Relation between thymidylate synthase expression and survival in colon carcinoma, and determination of appropriate application of 5-fluorouracil by immunohistochemical method

The Treatment of Human Colon Xenografts Tumor in Mice with Platinum Nanosphere-5-Fluorouracil-Bovine Albumin

Because 5-fluorouracil (FLU) has side effects in cancer treatment, the use of FLU in therapeutic activities is limited. To overcome this challenge, the use of nano-platforms for its targeting is f great interest in biomedical fields. For this purpose, to reduce the FLU toxicity and improve the its efficacy, platinum nanospheres (PtNS) with anti-cancer properties were used. After producing PtNS by hydrothermal method and loading FLU and bovine albumin (bAL) (PtNS-FLU-bAL), its physicochemical properties were investigated. After evaluating the drug release capability, the toxicity of PtNS-FLU-bAL on HCT-116 cells was assessed by MTT and flow-cytometry. Also, the effects of the nanospheres on tumor status, liver and kidney tissues were evaluated. The results indicate uniform size of the PtNS-FLU-bAL (79±2.04 nm) with spherical shape, loading of more than 50% of the FLU (in the ratio of 2:1 FLU to PtNS-bAL), optimal release of the FLU from the PtNS-FLU-bAL (83.1% in pH = 6), and the high toxicity of the PtNS-FLU-bAL on HCT-116 cells. Also, the toxicity mechanism indicated more apoptosis induction by increasing the expression of TNF-α, Bax, Fas, and Caspase-3 genes for PtNS-FLU-bAL compared to the free FLU. Moreover, the results showed a higher FLU concentration in cancerous tissue and a 1.5-fold reduction in tumor growth by the PtNS-FLU-bAL compared to the free FLU. Overall, the results show that the PtNS-FLU-bAL can enhance the success of colorectal cancer treatment effectively and safely.

Expression of astrocyte-elevated gene-1 indicates prognostic value of fluoropyrimidine-based adjuvant chemotherapy in resectable stage III colorectal cancer

It is unclear which prognostic factor such as pathological features and gene mutation are majorly relevant for stage III disease and whether they aid in determining patients who will be benefit from postoperative adjuvant chemotherapy. The expression of astrocyte-elevated gene-1 (AEG-1), thymidylate synthase (TS), excision repair cross-complementation group 1 (ERCC1), epidermal growth factor receptor (EGFR), and vascular endothelial growth factor (VEGF) was examined to investigate their role in adjuvant chemotherapy for patients with resectable stage III colorectal cancer (CRC). A significant positive correlation was observed between AEG-1, TS, ERCC1, EGFR, and VEGF gene expression levels in CRC cell lines, and low AEG-1 and TS expression were highly sensitive to 5-fluorouracil treatment. Our results showed that AEG-1 expression was high in T4 and caused CRC recurrence or metastasis. Patients with T4, high AEG-1, TS and VEGF expression had a significantly short disease-free survival and overall survival. In multivariate Cox regression analysis, high AEG-1 expression could be an independent prognostic factor indicating poor survival in patients with resectable stage III CRC treated with adjuvant chemotherapy. In conclusion, AEG-1 expression and tumor grade are potential prognostic factors for recurrence and survival in patients with stage III CRC receiving adjuvant fluoropyrimidine-based chemotherapy.

Prognostic and Predictive Role of Excision Repair Cross-complementation Group 1 and Thymidylate Synthase in Colorectal Carcinoma Patients Received FOLFOX Chemotherapy: An Immunohistochemical Study

BACKGROUND AND STUDY AIMS

We aim to determine the frequency of thymidylate synthase (TS) and excision repair cross-complementation group 1 (ERCC-1) immunohistochemical (IHC) expression and its relationship with clinicopathologic variables in colorectal carcinoma (CRC) patients. In addition, we aim to assess the correlation between TS and ERCC-1 expression and the response of these cases to oxaliplatin and 5-fluorouracil chemotherapy (FOLFOX).

PATIENTS AND METHODS

Fifty-one CRC patients were prepared for IHC analysis of ERCC-1 and TS protein expression. All patients received oxaliplatin and 5-fluorouracil combined chemotherapy (FOLFOX) and were followed up for 24 months.

RESULTS

The data analysis showed that high ERCC-1 and TS expression was significantly associated with early treatment failure (P=0.020 and 0.000). In contrast, TS immunoexpression affects the disease-free survival rate (P=0.010). The presence of deep tumor invasion, distant metastasis, lymph node metastasis, and high Dukes' classification were significantly statistically associated with early treatment failure (P=0.001, 0.000, 0.041, and 0.015, respectively).

CONCLUSIONS

Our results showed that both ERCC-1 and TS are predictive factors for early treatment failure in CRC patients. TS protein is a prognostic factor for disease-free survival rates. This supports the theory that both ERCC-1 and TS can be used to improve chemotherapeutic outcomes in CRC patients. High expression of TS and ERCC-1 helps in the identification of cases that will get fewer benefits from FOLFOX chemotherapy. As an innovative strategy, in these cases, we can use alternative chemotherapeutic regimens or add an extra agent. In addition, Dukes' classification and lymph node metastasis are predictive factors for early treatment failure. Thus, all those values can be used to predict CRC patients with bad prognosis and those who will get fewer benefits from FOLFOX.

Determination of thymidine phosphorylase expression level facilitates recurrence risk stratification in stage II/III colorectal cancer following adjuvant chemotherapy with oral fluoropyrimidines

The present study aimed to prospectively clarify the prognostic effect of the expression of several genes that are known to modulate 5-fluorouracil effects in 63 patients who underwent curative resection for stage II/III colorectal cancer following adjuvant chemotherapy with oral fluoropyrimidines between 2008 and 2012. Thymidine phosphorylase (TP) expression in primary tumours was significantly lower in the recurrence group compared with the no-recurrence group (P=0.03), whereas, expression levels of genes that encoded thymidylate synthase, dihydropyrimidine dehydrogenase, folylpolyglutamate synthase, γ-glutamyl hydrolase and dihydrofolate reductase were not statistically different in tumours from the recurrence and no-recurrence groups. In the multivariate analysis using stepwise Cox proportional hazards regression, the following factors were significantly associated with shorter relapse-free survival following adjuvant chemotherapy with oral fluoropyrimidines: Venous invasion [present; hazard ratio (HR)=6.51; 95% confidence interval (CI): 1.55-27.4; P=0.01), Tumour-Node-Metastasis stage (3b; HR=6.18; 95% CI: 1.36-28.2; P=0.02) and TP expression (low; HR=9.61; 95% CI: 1.81-51.0; P=0.04). Patients with two or more risk characteristics had significantly shorter 5-year relapse-free survival compared with patients with one or no risk characteristics (55.8 vs. 91.8%; log-rank P=0.0006). We concluded that low TP expression is an independent predictive factor for poor prognosis in colorectal cancer. Therefore, determining TP expression may help to improve recurrence risk stratification in patients with stage II/III colorectal cancer following adjuvant chemotherapy with oral fluoropyrimidines.

Are Colon and Rectal Cancer Two Different Tumor Entities? A Proposal to Abandon the Term Colorectal Cancer

Colon cancer (CC) and rectal cancer (RC) are synonymously called colorectal cancer (CRC). Based on our experience in basic and clinical research as well as routine work in the field, the term CRC should be abandoned. We analyzed the available data from the literature and results from our multicenter Research Group Oncology of Gastrointestinal Tumors termed FOGT to confirm or reject this hypothesis. Anatomically, the risk of developing RC is four times higher than CC, while physical activity helps to prevent CC but not RC. Obvious differences exist in molecular carcinogenesis, pathology, surgical topography and procedures, and multimodal treatment. Therefore, we conclude that CC is not the same as RC. The term "CRC" should no longer be used as a single entity in basic and clinical research as well as other areas of classification.

