Thymidylate Synthase Levels Research Articles

Targeting CCR3 with antagonist SB 328437 sensitizes 5‑fluorouracil‑resistant gastric cancer cells: Experimental evidence and computational insights.

Gastric cancer (GC) ranks fifth globally in cancer diagnoses and third for cancer-related deaths. Chemotherapy with 5-fluorouracil (5-FU), a primary treatment, faces challenges due to the development of chemoresistance. Tumor microenvironment factors, including C-C motif chemokine receptor 3 (CCR3), can contribute to chemoresistance. The present study evaluated the effect of CCR3 receptor inhibition using the antagonist SB 328437 and the molecular dynamics of this interaction on resistance to 5-FU in gastric cancer cells. The 5-FU-resistant AGS cell line (AGS R-5FU) demonstrated notable tolerance to higher concentrations of 5-FU, with a 2.6-fold increase compared with the parental AGS cell line. Furthermore, the mRNA expression levels of thymidylate synthase (TS), a molecular marker for 5-FU resistance, were significantly elevated in AGS R-5FU cells. CCR3 was shown to be expressed at significantly higher levels in these resistant cells. Combining SB 328437 with 5-FU resulted in a significant decrease in cell viability, particularly at higher concentrations of 5-FU. Furthermore, when SB 328437 was combined with 5-FU at a high concentration, the relative mRNA expression levels of CCR3 and TS decreased significantly. Computational analysis of CCR3 demonstrated dynamic conformational changes, especially in extracellular loop 2 region, which indicated potential alterations in ligand recognition. Docking simulations demonstrated that SB 328437 bound to the allosteric site of CCR3, inducing a conformational change in ECL2 and hindering ligand recognition. The present study provides comprehensive information on the molecular and structural aspects of 5-FU resistance and CCR3 modulation, highlighting the potential for therapeutic application of SB 328437 in GC treatment.

Alliance EAY191-A6: FOLFOX in combination with binimetinib as second-line therapy for patients with advanced biliary tract cancers (BTCs) with MAPK pathway alterations: A ComboMATCH treatment trial.

TPS4196 Background: Advanced BTC patients have poor prognosis. Up to 40% of BTCs have KRAS mutations and are associated with worse overall survival (OS). With a median OS of 7.7 months in KRAS wild-type compared to 1.7 months in KRAS mutated disease, these alterations are independent poor prognostic factors in BTC. Gemcitabine and cisplatin (GC) with or without immunotherapy are often used as 1st-line therapies. However, there is a lack of data on best 2nd-line regimens. mFOLFOX6 (5-fluorouracil [5-FU], leucovorin [LV], oxaliplatin) or liposomal irinotecan+5-FU+LV are options when no biomarkers are found (e.g., MSI-H, BRAFV600E, FGFR-fusions, IDH1-mutation, HER2-overexpression). Prior studies do not demonstrate benefit with MEK inhibitors (MEKi), but none of the studies had biomarker selection. Pre-clinical studies in BTC cell lines suggest synergy between MEKi and 5-FU. Thymidylate synthase (TS )levels induced by 5-FU are downregulated by addition of binimetinib. Early clinical studies show safety and tolerance of this combination. In this study, we will evaluate if the combination of mFOLFOX6+binimetinib improves OS for patients with BTC and MAPK mutations compared to mFOLFOX6 alone in 2nd-line therapy. Methods: EAY191-A6 is a treatment study arm of the NCI ComboMATCH master registration trial EAY191. The A6 trial has a randomized phase II design, enrolling a maximum of 66 patients. Patients with any MAPK pathway mutations except those with available therapies will be eligible. Patient must first enroll to the EAY191 master trial. Local molecular results may be used for enrollment. Submission of tissue at baseline is mandatory. Eligible patients will be randomized 1:1 to mFOLFOX6 vs mFOLFOX6 + binimetinib (45 mg oral twice a day every 14 days). Stratification factors include location and stage of disease. Primary efficacy analysis will compare OS in the intent-to-treat population. If the observed hazard ratio (HR) of experimental arm vs standard of care is < 0.545 (corresponding to an observed increase in OS by 5 months or longer), experimental treatment will be considered superior. An interim futility analysis at 50% of expected events will be conducted. If the observed HR is ≥ 1, experimental treatment will not be considered superior, and accrual maybe suspended. Secondary endpoints include progression-free survival, objective response rate, duration of response, disease control rate and toxicity of treatments. Exploratory objectives include prognostic modeling, correlations of genomic alterations with response or resistance and use of machine learning for outcome prediction. This study is active and open to accrual. Clinical trial information: NCT05564403 .

