An improved method for the expression and purification of porcine dihydropyrimidine dehydrogenase.

Dihydropyrimidine dehydrogenase (DPD) catalyzes the reduction of uracil and thymine bases with electrons derived from NADPH. The mammalian DPD enzyme is a functional homodimer and has an elaborate cofactor arrangement. Two flavin cofactors (FAD and FMN) reside in two active site cavities that are separated by around 60 Å. The flavins are apparently bridged by four Fe4S4 clusters, two of which are provided by the partner protomer of the dimer. The study of DPD has been hampered by modest yield from both native sources and from heterologous expression in E. coli. In addition, minimal active enzyme is obtained when the DPD gene is fused to an N-terminal 6His-tag. This limitation has dictated the use of traditional purification methods that are made more challenging by apparent over-expression of truncated and/or non-active forms of DPD. Here we detail methods of expression and purification that result in a ~4-fold improvement in the yield of active porcine DPD when expressed in E. coli BL21 DE3 cells via the pET plasmid expression system. The addition of ferrous ions and sulfate during induction provide a small increase in purified active enzyme. However, the addition of FAD and FMN during cell lysis results in a substantial increase in activity that also reduces the relative proportion of non-active, high molecular weight protein contaminants. We also describe methods that permit correlation of the flavin content with the amount of active enzyme and thus permit simple, rapid quantitation and evaluation of purified DPD sample.

Pharmacokinetic and Pharmacodynamic Analyses of 5-Fluorouracil in East-Asian Patients with Nasopharyngeal Carcinoma.

BACKGROUND AND OBJECTIVE: 5-Fluorouracil plus cisplatin is the most commonly used chemotherapy regimen for nasopharyngeal carcinoma (NPC). The objective of this study was to establish an individualized 5-fluorouracil treatment model based on pharmacokinetic and pharmacodynamic analyses of 5-fluorouracil in East-Asian NPC patients. METHODS: A total of 122 NPC patients were administered 5-fluorouracil plus cisplatin treatment. Blood samples were collected to calculate the area under the concentration-time curve (AUC) for 5-fluorouracil, and expressions of thymidylate synthase (TS) and dihydropyrimidine dehydrogenase (DPD) at both protein and messenger RNA (mRNA) levels were analyzed in the tumor tissues from 73 patients in the same cohort. RESULTS: The results showed a wide (sevenfold) pharmacokinetic variability of 5-fluorouracil exposure (measured as AUC) based on body surface area (BSA) dosing. Pharmacokinetic analyses revealed that the 5-fluorouracil AUC range had a significant impact on the response of patients to 5-fluorouracil and related toxicities. Patients with 5-fluorouracil AUC <25 mg·h/L responded unsatisfactorily to 5-fluorouracil (overall response rate [ORR] 17.5 % lower than patients with AUC 25-35, p = 0.176; and 26.1 % lower than patients with AUC >35, p = 0.031). On the other hand, patients with 5-fluorouracil AUC >35 mg·h/L experienced more 5-fluorouracil-related toxicities (a grade 3 or higher toxicity rate 57.1 % higher than patients with AUC 25-35, p < 0.001; and 60.0 % higher than AUC >35, p < 0.001). The established 5-fluorouracil therapeutic window in head and neck cancer (HNC) [AUC 25-35 mg·h/L) was verified in our study. Pharmacodynamic analyses indicated a positive correlation between TS and DPD expression (p < 0.001) and, despite the pharmacokinetic influences, low expression of TS mRNA in tumor tended to have a better ORR (81.0 vs. 54.3 %, p = 0.051). No significant association was found between DPD expression and ORR. CONCLUSIONS: The therapeutic window of 5-fluorouracil for East-Asian NPC patients was verified as 25-35 mg·h/L based on lower toxicity and higher efficacy. TS mRNA expression showed potentially predictive value in 5-fluorouracil treatment, and personalized treatment based on pharmacokinetics and pharmacodynamics proved to be clinically beneficial and is worthy of further clinical studies.

