| Summary: | 碩士 === 高雄醫學大學 === 生物化學研究所 === 91 === Cdc kinase subunit 1 (Cks1) has been shown to involve in the regulation of cell cycle progression and p27kip1 degradation. However, the functional role of Cks1 in tumorigenesis is still unknown. In this study, we examined the expression of Cks1 in non-small cell lung tumor tissues and cell lines and tested the effect of Cks1 specific small interfering RNA (siRNA) on the proliferation of non-small cell lung cancer cells. Immunohistochemistry analysis showed that strong Cks1 expression was presented in 66 of 95(69%) of human lung tumor tissues. RT-PCR and western blotting analysis also showed that Cks1 was highly expressed in non-small cell lung cancer cell lines. However, no significant correlation between Cks1 and p27kip1 was found in primary non-small cell lung tumor tissues and cell lines. Transfection of Cks1 siRNA induced G2/M arrest in Cks1-overexpressing H358 lung cancer cells, followed by induced of apoptosis in these cells. We also studied the molecular mechanism by which Cks1 siRNA blocked cell cycle progression. Our results suggested that Cks1 siRNA reduced Cdc25C phosphorylation and activation and suppressed cyclinB1/Cdc2 kinase activity to induce G2/M arrest. Long-term treatment of Cks1 siRNA triggered apopotosis in human lung cancer cells. On the contrary, Cks1 siRNA did not affect viability of normal human lung fibroblasts under the same experimental condition. Taken together, these results suggest that Cks1 participates in the steps of lung tumorigenesis and Cks1 siRNA may be used as a therapeutic agent for the treatment of lung cancer.
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