Personalizing colon cancer therapeutics: targeting old and new mechanisms of action

The use of pharmaceuticals for colon cancer treatment has been increasingly personalized, in part due to the development of new molecular tools. In this review, we discuss the old and new colon cancer chemotherapeutics, and the parameters that have been shown to be predictive of efficacy and safety of these chemotherapeutics. In addition, we discuss how alternate pharmaceuticals have been developed in light of a potential lack of response or resistance to a particular chemotherapeutic.

Glycogen Synthase Kinase 3β Inhibitor (2'Z,3'E)-6-Bromo-indirubin- 3'-Oxime Enhances Drug Resistance to 5-Fluorouracil Chemotherapy in Colon Cancer Cells

OBJECTIVE

To explore the effects and mechanism of glycogen synthase kinase 3β (GSK-3β) inhibitor (2'Z,3'E)-6-bromo-indirubin-3'-oxime (BIO) on drug resistance in colon cancer cells.

METHODS

The colon cancer SW480 and SW620 cells were treated with BIO, 5-fluorouracil (5-FU) and BIO/5-FU, separately. Cell cycle distribution, apoptosis level and efflux ability of rhodamine 123 (Rh123) were detected by flow cytometry. The protein expressions of P-glycoprotein (P-gp), multidrug resistance protein 2 (MRP2), thymidylate synthase (TS), β-catenin, E2F-1 and Bcl-2 were detected by Western blot. β-catenin and P-gp were stained with double immunofluorescence and observed under a confocal microscope.

RESULTS

BIO up-regulated β-catenin, P-gp, MRP2 and TS, enhanced the efflux ability of Rh123, decreased Bcl-2 protein and gave the opposite effect to E2F-1 protein in SW480 and SW620 cells. Furthermore, BIO significantly inhibited cell apoptosis, increased S and G(2)/M phase cells, and reduced the cell apoptosis induced by 5-FU in SW480 cells, whereas the effects were slight or not obvious in SW620 cells.

CONCLUSION

GSK-3β was involved in drug resistance regulation, and activation of β-catenin and inhibition of E2F-1 may be the most responsible for the enhancement of 5-FU chemotherapy resistance induced by GSK-3β inhibitor BIO in colon cancer.

A combined analysis of mismatch repair status and thymidylate synthase expression in stage II and III colon cancer

This study in 716 colon cancer patients evaluates if a combined instead of a single marker analysis of mismatch repair (MMR) status and thymidylate synthase (TS) expression could individualize the treatment decision. The results indicate that a combined analysis of MMR status and TS expression can improve prediction of response to adjuvant 5-fluorouracil (5-FU)-based chemotherapy in stage III colon cancer.

BACKGROUND

Colon cancer with mismatch repair deficiency and low TS expression has been associated with an improved prognosis. Data also indicate that MMR proficient colon cancer with high TS expression has a better response to adjuvant 5-FU-based chemotherapy. This study evaluates if a combined analysis of MMR status and TS expression in colon cancer can add prognostic value and better predict response to adjuvant 5-FU-based chemotherapy. The potential relationship between MMR status and TS expression is also investigated.

PATIENTS AND METHODS

This study includes a subgroup of 716 patients with colon cancer out of 2224 stage II and stage III colorectal cancer patients enrolled in Nordic trials randomized to surgery alone or surgery plus adjuvant 5-FU-based chemotherapy. After immunohistochemical analysis of tumor MMR status and TS expression the patients were divided into 4 groups.

RESULTS

There was a nonsignificant difference in overall survival between group 1 (patients with deficient MMR tumors with low TS) and group 4 (patients with proficient MMR tumors expressing high TS). When comparing group 1 and group 4 patients treated with surgery alone a trend to better overall survival was found in group 1, P=.06. In group 4, stage III patients had a significantly improved survival when receiving adjuvant 5-FU-based chemotherapy compared with surgery alone, P=.01. No relationship was found between MMR status and TS expression.

CONCLUSIONS

A combined instead of a single marker analysis of MMR status and TS expression can improve the prediction of response to 5-FU-based chemotherapy in stage III colon cancer.

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.

Role of dihydropyrimidine dehydrogenase and thymidylate synthase expression in immunohistochemistry of intrahepatic cholangiocarcinoma

AIMS

  Dihydropyrimidine dehydrogenase (DPD) and thymidylate synthase (TS) are key enzymes in the metabolism of 5-fluorouracil and have been implicated as possible prognostic markers for cancer patients. However, the clinical roles of DPD and TS in intrahepatic cholangiocarcinoma (IHCC) have not been investigated. The aim of this study was to clarify the clinicopathological role of DPD and TS expressions in IHCC.

METHODS

  Twenty-nine patients who had undergone hepatic resection for IHCC were enrolled in this study. Expressions of DPD and TS in the resected IHCC specimens were examined using anti-DPD or anti-TS antibody. The patients were divided into positive and negative groups according to DPD/TS expressions: DPD-positive group (n = 18) and DPD-negative group (n = 11)/TS-positive group (n = 14) and TS-negative group (n = 15). Clinicopathological factors were compared between the two groups.

RESULTS

  The overall survival rate was significantly lower in the DPD-negative group than in the DPD-positive group (1-year 36.4% vs. 77.4%, 3-year 18.2% vs. 43.0%; P < 0.05). The disease-free survival rate in the DPD-negative group tended to be lower than that in the DPD-positive group. The overall survival rate or disease-free survival rate did not appear to be associated with the TS-expression status. The Ki-67 labeling index in the DPD-negative group was significantly higher than that in the DPD-positive group (16.9 ± 3.2% vs.13.2 ± 3.3%; P < 0.05).

CONCLUSIONS

  The negative DPD expression was significantly associated with the enhanced tumor cell proliferation and poorer prognosis in patients with IHCC. DPD expression is a potential prognostic indicator for IHCC.

A retrospective study on TS mRNA expression and prediction of the effects of adjuvant oral 5-fluorouracil in breast cancer

Nucleic acid-metabolizing enzymes, such as thymidylate synthase (TS), dihydropyrimidine dehydrogenase (DPD), thymidine phosphorylase (TP) and orotate phosphoribosyl transferase (OPRT), have attracted attention as candidates for response determinants of 5-fluorouracil (5-FU). Whether the expression levels of these enzymes can be adopted as valuable parameters for 5-FU sensitivity in breast cancer has yet to be elucidated. In the present study, intratumoral mRNA expression of TS, DPD, TP and OPRT were determined in formalin-fixed paraffin-embedded surgical specimens collected from 217 breast cancer patients, using the Danenberg Tumor Profile method, which combines microdissection and real-time-polymerase chain reaction. The significance of these enzymes as prognostic and 5-FU efficacy-predicting factors was evaluated. Our data showed that a low DPD expression is related to a high nuclear grade and other factors including hormone receptor-negativity. Low expression levels of TP were found in hormone receptor-negative tumors. TS and OPRT expression were not related to various clinicopathological factors, but patients with a high TS mRNA expression showed a significantly poorer prognosis in cases where 5-FU was not administered. The efficacy of 5-FU was more significant when administered for more than 6 months in the group with a high TS mRNA expression. These data suggest that TS mRNA expression in breast cancer tissue is an ideal predictor of outcomes for patients with no administration of 5-FU, and of the efficacy of 5-FU.

Effect of leucovorin on the antitumor efficacy of the 5-FU prodrug, tegafur-uracil, in human colorectal cancer xenografts with various expression levels of thymidylate synthase

The combination of oral tegafur-uracil (UFT) with leucovorin (LV) is used to treat patients with stage II to III colon cancer based on the results of postoperative randomized studies in which UFT/LV treatment showed an equivalent efficacy to intravenous 5-FU plus LV therapy. However, whether the addition of LV to UFT can elevate the antitumor activity of UFT in colorectal tumors with high expression levels of thymidylate synthase (TS), which affects 5-FU efficacy, remains to be clarified. This study investigated the effect of LV on the antitumor activity of UFT and/or 5-FU prodrugs in low folate diet-fed nude mice using human colorectal cancer xenografts with various expression levels of TS. The addition of LV to UFT resulted in a 55-79% inhibition of tumor growth among 11 types of colorectal tumor xenograft, whereas UFT alone showed 23-67% antitumor activity. Although there was an inverse relationship between the antitumor effect of UFT alone and UFT plus LV and tumoral TS activity, UFT plus LV appeared to have a more potent antitumor effect than UFT alone on colorectal tumors such as Co-3 and KM12C/5-FU with high expression levels of TS. This finding was confirmed by the significant positive correlation between the relative inhibition ratio of UFT/LV to UFT alone and TS levels in tumors. To investigate the reason for the higher efficacy of UFT/LV on colorectal cancer xenografts with high TS activity, intratumoral levels of reduced folates and a ternary complex of TS after oral UFT with or without LV were measured using Co-3 xenografts. Elevated levels of reduced folates and an increased ternary complex of TS in LV-treated tumors were noted. Our results indicate that a combined therapy of UFT with LV may contribute to the treatment of colorectal cancer patients with low and high expression levels of tumoral TS by increased formation of the ternary complex of TS leading to potentiated antitumor efficacy of UFT.