Rap1 GTPase is required for mouse lens epithelial maintenance and morphogenesis.

Rap1, a Ras-like small GTPase, plays a crucial role in cell-matrix adhesive interactions, cell-cell junction formation, cell polarity and migration. The role of Rap1 in vertebrate organ development and tissue architecture, however, remains elusive. We addressed this question in a mouse lens model system using a conditional gene targeting approach. While individual germline deficiency of either Rap1a or Rap1b did not cause overt defects in mouse lens, conditional double deficiency (Rap1 cKO) prior to lens placode formation led to an ocular phenotype including microphthalmia and lens opacification in embryonic mice. The embryonic Rap1 cKO mouse lens exhibited striking defects including loss of E-cadherin- and ZO-1-based cell-cell junctions, disruption of paxillin and ß1-integrin-based cell adhesive interactions along with abnormalities in cell shape and apical-basal polarity of epithelium. These epithelial changes were accompanied by increased levels of α-smooth muscle actin, vimentin and N-cadherin, and expression of transcriptional suppressors of E-cadherin (Snai1, Slug and Zeb2), and a mesenchymal metabolic protein (Dihydropyrimidine dehydrogenase). Additionally, while lens differentiation was not overtly affected, increased apoptosis and dysregulated cell cycle progression were noted in epithelium and fibers in Rap1 cKO mice. Collectively these observations uncover a requirement for Rap1 in maintenance of lens epithelial phenotype and morphogenesis.

Comparative functional analysis of DPYD variants of potential clinical relevance to dihydropyrimidine dehydrogenase activity.

Dihydropyrimidine dehydrogenase (DPD) is the initial and rate-limiting enzyme of the uracil catabolic pathway, being critically important for inactivation of the commonly prescribed anti-cancer drug 5-fluorouracil (5-FU). DPD impairment leads to increased exposure to 5-FU and, in turn, increased anabolism of 5-FU to cytotoxic nucleotides, resulting in more severe clinical adverse effects. Numerous variants within the gene coding for DPD, DPYD, have been described, although only a few have been demonstrated to reduce DPD enzyme activity. To identify DPYD variants that alter enzyme function, we expressed 80 protein-coding variants in an isogenic mammalian system and measured their capacities to convert 5-FU to dihydro-fluorouracil, the product of DPD catabolism. The M166V, E828K, K861R, and P1023T variants exhibited significantly higher enzyme activity than wild-type DPD (120%, P = 0.025; 116%, P = 0.049; 130%, P = 0.0077; 138%, P = 0.048, respectively). Consistent with clinical association studies of 5-FU toxicity, the D949V substitution reduced enzyme activity by 41% (P = 0.0031). Enzyme activity was also significantly reduced for 30 additional variants, 19 of which had <25% activity. None of those 30 variants have been previously reported to associate with 5-FU toxicity in clinical association studies, which have been conducted primarily in populations of European ancestry. Using publicly available genotype databases, we confirmed the rarity of these variants in European populations but showed that they are detected at appreciable frequencies in other populations. These data strongly suggest that testing for the reported deficient DPYD variations could dramatically improve predictive genetic tests for 5-FU sensitivity, especially in individuals of non-European descent.

A COX-2 inhibitor enhances the antitumor effects of chemotherapy and radiotherapy for esophageal squamous cell carcinoma.

