Thymidylate synthase as a chemotherapeutic drug target: Where are we after fifty years?

Berger, Franklin G.; Berger, Sondra H.

doi:10.4161/cbt.5.9.3414

Cited by 25 publications

(22 citation statements)

References 35 publications

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“…Thymidylate synthase (TYMS, EC 2.1.1.15) catalyzes the reductive methylation of 2ʹ-deoxyuridine-5ʹ-monophosphate (dUMP) by N 5 N 10 -methylenetetrahydrofolate (CH 2 H 4 PteGlu), to form dTMP and dihydrofolate (Carreras and Santi, 1995;Berger and Berger, 2006). The enzyme is indispensable to DNA synthesis and is therefore critical for replication and repair of the cellular genome in growing cells.…”

Section: Introductionmentioning

confidence: 99%

“…As a consequence, it has been an attractive target at which chemotherapeutic drugs are directed (Chu et al, 2003;Longley et al, 2003;Wilson et al, 2014). Inhibitors of TYMS, including both fluoropyrimidine and folate analogs, reduce de novo synthesis of dTMP, which leads to impaired DNA replication, genome damage, and programmed cell death (Carreras and Santi, 1995;Berger and Berger, 2006;Barbour and Berger, 2008). Fluoropyrimidines such as 5-fluorouracil (FUra) and 5-fluoro-2ʹ-deoxyuridine (FdUrd) are metabolized within cells to the potent TYMS inhibitor 5-fluoro-2ʹ-deoxyuridylic acid and have been important in the therapy of a variety of cancers, including those of the ovary, breast, and gastrointestinal tract (Chu et al, 2003;Longley et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

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Oxidative Stress and Response to Thymidylate Synthase-Targeted Antimetabolites

Özer¹,

Barbour²,

Clinton³

et al. 2015

Mol Pharmacol

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Thymidylate synthase (TYMS; EC 2.1.1.15) catalyzes the reductive methylation of 2ʹ-deoxyuridine-5ʹ-monophosphate (dUMP) by N 5 ,N 10 -methyhlenetetrahydrofolate, forming dTMP for the maintenance of DNA replication and repair. Inhibitors of TYMS have been widely used in the treatment of neoplastic disease. A number of fluoropyrimidine and folate analogs have been developed that lead to inhibition of the enzyme, resulting in dTMP deficiency and cell death. In the current study, we have examined the role of oxidative stress in response to TYMS inhibitors. We observed that intracellular reactive oxygen species (ROS) concentrations are induced by these inhibitors and promote apoptosis. Activation of the enzyme NADPH oxidase (NOX), which catalyzes one-electron reduction of O 2 to generate superoxide (O 2 d2 ), is a significant source of increased ROS levels in drug-treated cells. However, gene expression profiling revealed a number of other redox-related genes that may contribute to ROS generation. TYMS inhibitors also induce a protective response, including activation of the transcription factor nuclear factor E2-related factor 2 (NRF2), a critical mediator of defense against oxidative and electrophilic stress. Our results show that exposure to TYMS inhibitors induces oxidative stress that leads to cell death, while simultaneously generating a protective response that may underlie resistance against such death.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Oxidative Stress and Response to Thymidylate Synthase-Targeted Antimetabolites

Özer¹,

Barbour²,

Clinton³

et al. 2015

Mol Pharmacol

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“…Fluoropyrimidines, in particular, FUra and its nucleoside analogue 5'-fluoro-2'-deoxyuridine (FdUrd), are widely used agents and remain a major component of many standard regimens for various cancer types (Sotos et al, 1994;Milano et al, 2004;Soong and Diasio, 2005;Soong et al, 2008). FUra and FdUrd inhibit thymidylate synthase (TS), which blocks thymidylate (dTMP) production (Berger and Berger, 2006;Wyatt and Wilson, 2009) and leads to genome damage through misincorporation of uracil into DNA, and shuts off DNA synthesis and repair, triggering apoptosis (Danenberg, 1977;Spears et al, 1988;Krokan et al, 2002;Longley et al, 2003). It has been suggested that generation of reactive oxygen species (ROS) is one of the consequences of TS inhibition.…”