Abstract 2000: Role of O-GlcNAc conjugation and TS translational repression in 5-FU/LV resistance in CRC and CF10 response

Abstract Rationale: Fluoropyrimidine drugs (FPs; e.g., 5-FU) are widely used to treat colorectal cancer (CRC), the 3rd leading cause of cancer-related mortality. However, acquired resistance to 5-FU is a principal cause of treatment failure in the metastatic setting. Further, previous studies selected for cells resistant to single agent 5-FU however 5-FU is invariably used clinically in combination with the reduced folate leucovorin (LV). Our studies focus on resistance mechanisms upon treatment with 5-FU+LV in folate-restricted media and test if CF10, a novel polymeric FP being developed in our laboratory displays activity in CRC cells resistant to 5-FU+LV. Experimental: We selected CRC cells (HCT-116, LS174T, HCT15, MC38) resistant to 5-FU+LV by selecting for survival upon culture in folate-restricted media with stepwise increased concentrations of 5-FU+LV over 5 months. Since elevated thymidylate synthase (TS) levels were observed in multiple studies selecting CRC cells for 5-FU resistance, we performed Western blot on cell lysates from parental and (5-FU+LV)-R cells. Since Myc and p53 expression are regulated in part via translational inhibition by TS binding to these mRNAs we also compared Myc and p53 levels in parental and (5-FU+LV)-R cells by Western blot. Further, since TS, Myc, and p53 protein stability are all regulated in part via O-GlcNAc conjugation we tested if OGT levels were changed in (5-FU+LV)-R cells. Resistance factors for CF10 were also determined in (5-FU+LV)-R cells. Results: A surprising result was that basal TS levels were reduced in (5-FU+LV)-R cells relative to the parental cells. We also observed that TS levels were increased in both parental and (5-FU+LV)-R cells by 5-FU+LV treatment however the effect was much greater in (5-FU+LV)-R cells. We observed strongly decreased p53 and Myc levels in the (5-FU+LV)-R cells. CF10 treatment further decreased p53 and Myc levels in parental cells, but increased p53 and further decreased Myc in (5-FU+LV)-R cells. In contrast, 5-FU alone treatment in (5-FU+LV)-R cells increased Myc and decreased p53 levels and further decreased in combination with LV. CF10 retained strong activity in (5-FU+LV)-R cells. Conclusions: Overall, we have validated that cancer cells can be cultured under conditions with human-like folate levels and selected for resistance to 5-FU+LV under folate-restricted conditions. The causes of 5-FU+LV resistance are multi-factorial and include TS overexpression induced by 5-FU+LV treatment that may be mediated by O-GlcNAc conjugation. We demonstrated that CF10 is more potent than 5-FU, and importantly its potency advantage is enhanced in cells selected for 5-FU+LV resistance. Our studies support CF10 translation for treatment of metastatic CRC in patients with progressive disease following treatment with combination therapy that includes 5-FU+LV. Citation Format: Charles C. Okechukwu, Xue Ma, William H. Gmeiner. Role of O-GlcNAc conjugation and TS translational repression in 5-FU/LV resistance in CRC and CF10 response [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2000.

Astragali Radix-Curcumae Rhizoma inhibits colon cancer progression and enhances 5-FU efficacy by regulating hypoxia-inducible factors and tumor stem cells

The animal and cell models were used in this study to investigate the mechanism of Astragali Radix-Curcumae Rhizoma(HQEZ) in inhibiting colon cancer progression and enhancing the efficacy of 5-fluorouracil(5-FU) by regulating hypoxia-inducible factors and tumor stem cells. The animal model was established by subcutaneous transplantation of colon cancer HCT116 cells in nude mice, and 24 successfully modeled mice were randomized into model, 5-FU, HQEZ, and 5-FU+HQEZ groups. The tumor volume was measured every two days. Western blot was employed to measure the protein levels of epidermal growth factor receptor(EGFR), dihydropyrimidine dehydrogenase(DPYD), and thymidylate synthase(TYMS), the key targets of the hypoxic core region, as well as the hypoxia-inducible factors HIF-1α and HIF-2α and the cancer stem cell surface marker CD133 and SRY-box transcription factor 2(SOX2). The results of animal experiments showed that HQEZ slowed down the tumor growth and significantly increased the tumor inhibition rate of 5-FU. Compared with the model group, HQEZ significantly down-regulated the protein levels of EGFR and DPYD, and 5-FU+HQEZ significantly down-regulated the protein levels of EGFR and TYMS in tumors. Compared with the model group, HQEZ significantly down-regulated the protein levels of HIF-1α, HIF-2α, SOX2, and CD133 in the hypoxic core region. Compared with the 5-FU group, 5-FU+HQEZ lowered the protein levels of HIF-1α, HIF-2α, and SOX2. The cell experiments showed that the protein le-vels of HIF-1α and HIF-2α in HCT116 cells elevated significantly after low oxygen treatment. Compared with 5-FU(1.38 μmol·L~(-1)) alone, HQEZ(40 mg·mL~(-1)) and 5-FU+HQEZ significantly down-regulated the protein levels of HIF-1α, HIF-2α, and TYMS. In conclusion, HQEZ can inhibit the expression of hypoxia-responsive molecules in colon cancer cells and reduce the properties of cancer stem cells, thereby enhancing the therapeutic effect of 5-FU on colon cancer.