Cyclooxygenase-2 (COX-2) is a key enzyme of prostaglandin (PG) synthesis that has been demonstrated to be overexpressed in several types of cancers. The function of COX-2 in tumor progression has been recently elucidated. In tumors in which COX-2 is overexpressed, the antitumor effects are suppressed. We examined the effects of celecoxib, a COX-2 inhibitor, in enhancing the antitumor effects of chemotherapy and radiotherapy for esophageal squamous cell carcinoma (ESCC) by reducing the COX-2 activity. We used the human esophageal squamous cell lines TE2 and T.Tn treated with celecoxib and 5-FU/radiation, after which cell viability assays were performed. Changes in the expressions of dihydropyrimidine dehydrogenase (DPD), orotate phosphoribosyl transferase (OPRT) mRNA and PGE2 were also measured. In addition, apoptotic changes, and the invasion and migration activity in both the celecoxib and 5-FU treated cells were evaluated. The experiments showed that T.Tn and TE2 proliferation was strongly inhibited by the combination of 5-FU/radiation and the COX-2 inhibitor. Inhibiting the COX-2 activity induced a reduction in PGE2 levels in TE2/T.Tn cells. Following treatment with the COX-2 inhibitor and 5-FU, the OPRT expression was upregulated and the DPD expression was downregulated in the resistant cells. In addition, the combination treatment with the COX-2 inhibitor and 5-FU markedly inhibited both the cell invasion and migration activity. Therefore, COX-2 inhibitors can be useful enhancers of antitumor drugs and radiotherapy for ESCC.

microRNAs miR-27a and miR-27b directly regulate liver dihydropyrimidine dehydrogenase expression through two conserved binding sites.

Dihydropyrimidine dehydrogenase (DPD, encoded by DPYD) is the rate-limiting enzyme in the uracil catabolic pathway and has a pivotal role in the pharmacokinetics of the commonly prescribed anticancer drug 5-fluorouracil (5-FU). Deficiency of DPD, whether due to inadequate expression or deleterious variants in DPYD, has been linked to severe toxic responses to 5-FU. Little is known about the mechanisms governing DPD expression in the liver. In this report, we show increased accumulation of RNA-induced silencing complex (RISC) proteins on DPYD mRNA in cells overexpressing the highly homologous microRNAs (miRNA) miR-27a and miR-27b. These miRNAs were shown to repress DPD expression through two conserved recognition sites in DPYD. The IC50 of 5-FU for HCT116 cells overexpressing miR-27a or miR-27b was 4.4 µmol/L (both), significantly lower than that for cells expressing a nontargeting (scramble) control miRNA (14.3 µmol/L; P = 3.3 × 10(-5) and P = 1.5 × 10(-7), respectively). Mouse liver DPD enzyme activity was inversely correlated with expression levels of miR-27a (R(2) = 0.49; P = 0.0012) and miR-27b (R(2) = 0.29; P = 0.022). A common variant in the hairpin loop region of hsa-mir-27a (rs895819) was also shown to be associated with elevated expression of the miR-27a in a panel of cell lines (P = 0.029) and in a transgenic overexpression model (P = 0.0011). Furthermore, rs895819 was associated with reduced DPD enzyme activity (P = 0.028) in a cohort of 40 healthy volunteers. Taken together, these results suggest that miR-27a and miR-27b expression may be pharmacologically relevant modulators of DPD enzyme function in the liver. Furthermore, our data suggest that rs895819 may be a potential risk allele for 5-FU sensitivity.

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.

Protein-bound polysaccharide-K augments the anticancer effect of fluoropyrimidine derivatives possibly by lowering dihydropyrimidine dehydrogenase expression in gastrointestinal cancers.

