Thymidylate Synthase Promoter Research Articles

Thymidylate synthase drives the phenotypes of epithelial-to-mesenchymal transition in non-small cell lung cancer

BackgroundEpithelial-to-mesenchymal transition (EMT) enhances motility, stemness, chemoresistance and metastasis. Little is known about how various pathways coordinate to elicit EMT’s different functional aspects in non-small cell lung cancer (NSCLC). Thymidylate synthase (TS) has been previously correlated with EMT transcription factor ZEB1 in NSCLC and imparts resistance against anti-folate chemotherapy. In this study, we establish a functional correlation between TS, EMT, chemotherapy and metastasis and propose a network for TS mediated EMT.MethodsPublished datasets were analysed to evaluate the significance of TS in NSCLC fitness and prognosis. Promoter reporter assay was used to sort NSCLC cell lines in TSHIGH and TSLOW. Metastasis was assayed in a syngeneic mouse model.ResultsTS levels were prognostic and predicted chemotherapy response. Cell lines with higher TS promoter activity were more mesenchymal-like. RNA-seq identified EMT as one of the most differentially regulated pathways in connection to TS expression. EMT transcription factors HOXC6 and HMGA2 were identified as upstream regulator of TS, and AXL, SPARC and FOSL1 as downstream effectors. TS knock-down reduced the metastatic colonisation in vivo.ConclusionThese results establish TS as a theranostic NSCLC marker integrating survival, chemo-resistance and EMT, and identifies a regulatory network that could be targeted in EMT-driven NSCLC.

The thymidylate synthase enhancer region (TSER) polymorphism increases the risk of thymic lymphoid hyperplasia in patients with Myasthenia Gravis

BackgroundMyasthenia Gravis (MG) is caused, in approximately 80% of the patients, by autoantibodies against the nicotinic acetylcholine receptor (AChR). The disease is often associated with pathological changes of the thymus: thymic epithelial tumours are present in about 10–20% of the patients, while up to 80% of the patients with early disease onset have thymic hyperplasia. Folate metabolism is required for the production of DNA precursors and for proper DNA methylation reactions, and impaired folate metabolism has been often associated with cellular growth and cancer. MethodsWe investigated if major polymorphisms of folate-related genes, namely MTHFR c.677C>T, MTR c.2756A>G, MTRR c.66A>G and TYMS TSER (a 28-bp tandem repeat in the 5′ promoter enhancer region of TYMS) increase the risk of pathological changes of the thymus in AChR+ MG patients. A total of 526 AChR+ MG patients, including 132 patients with normal (involuted) thymus, 146 patients with thymic hyperplasia, and 248 patients with a thymoma were included in the study. Allele and genotype comparisons were performed among the three study groups, after correcting for multiple testing. ResultsThe frequency of the TYMS TSER 3R allele was significantly higher in MG patients with thymic hyperplasia (P=0.004), and the TYMS TSER 3R3R genotype was significantly associated with increased risk of thymic hyperplasia [OR 2.71 (95% CI: 1.34–5.47)]. ConclusionsThe 3R allele in the thymidylate synthase promoter enhancer region results in increased protein production, required for the synthesis of DNA precursors. The present study suggests that the TYMS TSER 3R allele increases the risk of thymic lymphoid hyperplasia in AChR+ MG patients.

The role of pharmacogenetics in the new ESMO colorectal cancer guidelines.

The role of pharmacogenetics in the new ESMO colorectal cancer guidelines.

High frequency of the 3R/3R polymorphism in the thymidylate synthase enhancer region in Indonesian childhood acute lymphoblastic leukemia

Background Deoxyuridylate monophosphate (dTMP) is neces-sary for DNA synthesis and thymidylate synthase (TS) is an im-portant target of cancer chemotherapy. Ethnic variations of thepolymorphic tandem repeat sequence in the enhancer region ofthe TS promoter has previously been described to influence theoutcome of acute lymphoblastic leukemia (ALL). A triple repeat isassociated with a higher TS gene expression than a double re-peat, resulting in poorer outcome of ALL patients treated with anti-folate methotrexate (MTX).Objective In this study, we determined the incidences of TS andmethylenetetrahydrofolate reductase (MTHFR) polymorphism andethnic variations between Indonesian and Caucasian ALL cellsamples obtained at diagnosis. Furthermore, we determined theinvolvement of TS polymorphisms in MTX sensitivity using athymidilate synthase inhibition assay (TSIA).Methods ALL cell samples were obtained at diagnosis from 101Indonesian and 157 Caucasian children treated with MTX prospec-tively. Genotyping for TS and MTHFR was analyzed by Genescanand Lightcycler. TS polymorphism was determined by PCR assayand MTHFR polymorphism and was analyzed by melting curveanalyses on lightcycler.Results Homozygous TS triple repeats were more than twice ascommon in Indonesian samples (76.3%) than in Caucasian samples(33.1%). Heterozygotes of the MTHFR mutations were seen in 15%of the screened Indonesian samples.Conclusion There are significant ethnic variations in TS generegulatory elements of leukemic cells. A difference was found be-tween the MTX sensitivity and a double or triple repeat in the Cau-casian ALL group. The samples with a triple repeat show a shift intheir distribution towards hypersensitivity to MTX. Further investi-gation on Indonesian samples may give insight in the role of poly-morphisms in MTX sensitivity

