Molecular determinants of folate levels after leucovorin administration in colorectal cancer.

PURPOSE: Oral leucovorin (LV) is used with uracil/tegafur (UFT) in the treatment of colorectal cancer (CRC). In order to find the factors related to the efficacy of LV in enhancing the antitumour effect of UFT, we investigated the relationships between the reduced folate levels in the CRC tissue after LV administration and the gene-expression levels of folate-metabolizing enzymes and folate transporters. METHODS: The subjects were 60 CRC patients, scheduled to undergo surgery. The control group (n = 30) did not receive LV. Three groups (n = 10 for each) received a single dose of oral LV at 25 mg, 4, 12 or 18 h before surgery (LV 4 h, LV 12 h or LV 18 h groups, respectively). The reduced folate levels in plasma and tissues were measured by high-performance liquid chromatography (HPLC) or a thymidylate synthase-FdUMP binding assay, respectively. The intratumoral expression levels of 34 genes were quantitatively evaluated with a real-time polymerase chain reaction (RT-PCR) assay. RESULTS: The reduced folate levels persisted for a longer period of time in the CRC tissue than in the plasma after LV administration. A multivariate logistic regression analysis revealed that high folylpolyglutamate synthase (FPGS) gene expression, low gamma-glutamyl hydrolase (GGH) gene expression and low ATP-binding cassette sub-family C, number 1 (ABCC1) gene expression in CRC tissues were predictive factors for a high reduced folate level after LV administration. CONCLUSIONS: The expression level of FPGS, GGH and ABCC1 in CRC tissues could predict the reduced folate level after LV administration, and these factors may determine the efficacy of LV treatment.

A metabonomic approach identifies human urinary phenylacetylglutamine as a novel marker of interstitial cystitis.

An ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) based metabonomic approach was applied to identify a candidate metabolite with not known to be associated with interstitial cystitis (IC). IC is a chronic clinical syndrome associated with urinary frequency and urgency and/or pelvic pain. The ability to non-invasively diagnose the early stage of IC would be important for improving the patient's quality of life. The current standard IC diagnosis is cystoscopy, which is invasive and painful. Urine samples from the following were taken and analyzed: 10 IC patients, 10 bacterial cystitis (BC) patients, and 10 healthy volunteers (HVs) to identify an IC marker; and subsequently analyzed 5 IC patients and 5 HVs for marker validation. The urinary marker of IC was identified as phenylacetylglutamine (PAGN) using NMR and MS/MS analysis. In addition, quantitative methods were developed to determining the urinary PAGN levels using UPLC-UV. The urinary level of PAGN measured relative to creatinine (Cr) was significantly elevated in IC patients (mean 0.47mg/mg Cr) compared with BC patients (mean 0.25mg/mg Cr) and HVs (mean 0.11mg/mg Cr). Interestingly, urinary PAGN/Cr ratios in patients with mild IC (grade I) and moderate IC (grade II) were higher than for patients with severe IC (grade III). Moreover, urinary PAGN/Cr ratios with mild and moderate IC patients (mean 0.30mg/mg Cr) were higher than HVs (mean 0.059mg/mg Cr), in the validation set. These findings establish urinary PAGN/Cr ratios as a novel urinary marker of IC, and may contribute to early diagnosis of IC patients.

Different histological types of non-small cell lung cancer have distinct folate and DNA methylation levels.

Aberrant DNA methylation is a commonly observed epigenetic change in lung cancer. Folate has been suggested to play a role in the homeostasis of DNA methylation and has also been implicated in cancer chemotherapy. We investigated a possible role for folate in DNA methylation by measuring folate concentrations in tumors and adjacent normal tissues from 72 non-small cell lung cancer (NSCLC) patients. These were compared to DNA methylation levels and to clinicopathological features. Folate concentrations were determined as the sum of 5,10-methylenetetrahydrofolate and tetrahydrofolate. The MethyLight assay was used to quantitate methylation in promoter regions of P16(CDKN2A), APC, CDH13, RARB, RASSF1, RUNX3, and MYOD1. Methylation of LINE-1 repeats was used as a surrogate for global methylation. Folate levels in tumors correlated positively with LINE-1, CDH13, and RUNX3 methylation. Folate concentrations and methylation of LINE-1, RASSF1, and RUNX3 were significantly higher in adenocarcinoma compared to squamous cell carcinoma (SCC). Two sets of array-based data retrieved from the Gene Expression Omnibus consistently showed that expression of FOLR1, a folate transport enzyme, and GGH, an enzyme that prevents folate retention, were higher and lower, respectively, in adenocarcinomas compared to SCC. This was independently validated by quantitative RT-PCR in 26 adenocarcinomas and 13 SCC. Our results suggest that folate metabolism plays a role in aberrant DNA methylation in NSCLC. The histological subtype differences in folate concentration and DNA methylation observed here were associated with distinct expression patterns for folate metabolizing enzymes. These findings may have clinical applications for histology-directed chemotherapy with fluoropyrimidine and anti-folates in NSCLC.