Abstract TP304: Ischemic Stroke Increases Levels of One-Carbon Enzymes and the Folate Receptor in Male and Female Brain Tissue

Stroke is the second most common cause of death worldwide and predominantly affects individuals over 65 years old. Its prevalence is projected to increase in parallel with the aging global population. Nutrition is a modifiable risk factor for ischemic stroke. Folates, B-vitamins and choline play a central role in one-carbon (1C) metabolism, which is a key metabolic network that integrates nutritional signals with biosynthesis, redox homeostasis, epigenetics, regulation of cell proliferation, and stress resistance. Our research group has previously shown that deficiencies in 1C lead to worsened stroke outcomes using preclinical models. However, the impact of ischemic stroke on 1C enzymes remains unknown. The objective of this study is to investigate whether ischemic stroke contributes to a change in the levels of 1C enzymes after ischemic stroke in male and female patients. Brain tissue sections from ischemic stroke patients and controls were stained, all tissue was co-stained with neuronal nuclei (NeuN) and DAPI (4′,6-diamidino-2-phenylindole). The colocalization of all three markers was evaluated by two individuals who were blinded to the experimental groups. Ischemic stroke increased neuronal levels of the folate receptor and 1C enzymes, methylenetetrahydrofolate reductase (MTHFR), thymidylate synthase (TS) and serine hydroxymethyltransferase (SHMT). In male stroke brain tissue was observed to have increased levels of MTHFR, TS, and SHMT. Female brain tissue had increases in the folate receptor and TS. The results suggest that ischemic stroke leads to increased demand on 1C and that there are some small differences between males and females.

Synthesis and Biological Evaluation of Novel Uracil Derivatives as Thymidylate Synthase Inhibitors.

Cell division is driven by nucleic acid metabolism, and thymidylate synthase (TYMS) catalyzes a rate-limiting step in nucleotide synthesis. As a result, thymidylate synthase has emerged as a critical target in chemotherapy. 5-Fluorouracil (5-FU) is currently being used to treat a wide range of cancers, including breast, pancreatic, head and neck, colorectal, ovarian, and gastric cancers The objective of this study was to establish a new methodology for the low-cost, one-pot synthesis of uracil derivatives (UD-1 to UD-5) and to evaluate their therapeutic potential in BC cells. One-pot organic synthesis processes using a single solvent were used for the synthesis of drug analogues of Uracil. Integrated bioinformatics using GEPIA2, UALCAN, and KM plotter were utilized to study the expression pattern and prognostic significance of TYMS, the key target gene of 5-fluorouracil in breast cancer patients. Cell viability, cell proliferation, and colony formation assays were used as in vitro methods to validate the in silico lead obtained. BC patients showed high levels of thymidylate synthase, and high expression of thymidylate synthase was found associated with poor prognosis. In silico studies indicated that synthesized uracil derivatives have a high affinity for thymidylate synthase. Notably, the uracil derivatives dramatically inhibited the proliferation and colonization potential of BC cells in vitro. In conclusion, our study identified novel uracil derivatives as promising therapeutic options for breast cancer patients expressing the augmented levels of thymidylate synthase.

One day versus two days of hepatic arterial infusion with oxaliplatin and fluorouracil for patients with unresectable hepatocellular carcinoma