Protein-bound polysaccharide-K (PSK) enhances the antitumor effect of anticancer drug when used clinically in combination with such drugs. PSK is known to act by immune-mediated mechanisms; however, the relationship between PSK and metabolic enzymes of anticancer drugs is unknown. We used the collagen gel droplet-embedded culture drug sensitivity test (CD-DST) clinically to evaluate the sensitivity of anticancer drugs. In the present study, we modified the CD-DST by adding peripheral blood mononuclear cells (PBMCs) (immuno-CD-DST) and examined the antitumor effect of PSK in combination with anticancer drugs. First, HCT116 human colon cancer cells were cultured with PSK and 5-fluorouracil (5-FU) or 5'-deoxy-5-fluorouridine (5'-DFUR) in the presence or absence of PBMCs, and the antiproliferative effects were compared. In the presence of PBMCs, PSK augmented the inhibitory effects of 5-FU and 5'-DFUR on HCT116 cell proliferation. Next, using human gastric cancer and colon cancer cell lines, the effects of PSK on mRNA expression of various metabolic enzymes of fluoropyrimidines: dihydropyrimidine dehydrogenase (DPD), thymidylate synthase, thymidine phosphorylase and orotate phosphoribosyl transferase, were examined by real-time PCR. PSK significantly enhanced DPD mRNA expression in all of the cancer cell lines tested, but not those of the other enzymes. Addition of IFN-α and TRAIL, cytokines known to inhibit DPD expression, to the cultures reduced DPD mRNA expression in the cancer cells. When PBMC samples collected from healthy volunteers were cultured with PSK, IFN-α mRNA expression increased in 3 of the 5 PBMC samples, while TRAIL mRNA expression was unchanged. The present results propose the possibility that PSK induces PBMCs to express IFN-α which inhibits DPD expression, and consequently augments the antitumor effect of 5-FU or 5'-DFUR. Immuno-CD-DST is useful for evaluating drugs with immunological mechanisms of action.

Substitution of anti-androgens and tegafur-uracil combination therapy for castration-resistant prostate cancer: results of a multi-center randomized phase II study.

We conducted this study to determine whether substitution with anti-androgen (SOA) and tegafur-uracil (a pro­drug of 5-FU) combination therapy is more effective than SOA alone after relapse from initial hormonal therapy. Patients who were histologically confirmed and relapsed after initial hormonal therapy were included. All patients were randomly allocated into two groups: SOA alone (group A) or SOA combined with tegafur-uracil (group B). The mRNA expression of four enzymes, including thymidylate synthase (TS), dihydropyrimidine dehydrogenase (DPD), orotate phospho-ribosyltransferase (OPRT) and thymidine phosphorylase (TP), in prostate cancer cells was analyzed by quantitative reverse-transcription polymerase chain reaction. Fifty-two patients were enrolled in this study. The median age was 77 (range: 47-92) years. The PSA response rate in group B (61.5%) tended to be higher compared to that in group A (34.6%) (p=0.095). Group B (median: 15.9 months) had a significantly longer time to PSA progression (TTP) compared to group A (6.4 months) (p=0.014). In patients with a lower TS expression or a higher OPRT expression, group B demonstrated a higher PSA response rate compared to group A (p=0.019 and p=0.041, respectively). In addition, in the patients with a lower TS expression, group B demonstrated a significantly longer TTP compared to group A (p=0.018). There were no severe adverse events in either treatment group. After relapse from initial hormonal therapy, SOA combined with tegafur-uracil is effective and well tolerated. The TS mRNA expression level may be a predictive factor for this combination therapy.

DPYD, TYMS, TYMP, TK1, and TK2 genetic expressions as response markers in locally advanced rectal cancer patients treated with fluoropyrimidine-based chemoradiotherapy.

This study is to investigate multiple chemotherapeutic agent- and radiation-related genetic biomarkers in locally advanced rectal cancer (LARC) patients following fluoropyrimidine-based concurrent chemoradiotherapy (CCRT) for response prediction. We initially selected 6 fluoropyrimidine metabolism-related genes (DPYD, ORPT, TYMS, TYMP, TK1, and TK2) and 3 radiotherapy response-related genes (GLUT1, HIF-1α, and HIF-2α) as targets for gene expression identification in 60 LARC cancer specimens. Subsequently, a high-sensitivity weighted enzymatic chip array was designed and constructed to predict responses following CCRT. After CCRT, 39 of 60 (65%) LARC patients were classified as responders (pathological tumor regression grade 2 ~ 4). Using a panel of multiple genetic biomarkers (chip), including DPYD, TYMS, TYMP, TK1, and TK2, at a cutoff value for 3 positive genes, a sensitivity of 89.7% and a specificity of 81% were obtained (AUC: 0.915; 95% CI: 0.840-0.991). Negative chip results were significantly correlated to poor CCRT responses (TRG 0-1) (P = 0.014, hazard ratio: 22.704, 95% CI: 3.055-235.448 in multivariate analysis). Disease-free survival analysis showed significantly better survival rate in patients with positive chip results (P = 0.0001). We suggest that a chip including DPYD, TYMS, TYMP, TK1, and TK2 genes is a potential tool to predict response in LARC following fluoropyrimidine-based CCRT.

