Thymidylate Synthase Inhibitor Research Articles

Ribosome Quality Control mitigates the cytotoxicity of ribosome collisions induced by 5-Fluorouracil.

Ribosome quality control (RQC) resolves collided ribosomes, thus preventing their cytotoxic effects. The chemotherapeutic agent 5-Fluorouracil (5FU) is best known for its misincorporation into DNA and inhibition of thymidylate synthase. However, while a major determinant of 5FU's anticancer activity is its misincorporation into RNAs, the mechanisms by which cancer cells overcome the RNA-dependent 5FU toxicity remain ill-defined. Here, we report a role for RQC in mitigating the cytotoxic effects of 5FU. We show that 5FU treatment results in rapid induction of the mTOR signalling pathway, enhanced rate of mRNA translation initiation, and increased ribosome collisions. Consistently, a defective RQC exacerbates the 5FU-induced cell death, which is mitigated by blocking mTOR pathway or mRNA translation initiation. Furthermore, 5FU treatment enhances the expression of the key RQC factors ZNF598 and GIGYF2 via an mTOR-dependent post-translational mechanism. This adaptation likely mitigates the cytotoxic consequences of increased ribosome collisions upon 5FU treatment.

An RNA damage response network mediates the lethality of 5-FU in colorectal cancer

5-fluorouracil (5-FU), a major anti-cancer therapeutic, is believed to function primarily by inhibiting thymidylate synthase, depleting deoxythymidine triphosphate (dTTP), and causing DNA damage. Here, we show that clinical combinations of 5-FU with oxaliplatin or irinotecan show no synergy in human colorectal cancer (CRC) trials and sub-additive killing in CRC cell lines. Using selective 5-FU metabolites, phospho- and ubiquitin proteomics, and primary human CRC organoids, we demonstrate that 5-FU-mediated CRC cell killing primarily involves an RNA damage response during ribosome biogenesis, causing lysosomal degradation of damaged rRNAs and proteasomal degradation of ubiquitinated ribosomal proteins. Tumor types clinically responsive to 5-FU treatment show upregulated rRNA biogenesis while 5-FU clinically non-responsive tumor types do not, instead showing greater sensitivity to 5-FU's DNA damage effects. Finally, we show that treatments upregulating ribosome biogenesis, including KDM2A inhibition, promote RNA-dependent cell killing by 5-FU, demonstrating the potential for combinatorial targeting of this ribosomal RNA damage response for improved cancer therapy.

NOD2 reduces the chemoresistance of melanoma by inhibiting the TYMS/PLK1 signaling axis

AbstractNucleotide-binding oligomerization domain 2 (NOD2) is an immune sensor crucial for eliciting the innate immune responses. Nevertheless, discrepancies exist regarding the effect of NOD2 on different types of cancer. This study aimed to investigate these function of NOD2 in melanoma and its underlying mechanisms. We have validated the tumor suppressor effect of NOD2 in melanoma. NOD2 inhibited the proliferation of melanoma cells, hindering their migration and invasion while promoting the onset of apoptosis. Our study showed that NOD2 expression is closely related to pyrimidine and folate metabolism. NOD2 inhibits thymidylate synthase (TYMS) expression by promoting K48-type ubiquitination modification of TYMS, thereby decreasing the resistance of melanoma cells to 5-fluorouracil (5-FU) and capecitabine (CAP). TYMS was identified to form a complex with Polo-like Kinase 1 (PLK1) and activate the PLK1 signaling pathway. Furthermore, we revealed that the combination of the PLK1 inhibitor volasertib (BI6727) with 5-FU or CAP had a synergistic effect repressing the proliferation, migration, and autophagy of melanoma cells. Overall, our research highlights the protective role of NOD2 in melanoma and suggests that targeting NOD2 and the TYMS/PLK1 signaling axis is a high-profile therapy that could be a prospect for melanoma treatment.