Homozygosity for the 2R Tandem Repeat Polymorphism in the Thymidylate Synthase (TS) Promoter Is Associated with Increased Risk for Bony Morbidity Among Children Treated for Acute Lymphoblastic Leukemia on DFCI Protocol 05-001

Introduction: Both fractures and avascular necrosis (AVN) of bone frequently complicate therapy for childhood acute lymphoblastic leukemia (ALL), resulting in significant pain and loss of function. Risk of bony morbidity has been associated with age >10 years and exposure to crucial components of leukemia therapy including corticosteroids, asparaginase, and methotrexate. To further define risk factors, we tested whether 19 common genetic polymorphisms were associated with bony morbidity among 637 children treated for ALL on Dana Farber Cancer Institute ALL Consortium protocol 05-001.Methods: Genomic DNA was isolated from peripheral blood or bone marrow collected at the time of remission. Nineteen candidate polymorphisms were selected a priori, targeting common variants within genes related to glucocorticoid metabolism, oxidative damage, and folate physiology. Single nucleotide polymorphisms were detected using PCR-based allelic discrimination assays. The number of 28bp nucleotide repeats within the 5' untranslated region of the gene for thymidylate synthase (TS) was assessed by PCR-product length analysis. The incidence of AVN and fracture were estimated by the cumulative incidence method identifying death and relapse as competing risks. Because the incidence of bony morbidity differed significantly between children above and below the age of 10 years, relationships between polymorphisms and bony morbidity were explored within these two age subgroups separately. Comparisons at the 0.10 significance level were modeled univariately and were considered in multivariable modeling using competing risks regression. Multivariable models for bony morbidity included sex, WBC at diagnosis, race, final risk group, and asparaginase randomization. Blood was collected during treatment for analysis of serum and RBC folate by HPLC.Results: Of the 637 patients tested, 627 achieved a complete remission and received post-induction therapy, of which 61 (9.7%) experienced AVN and 138 (22.0%) had ≥1 fracture. Both AVN and fracture were more common among those ≥10 years of age (22.9% AVN, 30.7% fracture) than younger children (5.5% AVN, p<0.0001 and 19.2% fracture, p=0.002). Homozygosity for the 2R TS polymorphism was observed in 129 (20.6%) of the 626 patients tested. This 2R/2R genotype was associated with a greater 5-year estimated incidence of AVN (11.6%; 95% CI 6.1-18.9%) than among those with 2R/3R or 3R/3R genotypes (4.1%, 95% CI 2.4-6.5%; p=0.0037; Figure [A]) among children < age 10, but not among older children. The increased risk of AVN in younger children remained significant in the multivariable risk regression model (adjusted hazard ratio 2.92; 95% CI 1.36-6.28; p=0.0059). Among children over age 10, this polymorphism was associated with an increased risk of bony fracture (multivariable HR 2.13; 95% CI 1.13-3.99; p=0.019; Figure [B]). No significant association was observed between bony morbidity and the other tested polymorphisms, including PAI-1 (rs6092), ABCB1 (rs1045642), and the vitamin D receptor Fok1 restriction site (rs228570) which have been previously linked to risk of AVN. Samples were available for analysis of serum and RBC folate at diagnosis (n=367), remission (n=347), 15 months post-remission (n=251), and at the conclusion of therapy (n=247). No significant association was observed between TS genotype and serum or RBC folate at any time point.Conclusions: Homozygosity for the 2R polymorphism in TS was associated with increased risk of bony morbidity among children treated for ALL. Interestingly, the impact of the polymorphism differed between those above the age of 10 years (associated with risk of fracture) and younger children (risk for AVN), suggesting that the pathophysiology of bony morbidity differs between these two age groups. This is the first report identifying a genetic risk factor for AVN specifically among children younger than 10 years, a group where AVN is significantly less frequent. This result suggests young children with ALL and the 2R/2R genotype should be monitored more closely for the development of AVN during therapy for ALL. [Display omitted] DisclosuresSilverman:Seattle Genetics, Inc.: Research Funding.