Prognostic significance of 5-fluorouracil metabolism-relating enzymes and enhanced chemosensitivity to 5-fluorouracil by 5-chloro 2,4-dihydroxy-pyridine in urothelial carcinoma.

BACKGROUND: Recently, S-1, a novel 5-fluorouracil (5-FU)-based agent containing the strong dihydropyrimidine dehydrogenase (DPD) inhibitor, 5-chloro-2,4-dihydropyrimidine (CDHP) has been clinically used to treat various non-urothelial carcinomas (UC). High levels of thymidylate synthase (TS), the target enzyme of 5-FU and DPD which degrades the majority of 5-FU, are associated with poor prognosis in some cancers. However, only a few reports have dealt with this in UC. The aim of this study was to investigate the clinical significance of TS and DPD in upper tract urothelial carcinoma (UTUC) and evaluate the role of TS and DPD on the sensitivity of 5-FU in UC cell lines and the anti-tumor effect of S-1 in UC xenograft model. METHODS: Firstly, we evaluated the immunohistochemical expression of TS and DPD in 176 patients with UTUC to determine their prognostic significance. Secondly, the levels of TS and DPD in UC cell lines were measured by ELISA and real-time PCR. Furthermore, the association between their levels and the sensitivity to 5-FU was examined using the small interfering RNA (siRNA) specific for TS and DPD. Thirdly, the anti-tumor effect of S-1 was evaluated in UC xenograft model. RESULTS: Immunohistochemical evaluation of TS and DPD in UTUC human samples revealed that TS expression was significantly associated with stage, grade, and lymphovascular invasion and DPD expression was significantly associated with grade. Multivariate analysis revealed that high TS expression was an independent predictor of disease-specific survival in them. In in vitro study using UC cell lines, high levels of TS and DPD were associated with low response to 5-FU and these associations were confirmed with siRNA specific for TS and DPD. In in vivo study using UC xenograft model, S-1 treatment dramatically inhibited tumor growth compared to controls, tegafur, or UFT in UC tumor with a high level of DPD. CONCLUSIONS: TS plays an important role in the prognosis of UTUC and S-1 may be a key agent for UC tumor, especially with a high level of DPD.

Antitumor efficacy of sequential treatment with docetaxel and 5-fluorouracil against human oral cancer cells.

Docetaxel (DOC) and 5-fluorouracil (5-FU) are important anticancer agents widely used in the treatment of a variety of cancers including oral squamous cell carcinoma (OSCC). The purpose of this study was to determine the antitumor efficacy of the sequential administration of DOC and 5-FU against OSCC cells (B88 and CAL27 cells) in vitro and in vivo. In in vitro growth inhibition assays, sequential treatment with DOC followed by 5-FU was more effective in inhibiting cancer cell growth than 5-FU followed by DOC, single treatment with DOC or 5-FU, or combined treatment with DOC and 5-FU. Furthermore, DOC followed by 5-FU significantly inhibited tumor growth in vivo compared to 5-FU followed by DOC. To understand the mechanisms underlying the enhanced growth inhibitory effect of the administration sequence, DOC followed by 5-FU, we examined the expression of 5-FU metabolic enzymes such as thymidylate synthase (TS), dihydropyrimidine dehydrogenase (DPD) and orotate phosphoribosyl transferase (OPRT), which were known to regulate the antitumor effect of 5-FU, by real-time RT-PCR and western blot analysis. Downregulation of TS and DPD expression and upregulation of OPRT expression were induced by DOC treatment, suggesting that DOC enhanced the efficacy of 5-FU by altering the expression of its metabolic enzymes. These results indicate that sequential treatment with DOC followed by 5-FU could be a promising therapeutic strategy for oral cancer.