BackgroundHepatic arterial infusion chemotherapy (HAIC) with oxaliplatin and 5-fluorouracil was effective in unresectable hepatocellular carcinoma (HCC). The program of FOLFOX-HAIC in HCC was performed for 1 day (HAIC 1d) or 2 days (HAIC 2d). We hereby retrospectively compared the efficacy and safety between these two treatment regimens and explored the predictive power of thymidylate synthase (TYMS), an enzyme involved in the DNA synthesis process and metabolism of fluorouracil.MethodsThis study included patients with a primary diagnosis of unresectable HCC. These patients received HAIC for 1 day or 2 days. The overall survival (OS), progression-free survival (PFS), tumor response, and adverse events were compared. The propensity score matching (PSM) was used to reduce bias. Peripheral blood samples before the treatments were collected and used to measure the concentration of TYMS through enzyme-linked immunosorbent assay (ELISA). ELISA was performed according to the manufacturers’ guidelines.ResultsWe included 368 patients for this study: 248 in the HAIC 1d group and 120 in the HAIC 2d group. There was no significant difference of OS between the two groups (14.5 for HAIC 1d vs 15.3 months for HAIC 2d, p=0.46). Compared with the HAIC 1d group, the HAIC 2d group did not prolong the PFS (7.3 vs 7.5 months, p=0.91) or elevate the tumor response (42.5% vs 39.1%, p=0.53) per RECIST 1.1. In the PSM cohort, the efficacy between the two groups was similar. The total frequencies of grade 3–4 events were higher with the HAIC 2d group than with the HAIC 1d group, especially in the PSM cohort (p=0.043). Additionally, patients with TYMS low level might benefit longer OS from the HAIC 2d group (18.7 vs 13.6 months, p=0.014).ConclusionsThere was not much of a difference in efficacy between the two groups, but the HAIC for 1 day might be safer, which needed further research. The level of TYMS might be the predictive biomarkers.

Targeting Thymidylate Synthase and tRNA-Derived Non-Coding RNAs Improves Therapeutic Sensitivity in Colorectal Cancer.

Some colorectal cancer (CRC) patients are resistant to 5-fluorouracil (5-FU), and high expression levels of thymidylate synthase (TS) contribute to this resistance. This study investigated whether quercetin, a representative polyphenol compound, could enhance the effect of 5-FU in CRC cells. Quercetin suppressed TS levels that were increased by 5-FU in CRC cells and promoted the expression of p53. Quercetin also induced intracellular and mitochondrial reactive oxygen species (ROS) production and Ca2+ dysregulation in a 5-FU-independent pathway in CRC cells. Furthermore, quercetin decreased mitochondrial membrane potential in CRC cells and inhibited mitochondrial respiration. Moreover, quercetin regulated the expression of specific tiRNAs, including tiRNAHisGTG, and transfection of a tiRNAHisGTG mimic further enhanced the apoptotic effect of quercetin in CRC cells. An enhanced sensitivity to 5-FU was also confirmed in colitis-associated CRC mice treated with quercetin. The treatment of quercetin decreased survival rates of the CRC mouse model, with reductions in the number of tumors and in the disease activity index. Also, quercetin suppressed TS and PCNA protein expression in the distal colon tissue of CRC mice. These results suggest that quercetin has the potential to be used as an adjuvant with 5-FU for the treatment of CRC.

Thymidylate synthase accelerates Men1-mediated pancreatic tumor progression and reduces survival.

Clinical studies of cancer patients have shown that overexpression or amplification of thymidylate synthase (TS) correlates with a worse clinical outcome. We previously showed that elevated TS exhibits properties of an oncogene and promotes pancreatic neuroendocrine tumors (PanNETs) with a long latency. To study the causal impact of elevated TS levels in PanNETs, we generated a mouse model with elevated human TS (hTS) and conditional inactivation of the Men1 gene in pancreatic islet cells (hTS/Men1-/-). We demonstrated that increased hTS expression was associated with earlier tumor onset and accelerated PanNET development in comparison with control Men1-/- and Men1+/ΔN3-8 mice. We also observed a decrease in overall survival of hTS/Men1+/- and hTS/Men1-/- mice as compared with control mice. We showed that elevated hTS in Men1-deleted tumor cells enhanced cell proliferation, deregulated cell cycle kinetics, and was associated with a higher frequency of somatic mutations, DNA damage, and genomic instability. In addition, we analyzed the survival of 88 patients with PanNETs and observed that high TS protein expression independently predicted worse clinical outcomes. In summary, elevated hTS directly participates in promoting PanNET tumorigenesis with reduced survival in Men1-mutant background. This work will refocus attention on new strategies to inhibit TS activity for PanNET treatment.

Long-term resistance to 5-fluorouracil promotes epithelial–mesenchymal transition, apoptosis evasion, autophagy, and reduced proliferation rate in colon cancer cells