Synthesis and anticancer evaluation of diaryl pyrido[2,3-d]pyrimidine /alkyl substituted pyrido[2,3-d]pyrimidine derivatives as thymidylate synthase inhibitors

Worldwide, colorectal cancer (CRC) is the third most common type of cancer and the second most common cause of cancer-related deaths. Thymidylate synthase (TS) is a crucial component of DNA biosynthesis and has drawn interest as an essential target for cancer treatment. In the current work, we have designed and synthesized twenty-eight new diaryl-based pyrido[2,3-d]pyrimidine/alkyl-substituted pyrido[2,3-d]pyrimidine derivatives and evaluated their anticancer activity against the HCT 116, MCF-7, Hep G2, and PC-3 cell lines cell lines. Additionally, we have carried out TS inhibitory activity and in silico studies for compounds 1n and 2j. All the synthesized compounds exhibited good anticancer activity, but among them, compounds 1n and 2j showed excellent anticancer activity, having IC50 values of 1.98 ± 0.69, 2.18 ± 0.93, 4.04 ± 1.06, and 4.18 ± 1.87 µM; and 1.48 ± 0.86, 3.18 ± 0.79, 3.44 ± 1.51, and 5.18 ± 1.85 µM, against the HCT 116, MCF-7, Hep G2, and PC-3 cell lines respectively with control raltitrexed (IC50 1.07 ± 1.08, 1.98 ± 0.72, 1.34 ± 1.0, and 3.09 ± 0.96 µM, respectively) and hTS inhibitory activity with IC50 values of 20.47 ± 1.09 and 13.48 ± 0.96 nM with control raltitrexed (IC50 14.95 ± 1.01 nM). Further, the mechanism of inhibition was revealed by molecular docking, which showed the binding pattern of 1n and 2j to the catalytic site of TS with docking scores of -10.6 and − 9.5 kcal/mol, respectively, with reference raltitrexed (-9.4 kcal/mol). Additionally, the assessment of physicochemical, biochemical, structural, and toxicological characteristics were also in the acceptable range for these compounds. Based on the anticancer activity of compounds, SAR was also performed for lead optimization.

Intersite communication in dimeric enzymes highlighted by structural and thermodynamic analysis of didansyltyrosine binding to thymidylate synthases

Intersite communication in dimeric enzymes, triggered by ligand binding, represents both a challenge and an opportunity in enzyme inhibition strategy. Though often understestimated, it can impact on the in vivo biological mechansim of an inhibitor and on its pharmacokinetics. Thymidylate synthase (TS) is a homodimeric enzyme present in almost all living organisms that plays a crucial role in DNA synthesis and cell replication. While its inhibition is a valid strategy in the therapy of several human cancers, designing specific inhibitors of bacterial TSs poses a challenge to the development of new anti-infective agents. N,O-didansyl-l-tyrosine (DDT) inhibits both Escherichia coli TS (EcTS) and Lactobacillus casei TS (LcTS). The available X-ray structure of the DDT:dUMP:EcTS ternary complex indicated an unexpected binding mode for DDT to EcTS, involving a rearrangement of the protein and addressing the matter of communication between the two active sites of an enzyme dimer. Combining molecular-level information on DDT binding to EcTS and LcTS extracted from structural and FRET-based fluorometric evidence with a thermodynamic characterization of these events obtained by fluorometric and calorimetric titrations, this study unveiled a negative cooperativity between the DDT bindings to the two monomers of each enzyme dimer. This result, complemented by the species-specific thermodynamic signatures of the binding events, implied that communication across the protein dimer was triggered by the first DDT binding. These findings could challenge the conventional understanding of TS inhibition and open the way for the development of novel TS inhibitors with a different mechanism of action and enhanced efficacy and specificity.

A novel cocrystal of 5-fluorouracil with 2,2’-dipyridylamine: Synthesis, structural characterization, thermal analysis and in silico anticancer evaluation as a thymidylate synthase inhibitor

A new cocrystal containing 5-fluorouracil (5-FU) and 2,2’-dipyridylamine (dpya) was successfully prepared by a slow evaporation solution method and characterized using solid-state techniques such as FTIR, thermal analysis (DTA/TG) and single crystal X-ray diffraction. X-ray crystallography indicated the formation of a 2:1 5-FU:dpya cocrystal. The 5-FU and dpya molecules in the cocrystal were linked by N−H···O, N−H···N, C−H···O and C−H···F hydrogen bonds, forming a two-dimensional layers, further extended to a three dimensional supramolecular network via π-stacking interactions. Thermal analysis data showed that the cocrystal exhibited a lower thermal stability than 5-FU, but it is more stable than dpya. Molecular docking method was used to investigate in silico anticancer activity of the new co-crystal against a cancer target protein, human thymidylate synthase (TS). The free binding affinity of the cocrystal towards TS was notably higher than those of both reference ligands 5-FU and 5-fluorodeoxyuridine monophosphate (FdUMP), indicating the enzyme inhibition and anticancer potential of the cocrystal. Additionally, the molecular dynamics (MD) simulation and binding free energy studies confirmed the stability of the TS-cocrystal complex in a period of 50 ns.

