title: Upregulated expression of S100A6 in human gastric cancer.
abstract: OBJECTIVE
  The expression of S100A6 (calcyclin), a member of the S100 calcium binding protein family, is elevated in a number of malignant tumors, but there have been few reports about its expression in gastric cancer. The aim of this study was to investigate its expression regulations in human gastric cancer and noncancerous mucosa, and the response to chemotherapeutic drugs in the gastric cancer cell line.
  
  
  METHODS
  In one matched gastric cancer sample pair, the serial analysis of gene expression (SAGE) experiment was conducted to compare the gene expression profiles between cancerous and adjacent tissues. To detect the expression regulations among more cancerous tissues, microarrays were carried out and real-time RT-PCR was conducted to validate the results. At the protein level, Western blot and tissue microarray (TMA) examination were further used to verify S100A6 expression. The regulation detection of S100A6 with flurouracil and doxorubicin at the mRNA and protein level was performed in the SGC7901 cell line.
  
  
  RESULTS
  With the SAGE strategy, five times more S100A6 tags were identified in cancer tissues than in normal tissues. With the cDNA microarray, S100A6 was found to be significantly upregulated in 21 of 42 (50%) nonselective gastric cancers. In 10 other paired samples, the upregulation of S100A6 was consolidated with RT-PCR and Western blot analysis as well. A total of 14 endoscopy-sectioned gastric noncancerous lesions and corresponding normal gastric mucosa were also applied to profile the gene expression; both cDNA microarray and RT-PCR demonstrated no significant alterations of S100A6 at the mRNA level. TMA examination showed that 34 of 52 (65.4%) cancer samples were positively stained, while only 17 of 80 (21.3%) noncancerous lesions were positively detected and all nine normal mucosae were detected to be negative. An in vitro experiment showed that in the gastric cell line SGC-7901, S100A6 mRNA was detected to be upregulated from 24 to 72 h after treatment with 5 mg/L 5-flurouracil or 0.3 mg/L doxorubicin, and there were two wave upregulations of the S100A6 protein.
  
  
  CONCLUSIONS
  The observed regulated expression of S100A6 suggests that it is associated with gastric cancer tumorigenesis and quantitation of S100A6 is a promising tool for diagnosis of gastric cancer.
authors.affiliation: State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China.
authors.forename: Yan Qing
authors.initials: YQ
authors.lastname: Yang
authors.forename: Lan Jing
authors.initials: LJ
authors.lastname: Zhang
authors.forename: Hui
authors.initials: H
authors.lastname: Dong
authors.forename: Chang Long
authors.initials: CL
authors.lastname: Jiang
authors.forename: Zheng Gang
authors.initials: ZG
authors.lastname: Zhu
authors.forename: Jian Xin
authors.initials: JX
authors.lastname: Wu
authors.forename: Yun Lin
authors.initials: YL
authors.lastname: Wu
authors.forename: Jun Song
authors.initials: JS
authors.lastname: Han
authors.forename: Hua Sheng
authors.initials: HS
authors.lastname: Xiao
authors.forename: Heng Jun
authors.initials: HJ
authors.lastname: Gao
authors.forename: Qing Hua
authors.initials: QH
authors.lastname: Zhang
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D000970:Antineoplastic Agents / Q000494:pharmacology; D015153:Blotting, Western; D018797:Cell Cycle Proteins / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor / Q000187:drug effects / Q000378:metabolism; D004317:Doxorubicin / Q000494:pharmacology; D005472:Fluorouracil / Q000494:pharmacology; D005753:Gastric Mucosa / Q000166:cytology / Q000473:pathology; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D007150:Immunohistochemistry; D020411:Oligonucleotide Array Sequence Analysis; D012333:RNA, Messenger / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000075383:S100 Calcium Binding Protein A6; D009418:S100 Proteins / Q000235:genetics* / Q000378:metabolism; D013274:Stomach Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D015854:Up-Regulation
chemical_list: D000970:Antineoplastic Agents; D018797:Cell Cycle Proteins; D012333:RNA, Messenger; D000075383:S100 Calcium Binding Protein A6; D009418:S100 Proteins; C055351:S100A6 protein, human; D004317:Doxorubicin; D005472:Fluorouracil