Expression of dihydropyrimidine dehydrogenase, orotate phosphoribosyl transferase and thymidylate synthase in patients with primary colorectal cancer, and associations with site of first metastasis.

AIM: The activity of the widely used anticancer drug 5-fluorouracil (5-FU) is determined by the presence of several enzymes, including dihydropyrimidine dehydrogenase (DPD), orotate phosphoribosyl transferase (OPRT), and thymidylate synthase (TS). This study compared the expression levels of these enzymes between primary colorectal cancer with and without distant metastases, and examined whether these expression patterns are associated with hematogenous metastasis. MATERIALS AND METHODS: Among 40 patients with colorectal cancer, 20 had no metastasis and 20 had distant metastasis. Strong expression on immunohistochemistry was classified as positive, while weak, moderate or no expression was classified as negative. RESULTS: Positive expressions of DPD, OPRT and TS in primary colorectal cancer tissue were seen in 47.5%, 75% and 20%, respectively. However, no relationships were observed among the expressions of DPD, OPRT and TS. Expressions of OPRT (p=0.029) and TS (p=0.017) in primary tissues were significantly associated with hematogenous metastasis. Patterns of the expression of the three enzymes varied, and were classified in six ways. A tendency was seen for primary colorectal cancer with DPD-high expression to have liver metastasis and for that with DPD-low expression, to have lung metastasis. CONCLUSION: High expression levels of OPRT and TS in colorectal cancer appear to be significantly involved in metastasis after curative surgery. The organs in which metastases arise may be controlled by the expression of DPD.

Thymidylate synthase expression is closely associated with outcome in patients with pulmonary adenocarcinoma.

The aim of this study is to elucidate the prognostic significance of thymidylate synthase (TS), orotate phosphoribosyltransferase (OPRT) and dihydropyrimidine dehydrogenase (DPD) in completely resected non-small cell lung cancer (NSCLC). One hundred and sixty patients with NSCLC were included in this study. Tumor sections were stained by immunohistochemistry for TS, OPRT, DPD, glucose transporter 1 (Glut1), hypoxia inducible factor-1α (HIF-1α), vascular endothelial growth factor (VEGF), microvessel density (MVD) determinated by CD34, epidermal growth factor receptor (EGFR), phosph-Akt, phosph-mammalian target of rapamycin (mTOR) and p53. TS, OPRT and DPD were positively expressed in 46, 71 and 54%, respectively. The expression of TS and OPRT was significantly higher in patients with non-adenocarcinoma (non-AC) (n = 53) than adenocarcinoma (AC) (n = 107), and DPD expression was higher in adenocarcinoma as compared with non-adenocarcinoma. A positive TS expression was an independent prognostic factor for predicting a poor outcome in patients with AC, but not in those with non-AC. In AC patients, TS expression was significantly associated with advanced stage, lymph node metastases, vascular invasion, Glut1, HIF-1α, angiogenesis, EGFR signaling pathway and p53. In patients with non-AC, TS expression was not closely correlated with outcome and these biomarkers. A positive TS expression was a powerful prognostic factor to predict a poor outcome in completely resected AC patients.

Role of thymidylate synthase and dihydropyrimidine dehydrogenase mRNA in intrahepatic cholangiocarcinoma.