Intrinsic PARG inhibitor sensitivity is mimicked by TIMELESS haploinsufficiency and rescued by nucleoside supplementation.

A subset of cancer cells are intrinsically sensitive to inhibitors targeting PARG, the poly(ADP-ribose) glycohydrolase that degrades PAR chains. Sensitivity is accompanied by persistent DNA replication stress, and can be induced by inhibition of TIMELESS, a replisome accelerator. However, the nature of the vulnerability responsible for intrinsic sensitivity remains undetermined. To understand PARG activity dependency, we analysed Timeless model systems and intrinsically sensitive ovarian cancer cells. We show that nucleoside supplementation rescues all phenotypes associated with PARG inhibitor sensitivity, including replisome speed and fork stalling, S-phase completion and mitotic entry, proliferation dynamics and clonogenic potential. Importantly nucleoside supplementation restores PARG inhibitor resistance despite the continued presence of PAR chains, indicating that sensitivity does not correlate with PAR levels. In addition, we show that inhibition of thymidylate synthase, an enzyme required for dNTP homeostasis, induces PARG-dependency. Together, these observations suggest that PARG inhibitor sensitivity reflects an inability to control replisome speed and/or maintain helicase-polymerase coupling in response to nucleotide imbalances.

Selective pharmaceutical sensitization design based on amino acid metabolism: 5-fluorouracil-sarcosine cocrystal prepared by wet powder grinding method

Pharmaceutical cocrystal is an emerging strategy not only to improve physicochemical properties, but also to generate synergistic effects. In this work, a novel cocrystal composed by 5-fluorouracil (5-FU) and sarcosine (SAR) was successfully assembled by wet powder grinding method. The cocrystal was characterized by single crystal X-ray diffraction (SCXRD), powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and Raman spectra. The differences of 1H NMR spectroscopy between 5-FU/SAR physical mixture (PM) and cocrystal hinted the existence of supramolecular interactions between 5-FU and SAR in solid and solution. Bioavailability of cocrystal was increased than 5-FU. Most importantly, the weak interactions between 5-FU and SAR in cocrystal solution induced the superior cellar inhibition activity on 4T1 and BEL-7402 cells compared than 5-FU and PM. Cocrystal can interfere with the stability of methionine cycle and tetrahydrofolate (FH4) level through the SAR-Gly-Met pathway, enhance the inhibition of thymidylate synthase (TS) compared to 5-FU, thereby interfering with cell cycle and inducing cell apoptosis. The results provided the novel strategy to develop the cocrystal drugs using bioactive amino acids as precursors to enhance the efficacy.

A modular, open-label, phase I/IIa study to evaluate the safety, tolerability, pharmacokinetics (PKs) and anti-tumour activity of a first-in-class (FIC) specific dUTPase inhibitor CV6-168 combined with anti-cancer treatments in patients (pts) with advanced malignancies.

TPS3170 Background: CV6-168 is a FIC DNA uracilation agent targeting the enzyme dUTPase with high specificity. CV6-168 induces misincorporation of uracil into DNA when combined with thymidylate synthase (TS) inhibitors resulting in significantly increased DNA damage and lethality in cancer cells and activation of immune stimulatory mechanisms. CV6-168 does not inhibit dihydropyrimidine dehydrogenase, the rate-limiting enzyme responsible for 5-FU catabolism avoiding fluoropyrimidine drug-drug interactions and complex dose modifications. This is a first-in-human, modular study initially investigating PK and safety of CV6-168 with bolus/infusional 5-fluorouracil (5-FU) and folinic acid (FA). Methods: Primary objective: characterise safety and tolerability of CV6-168 with 5-FU and FA. Secondary objectives: establish PK profile of CV6-168 and 5-FU alone and in combination and evaluate anti-tumour activity of the combination. Exploratory objectives: investigate multiple surrogate, tumour and circulating pharmacodynamic assays related to mechanism of action and predictive biomarkers for CV6-168 and 5-FU. Each module of this study investigates a different hypothesis, driven by emerging data. Module 1, investigating CV6-168/5-FU/FA, consists of Part A (dose escalation in up to 51 pts) where the maximum tolerated/feasible dose will be identified to guide dose optimisation; Part B, proof of concept [PoC] expansions and identification of the recommended Phase 2 dose/schedule; and optional Parts C (dose optimisation cohorts) and D (basket cohort expansions). Part A is a “3 + 3” dose escalation design in pts with incurable advanced solid tumours and Part B expansions, powered to compare response rates to historical data, will include 3 cohorts of different tumour types. Part C is a randomised comparison of 2 doses/schedules to be selected based on Part A and B data, with pt populations selected based on emerging data. Further Modules may explore: Combination of CV6-168/5-FU/FA with a PD-(L)1 inhibitor; Combinations with other standard of care treatments; Food effects on CV6-168 bioavailability; and Different CV6-168 formulations. This trial design 1) Allows one protocol responsive to emerging data for a compound with multiple hypotheses, supporting studies in multiple combinations, reducing time from emerging data to ‘first subject in study" compared with multiple individual studies; 2) Has the potential to reduce the number of pts unnecessarily exposed to a novel agent; and 3) Allows investigators to pre-empt emerging data and changes to the treatment landscape. These challenges in oncology drug development emphasize the need for flexible designs as the landscape of drug development continually evolves. Clinical trial information: ISRCTN12434145.

