title: Role of the Fas/FasL pathway in combination therapy with interferon-alpha and fluorouracil against hepatocellular carcinoma in vitro.
abstract: OBJECTIVE
  Several studies have reported the efficacy of combination therapy of interferon (IFN) alpha and 5-fluorouracil (5-FU) for hepatocellular carcinoma (HCC). However, the mechanism underlying the clinical anti-tumor effects of this treatment is not well understood. The aim of this study was to determine the role of Fas/FasL signaling in the anti-tumor effect of this combination therapy.
  
  
  RESULTS
  We used six human hepatoma cell lines, three of which are known Fas-expressing cells. Growth of Fas-positive hepatoma cell lines was inhibited by an agonistic anti-Fas antibody in a dose-dependent manner, and these effects were enhanced by IFNalpha or 5-FU alone, but even more so by combination therapy using both agents. Annexin-V assay implicated apoptosis as the main mechanism underlying these growth inhibitory effects, although changes in Fas expression regulated by IFNalpha and/or 5-FU did not correlate with increased apoptosis. Caspase-3 activation was exclusively increased by IFNalpha/5-FU combination treatment, which was compatible with enhancement of the synergistic apoptotic effect, and other caspases and apoptotic factors (FLIP, BCL-xl, and Bax) were also regulated by IFNalpha/5-FU. 51Cr-release assay revealed that pretreatment with IFN activated cytotoxicity of peripheral blood mononuclear cells (PBMCs) against HCC cells. The largest interaction was observed when both PBMC and HCC cells were pretreated with the combination of IFNalpha/5-FU. These cytotoxicities were markedly inhibited by a neutralizing anti-Fas antibody.
  
  
  CONCLUSIONS
  Our results indicated that IFNalpha/5-FU combination treatment enhances the induction of apoptosis and the cytotoxic effect of PBMCs via the Fas/FasL pathway. The Fas/FasL pathway seems, at least in part, to contribute to the anti-tumor effects of IFNalpha/5-FU against HCCs.
authors.affiliation: Department of Surgery, Graduate School of Medicine, Osaka University, Osaka, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Nakamura
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Nagano
authors.forename: Masato
authors.initials: M
authors.lastname: Sakon
authors.forename: Tameyoshi
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Hideo
authors.initials: H
authors.lastname: Ota
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Wada
authors.forename: Bazarragchaa
authors.initials: B
authors.lastname: Damdinsuren
authors.forename: Takehiro
authors.initials: T
authors.lastname: Noda
authors.forename: Shigeru
authors.initials: S
authors.lastname: Marubashi
authors.forename: Atsushi
authors.initials: A
authors.lastname: Miyamoto
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Takeda
authors.forename: Koji
authors.initials: K
authors.lastname: Umeshita
authors.forename: Shoji
authors.initials: S
authors.lastname: Nakamori
authors.forename: Keizo
authors.initials: K
authors.lastname: Dono
authors.forename: Morito
authors.initials: M
authors.lastname: Monden
mesh_terms: D000906:Antibodies / Q000008:administration & dosage / Q000627:therapeutic use; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000627:therapeutic use; D017209:Apoptosis / Q000187:drug effects; D001483:Base Sequence; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein / Q000235:genetics; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D004273:DNA, Neoplasm / Q000235:genetics; D004789:Enzyme Activation / Q000187:drug effects; D053222:Fas Ligand Protein / Q000378:metabolism*; D005472:Fluorouracil / Q000008:administration & dosage / Q000627:therapeutic use*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D007370:Interferon Type I / Q000008:administration & dosage / Q000627:therapeutic use*; D008113:Liver Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012334:RNA, Neoplasm / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins; D019014:fas Receptor / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D000906:Antibodies; D000970:Antineoplastic Agents; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; C481004:CH-11 anti-fas antibody, human; D004273:DNA, Neoplasm; C491901:FAS protein, human; D053222:Fas Ligand Protein; D007370:Interferon Type I; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D011994:Recombinant Proteins; D019014:fas Receptor; D020169:Caspases; D005472:Fluorouracil