The Value of Dihydrouracil/Uracil Plasma Ratios in Predicting 5-Fluorouracil-Related Toxicity in Colorectal Cancer Patients

This study investigated the relationship between the dihydrouracil/uracil (UH2/U) plasma ratio, a surrogate marker of dihydropyrimidine dehydrogenase (DPD) activity, and 5-fluorouracil (5-FU)-related early toxicity. Plasma UH2/U ratios were determined in 68 colorectal cancer patients and 100 healthy controls. A cutoff value indicative of DPD deficiency was calculated using receiver operator characteristics. Patients experiencing toxicity were screened for the DPD G-to-A point mutation within the 5′-splicing donor site of intron 14 (IVS14+1G>A). Overall, 24/68 patients (35%) experienced toxicity (all grades) and abnormal UH2/U ratios were demonstrated in 21/24 (87.5%) patients. Drug concentrations up to 130 times the recommended level were found in 13/24 (54%) patients experiencing toxicity. One patient experiencing toxicity was a heterozygous carrier of the IVS14+1G>A mutation. A low UH2/U plasma ratio had a sensitivity of 0.87 and specificity of 0.93 for predicting 5-FU-induced toxicity. Systematic detection of DPD-deficient patients using the UH2/U ratio could optimize 5-FU-based chemotherapy and minimize life-threatening toxicity.

Gene expression and effects of orally active derivatives of fluoropyrimidine on gastric and colorectal cancer

The effects of chemotherapy on gastrointestinal cancer are influenced by the chemotherapeutic sensitivity of the cancer cells. Determining the expression of genes related to chemotherapeutic sensitivity has been used as a molecular method. The aim of the study was to clarify the relationships between the expression of genes related to chemotherapeutic sensitivity and the effects of orally active derivatives of fluoropyrimidine on gastric and colorectal cancer. Forty-five patients who underwent adjuvant chemotherapy containing orally active derivatives of fluoropyrimidine after undergoing curative surgery for gastric or colorectal cancer were enrolled. Twenty-four patients had colorectal cancer and 21 patients had gastric cancer. Total RNA was extracted from formalin-fixed, paraffin-embedded specimens of the resected tumors, and the expression of 11 genes was measured using the RT-PCR method. We then analyzed the relationships between the gene expression and the postoperative relapse rate as well as the relationships between clinicopathological factors and postoperative relapse rate. The median observation period of the subjects was 41 months. Twelve out of the 21 gastric cancer patients (57%) and 11 out of the 24 colorectal cancer patients (46%) relapsed. Although the results of a univariate analysis revealed that expression of none of the evaluated genes was related to relapse in the gastric cancer patients, excision repair cross-complementing gene 1 (ERCC1) overexpression was related to the relapse rate in colorectal cancer patients (p=0.023). When 1.295 was set as the cut-off value for ERCC1 overexpression using the receiver operating characteristic (ROC) curve, 67% of patients with ERCC1 overexpression and 25% of patients without ERCC1 overexpression relapsed. The relapse-free survival rate was lower in the group with ERCC1 overexpression than in the group without ERCC1 overexpression (p=0.046). ERCC1 overexpression appears to be a useful predictor of relapse in colorectal cancer patients receiving adjuvant therapy with regimens including orally active derivatives of fluoropyrimidine.

Clinical implications of thymidylate synthetase, dihydropyrimidine dehydrogenase and orotate phosphoribosyl transferase activity levels in colorectal carcinoma following radical resection and administration of adjuvant 5-FU chemotherapy

BACKGROUND

A number of studies have investigated whether the activity levels of enzymes involved in 5-fluorouracil (5-FU) metabolism are prognostic factors for survival in patients with colorectal carcinoma. Most reports have examined thymidylate synthetase (TS) and dihydropyrimidine dehydrogenase (DPD) in unresectable or metastatic cases, therefore it is unclear whether the activity of these enzymes is of prognostic value in colorectal cancer patients treated with radical resection and adjuvant chemotherapy with 5-FU.

METHODS

This study examined fresh frozen specimens of colorectal carcinoma from 40 patients who had undergone curative operation and were orally administered adjuvant tegafur/uracil (UFT) chemotherapy. TS, DPD and orotate phosphoribosyl transferase (OPRT) activities were assayed in cancer tissue and adjacent normal tissue and their association with clinicopathological variables was investigated. In addition, the relationships between TS, DPD and OPRT activities and patient survival were examined to determine whether any of these enzymes could be useful prognostic factors.

RESULTS

While there was no clear relationship between pathological findings and TS or DPD activity, OPRT activity was significantly lower in tumors with lymph node metastasis than in tumors lacking lymph node metastasis. Postoperative survival was significantly better in the groups with low TS activity and/or high OPRT activity.

CONCLUSION

TS and OPRT activity levels in tumor tissue may be important prognostic factors for survival in Dukes' B and C colorectal carcinoma with radical resection and adjuvant chemotherapy with UFT.

G>C SNP of thymidylate synthase with respect to colorectal cancer

Several studies indicate that low thymidylate synthase (TS) protein levels in tumor and normal tissues of colorectal cancer patients are associated with better clinical response to fluorouracil-based chemotherapy and higher risk of toxicity. However, no correlation or even reverse correlation has also been reported. These conflicting results may be partly due to the methodological limitations of the immunohistochemical techniques generally used to quantify thymidylate synthase expression. In this sense, a genetic approach aiming at determining the influence of the TS gene polymorphisms on clinical outcome seems more appealing. So far three polymorphisms have been identified and studied in the TYMS gene: the variable number of 28-bp tandem repeats (2R or 3R) in the 5 UTR; the G>C substitution at the 12th nucleotide in the second repeat of the 3R allele (3RG>3RC) and the 6-bp deletion in the 3 UTR (+6bp/-6bp 3 UTR). In vitro studies indicate that each of these polymorphisms can influence thymidylate synthase expression. In particular, the G>C SNP, which alters the E-box sequence binding an upstream stimulatory factor (USF-1), seems more important than the variable number of tandem repeats in determining TS gene expression in that the 3RC allele has a reduced translational activity compared with the 3RG allele, while showing the same activity as the 2R allele. In contrast with the in vitro findings, the clinical studies in colorectal patients failed to find a consistent relationship between the G>C polymorphism and clinical outcome measures (response, survival or toxicity). This discrepancy may be due to methodological heterogeneities amongst the studies, including genotyping in normal or tumor tissues, loss of heterozygosity in tumor cells not evaluated, variable doses and schedules of fluorouracil-based therapy, and variable tumor stage. The complexity of TYMS gene regulation, and the possibility that other polymorphisms may contribute to fluorouracil response, call for further studies before TYMS genotyping can be used in clinical practice to select colorectal cancer patients who are most likely to benefit from chemotherapy.

Prognostic significance of thymidylate synthase, dihydropyrimidine dehydrogenase and thymidine phosphorylase protein expression in colorectal cancer patients treated with or without 5-fluorouracil-based chemotherapy

BACKGROUND

Low tumour expression levels of thymidylate synthase (TS), dihydropyrimidine dehydrogenase (DPD) and thymidine phosphorylase (TP) have been linked with improved outcome for colorectal cancer (CRC) patients treated with 5-fluorouracil (5-FU). It is unclear whether this occurs because such tumours have better prognosis or they are more sensitive to 5-FU treatment.

