Thymidylate Synthase Levels Research Articles

Molecular Profiling of Angiosarcomas of the Breast

ABSTRACT Aim: Angiosarcoma of the breast is a rare, aggressive soft tissue neoplasm occurring as either a primary or secondary malignancy due to previous radiotherapy for breast carcinoma. There is an unmet medical need for targeted therapies for angiosarcoma. Methods: Seventeen patients with angiosarcoma of the breast were identified (Caris Life Sciences) and profiled for biomarkers of drug response using multiplatform methodologies (Tumor DNA sequencing, gene copy number alterations, RNA/microarray and protein/IHC expression). Results: Eight primary, 5 post-radiation and 4 mammary angiosarcomas of unknown etiology were identified in women (age 31-85 years), all exhibiting multiple biomarker alterations. Eight out of 17 cases (47%) harbored overexpression (mRNA and/or protein) of the genes [VEGFR2 (5/17), PDGFRA/PDGFRB (3/17), c-KIT (2/17)] that can be targeted by multikinase inhibitor Sunitinib. Based on the VEGFR2 overexpression, one patient with recurrent, refractory angiosarcoma was treated with Sunitinib resulting in a complete remission and is disease free at 14 months. Also, multiplatform molecular profiling revealed useful predictors of various other treatment modalities including anthracyclines (overexpression of topoisomerase 2a in 69%), topo 1 inhibitors (topoisomerase 1 overexpression in 44%), and fluoropyrimidines (low levels of thymidylate synthase in 29%). One case devoid of the Sunitinib-associated genetic alterations harbored a KRAS mutation indicating a potential benefit of MEK inhibitors. Conclusions: A comprehensive molecular profiling of breast angiosarcomas enables identification of various molecular alterations that can be treated by both targeted and conventional treatment modalities. Disclosure: All authors have declared no conflicts of interest.

Raltitrexed induces mitochondrial‑mediated apoptosis in SGC7901 human gastric cancer cells.

Raltitrexed is a specific inhibitor of thymidylate synthase (TS), which has been considered as a potential chemotherapeutic agent for the treatment of advanced gastric cancer. In the present study, the apoptosis mechanisms of raltitrexed in SGC7901 human gastric cancer cells were investigated. The cytotoxic activity of raltitrexed on SGC7901 cells was determined by cell counting kit-8 (CCK-8) assay. The CCK‑8 assay indicated that raltitrexed inhibits SGC7901 cell growth in a dose- and time-dependent manner. The morphological changes were observed by fluorescent microscopy, and characteristic morphological changes, including nuclear shrinkage and apoptotic bodies, were observed following Hoechst 33258 staining. The effects on apoptosis, cell cycle, mitochondrial transmembrane potential and reactive oxygen species (ROS) were measured by flow cytometry. The analysis revealed that raltitrexed exerted a growth inhibitory effect by inducing time-dependent apoptosis and cell-cycle arrest at the G0/G1 phase. In addition, a compromised mitochondrial membrane potential and overproduction of ROS demonstrated the involvement of the mitochondrial signaling pathway. Raltitrexed‑induced caspase‑3‑dependent apoptosis was identified using a caspase-3 activity assay and pretreatment with the caspase-3 inhibitor, Ac‑DEVD‑CHO (sequence, Ac-Asp-Glu-Val-Asp-CHO). The activity of caspase-3 was analyzed with a spectrometer. The protein expression levels of Bax, Bcl-2, cytochrome c, cleaved caspase-3 and TS were examined by western blot and the mRNA expression level of TS was detected by quantitative polymerase chain reaction. The analysis revealed that the protein levels of Bax, cytochrome c and cleaved caspase‑3 were significantly increased by raltitrexed, while Bcl-2 expression levels were reduced. Furthermore, raltitrexed increased the expression of the TS protein and mRNA in a time‑dependent manner. These results indicate that raltitrexed induces the apoptosis of SGC7901 cells through the caspase‑3‑dependent mitochondrial signaling pathway and upregulates the expression of the TS protein and mRNA.

Prognostic significance of thymidylate synthase in postoperative non-small cell lung cancer patients.

