title: Role of crosstalk between interleukin-6 and transforming growth factor-beta 1 in epithelial-mesenchymal transition and chemoresistance in biliary tract cancer.
abstract: OBJECTIVE
  The mechanisms of progression in biliary tract cancer (BTC) with inflammation, including epithelial-mesenchymal transition (EMT), are not well understood. We focused on two inflammation-associated cytokines, interleukin-6 (IL-6) and transforming growth factor-beta 1 (TGF-β1), and investigated their expression and activity, as well as their relationship to key features of malignancy, in tumour samples from patients with BTC and in cultured BTC cells.
  
  
  METHODS
  We employed five BTC cell lines (MzChA-1, gemcitabine-resistant MzChA-1, HuCCT-1, KMCH and CCLP-1) to evaluate IL-6/TGF-β1 expression, tumour cell invasion, EMT and chemoresistance to gemcitabine in the presence or absence of recombinant human (rh) IL-6 and TGF-β1. Possible pathways were evaluated with specific pathway inhibitors and small interfering RNA (siRNA). We also used 20 resected specimens from patients with BTC to verify the results in vitro.
  
  
  RESULTS
  IL-6 and TGF-β1 expression was associated with features of malignancy such as EMT and chemoresistance in the four BTC cell lines. Addition of rh IL-6 and TGF-β1 increased endogenous IL-6 and TGF-β1 expression through crosstalk and induced cell invasion, EMT and chemoresistance. Smad4 functioned in this process in a dominant manner, and inhibition by SMAD4 siRNA reduced IL-6 and TGF-β1 expression, blocked invasion, and reversed EMT and chemoresistance in cells exposed to rh IL-6 and TGF-β1 and in gemcitabine-resistant cells. Immunohistochemistry in resected specimens revealed IL6, TGF-β1, N-cadherin and Smad4 staining at the invasion front.
  
  
  CONCLUSIONS
  Crosstalk between IL-6 and TGF-β1 is associated with malignant features, including EMT, and Smad4 works in a dominant manner to promote these features.
authors.affiliation: Department of Surgery, Graduate School of Medicine, Osaka University, Yamadaoka 2-2 (E2), Suita, Osaka 565-0871, Japan.
authors.forename: Daisaku
authors.initials: D
authors.lastname: Yamada
authors.forename: Shogo
authors.initials: S
authors.lastname: Kobayashi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Wada
authors.forename: Koichi
authors.initials: K
authors.lastname: Kawamoto
authors.forename: Shigeru
authors.initials: S
authors.lastname: Marubashi
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Eguchi
authors.forename: Hideshi
authors.initials: H
authors.lastname: Ishii
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Nagano
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Doki
authors.forename: Masaki
authors.initials: M
authors.lastname: Mori
mesh_terms: D000368:Aged; D001661:Biliary Tract Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects / Q000235:genetics; D003841:Deoxycytidine / Q000031:analogs & derivatives / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm / Q000187:drug effects / Q000235:genetics*; D058750:Epithelial-Mesenchymal Transition / Q000235:genetics*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D015850:Interleukin-6 / Q000235:genetics* / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D034622:RNA Interference; D011994:Recombinant Proteins / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051901:Smad4 Protein / Q000235:genetics / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000235:genetics* / Q000378:metabolism; D000093542:Gemcitabine
chemical_list: D015850:Interleukin-6; D011994:Recombinant Proteins; C497796:SMAD4 protein, human; D051901:Smad4 Protein; D053773:Transforming Growth Factor beta1; D003841:Deoxycytidine; D000093542:Gemcitabine