title: Co-expression of S100A14 and S100A16 correlates with a poor prognosis in human breast cancer and promotes cancer cell invasion.
abstract: BACKGROUND
  S100 family proteins have recently been identified as biomarkers in various cancers. Of this protein family, S100A14 and S100A16 are also believed to play an important role in tumor progression. The aim of the present study was to clarify the clinical significance and functional role of these molecules in breast cancer.
  
  
  METHODS
  In a clinical study, an immunohistochemical analysis of S100A14 and S100A16 expression in archival specimens of primary tumors of 167 breast cancer patients was performed. The relationship of S100A14 and S100A16 expression to patient survival and clinicopathological variables was statistically analyzed. In an experimental study, the subcellular localization and function of these molecules was examined by using the human breast cancer cell lines MCF7 and SK-BR-3, both of which highly express S100A14 and S100A16 proteins. Cells transfected with expression vectors and siRNA for these genes were characterized using in vitro assays for cancer invasion and metastasis.
  
  
  RESULTS
  Immunohistochemical analysis of 167 breast cancer cases showed strong cell membrane staining of S100A14 (53% of cases) and S100A16 (31% of cases) with a significant number of cases with co-expression (p < 0.001). Higher expression levels of these proteins were significantly associated with a younger age (<60 years), ER-negative status, HER2-positive status and a poorer prognosis. Co-expression of the two proteins showed more aggressive features with poorer prognosis. In the human breast cancer cell lines MCF7 and SK-BR-3, both proteins were colocalized on the cell membrane mainly at cell-cell attachment sites. Immunoprecipitation and immunofluorescence analyses demonstrated that the 100A14 protein can bind to actin localized on the cell membrane in a calcium-independent manner. A Boyden chamber assay showed that S100A14 and S100A16 knockdown substantially suppressed the invasive activity of both cell lines. Cell motility was also inhibited by S100A14 knockdown in a modified dual color wound-healing assay.
  
  
  CONCLUSIONS
  To our knowledge, this is the first report showing the correlation of expression of S100A14, S100A16, and co-expression of these proteins with poor prognosis of breast cancer patients. In addition, our findings indicate that S100A14 and S100A16 can promote invasive activity of breast cancer cells via an interaction with cytoskeletal dynamics. S100A14 and S100A16 might be prognostic biomarkers and potential therapeutic targets for breast cancer.
authors.affiliation: Department of Basic Pathology, Fukushima Medical University School of Medicine, Fukushima, 960-1295, Japan. mizuko@fmu.ac.jp.
authors.forename: Mizuko
authors.initials: M
authors.lastname: Tanaka
authors.affiliation: Department of Basic Pathology, Fukushima Medical University School of Medicine, Fukushima, 960-1295, Japan. naoichi@fmu.ac.jp.
authors.forename: Naoki
authors.initials: N
authors.lastname: Ichikawa-Tomikawa
authors.affiliation: Department of Basic Pathology, Fukushima Medical University School of Medicine, Fukushima, 960-1295, Japan. namiko.shishito@mt.strins.or.jp.
authors.forename: Namiko
authors.initials: N
authors.lastname: Shishito
authors.affiliation: Department of Basic Pathology, Fukushima Medical University School of Medicine, Fukushima, 960-1295, Japan. nishiura@fmu.ac.jp.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Nishiura
authors.affiliation: Department of Basic Pathology, Fukushima Medical University School of Medicine, Fukushima, 960-1295, Japan. yamat@fmu.ac.jp.
authors.forename: Tomiko
authors.initials: T
authors.lastname: Miura
authors.affiliation: Department of Basic Pathology, Fukushima Medical University School of Medicine, Fukushima, 960-1295, Japan. karin-h@fmu.ac.jp.
authors.forename: Ayumi
authors.initials: A
authors.lastname: Hozumi
authors.affiliation: Department of Basic Pathology, Fukushima Medical University School of Medicine, Fukushima, 960-1295, Japan. hidchiba@fmu.ac.jp.
authors.forename: Hideki
authors.initials: H
authors.lastname: Chiba
authors.affiliation: Department of Organ Regulatory Surgery, Fukushima Medical University School of Medicine, Fukushima, 960-1295, Japan. ysayaka@fmu.ac.jp.
authors.forename: Sayaka
authors.initials: S
authors.lastname: Yoshida
authors.affiliation: Department of Organ Regulatory Surgery, Fukushima Medical University School of Medicine, Fukushima, 960-1295, Japan. trcyn@cc.fmu.ac.jp.
authors.forename: Tohru
authors.initials: T
authors.lastname: Ohtake
authors.affiliation: Division of Diagnostic Pathology, Shizuoka Cancer Center Hospital, 1007 Shimonagakubo, Nagaizumi-cho, Sunto-Gun, Shizuoka, 411-8777, Japan. t.sugino@scchr.jp.
authors.forename: Takashi
authors.initials: T
authors.lastname: Sugino
mesh_terms: D000199:Actins / Q000378:metabolism; D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor; D001943:Breast Neoplasms / Q000235:genetics* / Q000401:mortality* / Q000473:pathology / Q000601:surgery; D002135:Calcium-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000235:genetics; D005260:Female; D015870:Gene Expression; D055785:Gene Knockdown Techniques; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged; D060787:Neoplasm Grading; D009367:Neoplasm Staging; D011379:Prognosis; D011485:Protein Binding; D021381:Protein Transport; D009418:S100 Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D000199:Actins; D014408:Biomarkers, Tumor; D002135:Calcium-Binding Proteins; D009418:S100 Proteins; C462950:S100A14 protein, human; C000589580:S100A16 protein, human