Dihydropyrimidine dehydrogenase and messenger RNA levels in gastric cancer: possible predictor for sensitivity to 5-fluorouracil

Energy decomposition and waterswapping analysis to investigate the SNP associated DPD mediated 5-FU resistance

5-fluorouracil is an essential component of systemic chemotherapy for colon, breast, head, and neck cancer patients. However, tumoral overexpression of the dihydropyrimidine dehydrogenase has rendered 5-FU clinically ineffective by inactivating it to 5'-6'-dihydro fluorouracil. The responses to 5-FU in terms of efficacy and toxicity greatly differ depending upon the population group, because of variability in the DPD activity levels. In the current study, key active site amino acids involved in the 5-FU inactivation were investigated by modelling the 3D structure of human DPD in a complex with 5-FU. The identified amino acids were analyzed for their possible missense mutations available in dbSNP database. Out of 12 missense SNPs, four were validated either by sequencing in the 1000 Genomes project or frequency/genotype data. The recorded validated missense SNPs were further considered to analyze the effect of their respective alterations on 5-FU binding. Overall findings suggested that population bearing the Glu611Val DPD mutation (rs762523739) is highly vulnerable to 5-FU resistance. From the docking, electrostatic complementarity, dynamics, and energy decomposition analyses it was found that the above mutation showed superior scores than the wild DPD -5FU complex. Therefore, prescribing prodrug NUC-3373 or DPD inhibitors (Gimeracil/3-Cyano-2,6-Dihydroxypyridines) as adjuvant therapy may overcome the 5-FU resistance.

Current Advances and Outlook in Gastric Cancer Chemoresistance: A Review

BACKGROUND

Surgical resection of the lesion is the standard primary treatment of gastric cancer. Unfortunately, most patients are already in the advanced stage of the disease when they are diagnosed with gastric cancer. Alternative therapies, such as radiation therapy and chemotherapy, can achieve only very limited benefits. The emergence of cancer drug resistance has always been the major obstacle to the cure of tumors. The main goal of modern cancer pharmacology is to determine the underlying mechanism of anticancer drugs.

OBJECTIVE

Here, we mainly review the latest research results related to the mechanism of chemotherapy resistance in gastric cancer, the application of natural products in overcoming the chemotherapy resistance of gastric cancer, and the new strategies currently being developed to treat tumors based on immunotherapy and gene therapy.

CONCLUSION

The emergence of cancer drug resistance is the main obstacle in achieving alleviation and final cure for gastric cancer. Mixed therapies are considered to be a possible way to overcome chemoresistance. Natural products are the main resource for discovering new drugs specific for treating chemoresistance, and further research is needed to clarify the mechanism of natural product activity in patients. .

Intratumoral gene expression of dihydrofolate reductase and folylpoly-c-glutamate synthetase affects the sensitivity to 5-fluorouracil in non-small cell lung cancer

BACKGROUND

Various factors related to the sensitivity of non-small cell lung carcinoma (NSCLC) to 5-fluorouracil (5-FU) have been reported, and some of them have been clinically applied. In this single-institutional prospective analysis, the mRNA expression level of five folic acid-associated enzymes was evaluated in surgical specimens of NSCLC. We investigated the correlation between the antitumor effect of 5-FU in NSCLC using an anticancer drug sensitivity test and the gene expression levels of five enzymes.

MATERIALS AND METHODS

Forty patients who underwent surgery for NSCLC were enrolled, and the antitumor effect was measured using an in vitro anticancer drug sensitivity test (histoculture drug response assay) using freshly resected specimens. In the same sample, the mRNA expression levels of five enzymes involved in the sensitivity to 5-FU were measured in the tumor using real-time PCR. The expression levels and the result of the sensitivity test were compared.

RESULTS

No correlation was found between dihydropyrimidine dehydrogenase (DPD), orotate phosphoribosyltransferase (OPRT), or DPD/OPRT expression and the antitumor effects of 5-FU. On the other hand, a correlation was found between thymidylate synthase (TS), folylpoly-c-glutamate synthetase (FPGS), and dihydrofolate reductase (DHFR) expression and 5-FU sensitivity.

CONCLUSION

Expression of FPGS and DHFR may be useful for predicting the efficacy of 5-FU-based chemotherapy for NSCLC.

Chemotherapy-induced necrotising tumour lysis and perforation of a huge gastric cancer simulating emphysematous pancreatitis

A 56-year-old man was diagnosed to have a huge gastric cancer extending from the lesser curvature of the stomach to the pancreas with multiple hepatic and peritoneal metastases. Two days after completing chemotherapy with cisplatin plus high dose leucovorin and fluorouracil, drastic necrotising tumour lysis led to gastric perforation and septic shock most likely due to bacterial peritonitis. The image of tumour lysis looked like an emphysematous pancreatitis. Afterwards, immunohistochemical study of the tumour specimen confirmed moderate positivity of dihydropyrimidine dehydrogenase and absence of Bcl-2 expression. The incomplete expression of dihydropyrimidine dehydrogenase and total deficiency of Bcl-2 are considered to be the main underlying causes of such extraordinary chemosensitivity and so severe a tumour lysis phenomenon. Pre-emptive intensive survey of possible biomarkers of chemosensitivity is thus highly recommended upon treating a massive gastric cancer.

Plasma microRNA profiles: identification of miR-1229-3p as a novel chemoresistant and prognostic biomarker in gastric cancer

This study aimed to explore novel microRNAs in plasma for predicting chemoresistance in adjuvant chemotherapy for patients with gastric cancer (GC). We used the Toray 3D-Gene microRNA array-based approach to compare preoperative plasma microRNA levels between GC patients with and without recurrences after curative gastrectomy. All patients underwent adjuvant chemotherapy with S-1, an oral fluoropyrimidine. Of 2566 candidates, six candidate microRNAs (miR-1229-3p, 1249-5p, 762, 711, 1268a and 1260b), which were highly expressed in the preoperative plasma of patients with subsequent recurrences, were selected. In a large-scale validation analysis by quantitative RT-PCR, we focused on high plasma levels of miR-1229-3p, which was an independent poor prognostic factor for recurrence free survival (P = 0.009, HR = 3.71). Overexpression of miR-1229-3p in GC cells induced significant chemoresistance to 5-fluorouracil (5-FU), up-regulation of thymidylate synthase (TS) and dihydroprimidine dehydrogenase (DPD) and down-regulation of SLC22A7 both in vitro and in vivo. Intraperitoneal injection of miR-1229-3p in mice induced significant chemoresistance to 5-FU, accompanied by high levels of miR-1229-3p in plasma and tumor tissue. These findings suggest that plasma miR-1229-3p might be a clinically useful biomarker for predicting chemoresistance to S-1 and selecting other or combined intensive chemotherapy regimens in GC patients.

Choice of Capecitabine or S1 in Combination with Oxaliplatin based on Thymidine Phosphorylase and Dihydropyrimidine Dehydrogenase Expression Status in Patients with Advanced Gastric Cancer

Purpose

To study the efficacy of capecitabine or S-1 plus oxaliplatin (CAPOX or SOX) for treating thymidine phosphorylase (TP)- or dihydropyrimidine dehydrogenase (DPD)-positive advanced gastric cancer.

Materials and Methods

Eighty-six patients with stage IIIC to IV gastric cancer were assessed for TP and DPD expression by immunohistochemistry. The association between CAPOX or SOX efficacy and TP/DPD expression was retrospectively analyzed.

Results

There were no significant differences in the objective remission rate (ORR, 52.27% vs. 47.62%; P>0.05), disease control rate (72.73% vs. 73.81%, P>0.05), progression-free survival (hazard ratio [HR], 1.119; 95% confidence interval [CI], 0.739-1.741; P=0.586), and overall survival (OS; HR, 0.855; 95% CI, 0.481-1.511; P=0.588) between CAPOX and SOX. A higher number of stage IV patients showed TP positivity, while DPD-positive patients predominantly showed intestinal type of gastric cancer. In TP-positive patients, the ORRs associated with CAPOX and SOX treatments were 57.14% and 38.10%, respectively; OS was better with CAPOX than with SOX (HR, 0.447; 95% CI, 0.179-0.978; P=0.046). Among DPD-positive patients, the SOX treatment-associated ORR (60.87%) was significantly higher than the CAPOX treatment-associated ORR (43.48%). Furthermore, SOX treatment resulted in better OS than did CAPOX treatment (HR, 2.020; 95% CI, 1.019-4.837; P=0.049).

