title: Cyclophilin A enhances cell proliferation and tumor growth of liver fluke-associated cholangiocarcinoma.
abstract: BACKGROUND
  Cyclophilin A (CypA) expression is associated with malignant phenotypes in many cancers. However, the role and mechanisms of CypA in liver fluke-associated cholangiocarcinoma (CCA) are not presently known. In this study, we investigated the expression of CypA in CCA tumor tissues and CCA cell lines as well as regulation mechanisms of CypA in tumor growth using CCA cell lines.
  
  
  METHODS
  CypA expression was determined by real time RT-PCR, Western blot or immunohistochemistry. CypA silence or overexpression in CCA cells was achieved using gene delivery techniques. Cell proliferation was assessed using MTS assay or Ki-67 staining. The effect of silencing CypA on CCA tumor growth was determined in nude mice. The effect of CypA knockdown on ERK1/2 activation was assessed by Western blot.
  
  
  RESULTS
  CypA was upregulated in 68% of CCA tumor tissues. Silencing CypA significantly suppressed cell proliferation in several CCA cell lines. Likewise, inhibition of CypA peptidyl-prolyl cis-trans isomerase (PPIase) activity using cyclosporin A (CsA) decreased cell proliferation. In contrast, overexpression of CypA resulted in 30% to 35% increases in proliferation of CCA cell lines. Interestingly, neither silence nor overexpression of CypA affected cell proliferation of a non-tumor human cholangiocyte cell line, MMNK1. Suppression of CypA expression attenuated ERK1/2 activity in CCA M139 cells by using both transient and stable knockdown methods. In the in vivo study, there was a 43% reduction in weight of tumors derived from CypA-silenced CCA cell lines compared with control vector CCA tumors in mice; these tumors with stable CypA silencing showed a reduced cell proliferation.
  
  
  CONCLUSIONS
  CypA is upregulated in majority of CCA patients' tissues and confers a significant growth advantage in CCA cells. Suppression of CypA expression decreases proliferation of CCA cell lines in vitro and reduces tumor growth in the nude mouse model. Inhibition of CypA activity also reduces CCA cell proliferation. The ERK1/2 pathway may be involved in the CypA-mediated CCA cell proliferation. Thus, CypA may represent an important new therapeutic target for liver fluke-associated CCA.
authors.affiliation: Molecular Surgeon Research Center, Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, Texas, USA.
authors.forename: Sumalee
authors.initials: S
authors.lastname: Obchoei
authors.forename: Sarah M
authors.initials: SM
authors.lastname: Weakley
authors.forename: Sopit
authors.initials: S
authors.lastname: Wongkham
authors.forename: Chaisiri
authors.initials: C
authors.lastname: Wongkham
authors.forename: Kanlayanee
authors.initials: K
authors.lastname: Sawanyawisuth
authors.forename: Qizhi
authors.initials: Q
authors.lastname: Yao
authors.forename: Changyi
authors.initials: C
authors.lastname: Chen
mesh_terms: D000818:Animals; D001650:Bile Duct Neoplasms / Q000209:etiology / Q000235:genetics* / Q000469:parasitology / Q000473:pathology; D001653:Bile Ducts, Intrahepatic / Q000187:drug effects / Q000378:metabolism / Q000469:parasitology / Q000473:pathology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D018281:Cholangiocarcinoma / Q000209:etiology / Q000235:genetics* / Q000469:parasitology / Q000473:pathology; D021984:Cyclophilin A / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D005210:Fasciola hepatica / Q000502:physiology*; D005211:Fascioliasis / Q000150:complications / Q000235:genetics / Q000473:pathology; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D008297:Male; D051379:Mice; D008819:Mice, Nude; D034741:RNA, Small Interfering / Q000494:pharmacology; D047368:Tumor Burden / Q000187:drug effects / Q000235:genetics; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics; D023041:Xenograft Model Antitumor Assays
chemical_list: D034741:RNA, Small Interfering; D021984:Cyclophilin A