Abstract A54: Inhibition of FOXM1 by thiostrepton increases sensitivity to 5-fluorouracil (5-FU) by downregulating thymidylate synthase (TS) in colorectal cancer

Abstract Background: 5-Fluorouracil (5-FU) is one of the most commonly used chemotherapy drugs for the treatment of colorectal cancer in the adjuvant and metastatic disease settings. One of the main targets of 5-FU is the enzyme thymidylate synthase (TS). High expression levels of TS in colorectal tumors removed from patients have been associated with drug resistance. The Forkhead box transcription factor M1 (FOXM1) has been demonstrated to regulate several aspects in cancer cells including: cell cycle progression, apoptosis, and cell survival. FOXM1 is over expressed in many types of cancers, including colorectal, and has been implicated in drug resistance in breast cancer. Thiostrepton is a thiazole antibiotic which selectively inhibits FOXM1. The relationship between FOXM1/TS and 5-FU resistance has not previously been established and may present a new treatment strategy. Purpose: In this study we sought to determine 1) the role of FOXM1 in regulation of TS, 2) whether inhibition of FOXM1 using thiostrepton or transient knockdown using a small interfering RNA would inhibit the TS expression in colorectal cancer cells, 3) whether combined therapy with 5-FU and thiostrepton would have a synergistic effect on cell survival, and 4) the effect of treatment with thiostrepton/ 5-FU/ combined thiostrepton and 5-FU on cellular migration and colony formation. Methods and results: HCT116, DLD1, and HT29 cells were treated with 0.5ug/ml 5-FU. TS and FOXM1 protein and mRNA expression were determined using Western blot and RTPCR. 5-FU treatment resulted in an initial increase (6h) followed by a decrease (48h) of both TS and FOXM1 in p53 wild type HCT116 cells, in p53 mutant DLD1 and HT29 cells whilst an initial increase was observed in both FOXM1 and TS there was no subsequent decrease. SRB assay was used to quantify the IC50 of 5-FU in HCT116, DLD1 and HT29 and was found to be 0.67±.23, 0.68±.22 and 3.09±.39 respectively. Transient knockdown of FOXM1 led to a significant decrease of TS in mRNA but not protein in HCT116 cells. For thiostrepton the IC50 was found to be 0.60uM, 1.07uM, and 3.54uM, in HCT116, DLD1 and HT29 cells, respectively. Combination of 5-FU and thiostrepton showed synergistic effects in all 3 colon cancer cell lines. Chromatin immunoprecipitation (ChIP) was performed in HCT116 and DLD1 cell lines to determine if FOXM1 binds to the TS promoter region (0 - 2000bp upstream of the TS transcription start site). 3 negative primers were designed further to 2000bp upstream region. ChIP data revealed enrichment for FOXM1 at the TS promoter (0-1500 bp upstream) and no enrichment observed in the negative control. Inhibition of FOXM1 by thiostrepton led to a drop in enrichment in the TS promoter region. These results confirmed the role of FOXM1 in TS regulation. Chip Sequencing (ChIP-seq) was then performed to study further FOXM1 targets and binding sites of FOXM1 to other well-known 5-FU targets such as thymidine phosphorylase (TP) and thymidine kinase 1 (TK-1). The FOXM1 specific ChIP-seq libraries and corresponding input controls were sequenced on the Illumina Hi Seq 2000. ChIP-seq confirmed that FOXM1 significantly binds to both these factors. FOXM1 binding to cell cycle regulatory genes E2F2 and E2F3 was also shown in both cell lines. Combination treatment of 5-FU and thiostrepton significantly decreases colony formation in HCT116, DLD1 and HT29 cell lines. 5-FU and thiostrepton combination also decreases migration in HCT116 cells. Conclusion: FOXM1 regulates the 5-FU target gene TS, and inhibition of FOXM1 acts enhances the cytotoxic effect of 5-FU in colorectal cancer cells and warrants further investigation as a new treatment strategy. Citation Format: Vidhya Varghese, Luca Magnani, Narumi Harada, Lam W. Eric, Laura Kenny. Inhibition of FOXM1 by thiostrepton increases sensitivity to 5-fluorouracil (5-FU) by downregulating thymidylate synthase (TS) in colorectal cancer. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Drug Sensitivity and Resistance: Improving Cancer Therapy; Jun 18-21, 2014; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(4 Suppl): Abstract nr A54.

Abstract LB-220: Forkhead box transciption factor M1 (FOXM1) plays a critical role in colorectal cancer resistance by regulating thymidylate synthase (TS)

