Serum human telomerase reverse transcriptase: a novel biomarker for breast cancer diagnosis.

BACKGROUND: Telomerase is a ribonucleoprotein complex composed mainly of a reverse transcriptase catalytic subunit, telomerase reverse transcriptase (hTERT). Expression of hTERT confers telomerase activity, indicating that hTERT is the rate-limiting component of human telomerase. The aim of the present study was to investigate the diagnostic implications of hTERT in the serum of breast cancer patients. METHODS: The study was conducted on 159 breast cancer patients and 41 healthy volunteers as controls. The evaluation of hTERT, cancer antigen 15.3 and carcinoembryonic antigen were performed by enzyme-linked immunosorbent assay, and analysed for their correlation with the patient's clinicopathological features. RESULTS: 27 of 52 (51.9%) patients with stage I breast cancer, 31 of 40 (77.5%) with stage II and 30 of 34 (88.2%) patients with stage III exhibited elevated hTERT levels. Serum hTERT levels showed significantly higher mean values in patients with breast cancer than healthy individuals. The sensitivity and specificity of hTERT in cancer diagnosis was 68.9 and 83.3%, respectively, which is significantly higher than conventional markers. The expression of serum hTERT was significantly correlated with telomerase activity in breast cancer tissues. Pretreatment serum hTERT levels showed a significant correlation with clinical stage, while correlation with nodal status and tumor size were marginal and no correlation was found with family history and age. CONCLUSION: Serum hTERT is useful for diagnosing and assessing the clinical stage of breast cancer and is superior to conventional markers. Therefore, serum hTERT could have a potential application as a novel biomarker for breast cancer diagnosis.

Capillary electrophoretic assay of acyl-CoA hydrolase activity.

Acyl-CoA hydrolases catalyze the hydrolysis of fatty acyl CoA thioesters to free fatty acids and coenzyme A. These enzymes play an important role in the maintenance of cellular acyl-CoA and free CoASH pools and in the detoxification of nonphysiological metabolites. The assays most commonly used for acyl-CoA hydrolase quantitation are spectrophotometric and radioisotopic methods, both of which have limitations. In this study, capillary electrophoresis was used as an effective analytical technique to characterize rat liver peroxisomal acyl-CoA hydrolase reactivity using octanoyl-CoA as a substrate at different reaction conditions. The substrate and product of acyl-CoA hydrolase were identified by their migration times and quantitated using the peak areas. The enzyme activity exhibited a typical Michaelis-Menten pattern with increasing octanoyl-CoA concentration. The apparent Km and Vmax of octanoyl-CoA hydrolysis were determined using the enzyme activity at varying substrate concentrations. The rate of hydrolysis of octanoyl-CoA with increasing enzyme concentration appeared as a hyperbolic plot. The enzyme activity became elevated with increasing incubation time, showing the highest activity at 20 min, after which it started to decrease as the incubation time increased. Thus, capillary electrophoresis has been shown to be an effective, rapid, and reproducible method for the characterization of acyl-CoA hydrolase.