PURPOSE: Thymidylate synthase (TS) and dihydropyrimidine dehydrogenase (DPD) are important enzymes in the metabolism of 5-fluorouracil and possible predictive markers. We conducted this study to clarify if TS and DPD gene expressions are a prognostic indicator for intrahepatic cholangiocarcinoma (IHCC). METHODS: The subjects of this study were 21 patients with IHCC who had undergone surgical resection. Intratumoral TS and DPD mRNA expressions were examined using the Danenberg tumor profile method and classified into two groups according to the median value of each. We then compared the clinicopathological variables, including prognosis, between the high and low expression groups. RESULTS: Low DPD expression was correlated with macroscopic type, namely, mass-forming + infiltrative (P = 0.08). Postoperative survival rates in the low DPD expression group were significantly lower than those in the high DPD expression group. Multivariate analysis revealed macroscopic type to be an independent prognostic factor, whereas TS mRNA expression did not correlate with any clinicopathological variables, including prognosis. CONCLUSIONS: Low DPD mRNA expression was related to macroscopic type and associated with poor prognosis. DPD mRNA expression in tumor cells is suggested to be an important regulator of malignant behavior in IHCC.

Low dihydropyrimidine dehydrogenase correlates with prolonged survival in patients with lung adenocarcinoma treated with 5-fluorouracil.

BACKGROUND: The enzyme dihydropyrimidine dehydrogenase (DPD) is involved in the metabolism of 5-fluorouracil (5-FU). The aim of this study was to clarify the correlation between the expression of DPD and the efficacy of 5-FU therapy in patients with lung adenocarcinoma (AD). PATIENTS AND METHODS: We examined surgically resected specimens from 90 stage I to IIIA patients with lung ADs to determine the level of intra-tumoral DPD mRNA. RESULTS: Administration of 5-FU improved the prognosis of patients with low DPD-expressing tumors, whereas it did not do so for patients with high DPD expressing tumors. Patients with low DPD-expressing tumors administered with 5-FU had a significantly better prognosis than those who underwent surgery alone. A Cox proportional hazards regression model revealed that administration of 5-FU was an independent variable to predict prognosis in patients with low DPD-expressing tumors. CONCLUSION: Quantification of DPD mRNA levels is useful for determining the subgroup of lung AD patients who would benefit most from 5-FU after surgery.

Prognostic impact of dihydropyrimidine dehydrogenase expression on pancreatic adenocarcinoma patients treated with S-1-based adjuvant chemotherapy after surgical resection.

BACKGROUND AND OBJECTIVES: The aim of this study is to investigate the prognostic value of intratumoral expression of thymidylate synthase (TS), dihydropyrimidine dehydrogenase (DPD), and orotate phosphoribosyltransferase (OPRT) in patients treated with S-1-based chemotherapy after surgical resection for pancreatic adenocarcinoma. METHODS: Intratumoral TS, DPD, and OPRT expression was investigated in 106 patients with resected pancreatic adenocarcinoma by immunohistochemistry. Associations between clinicopathological factors, including intratumoral TS, DPD, and OPRT expression, and survival were evaluated by univariate and multivariate analyses. RESULTS: Of 106 patients, 72 had received S-1-based adjuvant chemotherapy (S-1(+) group), and 34 had not (S-1(-) group). High TS, DPD, and OPRT expression was observed in 64%, 37%, and 66% of patients, respectively. Among S-1(+) group patients, survival was significantly better for patients with low DPD expression than for patients with high DPD expression (P = 0.022). Intratumoral DPD expression was the only independent prognostic factor for patients treated with S-1-based adjuvant chemotherapy by multivariate analysis (P = 0.037). Intratumoral TS and OPRT expression did not appear to influence survival. CONCLUSIONS: Intratumoral DPD expression may be a relevant predictive marker of survival benefit associated with S-1-based adjuvant chemotherapy for pancreatic adenocarcinoma.

Multicenter phase II trial of S-1 in patients with cytokine-refractory metastatic renal cell carcinoma.