Abstract Background: Tumor resistance to chemotherapy is a major challenge in cancer therapeutics today. 5-Fluorouracil (5-FU) is one of the most commonly used cancer therapeutic agents. The Forkhead box transcription factor M1 (FOXM1) has been shown to play vital roles in cell cycle progression, apoptosis, and cell survival. FOXM1 is over expressed in many types of cancers, including colorectal carcinoma and has been implicated in drug resistance in breast cancer. Thymidylate synthase (TS) enzyme is an important precursor in DNA synthesis. The mechanism of action of 5-FU has been associated with TS. High TS expression levels in tumors are generally related to 5-FU resistance. In this study we investigated the role of FOXM1 in 5-FU resistance and the therapeutic potential of the FOXM1 inhibitor thiostrepton (a thiazole antibiotic) in combination with 5-FU in colorectal cancer. We further analyzed the relation between TS and FOXM1 gene expressions in colorectal cancer. Methods and Results: HCT116, DLD1, and HT29 cells were treated with 5-FU to detect the protein, mRNA expression of FOXM1 and TS. This resulted in a decrease in TS and FOXM1 expression in p53 wild type HCT116 cells but not in p53 mutant DLD1 or HT29. We also observed that FOXM1 expression was significantly correlated with TS expression by thiostrepton treatment. The IC50 of 5-FU was determined by SRB assay and was found to be 0.92ug/mL, 0.45ug/mL and 2.8ug/mL, while thiostrepton IC50 was found to be 0.60uM, 1.07uM, and 3.54uM, in HCT116, DLD1, and HT29 cells respectively. Combination of 5-FU and thiostrepton showed synergistic effect in all 3 colorectal cancer cells. Chromatin immunoprecipitation (ChIP) was performed in HCT116 and DLD1 cells to determine if FOXM1 binds to the TS promoter region (0 - 2000bp upstream of the TS transcription start site). Three negative primers were designed further to 2000bp upstream region. ChIP data revealed enrichment for FOXM1 at the TS promoter (0 - 1500 bp upstream) and no enrichment observed in the negative control. Inhibition of FOXM1 by thiostrepton led to a decrease in enrichment in the TS promoter region. These results confirmed the role of FOXM1 in TS regulation. Chip Sequencing (ChIP-seq) was then performed to study further FOXM1 targets and binding sites of FOXM1 to other well-known 5-FU targets such as thymidine phosphorylase (TP) and thymidine kinase 1 (TK1). The FOXM1 specific ChIP-seq libraries and corresponding input controls were sequenced on the Illumina Hi Seq 2000. ChIP-seq confirmed that FOXM1 significantly binds to both these factors. FOXM1 binding to cell cycle regulatory genes E2F1, E2F2 and E2F3 was also shown in both cell lines. Conclusion: FOXM1 plays a critical role in 5-FU drug resistance by regulating 5-FU target genes such as TS, TK1. Inhibition of FOXM1 acts synergistically with 5-FU in colorectal cancer and warrants further investigation as a new treatment strategy. Citation Format: Vidhya Varghese, Luca Magnani, Narumi Harada, Francesco A. Mauri, Eric W. Lam, Laura M. Kenny. Forkhead box transciption factor M1 (FOXM1) plays a critical role in colorectal cancer resistance by regulating thymidylate synthase (TS). [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr LB-220. doi:10.1158/1538-7445.AM2014-LB-220

A DPYD Variant (Y186C) Specific to Individuals of African Descent in a Patient With Life-Threatening 5-FU Toxic Effects: Potential for an Individualized Medicine Approach

5-Fluorouracil (5-FU) is commonly administered as a therapeutic agent for the treatment of various aggressive cancers. Severe toxic reactions to 5-FU have been associated with decreased levels of dihydropyrimidine dehydrogenase (DPD) enzyme activity. Manifestations of 5-FU toxicity typically include cytopenia, diarrhea, stomatitis, mucositis, neurotoxicity, and, in extreme cases, death. A variety of genetic variations in DPYD, the gene encoding DPD, are known to result in decreased DPD enzyme activity and to contribute to 5-FU toxic effects. Recently, it was reported that healthy African American individuals carrying the Y186C DPYD variant (rs115232898) had significantly reduced DPD enzyme activity compared with noncarriers of Y186C. Herein, we describe for the first time, to our knowledge, an African American patient with cancer with the Y186C variant who had severe toxic effects after administration of the standard dose of 5-FU chemotherapy. The patient lacked any additional toxic effect-associated variations in the DPYD gene or the thymidylate synthase (TYMS) promoter. This case suggests that Y186C may have contributed to 5-FU toxicity in this patient and supports the use of Y186C as a predictive marker for 5-FU toxic effects in individuals of African ancestry.

Gene polymorphisms of folate metabolizing enzymes and susceptibility to lung adenocarcinoma in Serbia.

e12020 Background: Methylenetetrahydrofolate reductase (MTHFR) and thymidylate synthase (TS) are important enzymes of the folate metabolism and are suggested as new prognostic factors for lung cancer. Cytosine to thymine transition at nucleotide 677 (C677T) leads to reduced MTHFR activity. The TS promoter has a tandem repeat polymorphism (2R, 3R) and a guanine to cytosine transition in the 3R allele related to TS protein expression. The aim of this study was to analyze the association of MTHFR and TS polymorphisms with lung adenocarcinoma in Serbia. Methods: A case-control study including 55 late-stage lung adenocarcinoma patients and 53 healthy subjects was performed. Restriction fragment length polymorphism analysis was used for MTHFR and TS genotyping. Depending on the presence of high (3RG) or low (2R, 3RC) expression alleles, TS functional groups were subclassified into HH (3RG/3RG), HL (2R/3RG, 3RG/3RC) and LL (2R/2R, 2R/3RC, 3RC/3RC) groups. Descriptive analyses included genotype and allelic frequencies; the odds ratio (OR) and 95 % confidence interval (CI) were calculated as an estimate of relative risk. Significance was considered for p &lt; 0.05. Results: The distribution of the MTHFR variants in patients vs. controls was 61.8 % vs. 24.5 % for CC, 32.7 % vs. 62.3 % for CT and 5.5 % vs. 13.2 % for TT. A significant difference in CC vs. TT+CT MTHFR genotype distribution was observed between patients and controls (χ2 = 13.79; OR = 4.98; 95 % CI, 2.14 – 11.61). There was no significant association between the TS polymorphisms and the risk of lung adenocarcinoma occurrence, but in the CT+TT MTHFR subgroup, a nonsignificant difference in LL vs. HL+HH TS genotype distribution was observed between patients and controls (χ2 = 0.04; OR = 1.07; 95% CI, 0.31 – 3.67). Conclusions: A significant corelation between the CC MTHFR genotype and lung adenocarcinoma occurence in Serbia was found. Also, there was no significant correlation with lung adenocarcinoma occurence in the CT+TT MTHFR subgroup for carriers of the LL TS genotype. As this study was performed on a relatively small sample size further large case-control studies including analysis of gene-gene interactions with genes coding for other folate metabolism enzymes is needed.

