title: Ectopic expression of guanylyl cyclase C in gastric cancer as a potential biomarker and therapeutic target.
abstract: OBJECTIVE
  To investigate the expression of guanylyl cyclase C (GCC) in human gastric cancer (GC) tissues and assess the effect of GCC small interfering RNA (siRNA) on the proliferation and apoptosis of SGC-7901.
  
  
  METHODS
  The expression of GCC in 30 specimens and three human GC cell lines (SGC-7901, AGS, NCI-N87) were detected by RT-PCR for messenger RNA (mRNA) by Western blot and immunofluorescence for proteins. Recombinant plasmids containing GCC siRNA and scrambled siRNA were constructed and transfected into SGC-7901 cells, respectively. A cell counting kit-8, flow cytometry (FCM) and terminal deoxynucleotidyl transferase (TDT)-mediated dUTP-biotin nick end-labeling were used to evaluate cell viability, cell cycle distribution and apoptosis, followed by wound healing assay and cell adherent assay for cell motility and adherent, respectively.
  
  
  RESULTS
  The expression of GCC was absent in paracancerous tissues, whereas the GCC mRNA and protein expressions were detected in 20/30 and 19/30 of GC specimens, respectively. Moreover, intestinal GC was statistically different from diffuse GC (P < 0.05). The proliferation of SGC-7901 cells was markedly inhibited by GCC siRNA-3 (P < 0.05) and cell morphological changes including volumetric reduction, karyopyknosis and karyorrhexis were observed. FCM showed that the cell count in the sub-G0/G1 peak increased from 5.47% (48 h after transfection) to 5.63% (72 h after transfection). The wound healing assay and cell adherent assay revealed that GCC gene silencing decreased cell motility and adherent.
  
  
  CONCLUSIONS
  The over-expression of GCC has been detected in intestinal type GC. GCC siRNA can effectively inhibit the proliferation and invasion of SGC-7901 cells and induce cell apoptosis. GCC might be a novel biomarker and therapeutic target for GC.
authors.affiliation: Department of Gastroenterology, Affiliated Hospital of Nantong University, Nantong, China. mzb63@163.com
authors.forename: Zhen Biao
authors.initials: ZB
authors.lastname: Mao
authors.forename: Jian Feng
authors.initials: JF
authors.lastname: Zhang
authors.forename: Zhong
authors.initials: Z
authors.lastname: Xu
authors.forename: Hui Jun
authors.initials: HJ
authors.lastname: Zhu
authors.forename: Jian Guo
authors.initials: JG
authors.lastname: Zhang
authors.forename: Zheng Ping
authors.initials: ZP
authors.lastname: Pan
authors.forename: Feng
authors.initials: F
authors.lastname: Xiao
authors.forename: Jun Ling
authors.initials: JL
authors.lastname: Yang
mesh_terms: D017209:Apoptosis; D014408:Biomarkers, Tumor / Q000235:genetics* / Q000378:metabolism; D015153:Blotting, Western; D000071616:CDX2 Transcription Factor; D002448:Cell Adhesion; D002455:Cell Division; D045744:Cell Line, Tumor; D005455:Fluorescent Antibody Technique; D015971:Gene Expression Regulation, Enzymologic; D015972:Gene Expression Regulation, Neoplastic; D015316:Genetic Therapy / Q000379:methods*; D006162:Guanylate Cyclase / Q000235:genetics* / Q000378:metabolism; D018398:Homeodomain Proteins / Q000235:genetics; D006801:Humans; D011230:Precancerous Conditions / Q000235:genetics / Q000473:pathology; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering; D000074261:Receptors, Enterotoxin; D050705:Receptors, Guanylate Cyclase-Coupled; D018000:Receptors, Peptide / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013274:Stomach Neoplasms / Q000235:genetics* / Q000473:pathology / Q000628:therapy*; D014162:Transfection
chemical_list: D014408:Biomarkers, Tumor; D000071616:CDX2 Transcription Factor; C491270:CDX2 protein, human; D018398:Homeodomain Proteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D018000:Receptors, Peptide; D006162:Guanylate Cyclase; D000074261:Receptors, Enterotoxin; D050705:Receptors, Guanylate Cyclase-Coupled