Expression of thymidylate synthase in gastric cancer patients treated with 5-fluorouracil and doxorubicin-based adjuvant chemotherapy after curative resection

STAT3 mediates RCP-induced cancer cell invasion through the NF-κB/Slug/MT1-MMP signaling cascade

Rab coupling protein (RCP) has been known to induce cancer invasion and metastasis, and STAT3 is one of major oncogenic factors. In the present study, we identify the critical role of STAT3 in RCP-induced cancer cell invasion. Immunohistochemical data of ovarian cancer tissues presented that levels of RCP expression are closely correlated with those of phospho-STAT3 (p-STAT3). In addition, ovarian cancer patients with high expression of both RCP and p-STAT3 had significantly lower progress-free and overall survival rates compared to those with low either RCP or p-STAT3 expression. Mechanistically, RCP induced STAT3 phosphorylation in both ovarian and breast cancer cells. Silencing or pharmacological inhibition of STAT3 significantly inhibited RCP-induced cancer cell invasion. In addition, we provide evidence that the β1 integrin/EGFR axis is important for RCP-induced STAT3 phosphorylation. Furthermore, STAT3 activated NF-κB for Slug expression that in turn upregulated MT1-MMP expression for cancer cell invasion. Collectively, our present data demonstrate that STAT3 is located downstream of the β1 integrin/EGFR axis and induces Slug and MT1-MMP expression for cancer cell invasion.

Relationship between the Expression of the Thymidylate Synthase and the Prognosis of Gastric Cancer Patients Treated with Combinational Chemotherapy Regimen Including Fluorouracil, Docetaxel and Cisplatin

Background: Thymidylate synthase is one of the target enzymes of 5-fluorouracil. However, the clinical and prognostic significance of TS expression in gastric cancer has remained controversial. In this study, the expression of thymidylate synthase was evaluated in gastric cancer patients treated with combinational chemotherapy; moreover, the association between TS expression and clinicopathologic characteristics and overall survival of the patients were also assessed.

Materials and Methods: In this descriptive study, 89 pathological samples were gathered from patients at Kermanshah hospitals during 2008-2017. The survival status of patients was recorded and their overall survival was evaluated individually.

Results: The average survival period for low and high thymidylate synthase groups was 54 and 50 months, respectively, meaning higher survival time in the lower thymidylate group. But this difference was not statistically significant (log Rank=0.88). In addition, sex, stage, recurrence, and survival had no significant difference between the low and high expression of thymidylate synthase groups (p=0.89).

Conclusion: The results clearly indicated that the level of thymidylate synthase is not a significant modulator of 5- fluorouracil in gastric cancer patients. Nevertheless, evaluation of the level of the enzymes and markers as well as their effects are highly recommended for accurate selection of chemotherapeutical strategies.

Immunohistochemistry Biomarkers Predict Survival in Stage II/III Gastric Cancer Patients: From a Prospective Clinical Trial

Purpose

Identification of biomarkers to predict recurrence risk is essential to improve adjuvant treatment strategies in stage II/III gastric cancer patients. This study evaluated biomarkers for predicting survival after surgical resection.

Materials and Methods

This post-hoc analysis evaluated patients from the CLASSIC trial who underwent D2 gastrectomywith orwithout adjuvant chemotherapy (capecitabine plus oxaliplatin) at the Yonsei Cancer Center. Tumor expressions of thymidylate synthase (TS), excision repair cross-complementation group 1 (ERCC1), and programmed death-ligand 1 (PD-L1) were evaluated by immunohistochemical (IHC) staining to determine their predictive values.

Results

Among 139 patients, IHC analysis revealed high tumor expression of TS (n=22, 15.8%), ERCC1 (n=23, 16.5%), and PD-L1 (n=42, 30.2%) in the subset of patients. Among all patients, high TS expression tended to predict poor disease-free survival (DFS; hazard ratio [HR], 1.80; p=0.053), whereas PD-L1 positivity was associated with favorable DFS (HR, 0.33; p=0.001) and overall survival (OS; HR, 0.38; p=0.009) in multivariate Cox analysis. In the subgroup analysis, poor DFS was independently predicted by high TS expression (HR, 2.51; p=0.022) in the adjuvant chemotherapy subgroup (n=66). High PD-L1 expression was associated with favorable DFS (HR, 0.25; p=0.011) and OS (HR, 0.22; p=0.015) only in the surgery-alone subgroup (n=73). The prognostic impact of high ERCC1 expression was not significant in the multivariate Cox analysis.