PATIENTS AND METHODS

Associations between TS, DPD and TP levels, determined by tissue microarrays and immunohistochemistry, and survival was evaluated in 945 CRC patients according to treatment status.

RESULTS

Low TS and DPD expression associated with worse prognosis in stage II [hazard ratio (HR) = 1.69, 95% confidence interval (CI) (1.09-2.63) and HR = 1.92 (95% CI 1.23-2.94), respectively] and stage III CRC patients treated by surgery alone [HR = 1.39 (95% CI 0.92-2.13) and HR = 1.49 (95% CI 1.02-2.17), respectively]. Low TS, DPD and TP associated with trends for better outcome in stage III patients treated with 5-FU [HR = 0.81 (95% CI 0.49-1.33), HR = 0.70 (95% CI 0.42-1.15) and HR = 0.66 (95% CI 0.39-1.12), respectively].

CONCLUSION

Low TS and DPD expression are prognostic for worse outcome in CRC patients treated by surgery alone, whereas low TS, DPD and TP expression are prognostic for better outcome in patients treated with 5-FU chemotherapy. These results provide indirect evidence that low TS, DPD and TP protein expression are predictive of good response to 5-FU chemotherapy.

Polymorphism of thymidylate synthase gene associated with its protein expression in human colon cancer

AIM: To correlate the polymorphisms in the 5’-untranslated region with thymidylate synthase (TS) protein expression in Han Chinese colonic neoplasms.

METHODS: Adenocarcinoma samples were from 68 patients who received no treatment before surgery. Tandem repeat length of TS gene was determined by PCR amplification of genomic DNA. Intratumoral TS protein expression was studied immunohistochemically in corresponding sections from paraffin-embedded primary foci. Immunoreactivity was semiquantitatively evaluated by immunoreactivity score (IRS).

RESULTS: Double-(2R) and triple-repeated (3R) sequences of the TS gene were found in the cancer tissues. Three genotypes of TS were found: 2R/2R (n = 6), 2R/3R (n = 22) and 3R/3R (n = 40). Patients who were homozygous for triple-repeated (3R/3R) sequences showed significantly higher IRS of TS than patients who were homozygous for double-repeated (2R/2R) sequences or heterozygous patients (2R/3R): 5.73 ± 3.25 vs 2.17 ± 1.47 or 3.77 ± 2.64, P = 0.008 or P = 0.015. But no statistical significance of IRS in cancer tissues was observed between 2R/3R genotype and 2R/2R genotype.

CONCLUSION: There is a relationship between TS genotype and TS protein expression in clinical specimens. The data might offer an advantage for selection of Chinese cancer patients to receive fluoropyrimidines treatment.

Biological predictive factors in rectal cancer treated with preoperative radiotherapy or radiochemotherapy

We analysed the expression of microsatellite instability, p53, p21, vascular endothelial growth factor and thymidylate synthase (TS) in pretreatment biopsy specimens from 57 locally advanced rectal cancers. The aim of the study was to correlate the expression of these markers with pathological response. Nineteen patients were treated with preoperative concomitant radiotherapy (RT) and fluorouracil/oxaliplatin-based chemotherapy (RCT), while 38 had RT alone. Pathological complete remission (pCR) and microfoci residual tumour (micR) occurred more frequently in patients treated with RCT (P=0.002) and in N0 tumours (P=0.004). Among patients treated with RCT, high TS levels were associated with a higher response rate (pCR+micR; P=0.015). No such correlation was found in the RT group. The other molecular factors were of no predictive value. Multivariate analysis confirmed a significant interaction between nodal status and the probability of achieving a pathological response (P=0.023) and between TS expression and treatment, indicating that a high TS level is predictive of a higher pathological response in the RCT subset (P=0.007). This study shows that lymph node status is the most important predictive factor of tumour response to preoperative treatment. Thymidylate synthase expression assessed immunohistochemically from pretreatment tumour biopsies may be a useful predictive marker of rectal tumour response to preoperative RCT.

The prognostic significance of thymidylate synthase and dihydropyrimidine dehydrogenase in colorectal cancer of 303 patients adjuvantly treated with 5-fluorouracil

Cytotoxic effect of 5-fluorouracil 5-FU is mediated through inhibition of thymidylate synthase (TS), and 5-FU is catabolised by dihydropyrimidine dehydrogenase (DPD). Efficacy of 5-FU may therefore depend on the TS and DPD activity of colorectal cancer. Archival tumour specimens from 303 consecutive patients were analysed for the expression of TS and DPD using immunohistochemistry. All patients were completely resected for colorectal cancer stages II-III and have subsequently received adjuvant treatment with 5-FU. In a multivariate analysis adjusting for the impact of bowel obstruction and vascular tumour invasion, diffuse TS pattern was significantly associated with increased risk of recurrence (hazard ratio (HR) = 1.9; 95% confidence interval (CI): 1.1-3.2; p = 0.02), but without significant association to death (HR = 1.6; 95% CI: 0.9-2.8; p = 0.08). High TS intensity was not significantly associated with lower risk of recurrence (HR = 0.6; 95% CI: 0.3-1.1; p = 0.07) or death (HR = 0.6; 95% CI: 0.3-1.2; p = 0.2). High DPD intensity was significantly associated with increased risk of recurrence (HR = 1.5; 95% CI: 1.1-2.3; p = 0.03) and death (HR = 1.6; 95% CI: 1.1-2.5; p = 0.02). Patients with a combination of low TS and high DPD intensity were at significantly increased risk of both recurrence (HR = 2.1; 95% CI: 1.0-4.2; p = 0.04) and death (HR = 2.0; 95% CI: 1.0-4.0; p = 0.05). No relationship between tolerability and toxicity of 5-FU and TS and DPD expression was found. It is concluded that characterizing colorectal carcinomas by TS and DPD expression may disclose subsets of patients with significantly greater risk of disease recurrence and early death. This may be utilized in the selection of patients for treatment approaches and for decision on follow-up programs.

Thymidylate synthase expression in resectable and unresectable pancreatic cancer: role as predictive or prognostic marker?

BACKGROUND AND AIMS

Thymidylate synthase (TS) is an important enzyme for DNA synthesis and the target for 5-fluorouracil (5-FU). Its expression may determine the outcome of patients with gastrointestinal cancers. We examined the prognostic and predictive value of TS-protein expression in patients with ductal adenocarcinoma of the pancreas.

METHODS

TS expression from 131 patients with ductal adenocarcinoma of the pancreas was analyzed by immunohistochemistry in paraffin-embedded primary tumour specimens or biopsies.

RESULTS

The median disease-specific survival among all patients (n=131) was 13 months. The invasion depth, the presence of metastases, grading and Union Internationale Contre le Cancer [International Union Against Cancer] (UICC) stage were associated with survival. Among resected patients (n=98), a difference in median survival was seen in the group receiving postoperative adjuvant treatment (21.1 months) compared with the group treated by surgery alone (12.4 months) (p=0.025). Low- and high-TS immunoreactivity was present in 74 (56%) and 56 (43%) of the cancers, respectively. One sample was not evaluable. No difference in median survival was observed among low- and high-TS-expressing tumours. Among patients undergoing resection and receiving postoperative intra-arterial chemotherapy (n=23), a marked trend to a longer median survival was seen for the group with low-TS-expressing tumours compared with the corresponding high-TS group (25.0 vs 16.0 months) (p=0.3834). There was no difference in survival among all palliative treated patients with low- and high-TS-expressing tumours.

CONCLUSION

Especially patients undergoing tumour resection with low-TS values seemed to have taken advantage from an intensified postoperative chemotherapeutic protocol. However due to the heterogeneous group of patients in the present report, larger trials of more homogenous patient populations will be necessary to confirm this hypothesis.