Material basis revelation of anti-hepatoma effect of Huachansu (Cinobufacini) through down-regulation of thymidylate synthase

ObjectiveHepatocellular carcinoma (HCC) is a leading cause of mortality worldwide. Huachansu (Cinobufacini) is active extract isolated from the dry skin of Bufo Bufo gargarizans. It has now been widely used in clinical treatment of cancer, this study is to clarify the material basis of down-regulation of thymidylate synthase (TYMS) induced by Huachansu. MethodsOur study utilized UPLC-MS/MS to identify major bioactive components from Huachansu. Cell Counting Kit 8 (CCK-8) assay and clone formation assay were used to examine the cell viability of tumor cells. TYMS and γ-H2AX level were detected by using quantitative real-time RT-PCR and/or western blotting. Small interfering RNA (siRNA) transfection was used to explore whether inhibition of TYMS could enhance the suppressive effect of Huachansu on cell growth of HCC cells. ResultsIn our study, firstly, we identify 21 major bioactive components from Huachansu. CCK-8 assay results showed that Huachansu and its bioactive bufadienolides (Bufalin, Bufotalin, Cinobufotalin, Desacetylcinobufagin, Arenobufagin, Telocinobufagin, and Resibufogenin) significantly inhibited the proliferation of HepG2 and SK-HEP-1 cells in a dose- and time-dependent manner. Further molecular mechanistic investigation demonstrates that Huachansu significantly suppresses thymidylate synthase (TYMS), the enzyme which provides the sole de novo source of thymidylate for DNA synthesis. The inhibition of TYMS could lead to cell-cycle block and DNA damage of HCC cells. Furthermore, we identified that Huachansu markedly increased γ-H2AX expression, which indicated the presence of DNA damage. Moreover, we confirmed that transfection of cells with small interfering RNA specific to TYMS could increase the suppressive effects of Huachansu on the HCC cells proliferation. Quantitative RT-PCR analysis showed that Huachansu treatment had no effect on the transcription level of TYMS. Furthermore, proteasomal inhibitor MG132 could block TYMS inhibition induced by Huachansu, and concomitant administration of protein synthesis inhibitor cycloheximide (CHX) with Huachansu could further suppress the protein level of TYMS, indicating that Huachansu promotes proteasome-dependent degradation of TYMS in liver cancer cells. More importantly, the bioactive bufadienolides of Huachansu such as Bufalin, Bufotalin, Cinobufotalin, Desacetylcinobufagin, Arenobufagin, Telocinobufagin, and Resibufogenin could also significantly restrain the protein level of TYMS, revealing the material basis of inhibition of TYMS exposed to Huachansu. 5-fluorouracil (5-FU) is a TYMS inhibitor, we also evaluate the effects of the combined treatment of Huachansu with 5-FU, the results show that interactions between Huachansu and 5-FU are synergistic or antagonistic. Thus, in clinical, attention should be paid to the dosage of Huachansu in combination with 5-FU. ConclusionHuachansu inhibits the growth and induces DNA damage of human HCC cells through proteasome-dependent degradation of TYMS, bioactive bufadienolides are the material basis of down-regulation of TYMS induced by Huachansu.

Tackling Antibiotic Resistance: Exploring 5-Fluorouracil as a Promising Antimicrobial Strategy for the Treatment of Streptococcus suis Infection.

