MAB4130 Sigma-AldrichAnti-Thymidylate Synthase Antibody, clone TS106

The aim of the present study was to investigate the clinicopathologic/prognostic significance of thymidylate synthase (TS), orotate phosphoribosyltransferase (OPRT), and thymidine phosphorylase (TP) proteins in postoperative non-small cell lung cancer (NSCLC) patients. Microarray slides from a set of 178 NSCLC patients were used for the detection of TS, OPRT, and TP expression by immunohistochemistry. The correlation between clinicopathologic factors and protein expression of three proteins was analyzed. Ninety seven carcinomas (57.4%) were TS-positive, 90 carcinomas (53.9%) were OPRT-positive, and 102 carcinomas (69.4%) were TP-positive. Compared with the TS-positive patients, the overall survival (OS) was significantly lower in the TS-negative patients (hazard ratio [HR] =1.766, 95% confidence interval [CI] =1.212-2.573, P=0.003). Significant differences between TS-positive and TS-negative patients was also observed in the following stratified analyses: 1) adenocarcinoma subgroup (HR =2.079, 95% CI =1.235-3.500, P=0.006); 2) less than 60-year-old subgroup (HR =1.890, 95% CI =1.061-3.366, P=0.031); 3) stage II/III subgroup (HR =1.594, 95% CI =1.036-2.453, P=0.034); and 4) surgery plus adjuvant therapy subgroup (HR =1.976, 95% CI =1.226-3.185, P=0.005). However, the OS was not significantly correlated with OPRT or TP protein expression. This study demonstrates that the TS level in tumor tissues may be a useful marker to predict the postoperative OS in NSCLC patients.

Colorectal carcinoma is etiopathologically heterogenic. It may develop through a sequence of mutations leading to chromosome instability or be a result of defects in DNA repair mechanisms manifested by microsatellite instability. Carcinomas of this type are supposed to be characterized by a better prognosis and a different response to chemotherapy. The main target of 5-fluorouracil (5-FU) treatment is thymidylate synthase (TS). High TS expression has been identified as promoting resistance to 5-FU. The objective of the present investigation was to determine whether microsatellite instability is associated with thymidylate synthase expression. Ninety-eight cases of colorectal carcinoma were studied. Microsatellite instability was evaluated in frozen material employing the PCR reaction with gel and capillary electrophoresis. TS expression levels were assessed in preparations stained immunohistochemically using a semiquantitative method on a scale with scores from 0 to 3. The MSI-H phenotype was detected in ten cases, MSI-L in 16, and MSS in 72. The mean TS expression score was 1.79. In the MSS group, the mean TS expression score was 1.69, in the MSI-L group the mean TS expression score was 1.73, and in the MSI-H group the mean TS expression score was 2.67. The differences between MSI-H and MSS/MSI-L were statistically significant (p0.0002 and p0.004, respectively). The results may explain the different response of MSI-H carcinomas to 5-FU treatment.

Thymidylate synthase (TS; EC 2.1.1.45) is an important therapeutic target for fluoropyrimidine cytotoxic drugs that are widely used for the treatment of solid tumors. Using the monoclonal antibody TS 106, we have developed an ultrasensitive enzyme-linked immunoassay (ELISA) for the detection and quantitation of TS. Using a chemiluminescent ELISA technique, TS was detectable in serially diluted lysates from NCI H630 and HCT 116 human colon carcinoma cell lines. The ELISA assay was reliably able to detect activity down to a level of 30 attamol of TS protein above background (P2 = 0.016). The usable range of detection was from 0.03 to 500 fmol of enzyme. There was a close correlation between the optical density signal and the total TS enzyme between both cell lines (r2 = 0.96). The ELISA was used to measure TS in cytosolic extracts from human tumor samples, and it was able to quantitate TS levels using as little as 1-mg tumor biopsy samples. The mean total TS measured by ELISA in seven tumor samples from patients with breast cancer and sarcomas was 131 fmol/mg cytosolic protein (range 60-240) compared with a mean TS of 85 fmol/mg cytosolic protein (range 35-163) using the fluorodeoxyuridine monophosphate binding assay. While the TS levels were uniformly higher when measured by ELISA, there was close proportional agreement between both assays (r2 = 0.84). Thus, the chemiluminescent TS ELISA would appear to be an extremely sensitive and specific assay that may be used to quantitate TS in tumor tissue specimens.