Results of a phase II study assessing efficacy and tolerance of fluorouracil (FU), leucovorin, irinotecan, and bevacizumab (FOLFIRI + B) in first-line metastatic colorectal cancer (MCRC): The Omega Trial (NTC 00467142).

e14023 Background: This phase II study evaluates efficacy and tolerance of FOLFIRI+B in first-line MCRC treatment and assesses several genetic polymorphisms as potential markers of treatment activity or toxicity. Methods: Adult patients (pts) with histologically-proven, non-resectable MCRC, ECOG≤2, were included in this two-stage Simon’s design requiring 61 evaluable pts. 14-day cycles consisted of B (5mg/kg), irinotecan (180mg/m²), bolus FU (400mg/m²) and leucovorin (400mg/m²) followed by a 46-hour infusion of FU (2400mg/m²). UGT1A1, thymidylate synthase and VEGFA promoter SNPs were assessed. Primary endpoint was response rate according to RECIST criteria. Results: Sixty-two pts (25 male) from 7 centers were enrolled between Jan07 – Aug09. Median age: 68 years (1st-3rd quartile : 60.4-75.4]); ECOG 0-1 (95.2%); primary tumor location was colon (85.4%) or rectum (14.6%). Principal MCRC locations were: liver (54 pts), lung (28 pts) or peritoneum (17 pts). All pts were evaluable for toxicity. 1058 cycles were administered, median of 13 (range 3-62). Grade 3/4 toxicities were: neutropenia 19.4%; no febrile neutropenia; diarrhea 11.3%; nausea-vomiting 1.6%. No hypertension, thrombotic events, proteinuria or gastrointestinal perforation were observed. 59/62 pts were evaluable for efficacy with 28 pts in PR (47.5%; 95%CI 34.3-60.9), 20 with SD (33.9%) and 11 in PD (18.6%). Median response duration: 9.5 months (range 2.7-20); median time to progression: 10.3 months (range 8.8-11.7); median overall survival (OS) 25.7 months (range 20.2-29.7). 11/59 unresectable pts could finally be resected. To date, three VEGFA polymorphisms have been identified and associations with OS tested. The common genotype of rs25648 is associated with better OS (HR: 0.277; 95%CI: 0.12-0.64). Conclusions: FOLFIRI+B has a good safety profile, is active, with a long median OS leading to resect 18.6% of initially unresectable pts. Genetic polymorphism rs25648 has currently been identified as a marker of better OS, and further analyses for potential UGT1A1 and thymidylate synthase markers are underway.

Abstract 3689: Association of thymidylate synthase gene polymorphisms with efficacy and toxicity of oral fluoropyrimidine based chemotherapy in advanced gastric cancer

Abstract Purpose: Oral fluoropyrimidines (S-1 or capecitabine) are metabolized by different enzymes. We evaluated the association between polymorphisms of cytochrome P450 2A6 (CYP2A6), carboxylesterase 2(CES 2), thymidylate synthase (TS), and excision repair cross complementation group 1 (ERCC1) and toxicity of advanced gastric cancer patients treated with oral fluoropyrimidine based chemotherapy. Methods: A total of 123 patients received S-1 80mg/m2 or capecitabine 2000 mg/m2 plus oxaliplatin 130 mg/m2 for advanced gastric cancer. We analyzed polymorphisms of CYP2A6, CES 2, TS and ERCC1 by using genomic DNA extracted from prospectively collected peripheral blood sample. Associations between polymorphisms and toxicity of these patients treated with oral fluoropyrimidines based chemotherapy were evaluated individually. Results: Patients who were 2R/3R for the double repeat in the TS promoter region had more toxicity of oral fluoropyrimidines. Patients with a 2R/3R and 2R/2R or 3R/3R genotype had a grade 2 or more gastrointestinal toxicity rate of 50 and 22%, respectively (P = .049). Response rate was higher in patients with a 2R/3R than those with a 2R/2R or 3R/3R (50% vs. 32%, P = .082). Polymorphisms of CYP2A6, CES 2, and ERCC1 were not associated with efficacy and toxicity of oral fluoropyrimidine based chemotherapy for advanced gastric cancer. Conclusion. This study demonstrated that TS genotyping could be of help in predicting toxicity to oral fluoropyrimidine based chemotherapy in advanced gastric cancer patients. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3689. doi:1538-7445.AM2012-3689