The drug, 5-fluorouracil (5FU) is a standard first-line treatment for colorectal cancer (CRC) patients. However, drug resistance acquisition remains an important challenge for effective clinical outcomes. Here, we established a long-term drug-resistant CRC model and explored the cellular events underlying 5FU resistance. We showed that 5FU-treated cells (HCT-116 5FUR) using a prolonged treatment protocol were significantly more resistant than parental cells. Likewise, cell viability and IC50 values were also observed to increase in HCT-116 5FUR cells when treated with increasing doses of oxaliplatin, indicating a cross-resistance mechanism to other cytotoxic agents. Moreover, HCT-116 5FUR cells exhibited metabolic and molecular changes, as evidenced by increased thymidylate synthase levels and upregulated mRNA levels of ABCB1. HCT-116 5FUR cells were able to overcome S phase arrest and evade apoptosis, as well as activate autophagy, as indicated by increased LC3B levels. Cells treated with low and high doses displayed epithelial–mesenchymal transition (EMT) features, as observed by decreased E-cadherin and claudin-3 levels, increased vimentin protein levels, and increased SLUG, ZEB2 and TWIST1 mRNA levels. Furthermore, HCT-116 5FUR cells displayed enhanced migration and invasion capabilities. Interestingly, we found that the 5FU drug-resistance gene signature is positively associated with the mesenchymal signature in CRC samples, and that ABCB1 and ZEB2 co-expressed at high levels could predict poor outcomes in CRC patients. Overall, the 5FU long-term drug-resistance model established here induced various cellular events, and highlighted the importance of further efforts to identify promising targets involved in more than one cellular event to successfully overcome drug-resistance.

Immunohistochemistry with 3 different clones in anaplastic lymphoma kinase fluorescence in situ hybridization positive non-small-cell lung cancer with thymidylate synthase expression analysis: a multicentre, retrospective, Italian study.

ALK rearrangement is the only druggable oncogenic driver detectable by immunohistochemistry (IHC) not requiring further confirmation of positivity in accessing first-line specific inhibitors. ALK-positive patients experience clinical benefit from pemetrexed-based chemotherapy possibly due to lower thymidylate synthase (TS) levels. This study assesses agreement with three different ALK IHC clones in 37 FISH-positive NSCLC. TS expression by real time (RT)-PCR was compared with ALK FISH-negative cases. 37 ALK FISH-positive NSCLC cases diagnosed between 2010 and 2015 in 7 Italian centres were investigated with ICH using three different anti-ALK antibodies (ALK1, 5A4 and D5F3). Staining for ALK1 and 5A4 was graded as 0+,1+,2+, and 3+, while the scoring for D5F3 was recorded as negative or positive. Proportion agreement analysis was done using Cohen's unweighted kappa (k). TS and β-actin expression levels were analysed by quantitative RT-PCR. Comparison between TS expression in ALK FISH-positive specimens and a control cohort of ALK FISH-negative ones was performed with the Mann-Whitney and Kruskal-Wallis tests. Considering 2+ and 3+ as positive, the proportion of IHC agreement was 0.1691 (95% CI 0-0.4595) for ALK1/5A4, 0.1691 (95% CI 0-0.4595) for ALK1/D5F3, and 1 for D5F3/5A4. Considering 3+ as positive, it was 0.1543 (95% CI 0-0.4665) for ALK1/ 5A4, 0.0212 (95% CI 0-0.1736) for ALK1/D5F3, and 0.2269 (95% CI 0-0.5462) for 5A4/D5F3. Median TS expression was 6.07 (1.28-14.94) and ALK-positive cases had a significant lower TS expression than ALK-negative tumours (p = 0.002). IHC proved to be a reliable tool for the diagnosis of ALK-rearranged NSCLC. D5F3 and 5A4 clones have the highest percentage of agreement. TS levels are significantly lower in FISH-positive patients.

Gastric cancer with microsatellite instability displays increased thymidylate synthase expression.

Gastric cancer (GC) with microsatellite instability (MSI) is a less aggressive disease and associated with resistance to 5-fluorouracil (5-FU)-based chemotherapy (CMT). Thymidylate synthase (TS) is inhibited by 5-FU, and another potential mediator of therapeutic resistance to 5-FU. Therefore, we aimed to analyze the association between MSI and TS expression in GC, and its impact on disease outcomes. We retrospectively evaluated GC who underwent D2-gastrectomy. MSI and TS were analyzed by immunohistochemistry. We also investigated p53 expression, PD-L1 status, and tumor-infiltrating lymphocytes (CD4and CD8). Out of 284 GC, 60 (21.1%) were MSI. Median TS-score for all cases was 16.5. TS expression was significantly higher in MSI compared to microsatellite-stable (MSS;p < 0.001). Considering both status, GC were classified in four groups: 167 (58.8%) MSS + TS-low; 57 (20.1%) MSS + TS-High; 24 (8.5%) MSI + TS-low; and 36 (12.7%) MSI + TS-high. MSI + TS-high group had less advanced pTNM stage, higher CD8+T cells levels (p < 0.001) and PD-L1 positivity (p < 0.001). Normal p53 expression was related to MSI GC (p < 0.001). Improved survival was observed in MSI + TS-high, but no survival benefit was seen with CMT. MSI GC was associated with high TS levels, which may explain therapeutic resistance to 5-FU. Additionally, MSI + TS-high showed better survival, but without improvement with CMT.

Thymidylate Synthase Overexpression Drives the Invasive Phenotype in Colon Cancer Cells.

