title: CacyBP/SIP nuclear translocation induced by gastrin promotes gastric cancer cell proliferation.
abstract: OBJECTIVE
  To investigate the role of nuclear translocation of calcyclin binding protein, also called Siah-1 interacting protein (CacyBP/SIP), in gastric carcinogenesis.
  
  
  METHODS
  The expression of CacyBP/SIP protein in gastric cancer cell lines was detected by Western blot. Immunofluorescence experiments were performed on gastric cancer cell lines that had been either unstimulated or stimulated with gastrin. To confirm the immunofluorescence findings, the relative abundance of CacyBP/SIP in nuclear and cytoplasmic compartments was assessed by Western blot. The effect of nuclear translocation of CacyBP/SIP on cell proliferation was examined using MTT assay. The colony formation assay was used to measure clonogenic cell survival. The effect of CacyBP/SIP nuclear translocation on cell cycle progression was investigated. Two CacyBP/SIP-specific siRNA vectors were designed and constructed to inhibit CacyBP/SIP expression in order to reduce the nuclear translocation of CacyBP/SIP, and the expression of CacyBP/SIP in stably transfected cells was determined by Western blot. The effect of inhibiting CacyBP/SIP nuclear translocation on cell proliferation was then assessed.
  
  
  RESULTS
  CacyBP/SIP protein was present in most of gastric cancer cell lines. In unstimulated cells, CacyBP/SIP was distributed throughout the cytoplasm; while in stimulated cells, CacyBP/SIP was found mainly in the perinuclear region. CacyBP/SIP nuclear translocation generated a growth-stimulatory effect on cells. The number of colonies in the CacyBP/SIP nuclear translocation group was significantly higher than that in the control group. The percentage of stimulated cells in G1 phase was significantly lower than that of control cells (69.70% ± 0.46% and 65.80% ± 0.60%, control cells and gastrin-treated SGC7901 cells, P = 0.008; 72.99% ± 0.46% and 69.36% ± 0.51%, control cells and gastrin-treated MKN45 cells, P = 0.022). CacyBP/SIPsi1 effectively down-regulated the expression of CacyBP/SIP, and cells stably transfected by CacyBP/SIPsi1 were then chosen for further cellular assays. In CacyBP/SIPsi1 stably transfected cells, CacyBP/SIP was shown to be distributed throughout the cytoplasm, irregardless of whether they were stimulated or not. After CacyBP/SIP nuclear translocation was reduced, there had no major effect on cell proliferation, as shown by MTT assay. There had no enhanced anchorage-dependent growth upon stimulation, as indicated by colony formation in flat plates. No changes appeared in the percentage of cells in G0-G1 phase in either cell line (71.09% ± 0.16% and 70.86% ± 0.25%, control cells and gastrin-treated SGC7901-CacyBP/SIPsi1 cells, P = 0.101; 74.17% ± 1.04% and 73.07% ± 1.00%, control cells and gastrin-treated MKN45-CacyBP/SIPsi1 cells, P = 0.225).
  
  
  CONCLUSIONS
  CacyBP/SIP nuclear translocation promotes the proliferation and cell cycle progression of gastric cancer cells.
authors.affiliation: Hui-Hong Zhai, Juan Meng, Department of Digestive Diseases, General Hospital of Ningxia Medical University, Yinchuan 750004, Ningxia Hui Autonomous Region, China.
authors.forename: Hui-Hong
authors.initials: HH
authors.lastname: Zhai
authors.affiliation: Hui-Hong Zhai, Juan Meng, Department of Digestive Diseases, General Hospital of Ningxia Medical University, Yinchuan 750004, Ningxia Hui Autonomous Region, China.
authors.forename: Juan
authors.initials: J
authors.lastname: Meng
authors.affiliation: Hui-Hong Zhai, Juan Meng, Department of Digestive Diseases, General Hospital of Ningxia Medical University, Yinchuan 750004, Ningxia Hui Autonomous Region, China.
authors.forename: Jing-Bo
authors.initials: JB
authors.lastname: Wang
authors.affiliation: Hui-Hong Zhai, Juan Meng, Department of Digestive Diseases, General Hospital of Ningxia Medical University, Yinchuan 750004, Ningxia Hui Autonomous Region, China.
authors.forename: Zhen-Xiong
authors.initials: ZX
authors.lastname: Liu
authors.affiliation: Hui-Hong Zhai, Juan Meng, Department of Digestive Diseases, General Hospital of Ningxia Medical University, Yinchuan 750004, Ningxia Hui Autonomous Region, China.
authors.forename: Yuan-Fei
authors.initials: YF
authors.lastname: Li
authors.affiliation: Hui-Hong Zhai, Juan Meng, Department of Digestive Diseases, General Hospital of Ningxia Medical University, Yinchuan 750004, Ningxia Hui Autonomous Region, China.
authors.forename: Shan-Shan
authors.initials: SS
authors.lastname: Feng
mesh_terms: D021581:Active Transport, Cell Nucleus; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D049109:Cell Proliferation / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D005755:Gastrins / Q000494:pharmacology*; D006801:Humans; D034622:RNA Interference; D013274:Stomach Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D013997:Time Factors; D014162:Transfection
chemical_list: C491778:CACYBP protein, human; D002135:Calcium-Binding Proteins; D005755:Gastrins
keywords: Calcyclin binding protein/Siah-1 interacting protein; Gastric caner cells; Gastrin; Nuclear translocation
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