Conclusion

This study shows that high TS expression is a predictive factor for worse outcomes on capecitabine plus oxaliplatin adjuvant chemotherapy, whereas PD-L1 expression is a favorable prognostic factor in locally advanced gastric cancer patients.

Prognostic and Predictive Value of p21-activated Kinase 6 Associated Support Vector Machine Classifier in Gastric Cancer Treated by 5-fluorouracil/Oxaliplatin Chemotherapy

To determine whether p21-activated Kinase (PAK) 6 is a prognostic and predictive marker in gastric cancer (GC) and to construct a classifier that can identify a subset of patients who are highly sensitive to 5-fluorouracil/oxaliplatin chemotherapy. We retrospectively analyzed the expression levels of PAK6, cyclooxygenase 2, p21^WAF1, Ki-67, excision repair cross-complementing gene 1, and thymidylate synthase in 242 paraffin-embedded GC specimens of the training cohort by immunohistochemistry. Then, we used support vector machine (SVM)–based methods to develop a predictive classifier for chemotherapy (chemotherapy score – CS-SVM classifier). Further validation was performed in an independent cohort of 279 patients. High PAK6 expression was associated with poor prognosis and increased chemoresistance to 5-FU/oxaliplatin chemotherapy. The CS-SVM classifier distinguished patients with stage II and III GC into low- and high-CS-SVM groups, with significant differences in the 5-year disease-free survival (DFS) and overall survival (OS) in chemotherapy patients. Moreover, chemotherapy significantly prolonged the DFS and OS of the high CS-SVM patients in the training and validation cohorts. In conclusion, PAK6 was an independent prognostic factor and increased chemoresistance. The CS-SVM classifier distinguished a subgroup of stage II and III patients who would highly benefit from chemotherapy, thus facilitating patient counseling and individualizing the management.

•

p21-activated Kinase 6 was a predictive biomarker and increased chemoresistance to 5-FU/oxaliplatin chemotherapy.

•

The CS-SVM classifier distinguished a subgroup of stage II and III patients who would highly benefit from chemotherapy.

PAK6 was an independent prognostic factor and increased chemoresistance. The chemotherapy score – support vector machine classifier distinguished a subgroup of stage II and III patients who would highly benefit from chemotherapy. The model maybe useful for patient counseling and individualized treatment decision-making.

An individualized prognostic signature for gastric cancer patients treated with 5-Fluorouracil-based chemotherapy and distinct multi-omics characteristics of prognostic groups

5-Fluorouracil (5-FU)-based chemotherapy is currently the first-line treatment for gastric cancer. In this study, using gene expression profiles for a panel of cell lines with drug sensitivity data and two cohorts of patients, we extracted a signature consisting of two gene pairs (KCNE2 and API5, KCNE2 and PRPF3) whose within-sample relative expression orderings (REOs) could robustly predict prognoses of gastric cancer patients treated with 5-FU-based chemotherapy. This REOs-based signature was insensitive to experimental batch effects and could be directly applied to samples measured by different laboratories. Taking this unique advantage of the REOs-based signature, we classified gastric cancer samples of The Cancer Genome Atlas (TCGA) into two prognostic groups with distinct transcriptional characteristics, circumventing the usage of confounded TCGA survival data. We further showed that the two prognostic groups displayed distinct copy number, gene mutation and DNA methylation landscapes using the TCGA multi-omics data. The results provided hints for understanding molecular mechanisms determining prognoses of gastric cancer patients treated with 5-FU-based chemotherapy.

ERCC1 predicts outcome in patients with gastric cancer treated with adjuvant cisplatin-based chemotherapy

BACKGROUND

Adjuvant chemotherapy is gaining an increasing role in resectable gastric cancer. Customizing chemotherapy on the basis of chemosensitivity may improve outcome, and putative predictive molecular markers have been mostly evaluated in Asian patients. We profiled key DNA and damage signaling factors and correlated them with outcome, in a European cohort.

