Localization of thymidine phosphorylase expression in colorectal carcinoma tissues by in situ RT-PCR assay

Mucinous and non-mucinous colorectal cancers show differential expression of chemotherapy metabolism and resistance genes

Previous research has identified differences in mutation frequency in genes implicated in chemotherapy resistance between mucinous and non-mucinous colorectal cancers (CRC). We hypothesized that outcomes in mucinous and non-mucinous CRC may be influenced by expression of genes responsible for chemotherapy resistance. Gene expression data from primary tumor samples were extracted from The Cancer Genome Atlas PanCancer Atlas. The distribution of clinical, pathological, and gene expression variables was compared between 74 mucinous and 521 non-mucinous CRCs. Predictors of overall survival (OS) were assessed in a multivariate analysis. Kaplan-Meier curves were constructed to compare survival according to gene expression using the log rank test. The median expression of 5-FU-related genes TYMS, TYMP, and DYPD was significantly higher in mucinous CRC compared to non-mucinous CRC (p < 0.001, p = 0.003, p < 0.001, respectively). The median expression of oxaliplatin-related genes ATP7B and SRPK1 was significantly reduced in mucinous versus non-mucinous CRC (p = 0.004, p = 0.007, respectively). At multivariate analysis, age (odds ratio (OR) = 0.96, p < 0.001), node positive disease (OR = 0.49, p = 0.005), and metastatic disease (OR = 0.32, p < 0.001) remained significant negative predictors of OS, while high SRPK1 remained a significant positive predictor of OS (OR = 1.59, p = 0.037). Subgroup analysis of rectal cancers demonstrated high SRPK1 expression was associated with significantly longer OS compared to low SRPK1 expression (p = 0.011). This study highlights that the molecular differences in mucinous CRC and non-mucinous CRC extend to chemotherapy resistance gene expression. SRPK1 gene expression was associated with OS, with a prognostic role identified in rectal cancers.

A novel antimetabolite: TAS-102 for metastatic colorectal cancer

TAS-102 is a new oral anti-tumor drug, composed of a thymidine-based nucleoside analog (trifluridine: FTD) and a thymidine phosphorylase inhibitor (tipiracil hydrochloride: TPI). TAS-102 has been shown to significantly improve overall survival and progression-free survival in patients with refractory metastatic colorectal cancer (mCRC) in placebo-controlled randomized phase II and III trials. The current review summarizes mechanisms of action, pharmacokinetics/dynamics and preclinical and clinical data of TAS-102 in colorectal cancer. TAS-102 is a new salvage-line treatment option for patients with mCRC. TAS-102 is well tolerated and has great potential in future clinical drug combination therapies.

Thymidine phosphorylase expression is associated with time to progression in patients with metastatic colorectal cancer

Background

5-Fluorouracil (5-FU) is the cornerstone of chemotherapeutic treatment for patients with colorectal cancer. The enzyme thymidine phosphorylase (TP) catalyzes the conversion of 5-FU to its active metabolite, 5-fluoro-2’-deoxyuridine. TP is expressed in tumour epithelial cells and stromal cells, particularly in tumour-associated macrophages. These macrophages may affect sensitivity to chemotherapy. Previously, we identified TP as a predictive factor in microdissected tumour samples of patients with advanced colorectal cancer. In the present study, we analysed TP expression in tissues and associated stromal cells from patients with advanced colorectal cancer and associated TP levels to tumour response and time-to-event variables during first-line chemotherapy treatment. We also investigated the association between serum TP levels at the time of surgery and gene expression in primary tumour tissues.

Methods

This study included 125 patients with metastatic colorectal cancer treated with first-line 5-FU-based chemotherapy. To quantify TP gene expression levels in tumour tissues, real-time polymerase chain reaction was performed using the 7500 Fast Real-Time PCR system (Applied Biosystems, Foster City, CA, USA). TP protein concentration in matched serum samples was determined using an enzyme-linked immunosorbent assay system (USCN Life Science Inc.).

Results

The tumour response rate was 31%, and 30% of patients exhibited stable disease. No associations between TP expression level and age or gender were observed. Levels of TP mRNA in mucosa and tumours were positively correlated (r = 0.41, p < 0.01). No correlation between TP expression and tumour response rate was observed. Time to progression was significantly longer in patients with high TP expression (p < 0.01). Serum TP protein levels were not associated with tumour response or time-to-event variables and did not correlate with gene expression in tumour tissues.