Conclusions

No significant difference in clinical efficacy was found between CAPOX and SOX. TP-positive patients might respond better to CAPOX while DPD-positive patients may respond better to SOX. Our findings might serve as a guide for personalized chemotherapy for gastric cancer.

Tailored therapy in patients treated with fluoropyrimidines: focus on the role of dihydropyrimidine dehydrogenase

Fluoropyrimidines are widely used in the treatment of solid tumors, mainly gastrointestinal, head and neck and breast cancer. Dihydropyrimidine dehydrogenase (DPD) is the rate-limiting enzyme for catabolism of 5-FU and it is encoded by DPYD gene. To date, many known polymorphisms cause DPD deficiency and subsequent increase of 5-FU toxicity. In addition, reduced inactivation of 5-FU could lead to increased 5-FU intracellular concentration and augmented efficacy of this drugs. Therefore DPD expression, particularly intratumoral, has been investigated as predictive and prognostic marker in 5-FU treated patients. There also seems to be a tendency to support the correlation between DPD expression and response/survival in patients treated with fluoropyrimidine even if definitive conclusions cannot be drawn considering that some studies are conflicting. Therefore, the debate on intratumoral DPD expression as a potential predictor and prognostic marker in patients treated with fluoropyrimidines is still open. Four DPD-polymorphisms are the most relevant for their frequency in population and clinical relevance. Many studies demonstrate that treating a carrier of one of these polymorphisms with a full dose of fluoropyrimidine can expose patient to a severe, even life-threatening, toxicity. Severe toxicity is reduced if this kind of patients received a dose-adjustment after being genotyped. CPIC (Clinical Pharmacogenetics Implementation Consortium) is an International Consortium creating guidelines for facilitating use of pharmacogenetic tests for patient care and helps clinicians ensuring a safer drug delivery to the patient. Using predictive DPD deficiency tests in patients receiving 5FU-based chemotherapy, in particular for colorectal cancer, has proven to be a cost-effective strategy.

The Impact of the Expression Level of Intratumoral Dihydropyrimidine Dehydrogenase on Chemotherapy Sensitivity and Survival of Patients in Gastric Cancer: A Meta-Analysis

The potential impact that the intratumoral expression level of dihydropyrimidine dehydrogenase (DPD) has on chemotherapy sensitivity and long-term survival for gastric cancer (GC) patients remains controversial; therefore, this study seeks to clarify this issue. Our meta-analysis was performed using Review Manager (RevMan) 5.3 software. In vitro drug sensitivity tests, correlation coefficients between sensitivity to 5-fluorouracil (5-FU), and expression levels of intratumoral DPD were used as effective indexes to analyse. Overall survival (OS) and progression-free survival (PFS) were used as endpoints for patient outcome, and hazard ratios (HRs) and 95% confidence intervals (CIs) were noted as measures of effect. There were 15 eligible studies including 1805 patients for the final analysis. The analysis revealed a statistically significant difference between the expression level of intratumoral DPD activity, DPD mRNA levels, and sensitivity to 5-FU in GC patients, with high expression levels of intratumoral DPD resulting in low sensitivity to 5-FU. However, no matter what therapeutic regimens were used, there was no significant difference for patient outcomes between high and low DPD expression groups, either in OS or in PFS. In conclusion, high levels of intratumoral DPD expression have a negative impact on sensitivity to 5-FU in GC patients, but no prognostic value for long-term survival was uncovered.

Novel Deleterious Dihydropyrimidine Dehydrogenase Variants May Contribute to 5-Fluorouracil Sensitivity in an East African Population

Clinical studies have identified specific genetic variants in dihydropyrimidine dehydrogenase (DPD; DPYD gene) as predictors of severe adverse toxicity to the commonly used chemotherapeutic 5-fluorouracil (5-FU); however, these studies have focused on European and European-American populations. Our laboratory recently demonstrated that additional variants in non-European haplotypes are predictive of 5-FU toxicity. The objective of this study was to identify potential risk variants in an understudied East African population relevant to our institution's catchment area. The DPYD protein-coding region was sequenced in 588 individuals of Somali or Kenyan ancestry living in central/southeast Minnesota. Twelve novel nonsynonymous variants were identified, seven of which significantly decreased DPD activity in vitro. The commonly reported toxicity-associated variants, *2A, D949V, and I560S, were not detected in any individuals. Overall, this study demonstrates a critical limitation in our knowledge of pharmacogenetic predictors of 5-FU toxicity, which has been based on clinical studies conducted in populations of limited diversity.

Construction of possible integrated predictive index based on EGFR and ANXA3 polymorphisms for chemotherapy response in fluoropyrimidine-treated Japanese gastric cancer patients using a bioinformatic method

Background

Variability in drug response between individual patients is a serious concern in medicine. To identify single-nucleotide polymorphisms (SNPs) related to drug response variability, many genome-wide association studies have been conducted.

Methods

We previously applied a knowledge-based bioinformatic approach to a pharmacogenomics study in which 119 fluoropyrimidine-treated gastric cancer patients were genotyped at 109,365 SNPs using the Illumina Human-1 BeadChip. We identified the SNP rs2293347 in the human epidermal growth factor receptor (EGFR) gene as a novel genetic factor related to chemotherapeutic response. In the present study, we reanalyzed these hypothesis-free genomic data using extended knowledge.

Results

We identified rs2867461 in annexin A3 (ANXA3) gene as another candidate. Using logistic regression, we confirmed that the performance of the rs2867461 + rs2293347 model was superior to those of the single factor models. Furthermore, we propose a novel integrated predictive index (iEA) based on these two polymorphisms in EGFR and ANXA3. The p value for iEA was 1.47 × 10⁻⁸ by Fisher’s exact test. Recent studies showed that the mutations in EGFR is associated with high expression of dihydropyrimidine dehydrogenase, which is an inactivating and rate-limiting enzyme for fluoropyrimidine, and suggested that the combination of chemotherapy with fluoropyrimidine and EGFR-targeting agents is effective against EGFR-overexpressing gastric tumors, while ANXA3 overexpression confers resistance to tyrosine kinase inhibitors targeting the EGFR pathway.

Conclusions

These results suggest that the iEA index or a combination of polymorphisms in EGFR and ANXA3 may serve as predictive factors of drug response, and therefore could be useful for optimal selection of chemotherapy regimens.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1721-z) contains supplementary material, which is available to authorized users.

Novel 5-fluorouracil-resistant human esophageal squamous cell carcinoma cells with dihydropyrimidine dehydrogenase overexpression

5-Fluorouracil (5-FU) is a key drug for the treatment of esophageal squamous cell carcinoma (ESCC); however, resistance to it remains a critical limitation to its clinical use. To clarify the mechanisms of 5-FU resistance of ESCC, we originally established 5-FU-resistant ESCC cells, TE-5R, by step-wise treatment with continuously increasing concentrations of 5-FU. The half maximal inhibitory concentration of 5-FU showed that TE-5R cells were 15.6-fold more resistant to 5-FU in comparison with parental TE-5 cells. TE-5R cells showed regional copy number amplification of chromosome 1p including the DPYD gene, as well as high mRNA and protein expressions of dihydropyrimidine dehydrogenase (DPD), an enzyme involved in 5-FU degradation. 5-FU treatment resulted in a significant decrease of the intracellular 5-FU concentration and increase of the concentration of α-fluoro-ureidopropionic acid (FUPA), a metabolite of 5-FU, in TE-5R compared with TE-5 cells in vitro. Conversely, gimeracil, a DPD inhibitor, markedly increased the intracellular 5-FU concentration, decreased the intracellular FUPA concentration, and attenuated 5-FU resistance of TE-5R cells. These results indicate that 5-FU resistance of TE-5R cells is due to the rapid degradation of 5-FU by DPD overexpression. The investigation of 5-FU-resistant ESCC with DPYD gene copy number amplification and consequent DPD overexpression may generate novel biological evidence to explore strategies against ESCC with 5-FU resistance.