METHODS

Formalin-fixed tumor samples obtained from surgical specimens of patients treated with adjuvant cisplatin-based chemotherapy for gastric cancer were analyzed. Immunohistochemistry (IHC) was performed to analyze excision repair cross-complementing gene 1 (ERCC1) and thymidylate synthase (TS) expression, and p53 mutations were detected with direct sequencing.

RESULTS

Among the 68 patient recruited, the median age was 69 (range 30-74), and UICC stage was III in 44 patients (65 %). With a median follow-up of 40.5 months, disease-free and overall survival were 18.0 (95 % CI 13.4-22.76) and 56 months (95 % CI 44.87-67.13), respectively. ERCC1 score was 0 in 14 out 67 (21 %) cases, 1 in 19 (28 %), 2 in 20 (30 %) and 3 in 14 cases (21 %). Longer overall survival (p = 0.04) was found in patients categorized as ERCC1 negative by IHC according to median score. TS score was 0 in 16 out 67 (24 %) cases, 1 in 27 (40 %), 2 in 16 (24 %) and 3 in 8 cases (12 %). Mutations of p53 were found in 21 out 66 (32 %) cases. Neither TS nor p53 were found to correlate with outcome.

CONCLUSION

Excision repair cross-complementing gene 1 by IHC might predict patients more likely to benefit from adjuvant cisplatin-based chemotherapy in curatively resected gastric cancer. In patients exhibiting ERCC1 positive tumors, alternative regimens should be evaluated.

Predictive value of thymidylate synthase expression in gastric cancer: a systematic review with meta-analysis

PURPOSE

The relationship between thymidylate synthase (TS) expression and outcomes in gastric cancer (GC) patients remains controversial, although most studies reported poor survival and reduced response to fluoropyrimidine were related to high TS in tumors. We carried out a systematic review of the literature with meta-analysis to estimate the predictive value of TS expression from published studies.

METHODS

We identified 24 studies analysing the outcome data in gastric cancer stratified by TS expression. Effect measures of outcome were hazard ratios (HRs) for overall survival (OS) and event-free survival (EFS), or the odds ratio (OR) for overall response rate (ORR). HRs and ORs from these eligible studies were pooled using random-effects meta- analysis.

RESULTS

Fifteen studies investigated outcomes in a total of 844 patients with advanced GC, and nine studies investigated outcomes in a total of 1,235 patients with localized GC undergoing adjuvant therapy. Meta- analysis of estimates showed high TS expression was significantly associated with poor OS in the advanced setting (HR: 1.43, 95%CI: 1.08 - 1.90), and poor EFS in the adjuvant setting (HR: 1.53, 95%CI: 1.01 - 2.32). Subgroup analysis demonstrated TS expression to have even greater value in predicting OS, EFS and ORR in advanced GC patients treated with fluoropyrimidine monotherapy (HR for OS: 2.32, 95%CI: 1.53 - 3.50; HR for EFS: 1.76, 95%CI: 1.19 - 2.60; OR for ORR: 0.32, 95%CI: 0.11 - 0.95).

CONCLUSION

High levels of TS expression were associated with a poorer OS for advanced GC patients compared with low levels. In the adjuvant setting, high TS expression was also associated with a worse EFS. Additional studies with consistent methodology are needed to define the precise predictive value of TS.

Expression and prognostic significance of thymidylate synthase (TS) in pancreatic head and periampullary cancer

BACKGROUND

Pancreatic cancer has a dismal prognosis. Attempts have been made to improve outcome by several 5-FU based adjuvant treatment regimens. However, the results are conflicting. There seems to be a continental divide with respect to the use of 5-FU based chemoradiotherapy (CRT). Furthermore, evidence has been presented showing a different response of pancreatic head and periampullary cancer to 5-FU based CRT. Expression of thymidylate synthase (TS) has been associated with improved outcome following 5-FU based adjuvant treatment in gastrointestinal cancer. This prompted us to determine the differential expression and prognostic value of TS in pancreatic head and periampullary cancer.

PATIENTS AND METHODS

TS protein expression was studied by immunohistochemistry on original paraffin embedded tissue from 212 patients following microscopic radical resection (R0) of pancreatic head (n = 98) or periampullary cancer (n = 114). Expression was investigated for associations with recurrence free (RFS), cancer specific (CSS) and overall survival (OS), and conventional prognostic factors.