Streptococcus suis (S. suis) is a zoonotic pathogen with a global distribution, which causes serious diseases in both humans and animals and economic losses in the swine industry. As antibiotic resistance increases, there is an urgent imperative to explore novel antibacterial alternatives. In the present study, we selected the anticancer drug 5-fluorouracil (5-FU) approved by the Food and Drug Administration (FDA) as a candidate drug to treat S. suis infections. The results showed that various pathogens, especially S. suis, are more sensitive to 5-FU. Moreover, the cytotoxicity of 5-FU is relatively low. Extensive in vitro assays demonstrated the pronounced bacteriostatic and bactericidal efficacy of 5-FU against susceptible and multidrug-resistant S. suis strains. Its mechanisms of action include damage to the bacterial cell walls and membranes, resulting in the leakage of intracellular components, and the inhibition of thymidylate synthase (TS), leading to a depletion of deoxythymidine triphosphate (dTTP) pools, ultimately causing thymine-less death and lethal DNA damage in bacteria. Gene-knockout experiments further showed that 5-FU played a role by inhibiting the thyA gene-encoding thymidine synthase. Finally, we determined that S. suis infections can be alleviated by 5-FU in the mouse infection model. This study emphasizes the antibacterial potential of 5-FU against S. suis and provides evidence for its targeting of bacterial membrane damage and DNA damage. In summary, 5-FU can control S. suis infection and is expected to become a new alternative to antibiotics.

A phase I open-label, dose-escalation study of NUC-3373, a targeted thymidylate synthase inhibitor, in patients with advanced cancer (NuTide:301)

Purpose5-fluorouracil (5-FU) is inefficiently converted to the active anti-cancer metabolite, fluorodeoxyuridine-monophosphate (FUDR-MP), is associated with dose-limiting toxicities and challenging administration schedules. NUC-3373 is a phosphoramidate nucleotide analog of fluorodeoxyuridine (FUDR) designed to overcome these limitations and replace fluoropyrimidines such as 5-FU.Patients and methodsNUC-3373 was administered as monotherapy to patients with advanced solid tumors refractory to standard therapy via intravenous infusion either on Days 1, 8, 15 and 22 (Part 1) or on Days 1 and 15 (Part 2) of 28-day cycles until disease progression or unacceptable toxicity. Primary objectives were maximum tolerated dose (MTD) and recommended Phase II dose (RP2D) and schedule of NUC-3373. Secondary objectives included pharmacokinetics (PK), and anti-tumor activity.ResultsFifty-nine patients received weekly NUC-3373 in 9 cohorts in Part 1 (n = 43) and 3 alternate-weekly dosing cohorts in Part 2 (n = 16). They had received a median of 3 prior lines of treatment (range: 0–11) and 74% were exposed to prior fluoropyrimidines. Four experienced dose-limiting toxicities: two Grade (G) 3 transaminitis; one G2 headache; and one G3 transient hypotension. Commonest treatment-related G3 adverse event of raised transaminases occurred in < 10% of patients. NUC-3373 showed a favorable PK profile, with dose-proportionality and a prolonged half-life compared to 5-FU. A best overall response of stable disease was observed, with prolonged progression-free survival.ConclusionNUC-3373 was well-tolerated in a heavily pre-treated solid tumor patient population, including those who had relapsed on prior 5-FU. The MTD and RP2D was defined as 2500 mg/m2 NUC-3373 weekly. NUC-3373 is currently in combination treatment studies.Trial registrationClinicaltrials.gov registry number NCT02723240. Trial registered on 8th December 2015. https://clinicaltrials.gov/study/NCT02723240.

The Critical Function of microRNAs in Developing Resistance against 5- Fluorouracil in Cancer Cells.

Although there have been significant advancements in cancer treatment, resistance and recurrence in patients make it one of the leading causes of death worldwide. 5-fluorouracil (5-FU), an antimetabolite agent, is widely used in treating a broad range of human malignancies. The cytotoxic effects of 5-FU are mediated by the inhibition of thymidylate synthase (TYMS/TS), resulting in the suppression of essential biosynthetic activity, as well as the misincorporation of its metabolites into RNA and DNA. Despite its huge benefits in cancer therapy, the application of 5-FU in the clinic is restricted due to the occurrence of drug resistance. MicroRNAs (miRNAs) are small, non-coding RNAs that act as negative regulators in many gene expression processes. Research has shown that changes in miRNA play a role in cancer progression and drug resistance. This review examines the role of miRNAs in 5-FU drug resistance in cancers.