Impact of intratumoral expression levels of fluoropyrimidine-metabolizing enzymes on treatment outcomes of adjuvant S-1 therapy in gastric cancer

We analyzed the expression levels of fluoropyrimidine-metabolizing enzymes (thymidylate synthase [TS], dihydropyrimidine dehydrogenase [DPD], thymidine phosphorylase [TP] and orotate phosphoribosyltransferase [OPRT]) to identify potential biomarkers related to treatment outcomes in gastric cancer (GC) patients receiving adjuvant S-1 chemotherapy. In this study, 184 patients who received curative gastrectomy (D2 lymph node dissection) and adjuvant S-1 were included. Immunohistochemistry and quantitative reverse transcription polymerase chain reaction were performed to measure the protein and mRNA levels of TS, DPD, TP, and OPRT in tumor tissue. In univariate analysis, low intratumoral DPD protein expression was related to poorer 5-year disease-free survival (DFS; 78% vs. 88%; P = 0.068). Low intratumoral DPD mRNA expression (1st [lowest] quartile) was also related to poorer DFS (69% vs. 90%; P < 0.001) compared to high intratumoral DPD expression (2nd to 4th quartiles). In multivariate analyses, low intratumoral DPD protein or mRNA expression was related to worse DFS (P < 0.05), irrespective of other clinical variables. TS, TP, and OPRT expression levels were not related to treatment outcomes. Severe non-hematologic toxicities (grade ≥ 3) had a trend towards more frequent development in patients with low intratumoral DPD mRNA expression (29% vs. 16%; P = 0.068). In conclusion, GC patients with high intratumoral DPD expression did not have inferior outcome following adjuvant S-1 therapy compared with those with low DPD expression. Instead, low intratumoral DPD expression was related to poor DFS.

Enhancement of 5-fluorouracil-induced cytotoxicity by leucovorin in 5-fluorouracil-resistant gastric cancer cells with upregulated expression of thymidylate synthase

BACKGROUND

Elucidation of the mechanisms by which gastric cancer cells acquire resistance to 5-fluorouracil (5FU) may provide important clues to the development of effective chemotherapy for 5FU-resistant gastric cancer

METHODS

Four 5FU-resistant cell lines (MKN45/5FU, MKN74/5FU, NCI-N87/5FU, and KATOIII/5FU) were established by continuous exposure of the cells to progressively increasing concentrations of 5FU for about 1 year. Then, mRNA expression levels of four genes associated with 5FU metabolism, i.e., thymidylate synthase (TS), dihydropyrimidine dehydrogenase, thymidine phosphorylase, and orotate phosphoribosyltransferase, were quantitatively evaluated by real-time reverse transcriptase-polymerase chain reaction. In addition, TS protein expression was measured by Western blot analysis.

RESULTS

As compared with the parent cell lines, the 5FU-resistant cell lines showed 3.8- to 11.6-fold higher resistance to 5FU, as well as 1.9- to 3.5-fold higher TS mRNA expression and 1.6- to 7.1-fold higher TS protein expression. In contrast, the expressions of other genes did not differ significantly among the cell lines. The cytotoxicity of 5FU was enhanced 2.3- to 2.8 fold by leucovorin (LV) against three of the four 5FU-resistant cell lines.

CONCLUSIONS

Collectively, LV enhanced the cytotoxicity of 5FU not only against the parent gastric cancer cell lines, but also against the 5FU-resistant cell lines, even those with elevated TS expression levels. These results suggest that clinical studies of a combination of 5FU and LV are warranted in patients who have recurrent gastric cancer after 5FU-based therapy.

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

Purpose

To 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).

Methods

Formalin-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.

Results

High 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.

Conclusion

DPD 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.

Predicting the response to chemotherapy in gastric adenocarcinoma: who benefits from neoadjuvant chemotherapy?

Despite a decline in the overall incidence, gastric adenocarcinoma remains the second most common cause of cancer death worldwide and thus a significant global health problem. Even in early-stage locoregional confined disease the 5-year survival rarely exceeds 25-35 %. Randomized trials have demonstrated a benefit from neoadjuvant and perioperative chemotherapy. However the optimal approach in individual patients is not clear and remains controversial. A consistent finding is that patients who have a histopathological response to neoadjuvant therapy are more likely to receive a survival benefit. These clinical data provide a strong argument for the urgent development of methods to predict histopathological response to neoadjuvant therapies for gastric adenocarcinomas. Published data demonstrate that clinico-pathological features (tumour histology and location), imaging through metabolic response by FDG-PET and tissue/molecular biomarkers may all have a predictive value for neoadjuvant therapies. However it is still uncertain from published data whether or not they will be useful for clinical decision making in individual patients. Existing candidate biomarkers need to be properly qualified and validated and novel biomarkers are required and an optimal approach should involve the combination and integration of clinical, imaging, pathological and molecular biomarkers.

Relationship between gene expression of 5-fluorouracil metabolic enzymes and 5-fluorouracil sensitivity in primary cancer cells isolated from malignant ascites

This study was designed to investigate the predictive role of 5-FU metabolic enzymes in malignant ascites. Forty-three malignant ascites were collected and primary cancer cells were isolated. Gene expression was detected by quantitative RT-PCR. We found that DPD mRNA was higher in patients with pancreatic cancers than those with gastric cancers, colon cancers, and liver cancers. Significant correlations were found between expression of DPD and TP, and between TS and OPRT. mRNA levels of TS and OPRT correlated significantly with the chemosensitivity of 5-FU. Assessing gene expression would be useful in predicting 5-FU sensitivity for patients with malignant ascites.

Efficacy of laser capture microdissection plus RT-PCR technique in analyzing gene expression levels in human gastric cancer and colon cancer

Background

Thymidylate synthase, dihydropyrimidine dehydrogenase, thymidine phosphorylase, and orotate phosphoribosyltransferase gene expressions are reported to be valid predictive markers for 5-fluorouracil sensitivity to gastrointestinal cancer. For more reliable predictability, their expressions in cancer cells and stromal cells in the cancerous tissue (cancerous stroma) have been separately investigated using laser capture microdissection.

Methods

Thymidylate synthase, dihydropyrimidine dehydrogenase, thymidine phosphorylase, and orotate phosphoribosyltransferase mRNA in cancer cells and cancerous stroma from samples of 47 gastric and 43 colon cancers were separately quantified by reverse transcription polymerase chain reaction after laser capture microdissection.

Results

In both gastric and colon cancers, thymidylate synthase and orotate phosphoribosyltransferase mRNA expressions were higher (p < 0.0001, p <0.0001 respectively in gastric cancer and P = 0.0002, p < 0.0001 respectively in colon cancer) and dihydropyrimidine dehydrogenase mRNA expressions were lower in cancer cells than in cancerous stroma (P = 0.0136 in gastric cancer and p < 0.0001 in colon cancer). In contrast, thymidine phosphorylase mRNA was higher in cancer cells than in cancerous stroma in gastric cancer (p < 0.0001) and lower in cancer cells than in cancerous stroma in colon cancer (P = 0.0055).

Conclusion

By using this method, we could estimate gene expressions separately in cancer cells and stromal cells from colon and gastric cancers, in spite of the amount of stromal tissue. Our method is thought to be useful for accurately evaluating intratumoral gene expressions.

Correlation between clinical pathologic factors and activity of 5-FU-metabolizing enzymes in colorectal cancer

INTRODUCTION

Orotate phosphoribosyl transferase (OPRT), dihydropyrimidine dehydrogenase (DPD), and thymidylate synthase (TS) are initial key enzymes in the 5-fluorouracil (5-FU) metabolic pathway. The expression levels and activities of these three enzymes play important roles in the response of cancer patients to 5-FU-based chemotherapy.

PURPOSE

The purpose of this study was to investigate the relationship between the activities of 5-FU metabolic enzymes and clinicopathologic factors in colorectal cancer.

METHODS

We measured the activities of OPRT, DPD, and TS in colorectal cancer tissues. We also investigated the correlations between the activities of these three enzymes and clinicopathologic factors (histological type, depth of tumor invasion, extent of lymph node metastasis, Dukes' stage, lymphatic invasion, and vascular invasion). We examined 100 patients with surgically resected colorectal cancer.

RESULTS

Poorly differentiated adenocarcinoma showed significantly higher DPD activities than did moderately differentiated or well-differentiated adenocarcinoma. In patients with lymph-node metastasis, OPRT activity was significantly lower than in patients without lymph-node metastasis. No significant relation was found between TS activity and histological type, depth of tumor invasion, extent of lymph node metastasis, Dukes' stage, lymphatic invasion, or vascular invasion.

CONCLUSION

The response to 5-FU may be poor in patients with lymph-node metastasis, because of low OPRT activity, and in patients with poorly differentiated adenocarcinoma, because of high DPD activity.