The aim of the present study was to investigate the clinicopathologic/prognostic significance of thymidylate synthase (TS), orotate phosphoribosyltransferase (OPRT), and thymidine phosphorylase (TP) proteins in postoperative non-small cell lung cancer (NSCLC) patients. Microarray slides from a set of 178 NSCLC patients were used for the detection of TS, OPRT, and TP expression by immunohistochemistry. The correlation between clinicopathologic factors and protein expression of three proteins was analyzed. Ninety seven carcinomas (57.4%) were TS-positive, 90 carcinomas (53.9%) were OPRT-positive, and 102 carcinomas (69.4%) were TP-positive. Compared with the TS-positive patients, the overall survival (OS) was significantly lower in the TS-negative patients (hazard ratio [HR] =1.766, 95% confidence interval [CI] =1.212–2.573, P=0.003). Significant differences between TS-positive and TS-negative patients was also observed in the following stratified analyses: 1) adenocarcinoma subgroup (HR =2.079, 95% CI =1.235–3.500, P=0.006); 2) less than 60-year-old subgroup (HR =1.890, 95% CI =1.061–3.366, P=0.031); 3) stage II/III subgroup (HR =1.594, 95% CI =1.036–2.453, P=0.034); and 4) surgery plus adjuvant therapy subgroup (HR =1.976, 95% CI =1.226–3.185, P=0.005). However, the OS was not significantly correlated with OPRT or TP protein expression. This study demonstrates that the TS level in tumor tissues may be a useful marker to predict the postoperative OS in NSCLC patients.

THU0457 Tyms Polymorphisms and Methotrexate Therapeutic Outcome in Rheumatoid Arthritis Portuguese Patients: Analysis of Key Polymorphisms

BackgroundTherapeutic outcome of rheumatoid arthritis (RA) patients treated with methotrexate (MTX) could be conditioned by thymidylate synthase (TS) levels, which may be altered by genetic polymorphisms in TS gene (TYMS)...

Differential thymidylate synthase expression in lung cancer adenocarcinoma subtypes.

e18539 Background: Lung adenocarcinoma (ADC) is characterized by lower Thymidylate Synthase (TS) levels compared to squamous carcinoma and high sensitivity to Pemetrexed, an antifolate targeting TS...

Genetic Biomarkers for Fluorouracil Toxicity Prediction: The Long Road to Clinical Utility

Genetic Biomarkers for Fluorouracil Toxicity Prediction: The Long Road to Clinical Utility

Src Inhibition Is Still a Relevant Target in Pancreatic Cancer

It is with great interest and anticipation that Dr. Chee and colleagues report their phase II study results of dasatinib in the first-line treatment of patients with metastatic pancreatic cancer (PCa) [1]. The authors should be applauded for successfully conducting an important “window of opportunity” study with high hopes of demonstrating benefit. Unfortunately, the study failed to meet the prespecified primary endpoint of improving overall survival. However, we respectfully disagree with the authors’ conclusion that dasatinib has no clinical activity in metastatic PCa. Although it is true that this agent as monotherapy failed to achieve a meaningful composite outcome of overall survival in the patients treated, there were a number of individuals who had durable and sustained response to relatively brief therapy exposure. Whether due to the biologic agent or inherent in the individual patient’s disease biology, such findings are consistent with the National Cancer Institute’s recently reported goal of identifying exceptional responders to therapies. Such identification of clinical responders allows for the pursuit of deep interrogation of their cancer biology to determine a mechanistic rationale that might be exploited further for the benefit of all patients [2]. Thus, efforts should be made to better understand the outcomes and biologic “-omics” associated with the heterogeneous nature of the disease among individual patients with pancreatic cancer. There are significant preclinical data to support the rationale for Src inhibition as a potentially effective therapeutic target in PCa [3–6]. However, the presumption that a single biologic agent would significantly improve survival in metastatic PCa is inconsistent with prior clinical investigation and preclinical data. It may be more therapeutically effective and scientifically rational to consider Src inhibition in combination with cytotoxic therapies based on the following caveats: (a) Constitutively active Src is associated with increased chemoresistance in pancreatic cancer cells [7–9]. (b) Inhibition of Src reduces tumor expression of thymidylate synthase, the target enzyme of 5-fluorouracil; thus, lowering thymidylate synthase levels is associated with subsequent 5-fluorouracil chemoresistance reversal, resulting in substantially decreased in vivo tumor growth and inhibition of progressive distant metastases [10, 11]. (c) Dasatinib can synergistically inhibit oxaliplatin-induced Src activation, and Src inhibition can also increase oxaliplatin activity both in vitro and in vivo [12]. Therefore, we recommend continued investigations for our patients with PCa by developing rational combination therapies that capitalize on therapeutic Src inhibition. A combination clinical trial of Src inhibition with cytotoxic therapies to explore these hypotheses, with correlative molecular tumor and surrogate tissue analyses, is ongoing with active enrollment (NCI ClinicalTrials.gov #NCT01652976).