An insight into thymidylate synthase inhibitor as anticancer agents: an explicative review.

Cancer, a widespread challenge to global health, remains a puzzle of intricate molecular dynamics. This review article delves into the mystery of cancer, with a keen focus on understanding the contributory role of thymidylate synthase (TS) in cancer. TS, a vital enzyme in DNA synthesis and repair, emerges as a significant player in the narrative of cancer development. The conversion of deoxyuridine monophosphate (dUMP) to deoxythymidine monophosphate (dTMP) is a major step in producing DNA. Numerous malignancies, including those of the breast, colon, lung, and ovary, have been linked to dysregulation of TS activity. Overexpression or mutations of TS lead to uncontrolled cell proliferation and tumorigenesis molecular interactions and signalling pathways involving TS come under scrutiny, revealing the nuanced connections that propel its involvement in cancer progression. Beyond overexpression and mutations, there emerges a subtle layer of regulation that involves microRNAs (miRNAs). These tiny particles attach to the TS messenger RNA, causing translational repression or its degradation, which in turn affects TS activity. Moving towards the therapeutic realm, thymidylate synthase inhibition acts as a promising anti-cancer strategy. Targeting TS with small-molecule inhibitors could provide a novel approach to treat various cancers. By reducing the number of available nucleotides, TS inhibition would slow down or halt cancer cell division, thus depriving the tumor of the building blocks required for its proliferation and growth. The aim is to assess the viability and effectiveness of targeting TS to halt or slow down cancer progression. There is growing evidence that, in comparison to traditional TS inhibitors, few novel antifolate TS inhibitors are effective against a wider variety of neoplasms, such as lung carcinomas. It has been discovered that TS inhibitors increase cancer tissues' sensitivity to chemotherapy and radiation, increasing their vulnerability to these treatments. This article aims to provide a comprehensive insight into TS, examining its cellular details, detailing the heterocyclic moieties and molecular foundations, and providing a promising future outlook.

Mitochondrial and Cytosolic One-Carbon Metabolism Is a Targetable Metabolic Vulnerability in Cisplatin-Resistant Ovarian Cancer.

One-carbon (C1) metabolism is compartmentalized between the cytosol and mitochondria with the mitochondrial C1 pathway as the major source of glycine and C1 units for cellular biosynthesis. Expression of mitochondrial C1 genes including SLC25A32, serine hydroxymethyl transferase (SHMT) 2, 5,10-methylene tetrahydrofolate dehydrogenase 2, and 5,10-methylene tetrahydrofolate dehydrogenase 1-like was significantly elevated in primary epithelial ovarian cancer (EOC) specimens compared with normal ovaries. 5-Substituted pyrrolo[3,2-d]pyrimidine antifolates (AGF347, AGF359, AGF362) inhibited proliferation of cisplatin-sensitive (A2780, CaOV3, IGROV1) and cisplatin-resistant (A2780-E80, SKOV3) EOC cells. In SKOV3 and A2780-E80 cells, colony formation was inhibited. AGF347 induced apoptosis in SKOV3 cells. In IGROV1 cells, AGF347 was transported by folate receptor (FR) α. AGF347 was also transported into IGROV1 and SKOV3 cells by the proton-coupled folate transporter (SLC46A1) and the reduced folate carrier (SLC19A1). AGF347 accumulated to high levels in the cytosol and mitochondria of SKOV3 cells. By targeted metabolomics with [2,3,3-2H]L-serine, AGF347, AGF359, and AGF362 inhibited SHMT2 in the mitochondria. In the cytosol, SHMT1 and de novo purine biosynthesis (i.e., glycinamide ribonucleotide formyltransferase, 5-aminoimidazole-4-carboxamide ribonucleotide formyltransferase) were targeted; AGF359 also inhibited thymidylate synthase. Antifolate treatments of SKOV3 cells depleted cellular glycine, mitochondrial NADH and glutathione, and showed synergistic in vitro inhibition toward SKOV3 and A2780-E80 cells when combined with cisplatin. In vivo studies with subcutaneous SKOV3 EOC xenografts in SCID mice confirmed significant antitumor efficacy of AGF347. Collectively, our studies demonstrate a unique metabolic vulnerability in EOC involving mitochondrial and cytosolic C1 metabolism, which offers a promising new platform for therapy.