Thymidylate synthase messenger RNA expression in plasma from patients with colon cancer: prognostic potential

PURPOSE

Thymidylate synthase (TS), a critical target in fluorouracil-based chemotherapy, is a prognostic marker in colon carcinomas and a predictor of response to treatment. Tumor RNA has been detected in plasma from cancer patients and is associated with poor prognosis. This is the first study to examine extracellular TS mRNA in plasma from patients with colon carcinoma, and its possible relation with TS promoter enhancer region (TSER) polymorphism.

EXPERIMENTAL DESIGN

TS expression was measured in plasma from 88 patients and 26 controls, and in a tumor subgroup of this series by quantitative PCR. Genotyping for TSER polymorphism was done in 60 patients. Clinicopathologic variables were correlated with these molecular changes.

RESULTS

TS mRNA was detected in plasma in 47% of patients, showing significant differences from healthy controls. Patients with TS mRNA in plasma had higher levels of TS in tumor tissue than patients without. The presence of TS mRNA was associated with lymph node metastases and more advanced stages. Polymorphism TSER 3/3 was found in 38% of cases, and was significantly correlated with high amounts of TS mRNA in plasma.

CONCLUSIONS

Our results suggest that TS mRNA in plasma originated from tumors, it may indicate poor prognosis and might help to classify tumors in Dukes' stages B and C. The TSER genotype may influence TS mRNA expression in plasma.

Advances and challenges in fluoropyrimidine pharmacogenomics and pharmacogenetics

In cancer pharmacogenetics (the study of how variability in a single or set of known genes influences drug response) and pharmacogenomics (the study of variability on a genome-wide scale), one of the most important fields of research focuses on the fluoropyrimdines (FPs) and, in particular, 5-fluorouracil (5-FU). After over 40 years of use, FPs remain one of the most commonly used cancer chemotherapy agents and their application includes a wide spectrum of cancer types. FPs also continue to be the baseline component for many new regimens with novel molecular-targeted agents that are being rapidly introduced. Hence, it would seem appropriate that pharmacogenetic/genomic models for optimizing cancer patient management would involve indicators of FP response. In this article, the current trends in FP pharmacogenetics and pharmacogenomics are reviewed based on the advances made to date and the challenges faced in realizing their full potential.

Thymidine phosphorylase, dihydropyrimidine dehydrogenase and thymidylate synthase mRNA expression in primary colorectal tumors-correlation to tumor histopathology and clinical follow-up

AIM

Evaluation of thymidine phosphorylase (TP), dihydropyrimidine dehydrogenase (DPD), and thymidylate synthase (TS) mRNA levels in formalin-fixed, and paraffin-embedded tissues of patients with colorectal cancer and their prognostic and/or predictive value.

MATERIALS AND METHODS

Total RNA was isolated from microdissected, formalin-fixed, and paraffin-embedded tissues (controls and tumor) and subjected to quantitative RT-PCR (QRT-PCR) in the LightCycler system. Resulting mRNA levels correlated to tumor histology (n=102) and the clinical follow-up in patients treated by resection alone (n=40) and by resection plus adjuvant 5-FU-based chemotherapy (n=52).

RESULTS

Correlation to histopathological parameters revealed a significant association between tumor stage and the TP mRNA level (T and N category and UICC) as well as the TP:DPD (T and N category and UICC) and TS:DPD (T category) ratio. In addition, tumor differentiation was correlated to the TS mRNA level and the TS:DPD ratio. Finally, the TS:DPD ratio was a prognostic marker for overall survival in patients receiving resection alone (p=0.032). Moreover, a high TP:DPD ratio (>8.1; p=0.002) and, marginally, low DPD (<8.2; p=0.05) mRNA levels significantly correlated to disease-free survival.

CONCLUSION

We present a novel, standardized approach for TP, DPD, and TS mRNA quantification in archival tissue specimens and applied this to a large series of primary colorectal tumors. Correlations to histopathological parameters and clinical follow-up revealed an association of TP, DPD and TS mRNA expression patterns with tumor stage and suggested new prognostic and predictive markers for patients with colorectal cancer.

The effect of surgically induced ischaemia on gene expression in a colorectal cancer xenograft model

Delays in tissue fixation following tumour vascular clamping and extirpation may adversely affect subsequent protein and mRNA analysis. This study investigated the effect of surgically induced ischaemia in a xenograft model of a colorectal cancer on the expression of a range of prognostic, predictive, and hypoxic markers, with a particular emphasis on thymidylate synthase. Vascular occlusion of human tumour xenografts by D-shaped metal clamps permitted defined periods of tumour ischaemia. Alterations in protein expression were measured by immunohistochemistry and spectral imaging, and changes in mRNA were measured by reverse transcriptase–polymerase chain reaction. Thymidylate synthase expression decreased following vascular occlusion, and this correlated with cyclin A expression. A similar reduction in dihydropyrimidine dehydrogenase was also seen. There were significant changes in the expression of several hypoxic markers, with carbonic anhydrase-9 showing the greatest response. Gene transcriptional levels were also noted to change following tumour clamping. In this xenograft model, surgically induced tumour ischaemia considerably altered the gene expression profiles of several prognostic and hypoxic markers, suggesting that the degree of tumour ischaemia should be minimised prior to tissue fixation.

Adjuvant treatment strategies for early colon cancer

Colon cancer remains a major cause of death; however, in the last 3 years a number of trials have been published that have led to changes in the treatment of patients with this disease. Initially, the adjuvant treatment of patients following curative resection was based on their Dukes staging; this is now being refined by consideration of other pathological factors, as well as the investigation of newer prognostic markers such as p53, Ki67 and a number of genes on chromosome 18. Tumours generally develop from the progressive accumulation of genetic events, although some develop through mutation or inactivation of DNA mismatch repair proteins leading to microsatellite instability; this is particularly important in Lynch's syndrome. The loss of gene expression can occur by deletion or mutation of genes or by aberrant methylation of CpG islands. In patients with Dukes C colon cancer the standard of care for adjuvant chemotherapy was previously based on bolus fluorouracil (5-fluorouracil) and folinic acid (leucovorin) administered 5 days per month or weekly for 6 months. Recent studies with a combination of infusional fluorouracil, folinic acid and oxaliplatin have been found to be superior. A further study replacing fluorouracil with oral capecitabine has also demonstrated equivalent disease-free survival. Although some debate remains regarding the benefit of adjuvant treatment for patients with Dukes B colon cancer, the emerging consensus is that, for those patients who are younger and have high-risk features, chemotherapy should be discussed. A number of large vaccine trials have also been conducted in the adjuvant setting and, overall, these have been disappointing. This is a rapidly advancing area of therapy and the results of new trials are awaited to determine whether additional benefits can be achieved with biological therapies such as anti-vascular endothelial growth factor and anti-epithelial growth factor receptor monoclonal antibodies, which have already been shown to be effective in setting of metastatic colon cancer.

Prognostic value of Thymidylate Synthase, Epidermal Growth Factor Receptors and Vascular Endothelial Growth Factor in patients with stage III colon cancer

Purpose: We studied the prognostic value of thymidylate synthase (TS), Epidermal Growth Factor Receptors (EGFR) and Vascular Endothelial Growth Factor (VEGF) expression in primary colon cancer (CC). Patients and Methods : Those three markers were immunohistochemically assessed on tumor sections from 100 patients with CC Dukes C. All patients received the same adjuvant chemotherapy with FU/Leukovocin according to Mayo protocol. Considering the clinical course they were classified in two groups: bad in which all patients progressed and good in which neither progressed during the five year follow up period. Results: TS, EGFR and VEGF were an independent prognostic factor for time to progression (TTP) and overall survival (OS). Findings of at least two maximum expressed investigated markers, significantly increases the risk of progression which influences shorter five year survival, and the single maximum expression does not necessarily have to be a bad prognostic sign. Conclusion: Highest expression of TS, EGFR and VEGF carries prognostic significance with respect to TTP and OS for patients with Dukes C colon cancer.

Prognostic and predictive value of the thymidylate synthase expression in patients with non-metastatic colorectal cancer

AIMS

To assess the value of thymidylate synthase (TS) expression as a predictive factor in the efficacy of adjuvant chemotherapy in colorectal cancer, as well as its independent prognostic value for survival.

