title: An novel role of sphingosine kinase-1 (SPHK1) in the invasion and metastasis of esophageal carcinoma.
abstract: BACKGROUND
  Treatment failure for esophageal carcinoma is frequently due to lymph node metastasis and invasion to neighboring organs. The aim of the present study was to investigate invasion- and metastasis-related genes in esophageal carcinoma cells in vitro and in vivo.
  
  
  METHODS
  A metastasis model using a Matrigel invasion clonal selection approach was employed to establish a highly invasive subline EC9706-P4 from the esophageal carcinoma cell (ESCC) line EC9706. The differentially expressed genes of the subline and the parental cells determined by gene microarrays were further analyzed by RT-PCR and Western blotting.
  
  
  RESULTS
  We identified sphingosine kinase 1 (SPHK1) as an invasion and metastasis-related gene of esophageal cancer. SPHK1 was overexpressed in the EC9706-P4 subline with high invasive capacity. Among six ESCC lines tested, KYSE2 and KYSE30 cells showed the highest SPHK1 mRNA and protein expressions as well as the most invasive phenotype. By Western blotting, in 7/12 cases (58%), SPHK1 expression was higher in esophageal carcinomas than in the companion normal tissue. In 23/30 cases (76%), SPHK1 protein expression was upregulated in the tumors compared to matched normal tissue by immunohistochemistry (IHC). Esophageal carcinoma tissue microarray analysis indicated that SPHK1 expression correlated with the depth of tumor invasion (P < 0.0001) and lymph node metastasis (P = 0.016). By Kaplan-Meier analysis, strong SPHK1 expression was significantly associated with clinical failure (P < 0.01), suggesting the involvement of SPHK1 in aggressiveness of human esophageal carcinoma. SPHK1 overexpression significantly increased the invasiveness of EC9706 cells in vitro and also increased EC9706 cell growth and spontaneous metastasis in vivo, promoting significant increases in tumor growth, tumor burden and spontaneous lung metastasis in nude mice. SPHK1 expression significantly correlated with the expression of many EGFR pathway genes associated with invasion of cancer cells. SPHK1 protein expression also significantly correlated with the phosphorylation of EGFR.
  
  
  CONCLUSIONS
  In summary, our data implicate SPHK1 in the metastasis of esophageal cancer. Our study also identified downstream mediators of SPHK1 in esophageal cancer cells that may mediate enhanced malignant behavior, and several of these mediators may be useful as therapeutic targets.
authors.affiliation: Department of Hematology and Oncology, Children's Hospital of Soochow University, Suzhou, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Pan
authors.forename: Yan-Fang
authors.initials: YF
authors.lastname: Tao
authors.forename: Zhuan
authors.initials: Z
authors.lastname: Zhou
authors.forename: Bang-Rong
authors.initials: BR
authors.lastname: Cao
authors.forename: Shui-Yan
authors.initials: SY
authors.lastname: Wu
authors.forename: Yan-Lan
authors.initials: YL
authors.lastname: Zhang
authors.forename: Shao-Yan
authors.initials: SY
authors.lastname: Hu
authors.forename: Wen-Li
authors.initials: WL
authors.lastname: Zhao
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
authors.forename: Guo-Liang
authors.initials: GL
authors.lastname: Lou
authors.forename: Zhen
authors.initials: Z
authors.lastname: Li
authors.forename: Xing
authors.initials: X
authors.lastname: Feng
authors.forename: Jian
authors.initials: J
authors.lastname: Ni
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D004789:Enzyme Activation; D066246:ErbB Receptors / Q000378:metabolism; D004938:Esophageal Neoplasms / Q000201:enzymology* / Q000235:genetics / Q000473:pathology* / Q000628:therapy; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008207:Lymphatic Metastasis / Q000473:pathology*; D051379:Mice; D009361:Neoplasm Invasiveness; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism*; D015398:Signal Transduction; D016896:Treatment Outcome; D015854:Up-Regulation / Q000235:genetics; D000099157:Sphingosine Kinase
chemical_list: D066246:ErbB Receptors; D017853:Phosphotransferases (Alcohol Group Acceptor); D000099157:Sphingosine Kinase