Histone deacetylase inhibition synergistically enhances pemetrexed cytotoxicity through induction of apoptosis and autophagy in non-small cell lung cancer.

BackgroundNon-small cell lung cancer (NSCLC) is the leading cause of cancer-related death worldwide. Pemetrexed, a multi-target folate antagonist, has demonstrated efficacy in NSCLC histological subtypes characterized by low thymidylate synthase (TS) expression. Among many other potential targets, histone deacetylase inhibitors (HDACi) modulate TS expression, potentially sensitizing to the cytotoxic action of anti-cancer drugs that target the folate pathway, such as pemetrexed. Since high levels of TS have been linked to clinical resistance to pemetrexed in NSCLC, herein we investigated the molecular and functional effects of combined pemetrexed and ITF2357, a pan-HDACi currently in clinical trials as an anti-cancer agent.ResultsIn NSCLC cell lines, HDAC inhibition by ITF2357 induced histone and tubulin acetylation and downregulated TS expression at the mRNA and protein level. In combination experiments in vitro ITF2357 and pemetrexed demonstrated sequence-dependent synergistic growth-inhibitory effects, with the sequence pemetrexed followed by ITF2357 inducing a strikingly synergistic reduction in cell viability and induction of both apoptosis and autophagy in all cell line models tested, encompassing both adenocarcinoma and squamous cell carcinoma. Conversely, simultaneous administration of both drugs achieved frankly antagonistic effects, while the sequence of ITF2357 followed by pemetrexed had additive to slightly synergistic growth-inhibitory effects only in certain cell lines. Similarly, highly synergistic growth inhibition was also observed in patient-derived lung cancer stem cells (LCSC) exposed to pemetrexed followed by ITF2357. In terms of molecular mechanisms of interaction, the synergistic growth-inhibitory effects observed were only partially related to TS modulation by ITF2357, as genetic silencing of TS expression potentiated growth inhibition by either pemetrexed or ITF2357 and, to a lesser extent, by their sequential combination. Genetic and pharmacological approaches provided an interesting link between the autophagic and apoptotic pathways, and showed that sequential pemetrexed/ITF2357 causes a toxic form of autophagy with consequent activation of a caspase-dependent apoptotic program. In vivo experiments in NSCLC xenografts confirmed that sequential pemetrexed/ITF2357 is feasible and results in increased inhibition of tumor growth and increased mice survival.ConclusionsOverall, these data provide a strong rationale for the clinical development of sequential schedules employing pemetrexed followed by HDACi in NSCLC.Electronic supplementary materialThe online version of this article (doi:10.1186/1476-4598-13-230) contains supplementary material, which is available to authorized users.

High Expression of Dihydropyrimidine Dehydrogenase in Lung Adenocarcinoma is Associated With Mutations in Epidermal Growth Factor Receptor: Implications for the Treatment of Non–Small-Cell Lung Cancer Using 5-Fluorouracil