METHODS

We studied 114 high risk colorectal carcinoma patients (high risk stage II and stage III), distributed in two treatment groups: surgery alone (61 patients) or surgery followed by 5-FU-based chemotherapy (53 patients). TS protein expression in the tumour tissue was assessed by immunohistochemistry.

RESULTS

In the surgery alone subgroup, overall survival (OS) at 5 years were 77.5% for the patients with low TS expression, against 57.7% for the patients with high TS expression (p=0.006). Among patients with low TS, there was no difference in OS as a result of whether adjuvant chemotherapy was carried out or not (65.8 vs 77.5%, p=0.29). Among the patients with high TS, there was a significant gain in OS in favor of chemotherapy (87.8 vs 57.7%, p=0.04). Analyzing the complete sample, TS expression was not shown as an independent prognostic factor for survival in the multivariate analysis.

CONCLUSIONS

The immunohistochemical TS expression may be used for selecting patients for better adjuvant chemotherapy protocols. In this sample, TS expression was not an independent prognostic factor for survival.

Detection of Thymidylate Synthase Expression in Lymph Node Metastases of Colorectal Cancer Can Improve the Prognostic Information

Purpose

The level of thymidylate synthase (TS) in primary colorectal cancer (CRC) has been reported as a prognostic marker. The purpose of this study was to determine whether TS expression in lymph node metastases of Dukes' C CRC is a prognostic marker.

Patients and Methods

TS expression in the primary tumor and lymph node metastases from 348 patients with Dukes' C CRC was retrospectively assessed using immunohistochemistry and the monoclonal antibody TS 106. The patients had all been enrolled onto our previous study of 862 CRC patients who were included in Nordic trials that randomly assigned the patients to either surgery alone or surgery plus adjuvant chemotherapy.

Results

TS expression in lymph node metastases was a distinct prognostic marker in the entire study group for overall survival (OS; P = .02) and disease-free survival (DFS; P = .04). A low TS expression in the lymph node metastases correlated with a better clinical outcome. In the subgroup of patients treated with surgery alone, the expression of TS in lymph node metastases also had a prognostic value for OS (P = .04) and DFS (P = .03), but this was not the case for the other subgroup who received adjuvant fluorouracil-based chemotherapy (OS, P = .5; DFS, P = .2). The expression of TS in the primary tumor only had a significant prognostic value among patients who were treated with surgery alone (OS, P = .03; DFS, P = .03) and not among the entire patient population.

Conclusion

These data show that TS expression in lymph node metastases is a prognostic marker for patients with Dukes' C CRC.

Predictive value of thymidylate synthase and dihydropyrimidine dehydrogenase protein expression on survival in adjuvantly treated stage III colon cancer patients

BACKGROUND

The predictive value of thymidylate synthase (TS) and dihydropyrimidine dehydrogenase (DPD) expression on long-term survival by influencing 5-fluorouracil (5-FU) effect were determined in primary tumours and node metastases of stage III colon cancer patients treated adjuvantly with 5-FU regimens (n=391). The effect of TP 53 mutation status, which is thought to be functionally linked to TS inhibition, was also examined.

PATIENTS AND METHODS

TS and DPD protein expression was determined by immunohistochemical analysis using tissue microarrays of these colon tumours. Two hundred and twenty tumours had already been screened in a previous study for TP 53 mutations.

RESULTS

Low TS protein levels in primary stage III colon tumours appeared to be associated with mucinous histology and low DPD protein levels with young age at time of randomisation. Concordance between TS and DPD expression in primary and metastatic tumours was low. No associations were found between disease-free survival (DFS) and TS or DPD protein levels. When stratified by TP 53 mutation status DFS did not differ with TS expression.

CONCLUSIONS

Expression of TS and DPD proteins is not predictive for survival in patients with stage III colon cancer treated adjuvantly with 5-FU regimens. TS protein levels did not alter the effect of TP 53 mutation status.

Polymorphic tandem repeat sequences of the thymidylate synthase gene correlates with cellular-based sensitivity to fluoropyrimidine antitumor agents

PURPOSE

Thymidylate synthase (TS) is one of the target molecules for the antitumor effects of fluoropyrimidine drugs. The cellular thymidylate synthase level is one of the determining factors for the antitumor activity of fluoropyrimidines. TYMS, which encodes TS, has been reported to possess 28-bp tandem repeat sequences in its 5'-untranslated region, the number of which varies. In addition, single nucleotide polymorphisms have also been shown in a triple repeat sequence. In this study, correlation between the polymorphic tandem repeat sequences of the TYMS gene and the antitumor activities of 5-fluorouracil (5-FU) and 5-fluoro-2'-deoxyuridine (FUdR) were investigated with 30 established human cell lines derived from solid tumors.

METHODS

A reporter assay system was developed in order to compare the ability of the transactivation mediated by the double (2R) and triple (c- or g-type, 3Rc or 3Rg, respectively) repeat sequences using a human colon cancer cell line, DLD-1. The 50% inhibitory concentration (IC(50)) of cell growth by 5-FU and FUdR was measured with 30 different established cell lines of human solid tumors. Genotypes based on the number of the 28-bp TYMS tandem repeat for the above cell lines were determined by electrophoretical analysis of PCR products containing the repeat sequences and nucleotide sequencing.

RESULTS

The reporter activity mediated by the 3Rg sequence was significantly higher than that by the 2R and 3Rc sequences. Activities mediated by the 2R and 3Rc sequences were comparable. According to the reporter assay, 2R and 3Rc were judged as low TS expression alleles and 3Rg as a high TS expression allele. On the basis of IC(50) values, cells possessing the 2R/2R and 2R/3R repeat of TYMS were significantly more sensitive to FUdR than those with the 3R/3R repeat. Cells possessing 3Rg/3Rg (a high TS expression genotype) were significantly less sensitive to FUdR than cells with 2R/2R, 2R/3Rc, and 3Rc/3Rc (low TS expression genotypes).

CONCLUSIONS

Our results of the reporter assays using 2R, 3Rc, and 3Rg repeat sequences prompted us to classify 3Rg as a high TS expression allele, and 2R and 3Rc as low TS expression alleles. The cells with low TS expression alleles were shown to exhibit significantly higher FUdR sensitivity than the cells with high TS expression alleles for the first time. These results were consistent with numerous previous in vitro and in vivo findings that tumors showing high TS expression were less sensitive to fluoropyrimidines. These results support the idea that genotyping the tandem repeat sequences of TYMS in the 5'-untranslated region is useful for individualized therapy involving fluoropyrimidine antitumor drugs.

Predictive factors for response to chemotherapy in colorectal cancer patients

Colorectal cancer represents a major health problem in the western world. A lot of drugs have been employed in treatment of this disease, but only few data are available about predictive factors for response to anticancer treatments in colorectal cancer. Aim of this paper is to review the main data about this investigation field. Using a Medline database search (1966-2003) we reviewed all the relevant papers that investigate clinical and molecular predictors for response to the main drugs used in the treatment of colorectal cancer patients, both in adjuvant and in advanced setting. Moreover we comprehensively reviewed all the data published in abstract form during the most significant international meetings. Our review put in evidence the most important predictive factors for response in colorectal cancer patients treated with anticancer chemotherapy both in adjuvant and in advanced setting. The predictive factors are clustered on the basis of the different anticancer drugs. The results of this review provide the rationale basis for personalizing anticancer treatment in colorectal cancer patients by molecular and clinical features, aiming to improve response rate and reduce toxicities.

Influence of thymidylate synthase and p53 protein expression on clinical outcome in patients with colorectal cancer

AIMS

Thymidylate synthase (TS) and tumor suppressor p53 are two proteins with an influence on tumor resistance to radio-chemotherapy that is well known. For this reason we tested the effect of TS and p53 expression on clinical outcome (tumor recurrence and survival) in patients after curative tumor resection, especially in patients who received adjuvant radio-chemotherapy.