RESULTS

High cytosolic TS expression was present in 26% of pancreatic head tumours and 37% of periampullary tumours (p = .11). Furthermore, TS was an independent factor predicting favourable outcome following curative resection of pancreatic head cancer (p = .003, .001 and .001 for RFS, CSS and OS, respectively). In contrast, in periampullary cancer, TS was not associated with outcome (all p > .10).

CONCLUSION

TS, was found to be poorly expressed in both pancreatic head and periampullary cancer and identified as an independent prognostic factor following curative resection of pancreatic head cancer.

Helicobacter pylori infection as an independent prognostic factor for locally advanced gastric cancer patients treated with adjuvant chemotherapy after curative resection

A few studies reported the association between negative Helicobacter pylori infection and poor clinical outcome in resected gastric cancer patients. We investigated the H. pylori infection status and its association with the clinical outcome in 274 locally advanced gastric cancer patients (American Joint Committee on Cancer stage IB: 25, II: 82, IIIA: 80, IIIB: 39 and IV: 48) who underwent adjuvant chemotherapy after curative resection (≥ D2 dissection). H. pylori infection status in hematoxylin and eosin stained corporal and antral mucosa of non-tumor tissue was graded according to the updated Sydney System and categorized as H. pylori negative (normal or mild infection) and H. pylori positive (moderate or marked infection). Eighty-one patients received 5-fluorouracil (5-FU) and doxorubicin-based chemotherapy, while 193 patients underwent 5-FU, mitomycin-C and polysaccharide-K chemotherapy. The median follow-up duration of survivors was 144 (120-184) months. In univariate analysis, patients with H. pylori negative status (108 patients) demonstrated significantly poor 10-year overall survival (OS) compared to those with H. pylori-positive status (166 patients; 21.3% vs. 71.1%, p < 0.0001). H. pylori negative status was associated with poor outcome in all stages except stage IIIB. In multivariate analysis, H. pylori-negative status was the most significant independent prognostic factor of poor OS (hazard ratio: 3.45, 95% confidence interval: 2.43-4.89, p < 0.0001) followed by old age (>54 years, p < 0.0001), advanced stage (stage III or IV, p = 0.001), and Borrmann type IV (p = 0.027). H. pylori infection status seems to have strong prognostic significance in locally advanced gastric cancer. H. pylori-negative patients may need careful follow-up after curative resection.

New insights into the mechanisms of gastric cancer multidrug resistance and future perspectives

Gastric cancer is still the second leading cause of cancer death worldwide. Chemotherapy is one of the major treatment options for advanced gastric cancer. The efficacy of chemotherapy for gastric cancer is poor due to insensitivity and the development of multidrug resistance (MDR). Gastric cancer MDR involves a large number of molecules and complex mechanisms. Classical drug-resistant molecules, such as P-glycoprotein/ABCB1 and MRP1/ABCC1, have been found to play important roles in mediating MDR in some gastric cancers. In recent years, new molecules and mechanisms have been found to be associated with the development of gastric cancer MDR and might provide new targets for tackling gastric cancer MDR. Combined use of molecularly targeted therapy with chemotherapy may offer improved outcomes for gastric cancer patients and might provide new threads of hope for gastric cancer treatment.

HIF-1alpha is an unfavorable determinant of relapse in gastric cancer patients who underwent curative surgery followed by adjuvant 5-FU chemotherapy

Among several chemotherapeutic agents, 5-fluorouracil (5-FU) has been widely used as a key drug in adjuvant chemotherapy for gastric cancer. However, no reliable marker, which predicts the response to 5-FU in an adjuvant setting, has been identified. Hypoxia-induced drug resistance, via upregulation of HIF-1alpha, is a major obstacle in the development of effective cancer therapy. However, few clinical studies have so far assessed the relationship between the HIF-1alpha expression and the chemo-resistance of gastric cancer patients in an adjuvant setting. We established 2 HIF-1alpha knockdown gastric cancer cell lines in order to clarify the role of HIF-1alpha in chemo-resistance against 5-FU. Furthermore, expression of HIF-1alpha was immunohistochemically assessed in 91 resected specimens. Sixty-four of 91 patients received 5-FU adjuvant chemotherapy after surgery. HIF-1alpha expression was associated with the significantly shorter relapse-free survival and disease-specific survival in the 64 patients of adjuvant group (p = 0.026, 0.014, respectively), but not in the 27 of surgery group. Multivariate analysis showed that HIF-1alpha was an independent risk factor for relapse in 64 patients in the adjuvant group (p = 0.029). In conclusion, the current study confirmed, for the first time that HIF-1alpha expression is an independent risk factor for relapse in high-risk gastric cancer patients who underwent curative surgery followed by adjuvant 5-FU chemotherapy. A favorable effect of 5-FU might therefore be expected in patients that do not express HIF-1alpha, whereas, other types of chemotherapy or additional treatments, such as HIF-1alpha inhibitors, should be considered in patients that do express HIF-1alpha.