BackgroundIt has been shown that 5-fluorouracil (5-FU) sensitivity in patients with non–small-cell lung cancer (NSCLC) is associated with epidermal growth factor receptor (EGFR) mutation status. However, the relationship between dihydropyrimidine dehydrogenase (DPD), a 5-FU degrading enzyme, and EGFR mutation status is unknown. Here, we focus on clinicopathologic factors and in vitro correlations between DPD expression and EGFR mutation status. Patients and MethodsEGFR mutations and messenger RNA (mRNA) levels of DPD and thymidylate synthase (TS) were analyzed in 47 resected NSCLC tumors by laser-capture microdissection. In addition, relationships between EGFR mutation status and the immunohistochemical expression of DPD and TS in 49 patients with primary NSCLC who were treated with a 5-FU derivative of S-1 postoperatively were examined. Correlations among clinicopathologic factors were evaluated. The effect of epidermal growth factor on DPD expression was also investigated in vitro in various cell lines. ResultsAdenocarcinoma in situ showed significantly higher DPD mRNA levels and more EGFR mutation frequency than other histological types (P < .05). DPD immunopositive cases were more frequently observed in adenocarcinoma, in females, and in nonsmokers. DPD immunopositive cases were correlated with EGFR mutation status (P < .003). The prognoses of wild-type EGFR and mutated EGFR populations were similarly favorable with postoperative S-1 treatment, which overcomes the problem of 5-FU degradation in mutated EGFR. In vitro, EGFR-mutated cell lines showed high DPD mRNA and protein expression. ConclusionHigh DPD expression was shown to be correlated with EGFR mutation in adenocarcinoma cells and tissues. Clinicians should take this finding into consideration when using 5-FU to treat patients with NSCLC.

18F-FDG uptake on PET is a predictive marker of thymidylate synthase expression in patients with thoracic neoplasms

The aim of this study was to investigate the relationship between the expression levels of thymidylate synthase (TS) and 2-[¹⁸F]-fluoro-2-deoxy-D-glucose (¹⁸F-FDG) uptake on positron emission tomography (PET) in various thoracic neoplasms. In total, 392 patients [non-small cell lung cancer (NSCLC) (n=140), malignant pleural mesothelioma (MPM) (n=21), pulmonary metastatic tumors (PMT) (n=148), thymic epithelial tumors (n=49) and pulmonary neuroendocrine (NE) tumor (n=34)] who underwent ¹⁸F-FDG PET before treatment were included in this study. Tumor sections were stained using immunohistochemistry for determination of TS, orotate phosphoribosyltransferase (OPRT), dihydropyrimidine dehydrogenase (DPD), vascular endothelial growth factor (VEGF), microvessel density (MVD), CD34 and p53. The expression of TS in thoracic neoplasms had a positivity of 58% (230/392), and the positive rates of TS expression in NSCLC, PMT, thymic epithelial tumor, NE tumor and MPM samples were 56, 57, 57, 85 and 47%, respectively. The positivity of TS expression was significantly higher in NE tumors compared to that in other thoracic tumors. A statistically significant correlation between TS expression and ¹⁸F-FDG uptake was observed in thoracic neoplasms, in particular primary lung adenocarcinomas, high-grade NE tumors, thymomas and MPMs. Moreover, TS expression was closely associated with angiogenesis, DPD, OPRT and p53. Our results indicated that SUV(max) by ¹⁸F-FDG uptake may be an alternative biomarker for predicting TS expression in patients with primary lung adenocarcinoma, high-grade NE tumor, thymoma and MPM.

Associations between TS, TTF-1, FR-α, FPGS, and Overall Survival in Patients with Advanced Non–Small-Cell Lung Cancer Receiving Pemetrexed Plus Carboplatin or Gemcitabine Plus Carboplatin as First-Line Chemotherapy

Pemetrexed is effective in the treatment of non-small-cell lung cancer, mainly in nonsquamous cell carcinomas. Inhibition of thymidylate synthase (TS) is considered the key mechanism of action. Folate receptor-α facilitates uptake of pemetrexed. Polyglutamation by folylpolyglutamate synthetase enhances activity and prolongs cellular retention of pemetrexed. Thyroid transcription factor-1 (TTF-1) is mainly positive in nonsquamous cell carcinoma and has been proposed as a marker for sensitivity to pemetrexed. The aim was to investigate associations between these biomarkers and survival in patients who participated in a phase III trial comparing pemetrexed plus carboplatin with gemcitabine plus carboplatin as first-line chemotherapy in advanced non-small-cell lung cancer (n = 436). In this study, there was no difference in overall survival between the two regimens. Formalin-fixed, paraffin-embedded biopsies were collected. Percentages of tumor cells positive and highly positive for the biomarkers were assessed using immunohistochemistry (IHC) and an IHC score was calculated (range, 0-200). Two hundred thirty-six biopsies were analyzed (pemetrexed plus carboplatin: n = 114, gemcitabine plus carboplatin: n = 122). There was a significant difference in overall survival between those with TTF-1-positive and -negative tumors (10.4 versus 6.0 months; p < 0.001) and those with a low and a high TS IHC score (9.7 versus 6.2 months; p < 0.001). Folate receptor-α and folylpolyglutamate synthetase were not significant prognostic factors. In multivariate analyses adjusting for established prognostic characteristics, TS (p = 0.002) and TTF-1 (p = 0.003) remained significant. There were no differences in survival between the treatment arms depending on biomarker scores. TTF-1 positivity and low TS level were associated with prolonged survival. The associations between the biomarkers and overall survival were similar for both chemotherapy regimens.

