Study On Diagnostic Value Of Telomerase Activity In Peripheral Blood Mononuclear Cells From Lung Cancer Patients

Background: The reactivation of telomerase is believed to play an important role in immortalization and carcinogenesis. Many studies have been made on the samples obtained from tissues or cells of lung cancer, which showed positive results of the reactivation of telomerase activity. However, a few researches have been done on the blood that is easy to be taken. Objectives: To investigate the expression of telomerase activity (TA) in peripheral blood mononuclear cells (PBMNC) from patients with lung cancer, benign lung diseases and healthy volunteers, and then to study the clinical significance for the diagnosis of lung cancer. Methods: PBMNC were isolated from peripheral blood of 77 participating persons using Ficoll. Telomerase activity was detected using the polymerase chain reaction enzyme-linked immunosorbent (PCR-ELISA) in assay test based on the telomerase repeat amplification protocol (TRAP) method. The clinical applicability of this technique was explored by evaluating 15 healthy volunteers, 20 patients with benign lung diseases, and 42 cases of lung cancer containing different pathological types and different clinical stages. The data such as sensitivity, specificity of TA was reliable and compared with those of CEA. The statistic was performed using F test, t or t' test and chi-square test, correlation among TA,CEA and clinical characters was analyzed too. Results: 69.05% of lung cancer patients (29/42) were positive for TA, the mean OD level was 0.45 0.37,while only 10% benign lung diseases (2/20) showed positive with OD level 0.11 0.06, and all healthy people were negative with OD level 0.08 0.03. TA in lung cancer was significantly higher than that in benign lung diseases and henlthy people (P<0.05).There was no significant correlation between WBC and TA among three groups. The specificity and sensitivity of TA in lung cancer was 90%, 69.05% respectively, which was more valuable than CEA (P<0.01). 25% of lung cancer (1/4) in stage I were positive for TA, the mean OD level was 0.12 + 0.096, whereas all of 8 patients in stage IV were positive with OD level 0.88 0.451, which showed positive correlation between TA and clinical stage (r=0.585, P=0.001). There was no significant correlation between TA and pathological type adjusted for TNM stage, even though the positive rate in SCLC was 100%. Conclusions: The positive rate of telomerase activity is significantly higher in lung cancer than that of CEA, and there is no significant influence of WBC on TA. It can be concluded that PCR-TRAP-ELISA can be used in the diagnosis of lung cancer. The expression of telomerase may be a crucial step in bronchial carcinogenesis. Therefore, telomerase activity can be used as a good molecular marker, it's a minimally invasive and specific approach for monitoring lung cancer prognosis and directing therapy.