PATIENTS AND METHODS

A total of 120 patients with colorectal cancer were included in the study. A curative resection was possible in 83 patients, and 30 of this group received adjuvant therapy. For the immunohistochemical staining of tumor specimens, monoclonal antibody (mAb) TS 106 against TS and mAb DO-1 against p53 protein were used. TS positivity was defined as a moderate to high staining intensity in the cytoplasma of cells and p53 positivity as nuclear staining of tumor cells in >10% of these cells.

RESULTS

Thymidylate synthase immunoreactivity was found in 59% of all cases and p53 staining in 51%. No relation between clinicopathological features and p53 expression was found in contrast to TS expression, where a highly significant association of TS-positive cases with tumor invasion (pT) was observed. Curatively resected patients with a TS-positive tumor developed tumor recurrence/distant metastases significantly more often than TS negative tumors. The same result was found when comparing p53-positive with p53-negative tumors and TS+/p53+ with TS-/p53- tumors. TS expression was highly significantly associated with poor survival and was the strongest independent prognostic factor in multivariate analysis, followed by lymph node status.

CONCLUSION

Thymidylate synthase expression seems to be an independent prognostic factor and a possible predictor of tumor recurrence in patients with colorectal cancer.

Two proliferation-related proteins, TYMS and PGK1, could be new cytotoxic T lymphocyte-directed tumor-associated antigens of HLA-A2+ colon cancer

PURPOSE

The purpose of this work was to provide a scientific basis for specific immunotherapy of colon cancer.

EXPERIMENTAL DESIGN

This study focused on identification of colon tumor-associated antigens and HLA-A2-restricted and tumor-reactive cytotoxic T lymphocytes (CTLs) generated from tumor-infiltrating lymphocytes of a colon cancer patient. A gene expression cloning method was used to identify genes coding for tumor antigens. Fifty-six peptides with HLA-A2-binding motifs encoded by these proteins were examined for their ability to induce HLA-A2-restricted and tumor-reactive CTLs.

RESULTS

We identified the following three genes coding for proliferation-related proteins: thymidylate synthase (TYMS), which is involved in chemoresistance (5-fluorouracil); 5'-aminoimidazole-4-carboxamide-1-beta-d-ribonucleotide transfolmylase/inosinicase (AICRT/I); and phosphoglycerate kinase 1 (PKG1), which was secreted by tumor cells and involved in the angiogenic process. TYMS was preferentially expressed in tumor cells, whereas AICRT/I and PKG1 were equally expressed in both cancer cells and normal tissues at the mRNA level. Among 56 peptides with HLA-A2-binding motifs encoded by these proteins, 8 peptides were recognized by the CTLs, and 5 of 8 peptides were also recognized by the CTL precursors without ex vivo activation in the peripheral blood of colon cancer patients. Furthermore, four of them (one each from TYMS and PKG1 and two from AICRT/1) possessed the ability to induce HLA-A2-restricted and peptide-specific CTLs cytotoxic to colon tumor cells in peripheral blood mononuclear cells of colon cancer patients.

CONCLUSIONS

TYMS and PGK1, as well as their epitope peptides, might be appropriate target molecules for specific immunotherapy of HLA-A2(+) colon cancer patients because of the positive role of TYMS and PGK1 in chemoresistance (5-fluorouracil) and angiogenesis of tumor cells, respectively.

Intratumoral molecular or genetic markers as predictors of clinical outcome with chemotherapy in colorectal cancer

Identification of molecular markers at either the intragenic, chromosomal, mRNA, or protein level that might predict whether colorectal cancer patients are likely to benefit from adjuvant or palliative therapy is a high priority. The majority of clinical studies addressing this issue, particularly those done in the adjuvant setting, analyzed tumor samples from patients treated in the era when 5-fluorouracil (5-FU) alone or combined with leucovorin or levamisole were the mainstay of therapy. This review highlights some of the intratumoral molecular markers that may have importance as predictors of benefit with 5-FU-based therapy. Although the goal of these investigations is to one day permit selection of therapy for an individual patient based on the tumor phenotype, prospective studies have yet to be conducted that test whether selection of therapy based on molecular markers results in an improved outcome.

Pharmacogenomics in colorectal carcinomas: Future perspectives in personalized therapy

The recent introduction of new drugs such as capecitabine, irinotecan, and oxaliplatinum has greatly improved the clinical outcome of patients with advanced/metastatic colorectal cancer. Nevertheless, some patients may suffer from the adverse drug reactions which will probably be the main cause of chemotherapy failure. The goal of pharmacogenomics is to find correlations between therapeutic responses to drugs and the genetic profiles of patients; the different responses to a particular drug are due, in fact, not only to the specific clinico-pathological features of the patient or to environmental factors, but also to the ethnic origins and the particular individual's genetic profile. Genes which codify for the metabolism enzymes, receptor proteins, or protein targets of chemotherapy agents often present various genetic polymorphisms. The main aim of this review is to provide an overview of the known polymorphisms present in the genes which codify for factors (thymidylate synthase dihydropyrimidine dehydrogenase, uridine diphosphate (UDP)-glucuronosyl-transferase 1A1, enzymes implicated in DNA repair) involved in the action mechanisms of the drugs now utilized in chemotherapeutic treatment of colorectal carcinoma, such as fluoropyrimidines, irinotecan, and platinum agents.

Thymidylate Synthase Expression in Normal Colonic Mucosa: A Predictive Marker of Toxicity in Colorectal Cancer Patients Receiving 5-Fluorouracil-Based Adjuvant Chemotherapy

OBJECTIVES

We retrospectively evaluated the relevance of thymidylate synthase (TS) expression in normal colonic mucosa as a predictive factor of toxicity in colorectal cancer patients receiving adjuvant fluorouracil (5-FU)-based chemotherapy.

METHODS

TS expression was immunohistochemically assessed on normal colonic mucosa from 50 patients with colorectal cancer Dukes' stages B (15 patients) and C (35 patients) treated with 5-FU-based adjuvant chemotherapy.

RESULTS

The incidence of grade 2-3 diarrhea and stomatitis (according to WHO) was demonstrated to be significantly higher in patients with low nuclear TS expression in normal mucosa than in those with high TS expression (p < 0.0001). Moreover, patients with low TS expression in normal colonic mucosa developed weight loss and worsening of the performance status (according to ECOG score) more commonly than patients with high TS expression (p = 0.005 and p = 0.02, respectively). Furthermore, low TS expression in normal colonic mucosa significantly correlated with a higher rate of a delay of chemotherapy courses, dose reduction and treatment discontinuation.

CONCLUSIONS

Immunohistochemical TS expression in normal colonic mucosa may represent an important predictive parameter for identifying a subset of patients with a high risk of developing severe 5-FU-related toxicities.

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.

Thymidylate synthase expression and prognosis in colorectal cancer: a systematic review and meta-analysis

PURPOSE

A number of studies have investigated the relationship between thymidylate synthase (TS) expression and survival in colorectal cancer (CRC) patients. Although most have reported poorer overall and progression-free survival with high TS expression, estimates of the hazard ratio (HR) between studies differ wildly. To derive a more precise estimate of the prognostic significance of TS expression, we have reviewed published studies and carried out a meta-analysis.

MATERIALS AND METHODS

Twenty studies stratifying overall survival and/or progression-free survival in CRC patients by TS expression status were eligible for analysis. The principal outcome measure was the HR. Data from these studies were pooled using standard meta-analysis techniques.

RESULTS

Thirteen studies investigated outcome in a total of 887 cases with advanced CRC, and seven studies investigated outcome in a total of 2,610 patients with localized CRC. A number of methods were used both to assess TS expression and to assign TS status. Sample sizes varied greatly, small sample sizes being a feature of the advanced disease studies. The combined HR estimate for overall survival (OS) was 1.74 (95% CI, 1.34 to 2.26) and 1.35 (95% CI, 1.07 to 1.80) in the advanced and adjuvant settings, respectively, but there was evidence of heterogeneity and possible publication bias.

CONCLUSION

Tumors expressing high levels of TS appeared to have a poorer OS compared with tumors expressing low levels. Additional studies with consistent methodology are needed to define the precise prognostic value of TS.