Expression of thymidylate synthase predicts clinical outcomes of pemetrexed-containing chemotherapy for non-small-cell lung cancer: a systemic review and meta-analysis

Observational and preclinical studies suggested an association between the expression of thymidylate synthase (TS) and clinical effects of pemetrexed-based chemotherapy in non-small-cell lung cancer (NSCLC) patients. However, the predictive value of TS for pemetrexed-containing chemotherapy regimen remained controversial. The aim of the study was to further appraise the association between the expression of TS and clinical efficacy pemetrexed-based chemotherapy in NSCLC patients. We searched in MEDLINE (PubMed), EMBASE, and Cochrane Library from January 1945 to May 2013. Two authors independently extracted information from the characteristics of study participants. Primary outcomes included therapeutic response (TR; i.e., complete response + partial response vs. stable disease + progressive disease), progression-free survival (PFS), and overall survival (OS). Relative risk (RR) and hazard ratio (HR) were used for evaluating the risk or hazard. Eight studies were included in the meta-analysis. Better response usually appeared in NSCLC patients with a lower expression of TS [RR = 2.06 95 % confidence intervals (CI) 1.44, 2.96]. There was a significant association between TS expression and outcomes of pemetrexed-based chemotherapy for NSCLC (PFS: HR = 0.63 95 % CI 0.52, 0.76; OS: HR = 0.74, 95 % CI: 0.63, 0.88). In addition, no evidence of publication bias was observed. This meta-analysis evaluated the predictive value of TS and provided evidence that NSCLC patients with lower TS expression could significantly benefit from pemetrexed-based chemotherapy. This increased level of TS was probably an independent risk factor of potential resistance against pemetrexed.

Clinical significance of the thymidylate synthase, dihydropyrimidine dehydrogenase, and thymidine phosphorylase mRNA expressions in hepatocellular carcinoma patients receiving 5-fluorouracil-based transarterial chemoembolization treatment

PurposeTo determine whether 5-fluorouracil (5-FU) sensitivity is associated with the mRNA expressions of thymidylate synthase (TS), dihydropyrimidine dehydrogenase (DPD), and thymidine phosphorylase (TP) in patients with hepatocellular carcinoma (HCC) treated with 5-FU-based transarterial chemoembolization (TACE).MethodsFormalin-fixed, paraffin-embedded tumor specimens from 40 patients treated with 5-FU-based TACE were selected for the examination of TS, DPD, and TP expression level by a quantitative real-time reverse transcription- polymerase chain reaction (PCR) technique. Patients were categorized into high and low expression groups according to the median expression level of each enzyme. Associations between the mRNA expression levels of TS, DPD, and TP and clinical parameters including treatment efficacies, clinicopathological factors, and prognosis were assessed.ResultsHigh DPD expression was associated with worse treatment outcome, including intrahepatic disease progression rate (hazard ratio [HR] for high DPD versus low DPD, 2.212; 95% confidence interval [CI], 1.030–4.753; P = 0.042), extrahepatic disease progression rate (HR for high versus low DPD, 3.171; 95% CI, 1.003–10.023; P = 0.049), and progression-free survival (HR for high versus low DPD, 2.308; 95% CI, 1.102–4.836; P = 0.027). No correlation was found between the mRNA expression of TS/TP and treatment outcome.ConclusionDPD mRNA expression level was negatively correlated with the clinical outcomes of HCC patients treated with 5-FU-based TACE. These results provide indirect evidence that high DPD mRNA expression is a predictive marker of treatment resistance for 5-FU.

