title: Identification and functional validation of caldesmon as a potential gastric cancer metastasis-associated protein.
abstract: 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 34 were down-regulated in the metastatic versus primary gastric cancer cell lines respectively. Several of these dysregulated proteins, including caldesmon, were verified using Western blotting. It was found that caldesmon expression was decreased in the two metastasis-derived cell lines, and this was confirmed by further analysis of 7 gastric cancer cell lines. Furthermore, immunohistochemical staining of 9 pairs of primary gastric cancer and the matched lymph node metastasis tissue also corroborated this observation. Finally, knockdown of caldesmon using siRNA in AGS and FU97 gastric cancer cells resulted in an increase in cell migration and invasion, while the overexpression of caldesmon in AZ521 cells led to a decrease in cell migration and invasion. This study has thus established the potential role of caldesmon in gastric cancer metastasis, and further functional studies are underway to delineate the underlying mechanism of action of this protein.
authors.affiliation: Department of Biochemistry, National University of Singapore, 8 Medical Drive, Singapore 117597.
authors.forename: Qian
authors.initials: Q
authors.lastname: Hou
authors.forename: Hwee Tong
authors.initials: HT
authors.lastname: Tan
authors.forename: Kiat Hon
authors.initials: KH
authors.lastname: Lim
authors.forename: Teck Kwang
authors.initials: TK
authors.lastname: Lim
authors.forename: Avery
authors.initials: A
authors.lastname: Khoo
authors.forename: Iain B H
authors.initials: IB
authors.lastname: Tan
authors.forename: Khay Guan
authors.initials: KG
authors.lastname: Yeoh
authors.forename: Maxey C M
authors.initials: MC
authors.lastname: Chung
mesh_terms: D014408:Biomarkers, Tumor / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D015153:Blotting, Western; D002148:Calmodulin-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D002465:Cell Movement; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D055785:Gene Knockdown Techniques; D006801:Humans; D007150:Immunohistochemistry; D008207:Lymphatic Metastasis / Q000175:diagnosis / Q000235:genetics*; D009363:Neoplasm Proteins / Q000235:genetics* / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013274:Stomach Neoplasms / Q000175:diagnosis / Q000235:genetics* / Q000378:metabolism
chemical_list: D014408:Biomarkers, Tumor; D002148:Calmodulin-Binding Proteins; D009363:Neoplasm Proteins; D034741:RNA, Small Interfering