Prognostic value of methlylenetetrahydrofolate reductase (MTHFR), thymidylate synthase (TS) promoter, and p53 codon 72 variants and survival in advanced non-small cell lung cancer (NSCLC).

e21161 Background: Folate plays an important role as a cofactor of enzymes involved in DNA synthesis and in the regulation of gene expression through methylation. Hypometylation of the p53 tumor su...

Impact of thymidylate synthase promoter and DNA repair gene polymorphisms on susceptibility to childhood acute lymphoblastic leukemia

The aim of this study was to evaluate the frequency of polymorphisms in the TYMS, XRCC1, and ERCC2 DNA repair genes in pediatric patients with acute lymphoblastic leukemia using polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism (RFLP) approaches. The study was conducted in 206 patients and 364 controls from a Brazilian population. No significant differences were observed among the analyzed groups regarding XRCC1 codon 399 and codon 194 and ERCC2 codon 751 and codon 312 polymorphisms. The TYMS 3R variant allele was significantly associated with a reduced risk of childhood ALL, represented by the sum of heterozygous and polymorphic homozygous genotypes (odds ratio 0.60; 95% confidence interval 0.37–0.99). The results suggest that polymorphism in TYMS may play a protective role against the development of childhood ALL.

Molecular analysis of the polymorphisms of thymidylate synthase on cell‐free circulating DNA in blood of patients with advanced colorectal carcinoma

As a key enzyme in folate metabolism, the thymidylate synthase (TS) is important for the synthesis of nucleotides. Its polymorphisms may affect the TS gene expression and the susceptibility for Fluoropyrimidine (FU)-based chemotherapies. In this study, we assessed the relationship between the TS genotypes and clinical outcome to 5-FU-based chemotherapy, and examined whether cell-free circulating DNA is applicable for these molecular analyses. We combined the variable number tandem repeat (VNTR) and single nucleotide (SNP) polymorphisms of the TS promoter and the deletion variants (1494del6) in the 3'UTR with the occurrence of loss of heterozygosity (LOH) at the microsatellite markers D18S59, D18S1140, and D18S976 mapped up- and downstream to the TS locus. Cell-free blood DNA, tumor tissues, and leukocytes of 51 patients with advanced colorectal cancer were used. Genotyping revealed linkage disequilibrium between TS promoter and 3'UTR (p = 0.03) in blood and leukocytes. Inverse associations of the response to therapy with the number of polymorphisms (p = 0.05) and the 494del6 polymorphism (p < 0.02) were detected on serum DNA. The quantification of serum DNA showed significant correlations with the 1494del6 variant (p = 0.006) in tumor tissues and the combined polymorphisms in leukocytes (p < 0.04). In contrast to the low LOH frequency in blood, LOH spanned more than one marker in the primary tumor of the majority of the patients suggesting the loss of the entire TS locus. Our data provide insight into the molecular diversity of the regulation of the TS gene expression. This is the first study that compares multi-variant TS genotypes in different clinical specimens.

Lapatinib, a Dual EGFR and HER2 Tyrosine Kinase Inhibitor, Downregulates Thymidylate Synthase by Inhibiting the Nuclear Translocation of EGFR and HER2

BackgroundEpidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) has been shown to exert a synergistic antitumor effect when combined with fluoropyrimidine. This synergy may be attributable to the downregulation of thymidylate synthase (TS), which is frequently overexpressed in fluoropyrimidine-resistant cancer cells. However, the molecular mechanism underlying the downregulation of TS has yet to be clearly elucidated.Methodology and Principal FindingsIn this study, we demonstrate that lapatinib, a dual TKI of EGFR and HER2 downregulates TS via inhibition of the nuclear translocation of EGFR and HER2. From our cDNA microarray experiments, we determined that a variety of nucleotide synthesis-related genes, including TS, were downregulated with lapatinib, and this was apparent in HER2-amplified cells. Targeted and pharmacologic inhibition assays confirmed that the dual inhibition of EGFR and HER2 is required for the more effective reduction of TS as compared to what was observed with gefitinib or trasutuzumab alone. Additionally, we determined that co-transfected EGFR and HER2 activate the TS gene promoter more profoundly than do either EGFR or HER2 alone. The translocation of EGFR and HER2 into the nucleus and the subsequent activation of the TS promoter were inhibited by lapatinib.Conclusions and SignificanceThese results demonstrate that lapatinib inhibits the nuclear translocation of EGFR and HER2 and downregulates TS, thus sensitizing cancer cells to fluoropyrimidine.

