| Telomerase is a ribonucleprotein enzyme responsible in most eukaryotes that synthesizes telomerie DNA onto chromosomes ends using a segment of Its RNA component as a template .The human telomerase contains the RNA subunits, the catalytic subunits and the telomerase-associated protein. It has been demostrated that telomerase is associated with the formation and progression of tumor. Telomerase activity cannot be detected in normal human somatic cells except for germline cells and hematopoietic stem cells. Telomerase activity reappears in about 85% of human tumors. It appears that telomerase play an important role in tumor proliferation. Telomerase is a target of tumor therapy, because inhibition of telomerase may lead to inhibition of tumor.Lung carcinoma is one of the commonest cancers in the world.Because over-half patients with lung carcionma are in the advanced stage and lose the chance of surgical therapy, the chemotherapy plays an improtant role in lung carcinoma treatment. Cisplatin is a wide-range antitumor drug and a main drug of anti lung carcinoma. The present study was designed to investigate the effects of cisplatin on telomerase activity of SPCA-1 cell line with nonradioactive TRAP method. Meanwhile, we observed cell growth inhibition and cell apoptosis. The inhibition of telomerase activity was probably one of important mechanisms of killing lung cancer cells by cisplatin. Change of telomerase activity can be considered as a target, which will be used for judging the prognosis and chemotherapeutic effect of cisplatin. Materials and Methods1. SPCA-1 was obtained from Cell Bank of Chinese Academy of Sciences.2. SPCA-1 was incubated with different concentration of cisplatin for 72 hours. Telomerase activity was measured using nonradioactive TRAP method. The cell growth inhibition was analysed with MTT assay. Cell apoptosis was evaluated by electron microscopy and flow cytometry. SPCA-1 without cisplatin treatment was normal control. Cell telomerase extracts of the normal control were divided into two parts, one was positive control, the other which was incubated with 5mg/ml RNase A for 20 minutes at 37 was negative control.Results1. According to the results of MTT assay, cisplatin could inhibit cell proliferation in concentration-dependent way. There were statistical significance (p<0.05) between experimental groups and the normal controls.2. Telomerase activity was detected in the positive controls, but not in the negative controls. Telomerase activities which SPCA-1 cells were treated with 0.1, 0.2, 0.4, 0.8 and 1.6 u.g/ml of cisplatin were 62.47+1.08, 56.53+1.24, 51.53+1.35, 36.18+1.43 and 14.15+0.39 respectively. There were statistical significance (p<0.05) between experimental groups and the positive controls. Moreover, There was statistical significance (p<0.05) among different experimental groups.3. Morphological changes of cell apoptosis were observed using electron microscopy. Datas from flow cytometry proved that apoptosis rates were 11.35%, 23.30%, 49.08%, 69.55% and 74.97% respectively in different experimental groups and 6.84% in the normal control. Conclusion1. Cisplatin can inhibit telomerase activity of SPCA-1 cell lines in concentration-dependent way. Meanwhile, cell growth inhibition and cell apoptosis can be observed. Telomerase activities decreased along with increased cisplatin concentration, at the same time, cell growth inhibition rate and cell apoptosis rate increased.2. The inhibition of telomerase activity was probably one of important mechanisms of killing lung cancer cells by cisplatin.3. The changes of telomerase activity can be considered as a marker of prognosis and chemotherapeutic effect.
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