title: SPOP suppresses tumorigenesis by regulating Hedgehog/Gli2 signaling pathway in gastric cancer.
abstract: BACKGROUND
  Recent evidence suggests that aberrant activation of Hedgehog (Hh) signaling by Gli transcription factors is characteristic of a variety of aggressive human carcinomas including gastric cancer. Speckle-type POZ protein, SPOP, is an E3 ubiquitin ligase adaptor, and it is found to inhibit oncogenic signaling. However, the molecular mechanisms are largely unknown.
  
  
  METHODS
  In this study, we characterized the expression of SPOP in 88 pairs of gastric cancer tissues and adjacent tissues by immunohistochemical staining and Western blotting. The relationship between SPOP expression and clinical pathologic factors was analyzed. Transfected gastric cancer cell lines were used in cell viability, wound healing and colony formation assays. The interaction of SPOP with Gli2 and other related apoptotic proteins was assessed by immunoprecipitation, Western blotting, real-time PCR and dual luciferase reporter assays. Intracellular interaction of SPOP and Gli2 was visualized by immunofluorescent staining in gastric cancer cells.
  
  
  RESULTS
  Immunohistochemical staining of SPOP can be detected in gastric cancer tissues but much less than adjacent gastric tissues (P < 0.01). High SPOP expression is negatively correlated with lymph node metastasis, poor histological differentiation, and tumor malignancy according to TNM staging. In vitro experiments revealed that over-expression of SPOP prevented tumor cells from proliferation, migration and colony formation in gastric cancer cell lines. Likewise, repression of SPOP promoted cell viability, migration, proliferation, and attenuated apoptosis. Mechanistic studies revealed that increasing SPOP accelerated Gli2 degradation but regardless of Gli2 synthesis. Furthermore, cytoplasmic Gli2 decreased markedly along with the abundant expression of SPOP in MKN45 cells.
  
  
  CONCLUSIONS
  Our findings indicate that SPOP plays critical roles in suppressing gastric tumorigenesis through inhibiting Hh/Gli2 signaling pathway. It may provide an alternative strategy for developing therapeutic agents of gastric cancer in future.
authors.forename: Chunyan
authors.initials: C
authors.lastname: Zeng
authors.forename: Yao
authors.initials: Y
authors.lastname: Wang
authors.forename: Quqin
authors.initials: Q
authors.lastname: Lu
authors.forename: Jiang
authors.initials: J
authors.lastname: Chen
authors.forename: Junyan
authors.initials: J
authors.lastname: Zhang
authors.forename: Tao
authors.initials: T
authors.lastname: Liu
authors.forename: Nonghua
authors.initials: N
authors.lastname: Lv
authors.forename: Shiwen
authors.initials: S
authors.lastname: Luo
mesh_terms: D000328:Adult; D000368:Aged; D000818:Animals; D017209:Apoptosis / Q000235:genetics; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000235:genetics; D049109:Cell Proliferation; D002471:Cell Transformation, Neoplastic / Q000378:metabolism*; D005260:Female; D015870:Gene Expression; D006364:Hedgehogs / Q000378:metabolism*; D006801:Humans; D051741:Kruppel-Like Transcription Factors / Q000378:metabolism*; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D060787:Neoplasm Grading; D009367:Neoplasm Staging; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D034741:RNA, Small Interfering; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D013274:Stomach Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D000075746:Zinc Finger Protein Gli2
chemical_list: D051741:Kruppel-Like Transcription Factors; D009687:Nuclear Proteins; D034741:RNA, Small Interfering; D012097:Repressor Proteins; C509761:SPOP protein, human; D000075746:Zinc Finger Protein Gli2