Please use this identifier to cite or link to this item: http://scholarbank.nus.edu.sg/handle/10635/49112
Title: Identification and Functional Validation of Caldesmon as a Potential Gastric Cancer Metastasis-Associated Protein
Authors: HOU QIAN
Keywords: caldesmon, gastric cancer, metastasis, iTRAQ, biomarker
Issue Date: 20-Aug-2013
Citation: HOU QIAN (2013-08-20). Identification and Functional Validation of Caldesmon as a Potential Gastric Cancer Metastasis-Associated Protein. ScholarBank@NUS Repository.
Abstract: Gastric cancer is the fourth most common cancer in the world and the second most common cause of cancer-related death. The rate of metastasis is high in gastric cancer patients. During cancer metastasis progression, the tumor cells underwent a plethora of molecular and morphological changes to become motile and invasive for the malignant transformation. Thus discovery of the molecules that were involved in metastasis progression is critical for early diagnosis and prognosis for gastric cancer patients. In this study, we aim to identify biomarkers for gastric cancer metastasis using a quantitative proteomics approach. The proteins extracted from a panel of 4 gastric cancer cell lines, two derived from primary cancer (AGS, FU97) and two from lymph node metastasis (AZ521, MKN7) were labeled with iTRAQ (8-plex) reagents and analyzed by 2D - LC MALDI-TOF/TOF MS. In total, 641 proteins were identified with at least a 95% confidence. Using cutoff values of >1.5 and <0.67, 19 proteins were found to be up-regulated and 33 were down-regulated in the metastatic versus primary gastric cancer cell lines respectively. Among these dysregulated proteins, fascin and UCHL1 expressions were increased while caldesmon expression decreased in the metastasis-derived cancer cell lines as verified by western blotting. The trend of expression of fascin and caldesmon in the metastasis-derived cell lines were further confirmed by the analysis of a panel of eleven gastric cancer cell lines. Furthermore, immunohistochemical staining of 9 pairs of primary gastric cancer tissues and the matched lymph node metastasis tissue also corroborated this observation. Tissue microarray analysis showed that fascin expression was correlated with gastric cancer serosal invasion and lymph node metastasis. In patients with well-differentiated gastric cancer, positive expression of fascin is associated with poorer survival. On the other hand, the expression of caldesmon in tumor tissues was scarce. Pericellular caldesmon expression is correlated with serosal invasion. xii As caldesmon is a novel target associated with gastric cancer, we studied its function in gastric cancer cell lines. Knockdown of caldesmon using siRNA in AGS and FU97 gastric cancer cells resulted in an increase in cell migration and invasion, while the over-expression of caldesmon in AZ521 cells led to a decrease in cell migration and invasion, and increase in cell adhesion. To elucidate caldesmon interacting partners, co-immunoprecipitation coupled to in-gel digestion experiment identified myosin, tropomyosin and other actin cytoskeleton regulating proteins as caldesmon interacting proteins. This study has thus established the potential role of caldesmon in gastric cancer metastasis.
URI: http://scholarbank.nus.edu.sg/handle/10635/49112
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