Sodium Butyrate Inhibits the Expression of Thymidylate Synthase and Induces Cell Death in Colorectal Cancer Cells.

The most commonly used chemotherapy for colorectal cancer (CRC) is the application of 5-fluorouracil (5-FU). Inhibition of thymidylate synthase (TYMS) expression appears to be a promising strategy to overcome the decreased sensitivity to 5-FU caused by high expression of TYMS, which can be induced by 5-FU treatment. Several compounds have been shown to potentially inhibit the expression of TYMS, but it is unclear whether short-chain fatty acids (SCFAs), which are naturally produced by bacteria in the human intestine, can regulate the expression of TYMS. Sodium butyrate (NaB) is the most widely known SCFA for its beneficial effects. Therefore, we investigated the enhancing effects on inhibition of cell viability and induction of apoptosis after co-treatment of NaB with 5-FU in two CRC cell lines, HCT116 and LoVo. This study suggests that the effect of NaB in improving therapeutic sensitivity to 5-FU in CRC cells may result from a mechanism that strongly inhibits the expression of TYMS. This study also shows that NaB inhibits the migration of CRC cells and can cause cell cycle arrest in the G2/M phase. These results suggest that NaB could be developed as a potential therapeutic adjuvant to improve the therapeutic effect of 5-FU in CRC.

Abstract IA022: Uracil DNA glycosylase activity limits deoxyuridine contamination in genomic DNA and is essential for the type-1 interferon response in cells treated with ATR kinase inhibitors

Abstract Most chemotherapies target DNA replication, and their efficacy depends on the DNA damage response that integrates DNA repair with the cell cycle. Widely used standard-of-care antimetabolites inhibit thymidylate synthase and increase the incorporation of deoxyuridine (dU) into DNA by polymerases. Contamination of dU in DNA is limited by the DNA damage response kinase ATR that induces cell cycle checkpoints and reduces the rate of DNA replication. ATR inhibitors (ATRi) induce origin firing across active replicons and cause ribonuclease reductase degradation in otherwise unperturbed cells. This increases both the amount of DNA replication and the amount of free dUTP in cells. Thus, ATRi increase the incorporation of dU into DNA by polymerases. Since ATRi also inhibit cell cycle checkpoints, ATRi induce more dU contamination than antimetabolites. ATRi-induced dU contamination in DNA is associated with an innate immune response. We showed this with the simple observation that ATRi-induced dU contamination and IFN-α/β expression is reversed by low doses of thymidine. Here we show that ATRi-induced IFN-α/β response is dependent on uracil DNA glycosylase (UNG) which removes dU from DNA. Our data are consistent with a model in which UNG-dependent base excision repair (BER) removes dU from DNA, ultimately generating cytoplasmic dsDNA that induces IFN-α/β. We propose that ATRi-induced dU contamination contributes to dose-limiting leukocytopenia and inflammation in the clinic and CD8+ T cell dependent anti-tumor responses in mouse models of cancer treated with radiation therapy. Citation Format: Pinakin Pandya, Frank P. Vendetti, Joseph A. Ghoubaira, Sudipta Pathak, Joshua J. Deppas, Reyna E. Jones, Yunqi Zhang, Daniel Ivanov, Raquel Buj, Katherine M. Aird, Jan H. Beumer, Robert W. Sobol, Christopher J. Bakkenist. Uracil DNA glycosylase activity limits deoxyuridine contamination in genomic DNA and is essential for the type-1 interferon response in cells treated with ATR kinase inhibitors [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: DNA Damage Repair: From Basic Science to Future Clinical Application; 2024 Jan 9-11; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2024;84(1 Suppl):Abstract nr IA022.

Sitagliptin enhances the effects of 5-fluorouracil in cancer colon through inhibition of thymidylate synthase

Sitagliptin enhances the effects of 5-fluorouracil in cancer colon through inhibition of thymidylate synthase

Intake and biomarkers of folate and folic acid as determinants of chemotherapy-induced toxicities in patients with colorectal cancer: a cohort study