Impacts of excision repair cross-complementing gene 1 (ERCC1), dihydropyrimidine dehydrogenase, and epidermal growth factor receptor on the outcomes of patients with advanced gastric cancer

Using laser-captured microdissection and a real-time RT-PCR assay, we quantitatively evaluated mRNA levels of the following biomarkers in paraffin-embedded gastric cancer (GC) specimens obtained by surgical resection or biopsy: excision repair cross-complementing gene 1 (ERCC1), dihydropyrimidine dehydrogenase (DPD), methylenetetrahydrofolate reductase (MTHFR), epidermal growth factor receptor (EGFR), and five other biomarkers related to anticancer drug sensitivity. The study group comprised 140 patients who received first-line chemotherapy for advanced GC. All cancer specimens were obtained before chemotherapy. In patients who received first-line S-1 monotherapy (69 patients), low MTHFR expression correlated with a higher response rate (low: 44.9% vs high: 6.3%; P=0.006). In patients given first-line cisplatin-based regimens (combined with S-1 or irinotecan) (43 patients), low ERCC1 correlated with a higher response rate (low: 55.6% vs high: 18.8%; P=0.008). Multivariate survival analysis of all patients demonstrated that high ERCC1 (hazard ratio (HR): 2.38 (95% CI: 1.55-3.67)), high DPD (HR: 2.04 (1.37-3.02)), low EGFR (HR: 0.34 (0.20-0.56)), and an elevated serum alkaline phosphatase level (HR: 1.00 (1.001-1.002)) were significant predictors of poor survival. Our results suggest that these biomarkers are useful predictors of clinical outcomes in patients with advanced GC.

Alteration of dihydropyrimidine dehydrogenase expression by IFN-α affects the antiproliferative effects of 5-fluorouracil in human hepatocellular carcinoma cells

Dihydropyrimidine dehydrogenase (DPD) is the rate-limiting enzyme in the catabolism of 5-fluorouracil (5-FU) and its activity is closely associated with cellular sensitivity to 5-FU. This study examines the role of DPD in the antiproliferative effects of 5-FU combined with IFN-alpha on hepatocellular carcinoma (HCC) cells in culture and asks whether IFN-alpha could affect DPD expression. The combined action of IFN-alpha and 5-FU on three HCC lines was quantified by a combination index method. Coadministration of IFN-alpha and 5-FU showed synergistic effects against HAK-1A and KYN-2 but antagonistic effects against KYN-3. The cellular expression levels of DPD mRNA and protein were markedly up-regulated in KYN-3 cells by IFN-alpha but were down-regulated in HAK-1A and KYN-2. The expression of thymidylate synthase mRNA and protein was down-regulated by IFN-alpha in all three cell lines. Coadministration of a selective DPD inhibitor, 5-chloro-2,4-dihydroxypyridine (CDHP), enhanced the antiproliferative effect of 5-FU and IFN-alpha on KYN-3 approximately 4-fold. However, the synergistic effects of 5-FU and IFN-alpha on HAK-1A and KYN-2 were not affected by CDHP. The antiproliferative effect of 5-FU could thus be modulated by IFN-alpha, possibly through DPD expression, in HCC cells. Inhibition of DPD activity by CDHP may enhance the efficacy of IFN-alpha and 5-FU combination therapy in patients with HCC showing resistance to this therapy.

Role of thymidine phosphorylase and orotate phosphoribosyltransferase mRNA expression and its ratio to dihydropyrimidine dehydrogenase in the prognosis and clinicopathological features of patients with pancreatic cancer

BACKGROUND

Thymidine phosphorylase (TP), orotate phosphoribosyltransferase (OPRT), and dihydropyrimidine dehydrogenase (DPD) are important enzymes related to the metabolism of 5-fluorouracil and its derivatives. In this study, we analyzed the expression of these enzymes and evaluated the association between the expression of these enzymes and clinicopathological features and prognosis in patients with pancreatic cancer.

METHODS

TP, OPRT, and DPD mRNA expressions were detected using a real-time reverse transcriptional-polymerase chain reaction method or by immunohistochemistry, using surgical specimens obtained from 25 patients with pancreatic cancer.

RESULTS

TP mRNA expression was lower in cases with an alpha infiltration growth pattern than in cases with other infiltration growth patterns (P < 0.05). OPRT mRNA expression was higher in poorly differentiated-type cases than in differentiated type cases (P < 0.05). TP-, OPRT-, and DPD-positive stainings were found in 15 of 24 cases (63%), 10 of 19 cases (53%), and 14 of 21 cases (67%), respectively. There were significant correlations or trends between the mRNA and protein expressions of TP, OPRT, and DPD. Patients with a low TP/DPD ratio survived significantly longer than those with a high ratio (P < 0.05). Multivariate analysis demonstrated a significantly poorer outcome in patients with a high TP/DPD ratio compared with in patients with a low ratio (P < 0.05).

CONCLUSION

The TP/DPD ratio might be useful as a prognostic factor in patients with pancreatic cancer.

Correlation between thymidylate synthase and dihydropyrimidine dehydrogenase mRNA level and in vitro chemosensitivity to 5-fluorouracil, in relation to differentiation in gastric cancer

PURPOSE

It has been suggested that the gene expression levels of thymidylate synthase (TS) and dihydropyrimidine dehydrogenase (DPD) help in the prediction of the response to 5-fluorouracil (5-FU) in vivo and in vitro in gastric cancers.

METHODS

In this study, intratumoral TS and DPD gene expressions were evaluated with real time reverse transcriptional polymerase chain reaction technique to determine the correlation between the expression of these two genes and in vitro sensitivity to 5-FU, assessed by the histoculture drug response assay on 87 patients with gastric adenocarcinoma.

RESULTS

The sensitivity to 5-FU did not show any difference in clinicopathological groups. DPD gene level was higher in undifferentiated (n = 39) than differentiated (n = 48) tumors (P = 0.043). In differentiated tumors, TS gene expression levels were higher in the tumors with relative resistance to 5-FU, while in undifferentiated cases, DPD mRNA levels were higher in tumors that showed resistance to 5-FU in vitro (P = 0.043 and 0.007, respectively). DPD also had significant predictive value for 5-FU sensitivity in undifferentiated cases [R(S) = -0.401, P = 0.011]. TS and DPD gene expression levels were more highly correlated in undifferentiated compared to differentiated cases [R(S) = 0.515 and 0.359, respectively].

CONCLUSIONS

Different gene expression might be responsible for 5-FU sensitivity in gastric cancers of different histologic origin.

Gene expression of 5-fluorouracil metabolic enzymes in primary gastric cancer: correlation with drug sensitivity against 5-fluorouracil

Thymidylate synthase (TS), dihydropyrimidine dehydrogenase (DPD), thymidine phosphorylase (TP), and orotate phosphoribosyltransferase (OPRT) have been reported to be predictive parameters for the efficacy of fluoropyrimidine-based chemotherapy. mRNA expression of TS, DPD, TP, and OPRT were quantified by reverse-transcriptase polymerase chain reaction after harvesting cancer cells from 93 paraffin-embedded specimens of gastric cancer through laser capture microdissection. In vitro chemosensitivity testing by histoculture drug response assay was performed with surgically resected primary lesions of the same 93 patients. No significant correlation was observed between the mRNA expression and location of the tumor, histopathologic type, clinical stage, and other clinicopathologic variables, with the exception that OPRT mRNA had a weak correlation with drug sensitivity against 5FU (R=0.219, p=0.0343). OPRT was considered to have a major impact on drug sensitivity, although not sufficiently so to enable prediction of 5FU sensitivity solely based on the mRNA expression of this enzyme.

Prediction of clinical outcome of fluoropyrimidine-based chemotherapy for gastric cancer patients, in terms of the 5-fluorouracil metabolic pathway

Fluoropyrimidines are widely used in chemotherapy regimens for metastatic gastric cancer. Interindividual variation in the enzyme activity of the 5-fluorouracil (FU) metabolic pathway can affect the extent of 5-FU metabolism and affect the efficacy of 5-FU based chemotherapy. In this review, the role of the genetic factors affecting the therapeutic efficacy of fluoropyrimidines is discussed, with a special emphasis on enzymes involved in the 5-FU metabolic pathway. The gene expressions of thymidylate synthase, dihydropyrimidine dehydrogenase, thymidine phosphorylase, and orotate phosphoribosyltransferase are discussed in relation to the efficacy of fluoropyrimidine treatment for metastatic gastric cancer. These candidate genes, along with others yet to be identified, could allow accurate prediction of the clinical outcome in patients receiving fluoropyrimidine-based chemotherapy in the future. Well-designed and large prospective studies, which include relevant pharmacogenetic parameters, are needed to confirm the values required to predict clinical outcome.