Therapeutic enhancement of S‐1 with CPT‐11 through down‐regulation of thymidylate synthase in bladder cancer

Thymidylate synthase (TS), a target enzyme of 5-fluorouracil (5-FU), is significantly associated with prognosis in various cancers. Recently, it has been reported that S-1, a novel 5-FU-based agent has an effect on bladder cancer. However, in cells with high TS level, S-1 did not have significant effects. Therefore, we examined whether down-regulation of TS enhanced effects of S-1 in them. First, we measured TS level in an aggressive bladder cancer cell line, KU-19-19 by enzyme-linked immunosorbent assay (ELISA) and evaluated its sensitivity to 5-FU using a small interfering RNA (siRNA) for TS. Next, we measured TS mRNA after exposure to various agents. Finally, we evaluated enhancement of cytotoxicity of S-1 by CPT-11 (7-ethyl-10-[4-(1-piperidino)-1-piperidino]carbonyloxycamptothecin) which down-regulated TS in in vivo study. The median TS and dihydropyrimidine dehydrogenase (DPD) level was 53.3 ng/mg and 80.3 ng/mg in KU-19-19 cells, respectively. The 5-FU treatment in KU-19-19 cells transfected with siRNA for TS gene (TYMS) inhibited cell growth more significantly than that for nontargeting control. Down-regulation of TS was observed after exposure to SN-38 (7-ethyl-10-hydroxycamptothecin) in a dose-dependent manner. The combination treatment of 5-FU and SN-38 significantly inhibited cell growth, as compared to the single treatment. Meanwhile, in cells transfected with siRNA for TYMS, neither an additive nor a synergistic effect was observed. Also, combined S-1 and CPT-11 dramatically inhibited tumor growth, compared to S-1 or CPT-11 alone in in vivo study. In conclusion, CPT-11 down-regulated TS level and enhanced the effect of S-1. Thus, the combination therapy with S-1 and CPT-11 might be a novel modality for bladder cancer, even with high TS level.This study confirmed that thymidylate synthase (TS) level in an aggressive human bladder cancer cell line, KU-19-19, was relatively higher than that in other cancer and presented that irinotecan (CPT-11) could down-regulate TS. Finally, the combination therapy with S-1 and CPT-11 resulted in significant tumor growth inhibition through down-regulation of TS in KU-19-19. Thus, combined S-1 and CPT-11 might be a novel treatment in bladder cancer, even with high TS.

Synergistic Anticancer Effects of Polyphyllin I and Evodiamine on Freshly-Removed Human Gastric Tumors

ObjectiveThe present study was designed to examine the anticancer effect of Traditional Chinese Medicine of polyphyllin I (PPI) and evodiamine (EVO) on freshly–removed gastric tumor tissues.MethodsSixty freshly–removed gastric tumor tissues were collected. Their sensitivity to PPI, EVO, platinum (Pt), 5-FU, irinotecan (CPT-11) were determined by histoculture drug response assay (HDRA). Those samples were also formalin-fixed and paraffin-embedded, which were used to examine the mRNA expression levels of aprataxin(APTX), excision repair cross-complementing 1(ERCC1), thymidylate synthase(TS) and topoisomerase I(TOPO1) by quantitative RT-PCR. The association of the gene expression levels and in vitro sensitivity were analyzed.ResultsPPI, EVO, Pt, 5-FU and CPT-11 had anticancer effects on the freshly-removed gastric tumor tissues with average inhibition rates of 20.64%±14.25% for PPI, 21.14%±13.43% for EVO, 50.57%±22.37% for Pt, 53.54%±22.03% for 5-FU, and 39.33%±24.79% for CPT-11, respectively. Combination of PPI and Pt, EVO and Pt, EVO and 5-FU had higher inhibition rates than any single drug of them (P<0.001, P = 0.028, P = 0.017, respectively). The mRNA expression levels of ERCC1 were correlated with Pt sensitivity (rho = −0.645, P<0.001); the mRNA expression levels of TS were correlated with 5-FU sensitivity (rho = −0.803, P<0.001). There were also weak but significant correlations between APTX mRNA expression levels and CPT-11 sensitivity (rho = −0.376, P = 0.017) or EVO sensitivity (rho = −0.322, P = 0.036). ERCC1 mRNA expression levels was markedly suppressed by the presentation of PPI (P = 0.001) and slightly suppressed by the presentation of EVO (P = 0.04); whereas, TS mRNA expression levels was markedly decreased by the presentation of EVO (P = 0.017) and slightly decreased by the presentation of PPI (P = 0.047).ConclusionPPI and EVO both could inhibit the activity of freshly-removed gastric tumor, and they could enhance the anticancer effect of Pt and 5-FU by reducing the mRNA expression levels of ERCC1 and TS.