BackgroundCapecitabine is an oral chemotherapeutic drug showing antitumor activity through inhibition of thymidylate synthase, an enzyme involved in folate metabolism. There are concerns about the high intake of certain vitamins, and specifically folate, during chemotherapy with capecitabine. Whether folate or folic acid, the synthetic variant of the vitamin, impact treatment toxicity remains unclear. ObjectiveWe studied associations between intake and biomarkers of folate as well as folic acid and toxicities in patients with colorectal cancer (CRC) receiving capecitabine. MethodsWithin the prospective COLON (Colorectal cancer: Longitudinal, Observational study on Nutritional and lifestyle factors that influence recurrence, survival, and quality of life) cohort, 290 patients with stage II to III CRC receiving capecitabine were identified. Dietary and supplemental intake of folate and folic acid were assessed at diagnosis and during chemotherapy using questionnaires (available for 280 patients). Plasma folate and folic acid levels were determined by liquid chromatography tandem mass spectrometry (LC-MS/MS) and were available for 212 patients. Toxicities were defined as toxicity-related modifications of treatment, including dose reductions, regimen switches, and early discontinuation. Associations of intake and biomarkers of folate and folic acid with toxicities were determined using Cox proportional hazards regression adjusted for age and sex. ResultsIn total, 153 (53%) patients experienced toxicities leading to modification of capecitabine treatment. Folate intake and plasma folate levels were not associated with risk of toxicities. However, use of folic acid-containing supplements during treatment (hazard ratio (HR) 1.81 and 95% confidence interval (CI) 1.15-2.85) and presence of folic acid in plasma at diagnosis (HR 2.09, 95% CI: 1.24, 3.52) and during treatment (HR 2.31, 95% CI: 1.29, 4.13) were associated with an increased risk of toxicities. ConclusionsThis study suggests a potential association between folic acid and capecitabine-induced toxicities, providing a rationale to study diet-drug interactions and raise further awareness of the use of dietary supplements during oncological treatment. Clinical trial detailsThis trial was registered at clinicaltrials.gov as NCT03191110.

Abstract C029: Phase Ib/II open label, multi-arm, parallel cohort dose finding and expansion study of NUC-3373 in combination with pembrolizumab in patients with advanced solid tumors or docetaxel in patients with lung cancer (NuTide:303)

Abstract Background: NUC-3373 is a phosphoramidate transformation of fluorodeoxyuridine monophosphate (FUDR-MP) designed to replace fluoropyrimidines, such as 5-FU, which exert their activity via inhibition of thymidylate synthase (TS) and disruption of DNA synthesis and repair. Intracellular cleavage of NUC-3373 releases the anti-cancer metabolite FUDR-MP, thereby potentially improving the therapeutic ratio of 5-FU whilst reducing the practical barriers associated with 5-FU administration. In addition to generating high intracellular levels of FUDR-MP and being a potent inhibitor of TS, pre-clinical data have shown that NUC-3373 can enhance the activity of immunotherapy agents by promoting the release of damage associated molecular patterns, activating a natural killer cell response and reducing inhibitory signals on T-cells. Methods: NuTide:303 is a Phase Ib/II open label, multi-arm, parallel cohort dose finding and expansion study to assess the safety, PK and efficacy of NUC-3373 given in combination with leucovorin (LV) and either (i) pembrolizumab in patients (pts) with solid tumors in Module 1 or (ii) docetaxel in pts with non-small cell lung cancer (NSCLC) or pleural mesothelioma in Module 2. Both modules consist of dose-validation (Phase Ib) and dose-expansion (Phase II). The Phase Ib part will determine the MTD, safety and tolerability along with preliminary efficacy of the combinations (in 6 - 20 pts). In the Phase II part, an additional 20-40 pts will be added. In both modules, pts with measurable disease and ECOG PS 0-1 are eligible. For Module 1, pts diagnosed with any solid tumor who have progressed on ≤2 prior lines of therapy for advanced/metastatic disease (including 1 prior line of an immunotherapy-containing regimen), and for whom pembrolizumab treatment would be appropriate, are eligible. For Module 2, pts with advanced/metastatic NSCLC or pleural mesothelioma who have progressed on, or were unable to tolerate, ≤2 prior lines of chemotherapy-containing regimens for advanced/metastatic disease are eligible. Additional modules combining other agents with NUC-3373 + LV are being planned. Clinical trial information: NCT05714553 Citation Format: Richard H Wilson, Fiona Thistlethwaite, Fiona G McKissock, Elisabeth Oelmann, Jeffrey D Bloss, James F Spicer, Gary Middleton. Phase Ib/II open label, multi-arm, parallel cohort dose finding and expansion study of NUC-3373 in combination with pembrolizumab in patients with advanced solid tumors or docetaxel in patients with lung cancer (NuTide:303) [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr C029.