Effect of the methylenetetrahydrofolate reductase C677T polymorphism on chemosensitivity of colon and breast cancer cells to 5-fluorouracil and methotrexate

BACKGROUND

Although single nucleotide polymorphisms may be potentially important pharmacogenetic determinants of cancer therapy, functional evidence regarding their relevance is currently lacking. The C677T polymorphism in the methylenetetrahydrofolate reductase (MTHFR) gene is associated with changes in cellular composition of folates. We hypothesized that this polymorphism may modulate the cytotoxic effect of 5-fluorouracil (5FU) and methotrexate (MTX), two commonly used chemotherapeutic agents for colon and breast cancers, because the modes of action of 5FU and MTX are critically dependent on cellular composition of folates.

METHODS

Human HCT116 colon and MDA-MB-435 breast cancer cells were stably transfected with wild-type or mutant 677T human MTHFR cDNA. MTHFR enzyme activity and thermolability, intracellular folate composition, growth rate, and catalytic thymidylate synthase activity were determined. In vitro chemosensitivity to 5FU and MTX was determined using the sulforhodamine B assay. In vivo chemosensitivity of HCT116 cells to 5FU was determined in nude mice.

RESULTS

Compared with cells expressing the wild-type MTHFR, HCT116 and MDA-MB-435 cells expressing the mutant 677T MTHFR had decreased MTHFR activity, MTHFR thermolability, changed intracellular folate distribution, accelerated cellular growth rate, and increased thymidylate synthase activity. The MTHFR 677T mutation increased chemosensitivity of colon and breast cancers to 5FU, but decreased chemosensitivity of breast cancer cells to MTX. In nude mice, xenografts expressing the mutant 677T MTHFR grew faster, but were more sensitive to 5FU, than xenografts expressing the wild-type protein.

CONCLUSIONS

Our data provide evidence that the MTHFR C677T polymorphism affects the concentration and intracellular distribution of folates and changes the growth and chemosensitivity of colon and breast cancer cells. The MTHFR C677T polymorphism may be a useful pharmacogenetic determinant for providing rational and effective tailored chemotherapy.

Differential Expression of Thymidylate Synthase in Colorectal Tumors and Matched Lymph Nodes: Impact on Adjuvant Treatment

Although the expression of thymidylate synthase (TS) in metastatic colorectal cancer (CRC) may be a better predictor of response to 5-fluorouracil chemotherapy than TS expression in primary CRC, this enzyme has not been well studied in tumor-draining regional lymph nodes. We retrospectively examined TS expression in 12 primary CRC lesions (pT3) and matched sentinel lymph nodes. Of the 8 primary tumors that were TS-positive, 50 per cent (4/8) had tumor-positive lymph nodes and 50 per cent (4/8) had tumor-negative nodes. Of the 4 primary tumors that were TS-negative, 75 per cent (3/4) had tumor-positive nodes and 25 per cent (1/4) had tumor-negative nodes [κ = -0.1386, 95 per cent confidence interval: (-0.4820, 0.2048), P = 0.4284]. Of the 8 TS-positive primaries, 25 per cent (2/8) had TS-positive nodes and 75 per cent (6/8) had TS-negative nodes. Of the 4 TS-negative primaries, 50 per cent (2/4) had TS-positive nodes and 50 per cent (2/4) had TS-negative nodes [κ = -0.0131, 95 per cent confidence interval: (-0.2958, 0.2696), P = 0.9274]. Two of the three TS-negative primaries that had metastasized to regional lymph nodes were associated with TS-positive lymph nodes. Our findings indicate that expression of TS by a primary CRC does not correlate with nodal metastases or nodal TS expression. Nodal expression of TS may be important in predicting response to 5-fluorouracil when a primary CRC is TS-negative.

Prognostic molecular markers for planning adjuvant chemotherapy trials in Dukes' B colorectal cancer patients: how much evidence is enough?

The benefit of postoperative adjuvant chemotherapy in patients with Dukes' B colorectal cancer is still uncertain and its routine use is not recommended. Prognostic biomarkers may be useful for identifying high-risk patients with resected, node-negative disease, and this stratification may represent an innovative strategy for designing adjuvant chemotherapy trials. Featured prognostic molecular markers can be divided into the following categories: cell proliferation indices (Ki-67, Mib-1, proliferating cell nuclear antigen); oncogenes/tumor suppressor genes [p53, K-ras, Deleted in Colorectal Cancer (DCC), Bcl-2, c-erbB2]; DNA repair (microsatellite instability); markers of angiogenesis (vascular count, vascular endothelial growth factor); markers of invasion/metastasis (plasminogen-related molecules, matrix metalloproteinases); and biochemical markers (thymidylate synthase). Studies that have investigated their prognostic role in Dukes' B colorectal cancer patients are reviewed here. Current data do not provide sufficient evidence for the incorporation of available prognostic biomarkers into clinical practice. However, a biomarker-based approach could be an effective strategy for improving results of postoperative adjuvant treatments in high-risk Dukes' B colorectal cancer patients. Markers of altered DCC function have shown promising prognostic role and sufficient prevalence in retrospective investigations and they deserve further assessment in prospective studies.

Adjuvant chemotherapy in colon cancer: what is the evidence?

Over the last 12 years, numerous randomized trials have addressed the role of adjuvant chemotherapy in resected colon cancer. Together, these studies give conclusive evidence of the benefit of adjuvant 5-fluorouracil combined with folinic acid in stage III (node positive) disease and this is now considered the standard of care. The chemotherapy appears to be equally effective whether it is given daily for 5 days per month or on a weekly schedule. The overall effect is a relative reduction in tumour -recurrence of 25% or an absolute improvement in survival of 10%. However, doubt remains as to the role of adjuvant chemotherapy in stage II colon cancer. To date, most of the randomized trials have demonstrated a relative reduction in tumour recurrence but have not shown any significant impact on survival. It seems likely that this inability to demonstrate a survival benefit from adjuvant chemotherapy in stage II disease relates to the fact that the trials have been underpowered to do so. Nevertheless, the absolute survival advantage is only about 2% and clinicians need to weigh this against the costs and toxicities of the treatment when managing these patients.

Prognostic value of thymidylate synthase, Ki-67, and p53 in patients with Dukes' B and C colon cancer: a National Cancer Institute-National Surgical Adjuvant Breast and Bowel Project collaborative study

PURPOSE

To define the value of thymidylate synthase (TS), Ki-67, and p53 as prognostic markers in patients with stage II and III colon carcinoma.

PATIENTS AND METHODS

We retrospectively analyzed the prognostic value of TS, Ki-67, and p53 in 706 patients with Dukes' B (291 patients) or Dukes' C (415 patients) colon carcinoma who were treated with either surgery alone (275 patients) or surgery plus fluorouracil (FU)-leucovorin chemotherapy (431 patients) in National Surgical Adjuvant Breast and Bowel Project (NSABP) protocols C01-C04. All three markers were assayed using immunohistochemical techniques.

RESULTS

Using 5 years of follow-up data, our retrospective analysis demonstrated an association between TS intensity (relapse-free survival [RFS]: risk ratio [RR] = 1.46, P =.01; overall survival [OS]: RR = 1.54, P =.002), Ki-67 (RFS: RR = 0.76, P =.05; OS: RR = 0.62, P =.001), and p53 (RFS: RR = 1.49, P =.01; OS: RR = 1.21, P =.18) for RFS and OS. High TS intensity levels and positive p53 staining were associated with a worse outcome. Tumors containing a high percentage of Ki-67-positive cells enjoyed an improved outcome compared with those patients whose tumors contained relatively few positive cells. An interaction with treatment was not identified for any of the markers.

CONCLUSION

This retrospective investigation demonstrated that TS, Ki-67, and p53 staining each had significant prognostic value for patients with Dukes' B and C colon carcinoma. However, none of the markers could be used to clearly discern groups of individuals who would be predicted to derive greater or lesser benefit from the use of adjuvant chemotherapy.

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.