TS and MTHFR gene polymorphisms in patients (pts) with recurrent or metastatic squamous cell carcinoma of the head or neck (SCCHN) treated with pemetrexed (P) and bevacizumab (B)

e17011 Background: P inhibits multiple enzymes in folate metabolism. We examined polymorphisms in thymidylate synthase (TS) and methylenetetrahydrofolate reductase (MTHFR) in patients with SCCHN treated in a phase II clinical trial with P and B (ASCO 2008; A6069). Methods: All pts were treated with P 500 mg/m2 and B 15 mg/kg, given IV every 21 days until progression. Primary endpoint was time to progression (TTP). DNA was isolated from whole blood samples using commercially available kits. Polymorphisms examined were MTHFR (C677T, A1298C and G1793A) and TS (TS2R3R, TSG2RG and TSmut6). The MTHFR SNPs were detected using TaqMan based SNP genotyping kits from Applied Biosystems, run on the ABI Prism 7700 Sequence Detection systems v 1.7 (Foster City, CA). The TS promoter repeat and promoter SNP polymorphisms and the 3’ untranslated region 6 bp deletion polymorphism were determined using published methods to detect PCR product size and RFLP-PCR assays respectively. Results: 22 pts were genotyped from 34 enrolled. There was no significant difference in characteristics between pts with and without genotype data. For the MTHFR polymorphism C677T, there was a trend towards decreased disease control rate (DCR) (CR/PR/SD) (p = 0.058, Jonckheere-Terpstra trend test) and worse TTP (p = 0.04) transitioning from variant CC to CT to TT; comparing TT genotype versus CT and CC combined, pts with TT had inferior DCR (p = 0.03) and TTP (p = 0.0003); homozygotes with TT had a median TTP of 2.6 months (mo) 95% CI (1.4, NA) versus 5.6 mo (4.2, 11.4) for pts with CT or CC variants. For the MTHFR A1298C SNP, there was no significant difference in DCR between variants, median TTP for homozygotes pts with AA was 4.1 mo (2.6, NA) vs. 6.7 mo (5.1, NA) in pts with AC or CC variants (p = 0.084); median overall survival for AA was 10.2 mo (7.6, NA) and for AC or CC 17.6 mo (17, NA) (p = 0.045). The MTHFR G1793A and TS polymorphisms did not impact DCR, TTP or overall survival. There was no association between any polymorphism and the incidence of grade &gt;2 toxicities. Conclusions: Polymorphisms in MTHFR are potentially associated with antitumor efficacy of P-based therapy in recurrent or metastatic SCCHN. These results warrant validation in larger studies with P in SCCHN. No significant financial relationships to disclose.

Methylenetetrahydrofolate reductase (MTHFR) C677T and thymidylate synthase promoter (TSER) polymorphisms in Indonesian children with and without leukemia

Genetic variations in the polymorphic tandem repeat sequence of the enhancer region of the thymidylate synthase promoter ( TSER), as well as in methylenetetrahydrofolate reductase ( MTHFR) C677T polymorphism, influence methotrexate sensitivity. We studied these polymorphisms in children with acute lymphoblastic leukaemia (ALL) and in subjects without malignancy in Indonesia and Holland. The frequencies of TT and CT genotypes were two-fold higher in Dutch children. The TSER 3R/3R repeat was three-fold more frequent in the Indonesian children, while the 2R/2R repeat was only 1% compared to 21% in the Dutch children. No differences of these polymorphisms were found between ALL cells and normal blood cells, indicating an ethnic rather than leukemic origin. These results may have implications for treatment of Indonesian children with ALL.

Polymorphisms in the thymidylate synthase promoter and the DNA repair genes XRCC1 and XPD in a Brazilian population

Polymorphisms in genes responsible for maintaining genomic integrity are potential modifiers of disease risk. Since considerable interindividual and interethnic variation in DNA repair capacity has been associated with polymorphic alleles, we evaluated the frequency of the 2R/3R variants in the TS promoter, Arg194Trp and Arg399Gln in the XRCC1 gene, and Asp312Asn and Lys751Gln in the XPD gene in 364 healthy individuals from a Brazilian population separated by ethnicity (European ancestry and African ancestry). The genotypes were determined by PCR (TS) or by PCR-RFLP (XRCC1 and XPD). The frequency of the TS 3R allele was 0.56 for whites and 0.51 for nonwhites. In the case of the XRCC1 MspI polymorphism, the allele frequencies were 0.09 for 194Trp in both nonwhites and whites and 0.27 and 0.28 for 399Gln in nonwhites and whites, respectively. For the XPD 312Asn allele, we found a frequency of 0.25 in white individuals, which was significantly different (P = 0.025) from that seen in nonwhites (0.15). Similarly, the 751Gln polymorphic allele of the XPD gene was significantly more frequent (P < 0.002) in whites (0.30) than in nonwhites (0.20). The genotype frequencies were within Hardy-Weinberg equilibrium. We concluded that the genotype and allele frequencies of XPD gene polymorphism differed between white and nonwhite Brazilians, and that the frequencies of the XPD 312Asn and XRCC1 399Gln alleles in this Brazilian population showed ethnic variability when compared with those observed in other populations.