Section: Introductionmentioning

confidence: 99%

Differential oxidative response to fluoropyrimidines in colorectal cancer cell lines

Özer¹,

Barbour²

2017

Turk J Biol

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Colorectal cancer (CRC) is the second most common human malignancy in women and the third in men, accounting for approximately 8% of cancer-related deaths and 1.3 million newly diagnosed cases annually worldwide. CRC cell lines differ in morphological features, growth rate, and their genetic alterations, implicating the extent of variability among the lines. The goal of the current study was to investigate the phenotypes of CRC lines related to NADPH oxidase (NOX) activity and expression of NOX2 subunits in response to fluoropyrimidines. NOX activity in response to 5'-fluoro-2'-deoxyuridine (FdUrd) and VAS2780 was measured in CRC cell lines. Cells were treated with FdUrd in order to determine apoptotic cell death and mRNA expressions of NOX2 cytoplasmic subunits. We find that both basal and drug-induced NOX activity differ in the lines. Similarly, drug-mediated apoptotic indices vary in the cell lines at basal levels. Among NOX1 and NOX2 subunits, only NOX2 accessory subunits, p67phox, p40phox, and p47phox, differ in the lines. Our results show that CRC cells have diverse oxidative background and their oxidative response to anticancer drugs vary, while they all exhibit increases in NOX activity.

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“…As the sole de novo source of thymidylate synthesis in eukaryotic cells, for over 50 years, the enzyme has been a target in chemotherapy [3], with active forms of drugs being dUMP or N 5,10 -meTHF analogues that inhibit the enzyme [4,5]. Between dUMP analogues active in chemotherapy, the most prominent is 5-fluoro-dUMP (FdUMP), a strong thymidylate synthase inhibitor being the active form of drugs used in chemotherapy, such as 5-fluorouracil, 5-fluoro-2 0 -deoxyuridine and 5-fluorocytosine [2].…”

Section: Introductionmentioning

confidence: 99%

Mouse thymidylate synthase does not show the inactive conformation, observed for the human enzyme

et al. 2016

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Crystal structures of mouse thymidylate synthase (mTS) in complexes with (1) sulfate anion, (2) 2 0 -deoxyuridine 5 0 -monophosphate (dUMP) and (3) 5-fluorodUMP (FdUMP) and N 5,10 -methylenetetrahydrofolate (meTHF) have been determined and deposited in Protein Data Bank under the accession codes 3IHI, 4E5O and 5FCT, respectively. The structures show a strong overall similarity to the corresponding structures of rat and human thymidylate synthases (rTS and hTS, respectively). Unlike with hTS, whose unliganded and liganded forms assume different conformations (''inactive'' and ''active,'' respectively) in the loop 181-197, in each of the three mTS structures, the loop 175-191, homologous to hTS loop 181-197, populates the active conformer, with catalytic Cys 189 buried in the active site and directed toward C(6) of the pyrimidine ring of dUMP/FdUMP, pointing to protein's inability to adopt the inactive conformation. The binary structures of either dUMP-or sulfate-bound mTS, showing the enzyme with open active site and extended C-terminus, differ from the structure of the mTS-5-FdUMP-meTHF ternary complex, with the active site closed and C-terminus folded inward, thus covering the active site cleft. Another difference pertains to the conformation of the Arg44 side chain in the active site-flanking loop 41-47, forming strong hydrogen bonds with the dUMP/FdUMP phosphate moiety in each of the two liganded mTS structures, but turning away from the active site entrance and loosing the possibility of H-bonding with sulfate in the sulfate-bound mTS structure.

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Thymidylate synthase as a chemotherapeutic drug target: Where are we after fifty years?

Cited by 25 publications

References 35 publications

Oxidative Stress and Response to Thymidylate Synthase-Targeted Antimetabolites

Oxidative Stress and Response to Thymidylate Synthase-Targeted Antimetabolites

Differential oxidative response to fluoropyrimidines in colorectal cancer cell lines

Mouse thymidylate synthase does not show the inactive conformation, observed for the human enzyme

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