| Summary: | 碩士 === 國立陽明大學 === 生化暨分子生物研究所 === 96 === Adenocarcinoma is the most predominant histological subtype of lung cancer in Taiwan. Metastasis is the most significant factor threatening a cancer patient’s life. However, molecules and mechanisms involved in the complex series of steps in cancer metastasis have not been fully uncovered. In this study, we have applied subtractive hybridization and cDNA microarray techniques on paired primary and metastatic pulmonary adenocarcinoma tissues to search for differentially expressed genes associated with metastasis. Among the genes expressed at higher levels in the metastatic than in the primary tumor tissues, the CLU gene which encodes a secretory glycoprotein clusterin was particularly of interest. Increased CLU expression has been implicated in the progression of many human malignancies and in promoting metastasis of hepatocellular carcinoma. However, the precise molecular mechanism underlying the modulation of tumor progression and/or metastasis by clusterin is still unclear, and the relation of clusterin with the development of metastasis of lung adenocarcinoma has never been reported. To explore the involvement of clusterin in cancer metastasis, silencing of clusterin expression was performed in a highly metastatic human lung adenocarcinoma cell line CL1-5 using small interfering RNA. Suppression of cell migration was found in CLU-knocked down (CLUi) CL1-5 cells. Several clusterin isoforms, including three presumably glycosylated secretory isoforms which are separately translated from distinct CLU transcripts and one non-secretory nuclear isoform, have been reported. To find out which isoform(s) may participate in the regulation of cancer cell migration, four isoforms were individually transfected into CLUi cells. The data showed that all four isoforms could alleviate the CLU-silencing induced suppression of migration. Western analysis also revealed a negative correlation between levels of clusterin expression and the phosphorylation of the focal adhesion kinase on the Y397 residue (pY397-FAK) in lung adenocarcinoma cells. Taken together, our results suggest that clusterin may, through decreasing levels of pY397-FAK, enhance the migration capability of cancer cells and thereby contribute to the metastasis of lung adenocarcinoma.
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