title: Down-regulation of microRNA-494 via loss of SMAD4 increases FOXM1 and β-catenin signaling in pancreatic ductal adenocarcinoma cells.
abstract: OBJECTIVE
  Dysregulation of β-catenin and the transcriptional activator FOXM1 mediate oncogenesis, but it is not clear how these proteins become dysregulated in tumors that do not typically carry mutations in adenomatous polyposis coli (APC) or β-catenin, such as pancreatic ductal adenocarcinomas (PDACs). We searched for microRNAs that regulate levels of FOXM1 in PDAC cells and samples from patients.
  
  
  METHODS
  We identified microRNAs that affect levels of FOXM1 in PDACs using bioinformatic, genetic, and pharmacologic approaches. We altered expression of the microRNA-494 (miR-494) in PDAC cell lines (AsPC-1 and PANC-1) and examined the effects on FOXM1 and β-catenin signaling and cell proliferation and colony formation. The cells were injected into immunocompromised mice and growth of xenograft tumors and liver metastases were measured. We performed immunohistochemical analyses of 10 paired PDAC and nontumor pancreatic tissue samples collected from untreated patients during surgery.
  
  
  RESULTS
  We identified miR-494 as a negative regulator of FOXM1 levels in PDAC cells, and found that levels of this microRNA were reduced in PDAC specimens, compared with nontumor tissues. Loss of response of PDAC cells to transforming growth factor β, owing to SMAD4 deficiency, reduced expression of miR-494. Transgenic expression of miR-494 in PDAC cells produced the same effects as reducing expression of FOXM1 or blocking nuclear translocation of β-catenin, reducing cell proliferation, migration, and invasion, and increasing their sensitivity to gemcitabine. Reduced expression of miR-494 correlated with PDAC metastasis and reduced survival times of patients.
  
  
  CONCLUSIONS
  Loss of SMAD4 in PDAC cells leads to reduced levels of miR-494, increased levels of FOXM1, and nuclear localization of β-catenin. miR-494 might be developed as a prognostic marker for patients with PDAC or a therapeutic target.
authors.affiliation: Department of Gastroenterology, Shanghai Changhai Hospital, Second Military Medical University, Shanghai, People's Republic of China.
authors.forename: Lei
authors.initials: L
authors.lastname: Li
authors.affiliation: Department of Gastroenterology, Shanghai Changhai Hospital, Second Military Medical University, Shanghai, People's Republic of China. Electronic address: zhaoshenli.smmu.edu@hotmail.com.
authors.forename: Zhaoshen
authors.initials: Z
authors.lastname: Li
authors.affiliation: Department of Gastroenterology, Shanghai Changhai Hospital, Second Military Medical University, Shanghai, People's Republic of China; Department of Gastroenterology, Hepatology and Nutrition, The University of Texas MD Anderson Cancer Center, Houston, Texas. Electronic address: xiangyukong185@hotmail.com.
authors.forename: Xiangyu
authors.initials: X
authors.lastname: Kong
authors.affiliation: Shanghai Key Laboratory of Pancreatic Diseases Research and Department of Oncology, Shanghai Jiaotong University Affiliated First People's Hospital, Shanghai, People's Republic of China.
authors.forename: Dacheng
authors.initials: D
authors.lastname: Xie
authors.affiliation: Department of Gastroenterology, Hepatology and Nutrition, The University of Texas MD Anderson Cancer Center, Houston, Texas.
authors.forename: Zhiliang
authors.initials: Z
authors.lastname: Jia
authors.affiliation: Department of Gastroenterology, Hepatology and Nutrition, The University of Texas MD Anderson Cancer Center, Houston, Texas; Shanghai Key Laboratory of Pancreatic Diseases Research and Department of Oncology, Shanghai Jiaotong University Affiliated First People's Hospital, Shanghai, People's Republic of China.
authors.forename: Weihua
authors.initials: W
authors.lastname: Jiang
authors.affiliation: Department of Gastroenterology, Hepatology and Nutrition, The University of Texas MD Anderson Cancer Center, Houston, Texas; Shanghai Key Laboratory of Pancreatic Diseases Research and Department of Oncology, Shanghai Jiaotong University Affiliated First People's Hospital, Shanghai, People's Republic of China.
authors.forename: Jiujie
authors.initials: J
authors.lastname: Cui
authors.affiliation: Department of Gastroenterology, Shanghai Changhai Hospital, Second Military Medical University, Shanghai, People's Republic of China.
authors.forename: Yiqi
authors.initials: Y
authors.lastname: Du
authors.affiliation: Department of Gastroenterology, Hepatology and Nutrition, The University of Texas MD Anderson Cancer Center, Houston, Texas.
authors.forename: Daoyan
authors.initials: D
authors.lastname: Wei
authors.affiliation: Department of Neurosurgery, The University of Texas MD Anderson Cancer Center, Houston, Texas.
authors.forename: Suyun
authors.initials: S
authors.lastname: Huang
authors.affiliation: Department of Gastroenterology, Hepatology and Nutrition, The University of Texas MD Anderson Cancer Center, Houston, Texas. Electronic address: kepxie@mdanderson.org.
authors.forename: Keping
authors.initials: K
authors.lastname: Xie
mesh_terms: D021581:Active Transport, Cell Nucleus; D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D021441:Carcinoma, Pancreatic Ductal / Q000235:genetics / Q000378:metabolism* / Q000401:mortality / Q000556:secondary; D045744:Cell Line, Tumor; D002465:Cell Movement; D049109:Cell Proliferation; D002470:Cell Survival / Q000187:drug effects; D003841:Deoxycytidine / Q000031:analogs & derivatives / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D005260:Female; D000072278:Forkhead Box Protein M1; D051858:Forkhead Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D053208:Kaplan-Meier Estimate; D008113:Liver Neoplasms / Q000235:genetics / Q000378:metabolism / Q000556:secondary; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D010190:Pancreatic Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000401:mortality / Q000473:pathology; D034622:RNA Interference; D015398:Signal Transduction / Q000187:drug effects; D051901:Smad4 Protein / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors; D014162:Transfection; D015854:Up-Regulation; D051176:beta Catenin / Q000235:genetics / Q000378:metabolism*; D000093542:Gemcitabine
chemical_list: D000903:Antibiotics, Antineoplastic; C495270:CTNNB1 protein, human; C107585:FOXM1 protein, human; D000072278:Forkhead Box Protein M1; D051858:Forkhead Transcription Factors; C547168:MIRN494 microRNA, human; D035683:MicroRNAs; C497796:SMAD4 protein, human; D051901:Smad4 Protein; D051176:beta Catenin; D003841:Deoxycytidine; D000093542:Gemcitabine
keywords: Gene Regulation; Pancreatic Cancer; Signal Transduction; Tumor Progression