authors.forename: Keiji
authors.initials: K
authors.lastname: Ishida
authors.affiliation: Drug Discovery and Development I, Discovery and Preclinical Research Division, Taiho Pharmaceutical Co., Ltd., Tsukuba, Ibaraki 300-2611, Japan.
authors.forename: Nozomu
authors.initials: N
authors.lastname: Tanaka
authors.affiliation: Drug Discovery and Development I, Discovery and Preclinical Research Division, Taiho Pharmaceutical Co., Ltd., Tsukuba, Ibaraki 300-2611, Japan.
authors.forename: Akiko
authors.initials: A
authors.lastname: Osada
authors.affiliation: Drug Discovery and Development I, Discovery and Preclinical Research Division, Taiho Pharmaceutical Co., Ltd., Tsukuba, Ibaraki 300-2611, Japan.
authors.forename: Yukari
authors.initials: Y
authors.lastname: Yamada
authors.affiliation: Drug Discovery and Development I, Discovery and Preclinical Research Division, Taiho Pharmaceutical Co., Ltd., Tsukuba, Ibaraki 300-2611, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Okabe
authors.affiliation: Drug Discovery and Development I, Discovery and Preclinical Research Division, Taiho Pharmaceutical Co., Ltd., Tsukuba, Ibaraki 300-2611, Japan.
authors.forename: Kenichi
authors.initials: K
authors.lastname: Matsuo
mesh_terms: D000964:Antimetabolites, Antineoplastic / Q000493:pharmacokinetics / Q000494:pharmacology*; D015179:Colorectal Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D004273:DNA, Neoplasm / Q000737:chemistry*; D004338:Drug Combinations; D033721:Equilibrative Nucleoside Transporter 1 / Q000378:metabolism; D033722:Equilibrative-Nucleoside Transporter 2 / Q000378:metabolism; D005472:Fluorouracil / Q000493:pharmacokinetics / Q000494:pharmacology*; D045325:HCT116 Cells; D006801:Humans; D008297:Male; D011755:Pyrophosphatases / Q000378:metabolism; D011759:Pyrrolidines; D013379:Substrate Specificity; D013937:Thymidine Kinase / Q000378:metabolism*; D013941:Thymine; D014271:Trifluridine / Q000493:pharmacokinetics / Q000494:pharmacology*; D014498:Uracil / Q000031:analogs & derivatives* / Q000493:pharmacokinetics / Q000494:pharmacology
chemical_list: D000964:Antimetabolites, Antineoplastic; D004273:DNA, Neoplasm; D004338:Drug Combinations; D033721:Equilibrative Nucleoside Transporter 1; D033722:Equilibrative-Nucleoside Transporter 2; D011759:Pyrrolidines; C438649:SLC29A1 protein, human; C438654:SLC29A2 protein, human; C000613803:trifluridine tipiracil drug combination; D014498:Uracil; D013937:Thymidine Kinase; C092717:thymidine kinase 1; D011755:Pyrophosphatases; C023278:uridine triphosphatase; D013941:Thymine; D014271:Trifluridine; D005472:Fluorouracil