Thymidylate synthase (TYMS) is the crucial enzymatic precursor for DNA biosynthesis and, therefore, the critical target for numerous types of chemotherapy, including the most frequently applied agent in colon cancer treatment 5-fluorouracil (5-FU). TYMS also seems to be associated with cancer metastasis and acquiring mesenchymal character by tumor cells during epithelial–mesenchymal transition (EMT). Based on that knowledge, we decided to investigate the role of TYMS in the modulation of invasive ability in colon cancer cells, where its effect on cancer metastasis has not been studied in detail before. We employed colon cancer cells isolated from different stages of tumor development, cells undergoing EMT, and TYMS overexpressing cells. The elongation ratio, cell migration, invasion assay, and MMP-7 secretion were applied to analyze the cell behavior. Important epithelial and mesenchymal markers characteristic of EMT were examined at the protein level by Western blot assay. Overall, our study showed a correlation between TYMS level and invasion ability in colon cancer cells and, above all, a crucial role of TYMS in the EMT regulation. We postulate that chemotherapeutics that decrease or inhibit TYMS expression could increase the effectiveness of the therapy in patients with colon cancer, especially in the metastatic stage.

Genetic polymorphisms and gene expression of one-carbon metabolizing enzymes and their relation to breast cancer

BackgroundBreast cancer is considered the leading cause of cancer-related death among Egyptian women (15.41%). One of the common BC risk factors is the genetic factor. One-carbon metabolism is one of the pathways reported to increase BC risk by influencing DNA synthesis and methylation. Methyl tetrahydrofolate reductase (MTHFR), thymidylate synthase (TYMS) and DNA methyltransferase (DNMT) enzymes are key enzymes in one-carbon metabolism directly and through influencing folate metabolism. We aimed to study the association of the gene expression level and polymorphisms of MTHER C677T (rs1801133), TYMS (rs45445694), TYMS 3′UTR 1494del6 and ΔDNMT3B − 149C>T with breast cancer risk in a sample of Egyptian women.MethodsThis study was conducted on one hundred female breast cancer patients. Genotyping and gene expression of the MTHFR and TYMS (1494del6, rs45445694) and DNMT3B genes were performed.ResultsThere was no significant difference (OR 1.493; 95% CI 0.78–2.84; P = 0.288) in the frequency of the MTHFR (C677T) genotypes between breast cancer patients and control subjects and no significant difference in the frequency of the MTHFR mutant T allele. TYMS tandem repeats showed a significant difference (OR 2.232; CI 1.21–4.12; P = 0.01) in the frequency of the genotype 2R/3R among breast cancer patients and control subjects; however, the frequency of the 2R allele was not significantly different from that of the 3R allele (OR 1.461; 95% CI 0.96–2.21; P = 0.073). TYMS 3′-UTR 1494del6 showed a significant difference in the distribution of (+ 6/ + 6), (+ 6/− 6) and (− 6/− 6) genotypes between the patient and control groups (P ≤ 0.001*), and its corresponding mutant allele showed P value ≤ 0.001, 95% CI = 1.64–3.76 and OR = 2.483. The expression of MTHFR was downregulated by 0.62-fold in all malignant tissues compared to normal adjacent tissues (0.57 ± 0.20, P < 0.001*). On the other hand, no significant difference (P = 0.143) in the expression level of TYMS was found. Gene expression of DNMT3B was upregulated by 1.65-fold in all breast cancerous tissue samples compared with the control normal adjacent tissue with mean ± SD of 1.81 ± 0.63. (P ≤ 0.001*).ConclusionThe current study showed that the 2R/3R TYMS allele and DNMT3B (− 149C>T) SNP are associated with a high risk of breast cancer and that there is a correlation between the 3′-UTR 1494del6 polymorphism (genotype − 6/− 6) and breast cancer risk. A significant reduction was found in the MTHFR gene expression level in BC compared with control tissues, and the DNMT3B (− 149C>T) SNP did affect the DNMT3B expression level.

Inhibition of Protein Kinase CK2 Affects Thymidylate Synthesis Cycle Enzyme Level and Distribution in Human Cancer Cells.