Expression of thymidylate synthase determines the response of gastric cancer patients undergoing gastrectomy to 5-fluorouracil-based adjuvant chemotherapy

PURPOSE

We investigated whether the intensity of thymidylate synthase (TS) staining in tissue samples obtained from gastric cancer (GC) patients undergoing gastrectomy could predict response to 5-FU-based adjuvant chemotherapy after gastrectomy.

METHOD AND MATERIALS

Clinicopathological features of 124 patients with histologically proven GC who underwent radical gastrectomy were retrospectively reviewed. Tissue samples obtained from these patients were immunohistochemically stained for assessing TS expression. We arbitrarily classified the TS staining results as low (<20% cytoplasmic immunostaining) and high (> or =20% cytoplasmic immunostaining) TS expression.

RESULTS

The clinicopathological features of the low TS expression group patients were typically similar to those of the high TS expression group patients. However, multivariate forward stepwise logistic regression analysis revealed that low TS expression was independently associated with females and responders to 5-FU-based adjuvant chemotherapy. The median follow-up duration for the 124 GC patients who had undergone curative resection was 41.3 months. The GC patients who showed poor tumor differentiation and high TS expression had short disease-free survival (DFS) and overall survival (OS).

CONCLUSIONS

Low TS expression is significantly associated with female GC patients and responders to 5-FU-based adjuvant chemotherapy. It predicts longer DFS and OS in selected GC patients treated with 5-FU-based adjuvant chemotherapy after curative resection. The results suggest that prospective assessment of TS staining intensity in tissue samples obtained from GC patients undergoing gastrectomy would be useful to predict the patients who would be benefited from 5-FU-based adjuvant chemotherapy after gastrectomy.

Impact of E2F-1 expression on clinical outcome of gastric adenocarcinoma patients with adjuvant chemoradiation therapy

PURPOSE

There are no reliable prognostic markers that identify gastric cancer patients who may benefit from adjuvant chemoradiation therapy. E2F-1 was shown to be associated with radiosensitivity and chemosensitivity in certain tumor types. Therefore, we analyzed expression and prognostic significance of E2F-1 along with thymidylate synthase (TS) in R(0)-resected gastric adenocarcinoma patients, who underwent adjuvant chemoradiation therapy with 5-fluorouracil (5-FU) and leucovorin.

EXPERIMENTAL DESIGN

The chemosensitivity to 5-FU and radiosensitivity were tested in three E2F-1-overexpressed gastric cancer cell lines in vitro. The expressions of TS and E2F-1 were analyzed in 467 R(0)-resected primary gastric cancer patients, who received adjuvant chemoradiation therapy with 5-FU and leucovorin using tissue microarray.

RESULTS

The E2F-1 immunopositivity rate was 22.2% (103 of 465 samples) with a cutoff value of 5% immunoreactivity, whereas the TS-positive expression occurred in 19.0% of the 463 tumors tested. Using stepwise Cox proportional hazards regression modeling, multivariate analyses showed that the E2F-1 immunopositivity predicted more favorable survival as compared with the E2F-1 immunonegativity with borderline statistical significance [P = 0.050, hazard ratio (HR) = 0.702, 95% confidence interval, 0.487, 1.013]. However, the E2F-1 immunopositivity did not retain its statistical significance at multivariate analysis for predicting disease-free survival (data not shown, P = 0.270), but stage was the only influential factor for disease-free survival in stages IB to IV (M(0)) patients (P < 0.001). TS immunopositivity did not influence survival (P = 0.459) or disease-free survival (P = 0.447).