Capecitabine/Cyclophosphamide/Methotrexate for patients with metastatic breast cancer: a dose-finding, feasibility, and efficacy study

BACKGROUND

Capecitabine is a fluoropyrimidine carbamate that acts as a prodrug, mimics continuous infusion of 5-fluorouracil (5-FU), and has encouraging antitumor activity in women with metastatic breast cancer. We performed a feasibility study in which the 5-FU of the cyclophosphamide/methotrexate/5-FU regimen was substituted with capecitabine in a novel regimen applicable to women with breast cancer. Three doses of capecitabine were explored (1650 mg/m2, 1850 mg/m2, and 2000 mg/m2 per day from day 1 to day 14) in combination with intravenous bolus cyclophosphamide (600 mg/m2) and methotrexate (40 mg/m2), given on day 1 and day 8 every 4 weeks.

PATIENTS AND METHODS

From June 2002 to August 2004, 39 women with metastatic breast cancer were enrolled and were evaluable for toxicity and response.

RESULTS

Hematologic toxicity was mild for the majority of patients: grade 4 neutropenia and anemia and grade 3 thrombocytopenia occurred in 1 patient. Nonhematologic toxicity of grade > or = 3 occurred only at the highest dose level. Overall response rate was 44% (complete response rate, 13%; partial response rate, 31%). Clinical benefit including long-lasting (> or = 6 months) stable disease overall accounted for 82%. Responses were observed at each dose level. The median duration of response was 14 months (95% confidence interval, 10-28 months). At a median observation of 24 months (range, 8-36 months), time to progression was 13 months (95% confidence interval, 9-24 months).

CONCLUSION

The data of our study show that cyclophosphamide/methotrexate/capecitabine is feasible and active. The capecitabine dose of 1850 mg/m(2) orally on days 1-14 every 28 days was selected as the recommended dose in view of the higher likelihood of "on time" chronic therapy compared with the 2000-mg/m(2) dose.

Reg IV is a serum biomarker for gastric cancer patients and predicts response to 5-fluorouracil-based chemotherapy

Regenerating gene family, member 4 (Reg IV), a secreted protein, is overexpressed in several cancers, including gastric cancer (GC). In the present study, we measured Reg IV levels in sera from patients with GC by enzyme-linked immunosorbent assay. We also examined the effect of forced Reg IV expression on the apoptotic susceptibility to 5-fluorouracil (5-FU). Forced expression of Reg IV inhibited 5-FU-induced apoptosis. Induction of Bcl-2 and dihydropyrimidine dehydrogenase was involved in inhibition of apoptosis. Among 36 GC patients treated with a combination chemotherapy of low-dose 5-FU and cisplatin, all 14 Reg IV-positive patients showed no change or disease progression. The serum Reg IV concentration was similar between healthy individuals (mean+/-s.e., 0.52+/-0.05 ng/ml) and patients with chronic-active gastritis (0.36+/-0.09 ng/ml). However, the serum Reg IV concentration in presurgical GC patients was significantly elevated (1.96+/-0.17 ng/ml), even at stage I. The diagnostic sensitivity of serum Reg IV (36.1%) was superior to that of serum carcinoembryonic antigen (11.5%) or carbohydrate antigen 19-9 (13.1%). These results indicate that expression of Reg IV is a marker for prediction of resistance to 5-FU-based chemotherapy in patients with GC. Serum Reg IV represents a novel biomarker for GC.

Prediction of response to neoadjuvant chemotherapy in carcinomas of the upper gastrointestinal tract

Increasingly, multimodal treatment protocols are being employed to improve the survival of patients with locally advanced adenocarcinomas of the upper gastrointestinal tract; however, only 30%-40% of the patients respond to 5-fluoro-uracil (5-FU) and cisplatin-based neoadjuvant chemotherapy. The goal of our studies is the identification of reliable genetic markers--on the genomic DNA, messenger RNA (mRNA), or protein level-that could predict response of upper gastrointestinal carcinomas prior to neoadjuvant chemotherapy. In esophageal carcinomas, a higher gene expression of methylenetetrahydrofolate reductase (MTHFR), an enzyme involved in folate metabolism, was more frequently found in responding patients. In addition high gene expression of caldesmon and of the two drug carrier proteins MRP1 and MDR1 was associated with response to therapy. By performing a genome-wide profiling on the protein level in a small group of patients, new potential markers were identified that will have to be validated in ongoing studies. In gastric carcinomas, mutations of the p53 gene revealed no association with response or survival, but tumors with a high rate of loss of heterozygosity, as determined by microsatellite analysis, showed a better response to a cisplatin-based chemotherapy. Analysis of the expression of 5-fluorouracil (5-FU) (TS, DPD, TP)- and cisplatin (ERCC1, ERCC4, GADD45A, KU80)-related genes demonstrated an association of DPD expression with response and survival. The combined consideration of TP and GADD45 gene expression showed the most obvious association with therapy response in this tumor. Our studies point to promising markers with potential use for chemotherapy response prediction of adenocarcinomas of the upper gastrointestinal tract, but prospective studies for validation are necessary.

Chemotherapy sensitivity and resistance testing: to be "standard" or to be individualized, that is the question

Radical surgery with extended lymph-node dissection is the treatment of first choice and the only curative treatment for locally advanced gastric cancer. While recent combination chemotherapy with S-1 (a combination of tegafur with two biomodulators, gimeracil and oteracil) has achieved high response rates, controversy still remains regarding the significance of adjuvant cancer chemotherapy after surgery. We have been applying chemosensitivity testing in evaluating the appropriate adjuvant cancer chemotherapy for advanced gastric cancer. Our multiple studies have indicated that this chemosensitivity testing would be useful to improve the results of adjuvant chemotherapy, by increasing survivals in the sensitive group. The chemosensitivity testing is approved as "advanced clinical medicine" by the Japanese Ministry of Health, Welfare, and Labor at 11 institutes at present. While complete lymph-node dissection and chemosensitivity test-guided adjuvant chemotherapy has been reported to result in a survival benefit for patients with advanced gastrointestinal cancer, the clinical utility of the testing should be established by means of prospective, randomized clinical trials. Two pivotal clinical trials have been initiated to clarify the utility of chemosensitivity testing in the selection of the appropriate adjuvant cancer chemotherapy for gastric cancer.

Simple combinations of 5-FU pathway genes predict the outcome of metastatic gastric cancer patients treated by S-1

We evaluated the expression of 5-FU pathway genes in prechemotherapeutic fresh frozen samples obtained from primary tumors to predict response and survival of 59 metastatic gastric cancer patients treated with S-1 monotherapy as first line treatment. Five 5-FU pathway genes, including thymidylate synthase (TS), dihydropyrimidine dehydrogenase (DPD), orotate phosphoribosyltransferase (OPRT), thymidine phosphorylase (TP) and uridine phosphorylase (UP), were analyzed by the quantitative real-time reverse transcriptional PCR method. Median values of each gene were selected for cut-off values separating high and low gene expressions. In univariate analyses, low TS, high OPRT and low TP were significantly associated with a tumor shrinkage and a long survival, whereas DPD and UP gene expressions did not correlate with response and survival. Multivariate analyses revealed that independent variables were OPRT and TS for response and TS and TP for survival. When OPRT and TS were combined, a significantly increased accuracy rate of 91.5% was seen for response. Similarly, an increased hazard ratio of 10.29 was observed for survival in patients possessing low TS and low TP, compared with those with high TS or high TP. The simple combinations of 2 genes, OPRT and TS for response and TS and TP for survival, may allow identification of gastric cancer patients who will benefit from S-1 chemotherapy.

Orotate phosphoribosyl transferase mRNA expression in oral squamous cell carcinoma and its relationship with the dihydropyrimidine dehydrogenase expression and the clinical effect of 5-fluorouracil

In this study, we investigated whether orotate phosphoribosyl transferase (OPRT) correlates with the clinicopathological features and effect of 5-fluorouracil (5-FU) in human oral carcinoma. We examined the expression of OPRT mRNA by in situ hybridization in surgical specimens of oral squamous cell carcinoma. The expression of OPRT mRNA in oral carcinoma was observed in all specimens and such expression was higher than that seen in normal control tissue specimens. There was no correlation between the expression of OPRT mRNA and clinical factors, but the expression of OPRT mRNA was significantly associated with histological differentiation. The expression of OPRT mRNA showed correlation with effect of 5-FU for oral carcinoma in either in vivo or in vitro. These results suggest that the OPRT expressions may therefore be a prognostic factor of 5-FU efficacy in patients with oral squamous cell carcinoma.