Thymidylate synthase expression as predictive biomarker of pemetrexed sensitivity in advanced cancer patients.

11089 Background: Although a high level of thymidylate synthase (TS) expression in malignant tumours has been suggested to be related to a reduced sensitivity to the antifolate drug pemetrexed, no direct evidence for such an association has been demonstrated in routine clinical samples from patients treated with this drug. The purpose of this study was to evaluate the impact of quantitative TS expression in tumor cells as predictor of the efficacy in patients with advanced non-small cell lung cancer, small cell lung cancer (SCLC) and mesothelioma treated with pemetrexed in our institution. Methods: 54 patients were included in this study: 40 stage IV NSCLC (26 adenocarcinomas, 11 large cell, and 3 squamous cell carcinoma), 3 SCLC and 11 mesothelioma. 21 patients received platins-pemetrexed as first line NSCLC, 20 pemetrexed in monotherapy as second and further lines and 3 carboplatin-pemetrexed fo extensive disease SCLC. Total RNA was isolated by RNeasy FFPE procedure (Qiagen). The expression of TS was analyzed by RT-qPCR using appropriate mRNA specific primers and probes in LightCycler 480II platform at 45 cycles. TS levels was calibrated to expression in normal tissue. Results: From 54 cases, TS expression data were available in 32 cases, detecting overexpression in 23 (71.8%) and low expression in 9 (28.2%) patients. The response rate for patients with low TS expression was 0.63 compared with 0.15 in patients with overexpression (p=0.015). A significant benefit in time to progression was observed in patients with low expression (median TTP 12 vs. 2 months respectively, p= 0.002), whereas did not impact on overall survival (median OS 20 vs. 19 months respectively, p= 0.595). Conclusions: TS overexpression in tumor cells correlated with a reduced response to pemetrexed-containing chemotherapy and might be used as a predictive biomarker in advanced lung and mesothelioma cancer patients.

Uncommon and parallel developmental patterns of thymidylate synthase expression and localization in Trichinella spiralis and Caenorhabditis elegans

Abstract Trichinella spiralis is a parasitic nematode causing trichinellosis, a serious disease, and Caenorhabditis elegans is a free-living nematode, which is used as a model in parasitological studies. High levels of thymidylate synthase (EC 2.1.1.45; ThyA) and certain other enzymes involved in thymidylate biosynthesis were found throughout T. spiralis and C. elegans developmental cycles, including developmentally arrested forms, that is, T. spiralis muscle larva and C. elegans dauer larva. As ThyA activity is characteristic for cells that left the G0 phase of the cell cycle, an exceptional regulation of the cell cycle in nematodes is suggested, manifested by a global cell cycle arrest in developmentally arrested larvae of the two species. ThyA immunolocalization during development of T. spiralis and C. elegans revealed the presence of high enzyme levels not only in the developing embryos, where it was expected, but also in gonad primordia, egg and sperm cells, nerve ring and secretory cells, opening to T. spiralis esophagus and C. elegans pharynx, where it may point to those cell populations remaining cell cycle arrested.

NK4 regulates 5-fluorouracil sensitivity in cholangiocarcinoma cells by modulating the intrinsic apoptosis pathway

