title: Constitutive phosphorylation of the FOXO1 transcription factor in gastric cancer cells correlates with microvessel area and the expressions of angiogenesis-related molecules.
abstract: BACKGROUND
  Although FOXO transcription factors may have an anti-angiogenic role, little is known about their role in tumor angiogenesis. The present study was performed to investigate the correlation between the constitutive expression of phosphorylated FOXO1 (pFOXO1) and angiogenesis in gastric cancer.
  
  
  METHODS
  Immunohistochemistry was performed on tissue array slides containing 272 gastric carcinoma specimens, and the correlations between the cytoplasmic pFOXO1 expression in gastric cancer cells and CD34-immunopositive microvessel area (MVA) or the expressions of angiogenesis-related molecules were analyzed. In vitro analyses with Western blotting and semiquantitative reverse transcription-polymerase chain reaction were performed using the stable SNU-638 gastric cancer cell line transfected with lentivirus-delivered FOXO1 short hairpin RNA.
  
  
  RESULTS
  The cytoplasmic expression of pFOXO1 in tumor cells was observed in 85% of gastric carcinoma cases, and was found to be positively associated with higher MVA (P = 0.048). Moreover, pFOXO1 expression was positively correlated with the expressions of several angiogenesis-related proteins, including hypoxia inducible factor-1α (HIF-1α, P = 0.003), vessel endothelial growth factor (P = 0.004), phosphorylated protein kinase B (P < 0.001), and nuclear factor-κB (P = 0.040). In contrast, the expression of pFOXO1 was not correlated with that of phosphorylated signal transducer and activator of transcription 3 or β-catenin. In addition, cell culture experiments showed that FOXO1 suppression increased the mRNA and protein expressions of HIF-1α.
  
  
  CONCLUSIONS
  Our results suggest that pFOXO1 expression in cancer cells plays a role in gastric cancer angiogenesis via mechanisms involving various angiogenesis-related molecules. Animal experiments are needed to confirm the anti-angiogenic role of FOXO1 in human gastric cancer.
authors.affiliation: Department of Anatomy, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul 110-799, Korea.
authors.forename: Sue Youn
authors.initials: SY
authors.lastname: Kim
authors.forename: Jiyeon
authors.initials: J
authors.lastname: Yoon
authors.forename: Young San
authors.initials: YS
authors.lastname: Ko
authors.forename: Mee Soo
authors.initials: MS
authors.lastname: Chang
authors.forename: Jong-Wan
authors.initials: JW
authors.lastname: Park
authors.forename: Hee Eun
authors.initials: HE
authors.lastname: Lee
authors.forename: Min A
authors.initials: MA
authors.lastname: Kim
authors.forename: Ji Hun
authors.initials: JH
authors.lastname: Kim
authors.forename: Woo Ho
authors.initials: WH
authors.lastname: Kim
authors.forename: Byung Lan
authors.initials: BL
authors.lastname: Lee
mesh_terms: D042501:Angiogenic Proteins / Q000096:biosynthesis* / Q000235:genetics; D002277:Carcinoma / Q000098:blood supply / Q000235:genetics / Q000378:metabolism* / Q000473:pathology / Q000601:surgery; D045744:Cell Line, Tumor; D005260:Female; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D005743:Gastrectomy; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000096:biosynthesis / Q000235:genetics; D008297:Male; D055806:Microvessels / Q000473:pathology; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D009389:Neovascularization, Pathologic / Q000378:metabolism* / Q000473:pathology; D010766:Phosphorylation; D011379:Prognosis; D011499:Protein Processing, Post-Translational; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D012334:RNA, Neoplasm / Q000096:biosynthesis / Q000235:genetics; D034741:RNA, Small Interfering / Q000494:pharmacology; D013274:Stomach Neoplasms / Q000098:blood supply / Q000235:genetics / Q000378:metabolism* / Q000473:pathology / Q000601:surgery
chemical_list: D042501:Angiogenic Proteins; C085126:FOXO1 protein, human; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D009363:Neoplasm Proteins; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D034741:RNA, Small Interfering