Orotate phosphoribosyltransferase levels measured by a newly established enzyme-linked immunosorbent assay in gastric carcinoma

A number of enzymes have been shown to be involved in the process of activation and/or degradation of 5-fluorouracil (5-FU), and are potential candidates for predicting chemosensitivity to 5-FU. Among these, orotate phosphoribosyltransferase (OPRT EC 2.4.2.10) is a key enzyme related to the first-step activation process of 5-FU and has been shown to be an important enzyme that helps to predict sensitivity to 5-FU and its related derivatives. We developed a new enzyme-linked immunosorbent assay (ELISA) to accurately assess intratumoral activity of OPRT. A new sandwich ELISA was established using anti-OPRT polyclonal antibodies obtained from the rabbit immunized with the recombinant human peptides of the OPRT molecule. OPRT levels were measured in eight human cancer xenografts and in 75 gastric cancer tissues using both a newly established ELISA and a conventional enzyme assay, using radiolabeled 5-FU as a substrate. There was a significant correlation between OPRT levels measured by this ELISA and OPRT enzyme activity the in eight human cancer xenografts (r2 = 0.782) and gastric carcinoma tissue (r2 = 0.617). The ELISA system for OPRT requires a minimal amount of carcinoma tissue, making it an easy-to-use assay system to predict sensitivity to 5-FU and its derivatives in gastric carcinoma. There was a significant correlation between tumor growth inhibition rates against the oral administration of oral-uracil/tegafur (UFT) and OPRT enzyme activity in the human cancer xenografts (r2 = 0.574). These results suggest that this newly developed sandwich ELISA system for the quantification of OPRT levels is technically simple, feasible and a useful tool to predict sensitivity to fluoropyrimidine-based anticancer chemotherapy in patients with gastric carcinoma and other cancers.

Unpredicted severe toxicity after 5-fluorouracil treatment due to dihydropyrimidine dehydrogenase deficiency

Dihydropyrimidine dehydrogenase (DPD) is the initial and rate-limiting enzyme in the catabolism of 5-fluorouracil (5-FU). Thus, patients with a DPD deficiency are at risk of developing severe 5-FU-associated toxicity. A 37-year-old female with gastric cancer underwent a curative operation, followed by adjuvant chemotherapy consisting of 5-FU and epirubicin. After the first cycle of chemotherapy, the patient manifested grade 2 mucositis and febrile neutropenia, and when her treatment was subsequently continued with doxifluridine she developed severe mucositis and febrile neutropenia. A PCR study revealed that her DPD mRNA level was lower than that in a control group. Thus, when considering the routine use of 5-FU for the treatment of cancer patients, an analysis of DPD activity or screening for DPD mutations is warranted in confined patients who experience unpredicted severe toxicity after initial 5-FU administration, even though DPD deficiency is a rare metabolic defect.

Intermediate dose 5-fluorouracil-induced encephalopathy

As an acute neurotoxicity, high dose 5-fluorouracil (5-FU)-induced encephalopathy is well-known, but encephalopathy associated with lower dose is rarely reported. Here, we report a case of a male with anal cancer who was treated with 5-FU 1000 mg/m(2), continuous infusion for 5 days q4 weeks. At the second and the fourth cycles of chemotherapy, sudden confusion, cognitive dysfunction and disorientation occurred during 5-FU infusion. They were accompanied by hyperammonemia in the absence of focal neurological deficits or structural abnormalities. These symptoms completely disappeared and the serum ammonia level returned to normal after discontinuation of 5-FU and conservative care. In order to investigate a possible deficit of dihydropyrimidine dehydrogenase (DPD), we checked its mRNA level before and after treatment using real-time PCR. The patient's pre-treatment level was 80% compared with reference group, and it was elevated up to 187% of initial after 5-FU treatment, implying that that his encephalopathy may be 5-FU catabolite type rather than DPD deficiency. In conclusion, we report that encephalopathy can develop even with the dose of 5-FU lower than ever reported, and it should be considered as a differential diagnosis for proper management.

Combined GADD45A and thymidine phosphorylase expression levels predict response and survival of neoadjuvant-treated gastric cancer patients

PURPOSE

We evaluated the expression of seven therapy-related genes to predict the clinical outcome of advanced gastric cancer patients treated with a neoadjuvant chemotherapeutic protocol.

EXPERIMENTAL DESIGN

Pretherapeutic, formalin-fixed, and paraffin-embedded biopsies of 61 patients, who received a 5-fluorouracil (5-FU)- and cisplatin-based chemotherapy were studied. The expressions of the 5-FU-related genes TS, DPD, and TP and of the cisplatin-related genes ERCC1, ERCC4, KU80, and GADD45A were analyzed by quantitative real-time PCR. The expression levels of single genes and of various combinations were tested for an association with response and overall survival.

RESULTS

High DPD levels were more frequently found in nonresponding patients and were associated with worse survival. GADD45A and TP levels showed weak associations with response, but GADD45A expression correlated with survival. There was no association with response for TS expression, but tumors with a high TS level were associated with worse survival. The combination of GADD45A and TP revealed the strongest predictive effect. High expression values of TP and/or GADD45A were exclusively found in nonresponding patients (P = 0.002) and were associated with a significantly poorer survival (P = 0.04).

CONCLUSIONS

Combined gene expression levels of TP and GADD45A represent a new variable to predict the clinical outcome after neoadjuvant chemotherapy in gastric cancer. The association of DPD expression with response and survival underlines a predominant role of DPD to predict 5-FU sensitivity. The association of TS expression levels with survival but not with response suggests an importance of this gene for tumor progression.

Cancer cell adaptation to chemotherapy

Background

Tumor resistance to chemotherapy may be present at the beginning of treatment, develop during treatment, or become apparent on re-treatment of the patient. The mechanisms involved are usually inferred from experiments with cell lines, as studies in tumor-derived cells are difficult. Studies of human tumors show that cells adapt to chemotherapy, but it has been largely assumed that clonal selection leads to the resistance of recurrent tumors.

Methods

Cells derived from 47 tumors of breast, ovarian, esophageal, and colorectal origin and 16 paired esophageal biopsies were exposed to anticancer agents (cisplatin; 5-fluorouracil; epirubicin; doxorubicin; paclitaxel; irinotecan and topotecan) in short-term cell culture (6 days). Real-time quantitative PCR was used to measure up- or down-regulation of 16 different resistance/target genes, and when tissue was available, immunohistochemistry was used to assess the protein levels.

Results

In 8/16 paired esophageal biopsies, there was an increase in the expression of multi-drug resistance gene 1 (MDR1) following epirubicin + cisplatin + 5-fluorouracil (ECF) chemotherapy and this was accompanied by increased expression of the MDR-1 encoded protein, P-gp. Following exposure to doxorubicin in vitro, 13/14 breast carcinomas and 9/12 ovarian carcinomas showed >2-fold down-regulation of topoisomerase IIα (TOPOIIα). Exposure to topotecan in vitro, resulted in >4-fold down-regulation of TOPOIIα in 6/7 colorectal tumors and 8/10 ovarian tumors.

Conclusion

This study suggests that up-regulation of resistance genes or down-regulation in target genes may occur rapidly in human solid tumors, within days of the start of treatment, and that similar changes are present in pre- and post-chemotherapy biopsy material. The molecular processes used by each tumor appear to be linked to the drug used, but there is also heterogeneity between individual tumors, even those with the same histological type, in the pattern and magnitude of response to the same drugs. Adaptation to chemotherapy may explain why prediction of resistance mechanisms is difficult on the basis of tumor type alone or individual markers, and suggests that more complex predictive methods are required to improve the response rates to chemotherapy.

