Telomerase activity in peripheral blood for diagnosis of hepatoma

Background: Telomerase activity may be used as a molecular marker for the d etection of circulating hepatoma cells in blood of patients with hepatoma. Methods: Telomerase activity in peripheral blood from hepatocellular carcin oma (HCC) patients was assessed by using a highly sensitive and non-radiois otope telomerase polymerase chain reaction (PCR) ELISA. Initially, tissue t elomerase activity was measured in the hepatoma and non-tumour portions by using PCR ELISA within the same specimen, to compare its sensitivity with t he conventional telomeric repeat amplification protocol (TRAP) method. Seco nd, telomerase activity was measured in the peripheral blood obtained from patients with HCC, patients with chronic liver disease and in healthy contr ols. Results: Of the 17 HCC patients, telomerase activity was found to be positi ve in 14 (82%) by using TRAP and 15 (88%) by using PCR ELISA, indicating th at PCR ELISA is a reliable tool for the measurement of telomerase activity. By using the Telomerase PCR ELISA assay, telomerase activities in the peri pheral blood of 20 HCC patients was 1.65 +/- 0.78 units. This was significa ntly greater than the results obtained for 20 chronic liver disease patient s (0.43 +/- 0.36 units) and 20 healthy controls (0.39 +/- 0.14 units; P < 0 .0001). When the arbitrary cut-off level was set at 0.7 units (maximum valu e of healthy controls + 0.1), the positive frequency of telomerase activity was 25% for chronic liver disease and 80% for HCC patients (sensitivity 80 %, specificity 75%). Among the HCC patients, high telomerase activity in th e peripheral blood was shown at stage III HCC with vascular invasion (2.10 +/- 0.62 units, n = 9). This was significantly higher than patients at stag e II of HCC (1.28 +/- 0.72 units, n = 11, without vascular invasion; P = 0. 012). Conclusion: These results suggest that peripheral blood telomerase activity , which may reflect haematogenous micrometastasis, is potentially a practic al diagnostic/predictive marker of HCC. (C) 2000 Blackwell Science Asia Pty Ltd.