Thymidylate synthase (TS), dihydrofolate reductase (DHFR), and serine hydroxymethyltransferase (SHMT) constitute the thymidylate synthesis cycle providing thymidylate for DNA synthesis and repair. Our previous studies indicated that TS and DHFR are the substrates of protein kinase CK2. This work has been aimed at the elucidation of the effect of CK2 activity on cell cycle progression, thymidylate synthesis enzyme expression and localization, and the role of CK2-mediated TS phosphorylation in in vitro di- and trimolecular complex formation. The results were obtained by means of western blot, confocal microscopy, flow cytometry, quantitative polymerase chain reaction (QPCR), quartz crystal microbalance with dissipation monitoring (QCM-D), and microthermophoresis (MST). Our research indicates that CK2 inhibition does not change the levels of the transcripts; however, it affects the protein levels of DHFR and TS in both tested cell lines, i.e., A549 and CCRF-CEM, and the level of SHMT1 in CCRF-CEM cells. Moreover, we show that CK2-mediated phosphorylation of TS enables the protein (pTS) interaction with SHMT1 and leads to the stability of the tri-complex containing SHMT1, DHFR, and pTS. Our results suggest an important regulatory role of CK2-mediated phosphorylation for inter- and intracellular protein level of enzymes involved in the thymidylate biosynthesis cycle.

Evaluating serum level of thymidylate synthase in post burn keloid patients before and after intralesional injection of 5-fluorouracil.

BackgroundKeloids are fibrous lesions formed at the site of trauma due to types I and III collagen irregular production. The presence of thymidylate synthase (TS) is a must for DNA synthesis and repairs causing cell death. 5-fluorouracil (5-FU) is a fluorinated pyrimidine analogue acting as an anti-metabolic agent that inhibits thymidylate synthase and interferes with ribo-nucleic acid (RNA) synthesis.Objectiveswe aimed to evaluate the level of thymidylate synthase in post burn keloid patients before and after intralesional injection of 5-fluorouracil.MethodsThe study included 20 keloid patients and 20 healthy subjects as a control. Serum TS was estimated using commercially available enzyme-linked immunosorbent assay (ELISA) kits before and after treatment with 5-fluorouracil.ResultsThere was a statistically significant difference in TS levels before and after 5-FU treatment (p < 0.05). Also, results have shown that 5-FU injection has good satisfactory results in treatment of keloid causing reduction in scar volume and symptoms improvement (90% of the patients improved). On the other hand, there was no statistically significant difference in TS levels and the outcomes of the treatment.ConclusionOur findings suggest that intralesional 5-FU injection in keloid has very satisfactory results. However, thymidylate synthase enzyme has a minimal role in evaluating the treatment of keloid, so further studies are required to elaborate the relation between this enzyme and keloid scars.

Visfatin and Resveratrol Differentially Regulate the Expression of Thymidylate Synthase to Control the Sensitivity of Human Colorectal Cancer Cells to Capecitabine Cytotoxicity.

Colorectal cancer (CRC) is a highly lethal malignant cancer. Capecitabine, a 5-fluororacil (5-FU) derivate, is its first-line drug, but the resistance of CRC to capecitabine is still the most challenging factor for curing patients. It has been suggested that thymidylate synthase (TYMS) level might affect the capecitabine efficacy in CRC patients, but the mechanism still needs more elucidation. Obesity is a risk factor for CRC. Recently, a correlation between serum visfatin, an obesity-elicited adipokine, and CRC development has been found. Thus, the aim of present study is to examine the visfatin capacity in TYMS expression and in the development of capecitabine resistance of CRC. Moreover, an attractive natural component, i.e., resveratrol, has been proposed in anticancer therapy and has hence been examined in the present study to see its potential capacity in the alleviation of CRC resistance. Our results found that visfatin significantly reduces the CRC sensitivity to capecitabine by controlling the TYMS expression via p38 signaling and Sp1 transcription factor. Moreover, resveratrol could significantly alleviate the visfatin effect on capecitabine-treated CRC cells. These results provided new insights to understand the capecitabine susceptibility of CRC under a visfatin-containing environment and a possible therapeutic application of resveratrol in CRC patients with obesity.

Histone N-terminal acetyltransferase NAA40 links one-carbon metabolism to chemoresistance

Aberrant function of epigenetic modifiers plays an important role not only in the progression of cancer but also the development of drug resistance. N-alpha-acetyltransferase 40 (NAA40) is a highly specific epigenetic enzyme catalyzing the transfer of an acetyl moiety at the N-terminal end of histones H4 and H2A. Recent studies have illustrated the essential oncogenic role of NAA40 in various cancer types but its role in chemoresistance remains unclear. Here, using transcriptomic followed by metabolomic analysis in colorectal cancer (CRC) cells, we demonstrate that NAA40 controls key one-carbon metabolic genes and corresponding metabolites. In particular, through its acetyltransferase activity NAA40 regulates the methionine cycle thereby affecting global histone methylation and CRC cell survival. Importantly, NAA40-mediated metabolic rewiring promotes resistance of CRC cells to antimetabolite chemotherapy in vitro and in xenograft models. Specifically, NAA40 stimulates transcription of the one-carbon metabolic gene thymidylate synthase (TYMS), whose product is targeted by 5-fluorouracil (5-FU) and accordingly in primary CRC tumours NAA40 expression associates with TYMS levels and poorer 5-FU response. Mechanistically, NAA40 activates TYMS by preventing enrichment of repressive H2A/H4S1ph at the nuclear periphery. Overall, these findings define a novel regulatory link between epigenetics and cellular metabolism mediated by NAA40, which is harnessed by cancer cells to evade chemotherapy.