The aim of the present study was to investigate the role of NK4, an antagonist for hepatocyte growth factor (HGF) and the Met receptor, in regulating the response of cholangiocarcinoma (CCA) cells to 5-fluorouracil (5-FU). We established the CCA cell line, HuCC-T1, to produce abundant NK4 (Hu-NK4). Cell proliferation, cell cycle distribution, apoptosis, 5-FU metabolism and intracellular signaling were examined. There were no significant differences in the mRNA levels of thymidylate synthase, thymidine phosphorylase and dihydropyrimidine dehydrogenase between the mock-transfected control Hu-Em cells and Hu-NK4 cells, suggesting that NK4 expression does not alter 5-FU metabolism. Moreover, cell cycle analysis showed that 5-FU treatment caused a decrease in the proportion of cells in the G2/M phase while NK4 gene expression had little effect on the cell cycle distribution. However, 5-FU-induced apoptosis was significantly increased in the Hu-NK4 cells when compared to that in the Hu-Em cells. Further investigation revealed that NK4 gene expression enhanced 5-FU-induced caspase-3 and caspase-9 activation, and that the apoptosis of cells was associated with modulation of expression of the Bcl-2 family members. Furthermore, western blot analysis revealed that both NK4 and 5-FU were inhibitors for HGF-induced phosphorylation of Met, but they may be independent factors. Collectively, these results suggest that following 5-FU treatment in CCA cell lines, NK4 was involved in apoptosis induction through the intrinsic mitochondrial pathway. This indicates that NK4 may be an important mediator of 5-FU-induced cell death. Moreover, downregulation of NK4 in response to 5-FU may represent an intrinsic mechanism of resistance to this anticancer drug.

Novel MEK inhibitor trametinib and other retinoblastoma gene (RB)‐reactivating agents enhance efficacy of 5‐fluorouracil on human colon cancer cells

Chemotherapy for colorectal cancer has become more complicated and diversified with the appearance of molecular-targeting agents. 5-Fluorouracil (5-FU) has been a mainstay of chemotherapy for colorectal cancer, but it is still unknown whether the combining of 5-FU with novel molecular-targeting agents is effective. Thymidylate synthase (TS) is a direct target of 5-FU, and the low TS level has been generally supposed to sensitize 5-FU's efficacy. We therefore hypothesized that RB-reactivating agents could enhance the efficacy of 5-FU, because the RB-reactivating agents could suppress the function of transcription factor E2F of TS gene promoter. We used three RB-reactivating agents, trametinib/GSK1120212 (MEK inhibitor), fenofibrate (PPARα agonist), and LY294002 (PI3K inhibitor), with 5-FU against human colon cancer HT-29 and HCT15 cells. Trametinib induced p15 and p27 expression and reduced cyclin D1 levels in HT-29 cells. Fenofibrate also dephosphorlated ERK1/2 and reduced cyclin D1 levels in HT-29 cells. LY294002 induced p27 expression in HCT15 cells. All three agents caused dephosphorylation of RB protein and G1-phase arrest with a reduction of TS expression. As a consequence, the combination of 5-FU with each of the agents resulted in a significant decrease of colony numbers in HT-29 or HCT15 cells. These results suggest "RB-reactivation therapy" using molecular-targeting agents to be a new strategy for 5-FU-based chemotherapy. In particular, we strongly expect trametinib, which was discovered in Japan and was recently submitted to FDA for approval, to be used together with established regimens for colorectal cancer.

Thymidylate Synthase and Folyl-Polyglutamate Synthase Are Not Clinically Useful Markers of Response to Pemetrexed in Patients with Malignant Pleural Mesothelioma

Thymidylate synthase (TS) is a potential predictor of outcome after pemetrexed (Pem) in patients with malignant pleural mesothelioma (MPM), and assays measuring TS levels are commercially marketed. The goal of this study was to further evaluate the value of TS and to study another potential biomarker of response, the enzyme, folyl-polyglutamate synthase (FPGS), which activates Pem intracellularly. Levels of TS and FPGS were semi-quantitatively determined immunohistochemically using H-scores on tissue samples from 85 MPM patients receiving Pem as primary therapy. H-score was correlated with radiographic disease control rate (DCR), time to progression (TTP) and overall survival (OS). In addition, expression levels of TS and FPGS in MPM cell lines were determined using immunoblotting and correlated with their sensitivity to Pem-induced cell death. H-scores from patients with disease control versus progressive disease showed extensive overlap. There were no significant correlations of DCR, TTP, or OS to either TS levels (p = 0.73, 0.93, and 0.59, respectively), FPGS levels (p = 0.95, 0.77, and 0.43, respectively) or the ratio of FPGS/TS using the median scores of each test as cutoffs. There was no correlation between TS or FPGS expression and chemosensitivity of mesothelioma cells to Pem in vitro. Although previous retrospective data suggest that TS and FPGS expression might be potential markers of Pem efficacy in MPM, our data indicate these markers lack sufficient predictive value in individual patients and should not be used to guide therapeutic decisions in the absence of prospective studies.