Thymidylate synthase and dihydropyrimidine dehydrogenase gene expression in breast cancer predicts 5-FU sensitivity by a histocultural drug sensitivity test

Thymidylate synthase (TS), Dihydropyrimidine dehydrogenase (DPD) and Thymidine Phosphorylase (TP) gene expressions are reported to be predictive markers for 5-fluorouracil (5-FU) sensitivity in gastrointestinal cancer. However, in breast cancer, it is still controversial whether those molecular markers predict 5-FU sensitivity or not. One possible reason for the difficulty may be the histological heterogeneity in breast cancer specimens. In this study, TS, DPD and TP mRNA expression in 40 breast cancer tumors were semi-quantified separately in cancer cells (Ca), cancerous stroma (Str) and normal glands (Nor) using laser capture microdissection and real time RT-PCR (LCM+RT-PCR). The histoculture drug response assay (HDRA) for 5-FU sensitivity was performed for 22 tumors. TS and TP mRNA expressions were higher in Ca than Str, although DPD gene expression was lower in Ca than Str. The group of high TS and high DPD gene expression in Ca was resistant to 5-FU, and the group of low TS and low DPD gene expression in Ca was sensitive to 5-FU (P=0.048 chi-square test). TS and DPD mRNA expressions measured using LCM+RT-PCR might be useful predictive markers for 5-FU sensitivity in human breast cancer.

Evaluation of sensitivity to 5-FU on the basis of thymidylate synthase (TS)/dihydropyrimidine dehydrogenase (DPD) activity and chromosomal analysis in micro tissue specimens of breast cancer

BACKGROUND

Preoperative assessment of the anticancer drug sensitivity of tumors plays an important role in the selection of therapy. If evaluation of the 5-FU sensitivity of microtissue specimens obtained by techniques such as core needle biopsy could be performed, the addition of fluorouracil to adriamycin and cyclophosphamide may further enhance response rates. In order to evaluate a simple sensitivity test for the anti-tumor agent 5-fluorouracil (5-FU), we examined whether an assay of a small sample could measure mRNA to predict the activities of thymidylate synthase (TS) and dihydropyrimidine dehydrogenase (DPD). In addition, gene abnormalities on chromosomes 1 and 18 corresponding to DPD, TS and the relationships between the gene abnormalities and the amount of mRNA and activity were examined.

METHOD

TS and DPD activity were measured using the fluorodeoxyuridine monophosphate ligand binding assay and radio enzymatic assay, respectively, while mRNA levels were assayed by real-time polymerase chain reaction. Chromosome 1 and 18 aberrations were investigated by fluorescence in situ hybridization (FISH) with centromere probes.

RESULTS

TS mRNA and TS activity showed a positive correlation (r=0.518, p=0.0017). TS activity and TS mRNA were significantly higher in the nuclear grade 3 group than in the other groups (p=0.04, p=0.0072, respectively). TS activity and mRNA in tumor tissue tended to decrease in the progesterone receptor positive groups (p=0.059, p=0.066, respectively). There was no correlation between DPD mRNA and DPD activity in tumor tissue (r=0.139, p=0.4423). DPD mRNA was measured as 282.88+/-170.68 copies/cell in tumor tissue and 635.88+/-310.04 copies/cell in normal tissue, and was thus significantly higher in normal tissue (p<0.001).

CONCLUSIONS

TS mRNA showed a positive correlation with TS activity, suggesting that this method of using small amounts of tissue can replace anti-cancer drug sensitivity tests.

Tumoral drug metabolism: overview and its implications for cancer therapy

Drug-metabolizing enzymes (DME) in tumors are capable of biotransforming a variety of xenobiotics, including antineoplastics, resulting in either their activation or detoxification. Many studies have reported the presence of DME in tumors; however, heterogeneous detection methodology and patient cohorts have not generated consistent, firm data. Nevertheless, various gene therapy approaches and oral prodrugs have been devised, taking advantage of tumoral DME. With the need to target and individualize anticancer therapies, tumoral processes such as drug metabolism must be considered as both a potential mechanism of resistance to therapy and a potential means of achieving optimal therapy. This review discusses cytotoxic drug metabolism by tumors, through addressing the classes of the individual DME, their relevant substrates, and their distribution in specific malignancies. The limitations of preclinical models relative to the clinical setting and lack of data on the changes of DME with disease progression and host response will be discussed. The therapeutic implications of tumoral drug metabolism will be addressed-in particular, the role of DME in predicting therapeutic response, the activation of prodrugs, and the potential for modulation of their activity for gain are considered, with relevant clinical examples. The contribution of tumoral drug metabolism to cancer therapy can only be truly ascertained through large-scale prospective studies and supported by new technologies for tumor sampling and genetic analysis such as microarrays. Only then can efforts be concentrated in the design of better prodrugs or combination therapy to improve drug efficacy and individualize therapy.

Thymidylate synthase and dihydropyrimidine dehydrogenase gene expression in relation to differentiation of gastric cancer

Thymidylate synthase (TS) and dihydropyrimidine dehydrogenase (DPD) are important enzymes of DNA de novo synthesis and the salvage pathway in cancer cells, respectively. Intratumoral TS and DPD gene expressions were evaluated to determine the correlation between the expression of the 2 genes in both normal stromal tissues and tissues with different degrees of malignant differentiation in primary gastric cancer. The study population consisted of 78 consecutive patients with advanced gastric cancer who underwent surgical treatment. Laser-captured microdissection of malignant or normal stromal tissues was performed in formalin-fixed, paraffin-embedded specimens. After extraction of RNA, TS and DPD gene expressions were measured by the real-time reverse transcriptional PCR method. Apart from degree of differentiation, TS and DPD in malignant tissue showed no correlation with clinicopathologic factors. TS in malignant tissue was higher in differentiated type cases than undifferentiated type cases (p < 0.01). However, DPD in malignant tissue of undifferentiated type cases was statistically higher than that of differentiated type cases (p < 0.05). In normal stromal tissue, neither TS nor DPD had any correlation with clinicopathologic factors. TS in malignant tissue was statistically higher than in normal stromal tissue in both differentiated and undifferentiated types (p < 0.0001). DPD in differentiated type malignant tissue was statistically lower than in normal stromal tissue (p < 0.001), but no difference was seen in undifferentiated type cases. TS and DPD gene expressions in primary gastric cancer differ according to degree of differentiation and between malignant and normal stromal tissue.

Clinical significance of dihydropyrimidine dehydrogenase in adjuvant 5-fluorouracil liver perfusion chemotherapy for pancreatic cancer

OBJECTIVE

To clarify the relationship between intratumoral dihydropyrimidine dehydrogenase (DPD) expression and response to 5-fluorouracil (5-FU) liver perfusion chemotherapy (LPC) in pancreatic cancer patients, we evaluated DPD expression immunohistochemically in resected pancreatic cancer tissues.

SUMMARY BACKGROUND DATA

Pancreatic cancer is considered a disease with a poor prognosis even if aggressive resection is performed. One of the main causes of death is hepatic metastasis soon after surgery. As a treatment, we have assessed adjuvant LPC via the portal vein using 5-FU just after pancreatectomy for advanced pancreatic cancer since 1994. However, the results remain unsatisfying.

METHODS

Sixty-eight resected specimens were obtained from patients with pancreatic cancer from 1988 to 2000. Formalin-fixed paraffin-embedded tissues were immunostained with polyclonal anti-DPD antibody. The relation between intratumoral DPD expression and the prognoses of pancreatic cancer patients was investigated statistically.

RESULTS

Of the 68 tumors studied, 27 carcinomas (39.7%) were DPD(+), and 41 (60.3%) were DPD(-). In the DPD(+) group, there was no significant difference between the LPC(+) and LPC(-) subgroups, whereas in the DPD(-) group the LPC(+) subgroup showed a significantly higher survival rate than the LPC(-) subgroup. Moreover, in the LPC(+) group, overall survival in the DPD(-) subgroup was significantly better than in the DPD(+) subgroup.

CONCLUSIONS

An immunohistochemical evaluation of intratumoral DPD expression might be useful in predicting responsiveness to 5-FU-based chemotherapy in pancreatic cancer patients. In the DPD(-) group, liver perfusion chemotherapy using 5-FU via the portal vein is effective adjuvant therapy for pancreatic cancer once pancreatectomy has been performed.

Tailored Chemotherapy for Colorectal Cancer: A New Approach to Therapy

The treatment of colorectal cancer has advanced over the past several years with the introduction of several active agents. Determining which patients to treat with chemotherapy and choosing optimal treatment would allow practioners to maximize the benefit of chemotherapy. Several prognostic and predictive markers have been identified and include oncogenes, tumor suppressor genes, genes involved in angiogenic and apoptotic pathways and cell proliferation, and those encoding targets of chemotherapy. Specifically, prognostic markers include deletion of 18q (DCC), p27 and microsatellite instability. Predictive markers are those that may determine efficacy of drugs used in colorectal cancer such as fluropyrimidines and oxaliplatin. Alterations in gene expression, protein expression and polymorphic variants in genes encoding thymidylate synthase, dihydropyrimidine dehydrogenase, and thymidine phosphorylase and excision repair cross-complementing genes (ERCC1) may be useful as markers for clinical drug response, survival and host toxicity. The integration of these prognostic and predictive markers would allow individualized treatment for patients, maximizing therapeutic effect and minimizing exposure to toxicity.

