title: The H4 histamine receptor agonist, clobenpropit, suppresses human cholangiocarcinoma progression by disruption of epithelial mesenchymal transition and tumor metastasis.
abstract: Cholangiocarcinoma (CCA) is a biliary cancer arising from damaged bile ducts. Epithelial-mesenchymal transition (EMT) occurs as epithelial cells begin to resemble mesenchymal cells leading to increased invasion potential as the extracellular matrix (ECM) degrades. Histamine exerts its effects by way of four receptors (H1-H4 HRs). Clobenpropit, a potent H4HR agonist, inhibits mammary adenocarcinoma growth. We have shown that (1) cholangiocytes and CCA cells express H1-H4 HRs and (2) the H3HR decreases CCA proliferation. We evaluated the effects of clobenpropit on CCA proliferation, invasion, EMT phenotypes, and ECM degradation. In vitro, we used CCA cell lines to study proliferation, signaling pathways, and the morphological invasive potential. Gene and protein expression of the hepatobiliary epithelial markers CK-7, CK-8, and CK-19, the focal contact protein paxillin, and the mesenchymal markers fibronectin, s100A4, and vimentin were evaluated. Cell invasion across an ECM layer was quantitated and matrix metalloproteinase-1, -2, -3, -9, and -11 gene and protein expression was examined. Evaluation of the specific role of H4HR was performed by genetic knockdown of the H3HR and overexpression of H4HR. Proliferation was evaluated by proliferating cellular nuclear antigen immunoblotting. In vivo, xenograft tumors were treated with either vehicle or clobenpropit for 39 days. Tumor volume was recorded every other day. Clobenpropit significantly decreased CCA proliferation by way of a Ca(2+) -dependent pathway and altered morphological development and invasion. Loss of H3HR expression or overexpression of H4HR significantly decreased CCA proliferation. In vivo, clobenpropit inhibited xenograft tumor growth compared with controls.
  
  
  CONCLUSIONS
  Modulation of H4HR by clobenpropit disrupts EMT processes, ECM breakdown, and invasion potential and decreases tumor growth. Interruption of tumorigenesis and invasion by histamine may add to therapeutic advances for CCAs.
authors.affiliation: Central Texas Veterans Health Care System, Temple, TX, USA.
authors.forename: Fanyin
authors.initials: F
authors.lastname: Meng
authors.forename: Yuyan
authors.initials: Y
authors.lastname: Han
authors.forename: Dustin
authors.initials: D
authors.lastname: Staloch
authors.forename: Taylor
authors.initials: T
authors.lastname: Francis
authors.forename: Allison
authors.initials: A
authors.lastname: Stokes
authors.forename: Heather
authors.initials: H
authors.lastname: Francis
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001650:Bile Duct Neoplasms / Q000188:drug therapy* / Q000473:pathology; D001653:Bile Ducts, Intrahepatic / Q000473:pathology*; D001706:Biopsy; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D018281:Cholangiocarcinoma / Q000188:drug therapy* / Q000556:secondary; D000242:Cyclic AMP / Q000378:metabolism; D018450:Disease Progression; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects*; D005109:Extracellular Matrix / Q000187:drug effects / Q000201:enzymology; D054828:Histamine H3 Antagonists / Q000494:pharmacology; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology*; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D051379:Mice; D034741:RNA, Small Interfering / Q000494:pharmacology; D043562:Receptors, G-Protein-Coupled / Q000819:agonists* / Q000235:genetics / Q000378:metabolism; D011968:Receptors, Histamine / Q000235:genetics / Q000378:metabolism; D000074040:Receptors, Histamine H4; D015398:Signal Transduction / Q000187:drug effects; D013890:Thiourea / Q000031:analogs & derivatives* / Q000494:pharmacology; D023041:Xenograft Model Antitumor Assays
chemical_list: C418607:HRH4 protein, human; D054828:Histamine H3 Antagonists; D007093:Imidazoles; D034741:RNA, Small Interfering; D043562:Receptors, G-Protein-Coupled; D011968:Receptors, Histamine; D000074040:Receptors, Histamine H4; D015544:Inositol 1,4,5-Trisphosphate; D000242:Cyclic AMP; D013890:Thiourea; C086108:clobenpropit