CONCLUSION

E2F-1 is a potentially novel independent prognostic factor that may identify gastric cancer patients who will likely benefit from adjuvant chemoradiation therapy following curative resection.

ERCC1 mRNA levels and survival of advanced gastric cancer patients treated with a modified FOLFOX regimen

Molecular markers involved in DNA repair can help to predict survival in gastric cancer patients treated with 5-FU plus platinum chemotherapy. Excision repair cross-complementing 1 (ERCC1) and thymidylate synthase (TS) mRNA expression levels were assessed in advanced gastric cancer tumour samples using real-time quantitative PCR in 76 patients treated with a modified FOLFOX (biweekly oxaliplatin plus 5-FU and folinic acid) regimen. Median survival time in patients with low ERCC1 levels was significantly longer than in those with high levels (15.8 vs 6.2 months; P<0.0001). Patients with high TS levels had longer survival than those with low levels (12.2 vs 10.1 months; P=0.01). Forty-eight patients with low ERCC1 and high TS levels had a median survival of 16.1 months (P<0.0001). The hazard ratio for patients with high ERCC1 expression was 9.4 (P<0.0001). In patients with high mRNA levels of ERCC1, alternative chemotherapy regimens should be considered.

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.

Prognostic value of expression of ERCC1, thymidylate synthase, and glutathione S-transferase P1 for 5-fluorouracil/oxaliplatin chemotherapy in advanced gastric cancer

BACKGROUND

The aim of this study was to determine whether expressions of the excision repair cross-complementing (ERCC1), thymidylate synthase (TS), and glutathione S-transferase P1 (GSTP1) predict clinical outcome in patients with advanced gastric cancer treated with fluorouracil (5-fluorouracil)/oxaliplatin chemotherapy.

PATIENTS AND METHODS

The study population consisted of 64 advanced gastric cancer patients (median age 51 years). Patients were treated with oxaliplatin 85 mg/m(2) as a 2-h infusion at day 1 plus leucovorin 20 mg/m(2) over 10 min, followed by 5-FU bolus 400 mg/m(2) and 22-h continuous infusion of 600 mg/m(2) at days 1-2. Treatment was repeated in 2-week intervals. The expressions of ERCC1, TS, and GSTP1 of primary tumors were examined by immunohistochemistry.

RESULTS

The positive rates of ERCC1, TS, and GSTP1 were 70.3%, 29.7%, and 50.0%, respectively. The patients without ERCC1 expression were more likely to respond to chemotherapy (P = 0.045). There were no significant differences between response and TS or GSTP1 expression pattern (P = 0.813, P = 0.305, respectively). Median overall survival (OS) was significantly longer in patients without ERCC1 expression (P = 0.0396). TS or GSTP1 expression were not related to survival (P = 0.4578, P = 0.8121, respectively). Multivariate analysis revealed that ERCC1 expression significantly impacted on OS (hazard ratio 1.92, P = 0.037).

CONCLUSION

Immunohistochemical studies for ERCC1 may be useful in prediction of the clinical outcome in advanced gastric cancer patients treated with 5-FU and oxaliplatin.

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.

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.

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.

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.

Thymidylate synthase expression and prognosis of patients with gastrointestinal cancers receiving adjuvant chemotherapy: a review

BACKGROUND AND AIMS

Many studies have been published that report an association between thymidylate synthase (TS) and response to fluoropyrimidine-based chemotherapy and the overall outcome of patients with gastrointestinal cancer. The results have given rise to the possibility that, by determination of TS levels, the physician may decide if the patient has a potential benefit from fluoropyrimidine-based treatment, similar to measurements of oestrogen receptors in breast cancer. The purpose of this review is to summarize critically the reports on TS measurement in gastrointestinal cancer, focusing on the adjuvant fluoropyrimidine treatment situation.

METHODS

We reviewed more than 20 studies that reported the association of TS with the clinical outcome in patients with gastrointestinal cancer who had undergone complete resection of the primary tumour only or were receiving additional adjuvant chemotherapy.