PREDICTIVE MARKERS OF TREATMENT RESPONSE TO 5-FU AND GEMCITABINE IN PANCREATIC CANCER

Introduction: The RTOG 9704 prospective multicenter randomized adjuvant treatment trial demonstrated that the addition of gemcitabine to postoperative adjuvant 5-FU chemoradiation therapy improves survival in patients with pancreatic adenocarcinoma. Thymidylate synthase (TS) thymidine phosphorylase (TP) and methylenetetrahydrofolate reductase (MTHFR) are key enzymes in the metabolism of folate and 5-fluorouracil. Human equilibrative nucleoside transporter (hENT1) is involved in gemcitabine transport into cells. Retrospective studies in pancreatic cancer suggest that these markers may have prognostic and predictive value. We aim to study protein expression and polymorphisms of these markers in resected tumors from patients participating in the RTOG 9704 trial. Methods: A Tissue Microarray was constructed using 3 separate cores from 225 resected pancreatic tumors. Immunohistochemistry was performed to define TS, TP and hENT1 protein expression. TS promoter genotype (2 or 3 tandem repeats) and MTHFR genotype (C667T) was assessed using tumor DNA. Correlations between protein expression or genotype and prognostic or predictive factors were sought, by unconditional logistic regression analysis. Results: High TS nuclear expression, TP cytoplasmic expression, TP nuclear expression and TP stromal expression is seen in 30%, 86%, 65% and 92% of cases. There are statistically significant associations between higher pathologic grade and high expression of TP nuclear (p = 0.05) and TP cytoplasmic (p = 0.02). There is a trend towards nodal status and high TP nuclear marker levels (p = 0.09). The frequencies of TS promoter tandem repeat 2R/2R, 2R/3R and 3R/3R are 27%, 33%, and 38%. There is a non-significant trend towards 3R/3R TS genotype and high TS protein expression. 22% of cases had no expression of hENT1, compared with 38% with high expression. The frequencies of the MTHFR 667CC, 667CT, and 667TT genotypes are 48.8%, 41.1%, and 10.1%, respectively. 27.6% of patients with either 667CC or 667CT vs. 8.3% of patients with 667TT are early T stage (p = 0.12). Correlation analysis with treatment outcome and toxicity for this trial will be presented. Conclusions: This is the first study to analyze prognostic and predictive markers in a prospective randomized pancreatic cancer clinical trial. There is limited association between TS or TP protein expression and tumor demographic factors. There is a trend towards correlation between TS genotype 3R/3R and high TS protein expression in pancreatic cancer. MTHFR TT genotype was more likely to be associated with advanced T stage and may be associated with disease progression. The majority of tumors expressed hENT1. These markers may serve as useful predictors markers of response and toxicity in pancreatic cancer treatment.

Thymidylate synthase, dihydropyrimidine dehydrogenase and thymidine phosphorylase expression in colorectal cancer and normal mucosa in patients

To compare thymidylate synthase (TS), dihydropyrimidine dehydrogenase (DPD) and thymidine phosphorylase (TP) gene polymorphism and expression in colorectal cancer (CRC), and normal mucosa in chemotherapy-naïve patients. TS, DPD and TP mRNA expression was analysed by real-time reverse-transcription polymerase chain reaction in primary CRC and adjacent normal tissues from 53 patients with glyceraldehyde-3-phosphate dehydrogenase as housekeeping gene. TS promoter (TSER and C/G SNP) and DPD IVS14+1G>A genotypes were determined by polymerase chain reaction and restriction fragment length polymorphism assays. Moreover, the correlation between TS, DPD and TP expression and cytotoxicity of 5-fluorouracil was evaluated in Colo 320, HT-29, CaCo-2 and SW620 human CRC cell lines. TP and DPD mRNA expression was significantly different in tumour and normal tissue (7.51+/-13.50 vs. 1.10+/-0.57, P<0.05 and 0.60+/-0.63 vs. 1.17+/-0.55, P<0.0001, respectively), whereas no differences were observed in TS mRNA levels. High-grade, undifferentiated tumours (WHO grade 3) had significantly higher mRNA levels of TS with respect to moderately differentiated (WHO grade 2) carcinomas (0.38+/-0.37 vs. 0.00+/-0.44, respectively; P<0.05). Noteworthy, TS mRNA expression was significantly decreased (P<0.05) in homozygous TSER*3G/3G (-0.35+/-0.35) with respect to pooled homozygous TSER*2/2 and heterozygous TSER*2/3 genotypes (0.14+/-0.41). In-vitro results showed a higher sensitivity to 5-FU of cell lines with the lowest TS expression. The present results demonstrated significant differences in DPD and TP gene expression between normal mucosa and tumour samples, while TSER*3G/3G and high-grade histology were associated with significant variation in TS gene expression in tumour samples.