Thymidylate synthase, dihydropyrimidine dehydrogenase, orotate phosphoribosyltransferase mRNA and protein expression levels in solid tumors in large scale population analysis.

It has been reported that the expression of thymidylate synthase (TS), dihydropyrimidine dehydrogenase (DPD) and orotate phosphoribosyltransferase (OPRT) may predict the clinical efficacy of 5-fluorouracil (5-FU)-based therapy in cancer patients. We investigated the differences in the mRNA and protein expression of these enzymes in various tumor tissues. A total of 17,613 specimens of head and neck, gastric, colorectal, breast, lung and pancreatic cancer were collected from multiple facilities in Japan, and the mRNA and protein expression levels of the above enzymes were examined in 4,830 and 12,783 of these specimens, respectively. The mRNA levels were analyzed using RT-PCR in laser-captured microdissected formalin-fixed paraffin-embedded specimens, while the protein levels were analyzed by enzyme-linked immunosorbent assays. The median values of the relative TS, DPD and OPRT mRNA levels were 2.06, 0.803 and 1.17, respectively, while the median protein levels were 22.1, 134.8 and 3.81 ng enzyme/mg protein, respectively. The carcinomas were classified into two sets of four groups each using the overall median levels of TS and DPD or TS and OPRT as cutoff values. Approximately 60% of the gastric cancers exhibited elevated mRNA and protein expression levels of DPD, while >65% of the colorectal cancers showed low levels of DPD expression. Overall, 75% of the head and neck cancers exhibited high expression levels of DPD. Among the lung and pancreatic cancers, 50-74% showed low TS/high DPD expression. In conclusion, the mRNA expression and protein levels of TS, DPD and OPRT differed according to the type of cancer. The results of this large-scale population analysis are expected to be useful as reference data for predicting the relationship between the respective enzyme levels and the efficacy of 5-FU-based chemotherapy.

Pharmacokinetics of gamma-hydroxybutylic acid (GHB) and gamma-butyrolactone (GBL), the anti-angiogenic metabolites of oral fluoropyrimidine UFT, in patients with gastric cancer.

Gamma-hydroxybutylic acid (GHB) and gamma-butyrolactone (GBL), the metabolites of UFT, which is an oral fluoropyrimidine, have been reported to inhibit angiogenesis with IC50 values of 25.8 ng/ml. The pharmacokinetics of GHB and GBL were examined after the administration of UFT in patients with gastric cancer. The patients received 200 mg of UFT orally twice a day. Peripheral blood samples were collected at 0, 0.5, 1, 2 and 4 hr after the time of dosing on day 5. The baseline and endogenous GBL concentrations in plasma were 20.2 +/- 7.5 ng/ml for patients and 16.8 +/- 4.0 ng/ml for volunteers (P = 0.221). The values of C(max) for tegafur, uracil, 5-FU and GBL were 14.7 +/- 5.2 and 4.0 +/- 2.8 microg/ml, 191.2 +/- 115.3 and 147.5 +/- 57.3 ng/ml, respectively, and the values of Tmax were 1.0 +/- 0.6, 1.1 +/- 0.6, 0.9 +/- 0.6 and 1.2 +/- 0. 6 hr, respectively. The concentration of GBL was much higher than its IC50 value for angiogenesis. GBL is thus suggested to contribute to the anticancer effects of UFT in addition to that of 5-FU, which is continuously metabolized from UFT.

Validation of a simple gas chromatographic-mass spectrometric method for the determination of gamma-butyrolactone in human plasma.

A gas chromatographic-mass spectrometric (GC-MS) method is described for the determination of human plasma levels of gamma-butyrolactone (GBL) is described. The method is sensitive and simple. The plasma sample spiked with the internal standard was extracted by dichloromethane (CH(2)Cl(2)) in acidic conditions, and the concentrated organic layer was injected into GC-MS. Because of endogenous GBL in human plasma, the method used a standard calibration curve. The calibration curve was linear from 10 to 1000 ng/ml. The method has been validated for accuracy and precision with the relative error and C.V. for intra- and inter-day within 10%. GBL-spiked plasma samples stored at -80 degrees C were stable for a 3-month period. The stability of plasma samples after three cycles of freezing and thawing and of prepared samples on an autosampler for 48 h were demonstrated. Plasma concentrations of GBL before and after administration of UFT were 24.3+/-14.2 and 84.9+/-22.4 ng/ml, respectively.