Expression of astrocyte-elevated gene-1 indicates prognostic value of fluoropyrimidine-based adjuvant chemotherapy in resectable stage III colorectal cancer.

It is unclear which prognostic factor such as pathological features and gene mutation are majorly relevant for stage III disease and whether they aid in determining patients who will be benefit from postoperative adjuvant chemotherapy. The expression of astrocyte-elevated gene-1 (AEG-1), thymidylate synthase (TS), excision repair cross-complementation group 1 (ERCC1), epidermal growth factor receptor (EGFR), and vascular endothelial growth factor (VEGF) was examined to investigate their role in adjuvant chemotherapy for patients with resectable stage III colorectal cancer (CRC). A significant positive correlation was observed between AEG-1, TS, ERCC1, EGFR, and VEGF gene expression levels in CRC cell lines, and low AEG-1 and TS expression were highly sensitive to 5-fluorouracil treatment. Our results showed that AEG-1 expression was high in T4 and caused CRC recurrence or metastasis. Patients with T4, high AEG-1, TS and VEGF expression had a significantly short disease-free survival and overall survival. In multivariate Cox regression analysis, high AEG-1 expression could be an independent prognostic factor indicating poor survival in patients with resectable stage III CRC treated with adjuvant chemotherapy. In conclusion, AEG-1 expression and tumor grade are potential prognostic factors for recurrence and survival in patients with stage III CRC receiving adjuvant fluoropyrimidine-based chemotherapy.

Abstract 225: Computational analysis of 5-fluorouracil antitumor activity in colon cancer using a mechanistic pharmacokinetic/pharmacodynamic model

Abstract The purpose of this study is to develop a mechanistic pharmacokinetic/pharmacodynamic (PK/PD) model to quantitatively analyze the treatment outcome of 5-fluorouracil (5-FU) in colon cancer. Predicting the outcome of chemotherapeutic agents plays an essential role in improving dose strategies. To that end, we have developed an integrated mechanistic PK/PD model to analyze the kinetics of tumor response to 5-FU treatment. Compared to the existing PK/PD models, our model is novel in the way it incorporates the 5-FU metabolism pathway and downstream antiproliferative events to provide a comprehensive model of treatment outcome. 5-FU has been widely used to treat cancers, including colon cancer. 5-FU metabolites can be incorporated into RNA, DNA and also interfere with thymidylate synthase (TS) catalytic activity, which is the main mechanism of 5-FU cytotoxicity. TS activity has been shown to be the predictor for treatment efficacy. The conversion of deoxyuridine monophosphate (dUMP) to deoxythymidine monophosphate catalyzed by TS is the sole intracellular de novo source of thymidylate. The formation of a ternary complex between fluorodeoxyuridylate (FdUMP) and TS obstructs the access of dUMP to the TS nucleotide-binding site. Resultant thymidine deprivation and dUMP accumulation give rise to the deoxynucleotide triphosphate (dNTP) pool imbalance, which could trigger S-phase specific DNA fragmentation, cell cycle arrest and apoptosis. In our PK model, compartmental analysis is developed to track the distribution of 5-FU from its entry into body to interstitial fluid outside the tumor cells and to its cellular uptake. In the cell model, the connection of TS inhibition and dNTP pool imbalance is implemented. In addition to the central plasma and peripheral tissue compartments, our model includes compartments for: 5-FU concentration in the extracellular fluids; intracellular 5-FU; 5-FU anabolites; genomic 5-FU in RNA, and in DNA; and, TS - FdUMP complex. Posttreatment free TS level is used to compute the perturbed TS catalytic activity. Using the model outcome on TS inhibition, we modeled the kinetics of dNTP pool perturbation. The dNTP pool imbalance leads to double strand break (DSB) formation that initiates DNA damage repair response, kinetics of which are also modeled. Our model uses the law of mass action and Michaelian kinetics and each molecular reaction is expressed as a nonlinear differential equation. Time course data from the literature are used in parameter estimation. Our simulation results successfully captured the kinetics of treatment outcome from the administration of the 5-FU to downstream effects in the tumor. The next step in our effort is to expand the model to include the tumor growth kinetics. Citation Format: Chenhui Ma, Alexandru Almasan, Evren Gurkan-Cavusoglu. Computational analysis of 5-fluorouracil antitumor activity in colon cancer using a mechanistic pharmacokinetic/pharmacodynamic model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 225.