Correlation of thymidylate synthase, thymidine phosphorylase and dihydropyrimidine dehydrogenase with sensitivity of gastrointestinal cancer cells to 5-fluorouracil and 5-fluoro-2’-deoxyuridine

AIM: To determine the expression levels of three metabolic enzymes of fluoropyrimidines: thymidylate synthase (TS), thymidine phosphorylase (TP) and dihydropyrimidine dehydrogenase (DPD) in seven human gastrointestinal cancer cell lines, and to compare the enzyme levels with the sensitivity to 5-fluorouracil (5-FU) and 5-fluoro-2’-deoxyuridine (FdUrd).

METHODS: TS, TP and DPD mRNA levels were assessed by semi-quantitative RT-PCR, TP and DPD protein contents were measured by ELISA. Fifty percent inhibitory concentrations of growth (IC50), representing the sensitivity to drugs, were determined by MTT assay.

RESULTS: IC50 values ranged from 1.28 to 12.26 uM for 5-FU, and from 5.02 to 24.21 uM for FdUrd, respectively. Cell lines with lower DPD mRNA and protein levels tended to be more sensitive to 5-FU (P < 0.05), but neither TS nor TP correlated with 5-FU IC50 (P > 0.05). Only TS mRNA level was sharply related with FdUrd sensitivity (P < 0.05), but TP and DPD were not (P > 0.05). A correlation was found between mRNA and protein levels of DPD (P < 0.05), but not TP (P < 0.05).

CONCLUSION: DPD and TS enzyme levels may be useful indicators in predicting the antitumor activity of 5-FU or FdUrd, respectively.

Differences in dihydropyrimidine dehydrogenase activities between gastric and colorectal cancer

We studied the relation between clinicopathological factors and dihydropyrimidine dehydrogenase (DPD) activity in gastric and colorectal carcinomas. Specimens obtained by surgery from 27 gastric and 17 colorectal carcinomas and their normal mucosa were examined. The levels of DPD activity in the gastric carcinomas and their normal mucosa were significantly higher than those in colorectal carcinomas and their normal counterparts, respectively (both P's < 0.0001). The gastric carcinomas had significantly higher DPD activities than their normal mucosa (P = 0.028), but the colorectal carcinomas did not. Among the clinicopathological factors, which included invasion/metastatic status and staging, the only effect was that of the histological differences of gastric cancer on DPD activity. That is, the level of DPD activity of the histologically undifferentiated gastric carcinoma was significantly higher than that of the differentiated type. No prognostic predictive values of DPD were recognized in either gastric and colorectal cancer. In conclusion, the higher DPD activity in gastric cancer than colorectal cancer may be due to the higher DPD activity in the background mucosa of origin, and the higher population of undifferentiated type of histological classification, compared to the colorectal counterparts.

Gene expression in colorectal cancer and in vitro chemosensitivity to 5-fluorouracil: a study of 88 surgical specimens

To predict the sensitivity of colorectal cancer to 5-fluorouracil (5-FU), we compared the gene expression of surgically obtained colorectal cancer specimens with chemosensitivity to 5-FU as detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H tetrazolium bromide (MTT) assay. Eighty-eight patients with advanced and/or metastatic colorectal cancer provided written informed consent and entered the trial from September 2000 to October 2001. Fresh surgical specimens were used for the MTT assay, and sensitivity to 5-FU was evaluated at a cutoff concentration of 50 microg/ml and 48-h incubation time. Frozen samples were stored at - 80 degrees C until mRNA analysis of thymidylate synthetase (TS), dihydropyrimidine dehydrogenase (DPD), thymidine phosphorylase (TP), es-nucleoside transporter (NT), and E2F1 by real-time RT-PCR. The correlations between the variables were analyzed, and the predictive value of these mRNAs was assessed statistically using a receiver operating characteristic (ROC) curve. NT and DPD, TP and DPD, and TP and NT mRNA expression levels correlated significantly, while TS and E2F1 showed no correlations. High NT expression was associated with low sensitivity to 5-FU (P < 0.013), as were high DPD and E2F1 expression (P < 0.022 for both). High TP mRNA expression correlated with low sensitivity to 5-FU (P < 0.034), although high TS mRNA expression did not. ROC curves indicated that DPD and NT mRNAs were possible predictors of sensitivity to 5-FU, with cutoff values of 0.6 and 0.4, respectively. The sensitivity of colorectal cancer to 5-FU may be regulated by DPD, the rate-limiting enzyme of catabolism, and NT, an important transmembrane transporter of nucleosides.

New prognostic indicator for non-small-cell lung cancer, quantitation of thymidylate synthase by real-time reverse transcription polymerase chain reaction

Thymidylate synthase (TS) is an enzyme that catalyzes an important DNA biosynthesis process. The gene expression of TS has not been reported in non-small-cell lung cancer (NSCLC) patients. To clarify the correlation between TS mRNA levels and clinicopathological features of NSCLC, we examined 70 Stage I and II NSCLC patients for intra-tumoral expression of TS using TaqMan reverse transcription polymerase chain reaction (RT-PCR) assay and immunohistochemistry methods. We also investigated the TS promoter 28 bp polymorphism in 48 cancer tissues using PCR amplification of genomic DNA. Lung cancer tissue showed higher TS mRNA levels than normal lung tissue (Mann-Whitney U-tests; p = 0.0020). Further, TS mRNA expression was correlated with immunohistochemical TS expression (p = 0.029). We obtained 2 different DNA fragments, which indicated triple-repeat (3R) and double-repeat (2R) type alleles. Cancer tissues with the 3R/3R genotype showed significantly higher TS mRNA levels as compared to those with other genotypes (p = 0.0019). The TS genotype was also correlated with immunohistochemical TS expression (chi(2) test; p = 0.0079). The disease-free survival of the low TS mRNA level group was significantly better than those with high TS mRNA levels (log-rank test; p = 0.010), however, there were no significant differences found by immunohistochemical evaluation (p = 0.34) or TS genotype analysis (p = 0.11). A multivariate analysis revealed that high TS mRNA levels independently contributed to disease-free survival. The quantitation of TS mRNA levels is clinically more sensitive and useful for determining the prognosis of Stage I and II NSCLC patients than an immunohistochemical evaluation.

Intratumoural thymidylate synthase and dihydropyrimidine dehydrogenase activities are good predictors of 5-fluorouracil sensitivity in colorectal cancer

To identify factors that influence the clinical response to 5-fluorouracil (5-FU), we studied the correlation between in vitro sensitivity to 5-FU and the expression of seven biological markers. The markers, thymidylate synthase (TS), dihydropyrimidine dehydrogenase (DPD), pyrimidine nucleoside phosphorylase, p53 (wild/mutant), p21, cyclo-oxygenase-2, and inducible nitric oxide synthase were measured in tumour tissues from 32 colorectal cancer patients. The activities of TS and DPD were significantly lower in the tumours sensitive to 5-FU compared with those that were not sensitive to 5-FU. In tumours with TS < 3.7 pmol/min per mg protein and DPD < 98 pmol/min per mg protein, the percentage of cases sensitive to 5-FU (67%) and the mean percentage inhibition of tumour cells by 5-FU (42.8%) were significantly higher than in the other tumours (0% and 13.1%, respectively). The other biological markers did not correlate with in vitro sensitivity to 5-FU. Tumour sensitivity to 5-FU can be more precisely predicted by taking the activities of both TS and DPD into consideration than by using either alone.

Targeted therapy and pharmacogenomic programs

The goal in administering chemotherapeutics is to develop the ability to predict the outcome of therapy in terms of response and toxicity. Technology has been developed to allow tumor profiling with measurement of protein expression, gene expression levels of markers, and even genetic polymorphisms, which may predict response to particular chemotherapeutics. The chemotherapeutics for which particular markers have been shown to predict outcome include the fluoropyrimidines and platinums. The next step is to develop clinical trials that will assess prospectively the benefits of profiling a patient's particular tumor, which should translate into an improvement in response and toxicity.