RESULTS

Patients with metastasized disease who expressed high TS levels display a low probability of responding to fluoropyrimidine-based treatment and have a poorer survival rate. Patients with high TS levels who undergo complete surgical resection of the primary tumour also have a poorer prognosis than those with tumours with low TS expression. In contrast to advanced disease and to surgery alone, patients with high TS levels appear to benefit, especially, from adjuvant fluoropyrimidine-based chemotherapy after complete primary tumour resection, while patients with low TS levels do not.

CONCLUSION

Patients with gastrointestinal cancers that express high TS levels have a poor prognosis with regard to fluoropyrimidine-based palliative chemotherapy or complete primary tumour resection. In contrast, patients with high TS levels might benefit from adjuvant fluoropyrimidine-based treatment after primary tumour resection. However, additional prospective studies are mandatory to define the precise role of TS in adjuvant therapy.

Low Thymidylate Synthase Expression in the Primary Tumor Predicts Favorable Clinical Outcome in Resected Gastric Cancer Patients Treated with Adjuvant Tegafur

OBJECTIVE

To assess the thymidylate synthase protein (TS) in tumor cells of resected gastric cancer patients treated with adjuvant tegafur (TG), we reviewed the outcome of 94 randomized patients treated either with adjuvant TG plus mitomycin C (MMC) or MMC alone.

METHODS

TS was determined in 76 out of 94 patients, previously randomized to receive adjuvant TG, 500 mg/m(2)/day p.o. for 6 months plus four courses of MMC, 10- 20 mg/m(2) i.v. every 6 weeks or MMC alone. An immunohistochemical assessment with the monoclonal antibody TS-106 was performed.

RESULTS

Low TS was observed in 38 patients (20 treated with TG-MMC and 18 with MMC) and high TS in the other 38 patients (21 treated with TG-MMC and 17 with MMC). After 10 years' median follow-up time, 61% of adjuvant TG-MMC patients and 43% of MMC patients were alive and disease-free. Disease-free survival and overall survival were significantly better for patients treated with TG-MMC compared to MMC adjuvant (p = 0.0277 and p = 0.05), and low-TS compared to high-TS patients (p = 0.0184 and p = 0.0198). In 38 low-TS patients we observed an 83% chance to be disease-free in TG-MMC-treated patients and 55% in MMC-treated patients (p = 0.04).

CONCLUSIONS

A low TS level determines a subset of patients that may benefit from adjuvant oral TG when added to MMC showing a 5-year cure rate of more than 80%.

Evaluation of thymidylate synthase protein expression by Western blotting and immunohistochemistry on human colon carcinoma xenografts in nude mice

In this study we investigated the relationship between thymidylate synthase (TS) protein expression, evaluated by Western blotting analysis and by immunohistochemistry (IHC), and growth rate in human colon xenograft tumors in nude mice. Human colon cancer cell lines were used to induce xenograft tumors and the tumor mass growth rate was calculated by measuring tumor size variations over time. TS 106 monoclonal antibody was used for both Western blotting and IHC TS detection. Tumor cell growth fraction was measured by Ki67/MIB1 immunolabeling and tumor cell growth rate by evaluating the mean nucleolar size in silver-stained sections. TS Western blotting values were related to tumor mass growth rate (p<0.001) and cell growth rate (p=0.002) but not to cell growth fraction (p=0.676). The degree of the IHC staining showed only a trend to be associated with TS protein expression measured on Western blotting, and was not related either to tumor mass growth or cell proliferation rate. Tumor xenografts were also characterized for TS promoter tandem repeat and p53 status. No relationship was observed between these variables and TS expression evaluated by both Western blotting and IHC analysis. Our results demonstrate that TS expression evaluated by Western blotting analysis is directly related to the tumor mass growth rate and question the use of the IHC approach to obtain precise quantitative information on TS expression in tumor samples.