Conclusions

High TP gene expression in non-microdissected tumour tissues of patients with advanced colorectal cancer correlates with longer time to progression, which could be related to treatment. These results are in contrast to previous studies where microdissected tumour cells were analysed and may be due to the presence of adjacent stromal cells. Serum TP protein expression does not correlate to TP gene expression in tissues of patients with advanced colorectal cancer.

Thymidine Phosphorylase Gene Expression in Stage III Colorectal Cancer

BACKGROUND

The thymidine phosphorylase (TP) enzyme has several tumor-promoting functions. The aim of this study was to explore TP gene expression in relation to clinical and histopathological data obtained from patients with stage III colorectal cancer.

METHODS AND RESULTS

TP gene expression was analyzed by real-time quantitative PCR in tumor and mucosa samples from 254 patients. TP gene expression in tumors correlated with lymph node staging, with higher expression relating to a higher number of positive nodes and a worse N-stage. Higher TP expression was also associated with a worse histological tumor grade. Patients with rectal cancer had significantly higher TP expression in mucosa and tumors compared with patients having colon cancer.

CONCLUSION

Higher intratumoral TP expression appears to be related to a worse N stage, and thus, with a worse prognosis. TP gene expression measured in a preoperative biopsy could be of interest in preoperative staging.

ASCO 2006 Update of Recommendations for the Use of Tumor Markers in Gastrointestinal Cancer

Purpose

To update the recommendations for the use of tumor marker tests in the prevention, screening, treatment, and surveillance of gastrointestinal cancers.

Methods

For the 2006 update, an update committee composed of members from the full Panel was formed to complete the review and analysis of data published since 1999. Computerized literature searches of Medline and the Cochrane Collaboration Library were performed. The Update Committee's literature review focused attention on available systematic reviews and meta-analyses of published tumor marker studies.

Recommendations and Conclusion

For colorectal cancer, it is recommended that carcinoembryonic antigen (CEA) be ordered preoperatively, if it would assist in staging and surgical planning. Postoperative CEA levels should be performed every 3 months for stage II and III disease for at least 3 years if the patient is a potential candidate for surgery or chemotherapy of metastatic disease. CEA is the marker of choice for monitoring the response of metastatic disease to systemic therapy. Data are insufficient to recommend the routine use of p53, ras, thymidine synthase, dihydropyrimidine dehydrogenase, thymidine phosphorylase, microsatellite instability, 18q loss of heterozygosity, or deleted in colon cancer (DCC) protein in the management of patients with colorectal cancer. For pancreatic cancer, CA 19-9 can be measured every 1 to 3 months for patients with locally advanced or metastatic disease receiving active therapy. Elevations in serial CA 19-9 determinations suggest progressive disease but confirmation with other studies should be sought. New markers and new evidence to support the use of the currently reviewed markers will be evaluated in future updates of these guidelines.

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.

Identification of molecular markers for metastasis-related genes in primary breast cancer cells

Comparing differential gene expression profiles established by cDNA microarray between normal cells (N), primary carcinoma cells (T), and metastatic carcinoma cells (M) may determine those critical genes directly associated with progression and metastasis of breast cancer. Total RNA was extracted by laser microdissection (LMD) from 20 slices of T, N and M from 6 cases. After amplification by a T7-based system, differentially expressed genes between T, N and M were identified by cDNA microarray. In addition, to clarify the mechanism for altered gene expression, we determined the methylation status by sequencing after bisulfite treatment for intriguing genes. As a result, the expression of motility related protein-1 (MRP-1/CD9), peripheral myelin protein-22 (PMP-22), and caspase 3 (CASP-3) were down-regulated in M compared to T. We focused especially on MRP-1 and found that the expression status of MRP-1 was significantly inversely associated with stage of disease in 56 cases of breast cancer (P<0.05), and the relapse free survival in 5 years was significantly higher in MRP-1 positive cases than those negative cases (P<0.05). Conversely, overexpression, by 11-fold, of signal transduction and translation factors were observed in T compared to N. The cancer specific methylation was observed only in CASP-3 in a case. In conclusion, the establishment of the present assay allows us to detect genes directly associated with each cell population within tumor tissue and gives us clues to identify metastasis-related genes comprehensively in clinical breast cancer cases.

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

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