PURPOSE: This phase II multicenter trial was conducted to evaluate the activity and safety of S-1 in Japanese patients with metastatic renal cell carcinoma (mRCC). We also examined the relation between response and mRNA expression levels of enzymes involved in the metabolism of fluorouracil (FU). METHODS: Patients with mRCC who had received nephrectomy in whom cytokine-based immunotherapy was ineffective or contraindicated were studied. S-1 was administered orally at 80-, 100-, or 120-mg daily, assigned according to body surface area, on days 1 to 28 of a 42-day cycle. The primary end point was the objective response rate. The mRNA expression levels of FU-related enzymes were measured by reverse-transcriptase polymerase chain reaction in formalin-fixed, paraffin-embedded specimens of tumors obtained at nephrectomy. RESULTS: A total of 45 eligible patients were enrolled. Eleven (24.4%) of 45 patients had partial responses to S-1, and 28 (62.2%) had stable disease. Median progression-free survival was 9.2 months. The severity of most adverse events was mild to moderate. The most common grade 3/4 drug-related adverse events were neutropenia (8.9%) and anorexia (8.9%). The expression level of thymidylate synthase (TS) mRNA was significantly lower in patients who responded to treatment (t-test, P = .048), and progression-free survival was significantly longer in patients whose TS mRNA expression levels were below the median value, as compared with those with higher levels (log-rank test, P = .006). CONCLUSION: S-1 is active against cytokine-refractory mRCC. Quantification of TS mRNA levels in tumors before treatment may facilitate prediction of the response of mRCC to S-1.

Erlotinib in combination with capecitabine (5'dFUR) in resistant pancreatic cancer cell lines.

The combination of capecitabine and the tyrosine kinase inhibitor erlotinib has recently been tested in patients with gemcitabine-refractory pancreatic tumors, with limited success. To understand this lack of efficacy, we studied the molecular effects of these agents in Capan-1 and Capan-2 human pancreatic resistant cancer cells. Erlotinib up-regulated thymidine phosphorylase (+50%) and downregulated dihydropyrimidine dehydrogenase (+55%) in a cell-dependent manner, thus suggesting that the combination should result in synergism. However, only mild additivity was achieved at best when combining both drugs, and several sequences tested even led to strong antagonism. Further experiments were performed to understand this lack of efficacy. We found that the fluoropyrimidine down-regulated EGFR expression by 30%, an unexpected finding resulting in a possible reduction in efficacy when cells were subsequently exposed to erlotinib. We also observed marked drug-induced over-expression of both cytosolic and extracellular vascular endothelial growth factor (VEGF) secretion, thus possibly triggering proliferation. These preliminary findings strongly suggest that these observations could be new mechanisms in the development of acquired drug resistance in pancreatic cancer cells.

Synergistic antitumor activity of the SN-38-incorporating polymeric micelles NK012 with S-1 in a mouse model of non-small cell lung cancer.

The combination therapy of CPT-11, a prodrug of SN-38, with S-1, a dihydropyrimidine dehydrogenase inhibitory fluoropyrimidine, shows a high clinical response rate in non-small cell lung cancer (NSCLC). However, this combination causes severe toxicities such as diarrhea. Here, we investigated the advantages of treatment with the SN-38-incorporating polymeric micelles NK012 over CPT-11 in combination with S-1 in mice bearing a NSCLC xenograft in terms of antitumor activity and toxic effects, particularly intestinal toxicity. In vitro cytotoxic effects were examined in human NSCLC cell lines (A549, PC-9, PC-14, EBC-1 and H520). In vivo antitumor effects were evaluated in PC-14- and EBC-1-bearing mice after NK012 or CPT-11 administration on Days 0 and 7 and S-1 administration on Days 0-13. Pathological changes in the small intestine were also investigated. The in vitro growth inhibitory effects of NK012 were 56.8- to 622-fold more potent than those of CPT-11. NK012/S-1 treatment showed significantly higher antitumor activity both in PC-14-bearing (p = 0.0007) and EBC-1-bearing mice (p < 0.0001) than CPT-11/S-1 treatment. The deformity and decrease in the density of intestinal villi were more severe in CPT-11/S-1-treated mice than in NK012/S-1-treated mice. NK012/S-1 combination is a promising candidate regimen against NSCLC without inducing toxicities such as severe diarrhea and therefore warrants clinical evaluation.