Expression of multidrug resistance-associated protein1,P-glycoprotein, and thymidylate synthase in gastric cancer patients treated with 5-fluorouracil and doxorubicin-based adjuvant chemotherapy after curative resection

Both 5-fluorouracil and doxorubicin are commonly used agents in chemotherapy of gastric cancer in adjuvant setting as well as metastatic disease. In a variety of malignancies, high expression of multidrug resistance-associated protein1 and P-glycoprotein has been associated with resistance to doxorubicin, whereas 5-fluorouracil resistance has correlated with the level of thymidylate synthase expression. We evaluated the expression of multidrug resistance-associated protein1, P-glycoprotein, and thymidylate synthase using immunohistochemistry in 103 locally advanced gastric cancer patients (stage IB-IV) who underwent 5-fluorouracil and doxorubicin-based adjuvant chemotherapy after curative resection and investigated the association between their expression and clinicopathologic characteristics including prognosis of the patients. While high expression (> or =5% of tumour cells positive) of multidrug resistance-associated protein1 and P-glycoprotein was observed in 70 patients (68%) and 42 patients (41%), respectively, 65 patients (63%) had primary tumours with high expression (> or =25% of tumour cells positive) of thymidylate synthase. There was a significant association between multidrug resistance-associated protein1 and P-glycoprotein expression (P<0.0001) as well as P-glycoprotein and thymidylate synthase expression (P<0.0001). High multidrug resistance-associated protein1 and P-glycoprotein expressions were associated with well and moderately differentiated histology (P<0.0001 and P=0.03, respectively) and intestinal type (P<0.0001 and P=0.009, respectively). High multidrug resistance-associated protein1 expression correlated with lymph node metastasis (P=0.037), advanced stage (P=0.015), and older age (P=0.021). Five-year disease-free survival and overall survival of total patients were 55.2% and 56.2%, respectively, with a median follow-up of 68 months. There were no significant differences in disease-free survival and overall survival according to the expression of multidrug resistance-associated protein1 (P=0.902 and P=0.975, respectively), P-glycoprotein (P=0.987 and P=0.955, respectively), and thymidylate synthase (P=0.604 and P=0.802, respectively). Concurrent high expression of these proteins (high multidrug resistance-associated protein1/P-glycoprotein, high multidrug resistance-associated protein1/thymidylate synthase, high P-glycoprotein/thymidylate synthase) did not correlate with disease-free survival or overall survival. Even high expression of all three proteins was not associated with poor disease-free survival (P=0.919) and overall survival (P=0.852). In conclusion, high expression of multidrug resistance-associated protein1, P-glycoprotein, and thymidylate synthase did not predict poor prognosis of gastric cancer patients treated with 5-fluorouracil and doxorubicin-based adjuvant chemotherapy. A larger study including patients treated with surgical resection alone would be necessary.

Implication of thymidylate synthase in the outcome of patients with invasive ductal carcinoma of the pancreas and efficacy of adjuvant chemotherapy using 5-fluorouracil or its derivatives

Thymidine synthase (TS) is a key enzyme in the synthesis of pyrimidine in the de novo pathway of DNA synthesis and a major target of 5-fluorouracil (5-FU), but the implications of TS regarding human pancreatic cancer have not been reported. We assessed the expression of TS in invasive ductal carcinoma (IDC) of the pancreas by immunostaining and evaluated its clinicopathological significance, especially its implications regarding the efficacy of chemotherapy with 5-FU or its derivatives. The expression of TS in the nuclei of pancreatic cancer cells in 72 primary lesions of resectable IDC and 30 distant metastases of unresectable IDC was examined by immunostaining using anti-TS polyclonal antibody and immunoreactivity was classified into three categories: negative (-), low (+) and high (2+). High TS immunoreactivity was detected in 43% (31 of 72) of the primary lesions of the resectable IDCs and in 47% (18 of 38) of the metastatic lesions of the unresectable IDCs. The high TS in primary lesions showed a significantly inverse correlation with the level of nodal involvement. High TS immunoreactivity had a significant influence on the outcome of patients with resectable IDC and the rate of survival of the high TS immunoreactivity group was significantly higher than that of the negative or low reactivity groups, although high TS immunoreactivity did not have a significant influence on survival of the patients with unresectable IDC. The implications of TS immunoreactivity regarding the efficacy of 5-FU-based adjuvant chemotherapy (ACT) was also assessed. The high TS immunoreactivity group showed significantly better survival in both the patients who received ACT and those who were treated by surgery alone, in the resectable IDC among patients with resectable IDC. In cases of unresectable IDC, there were no differences in survival between the high and low TS groups among the patients who received ACT and those who were treated by surgery. In conclusion, high TS immunoreactivity was found to be cogent in predicting the prognosis of patients with pancreatic IDC, but its implications regarding the efficacy of 5-FU-based ACT are still unclear.