title: Synergy of interferon-alpha and 5-fluorouracil in human renal cell carcinoma requires p53 activity.
abstract: OBJECTIVE
  Immunochemical therapy combining cytokines and chemotherapeutic agents is expected to be effective for treating advanced renal cell carcinoma (RCC). We investigated the mechanism underlying the synergism of interferon-alpha (IFN-alpha) and 5-fluorouracil (5-FU) and the effect of p53 status on the synergy of the combined therapy in RCC cell lines.
  
  
  METHODS
  The synergy of IFN-alpha and 5-FU was analyzed by isobolographic analysis in five RCC cell lines. The effect of combined treatment on apoptosis induction was measured by flow cytometric analysis, Hoechst staining, and caspase activity assay; PCNA expression was investigated by Western blotting to examine the effect of combined treatment on the antiproliferative effect.
  
  
  RESULTS
  We demonstrated synergy of IFN-alpha and 5-FU in five RCC cell lines with wild-type p53. IFN-alpha suppressed the proliferation of RCC cells via G1 or G2/M cell cycle arrest without inducing apoptosis, whereas 5-FU induced apoptosis in a dosage-dependent manner. IFN-alpha enhanced the apoptosis of RCC cells induced by 5-FU, whereas 5-FU did not increase the antiproliferative effect of IFN-alpha. However, the synergistic inhibition by IFN-alpha and 5-FU was abolished when the cell lines were transfected with p53 dominant-negative vector.
  
  
  CONCLUSIONS
  The synergy of IFN-alpha and 5-FU requires p53 activity, suggesting that p53 status may serve as a predictive factor for response to the combination therapy. Because metastatic RCC frequently has p53 mutations, therapy restoring p53 may markedly improve the response rate of immunochemical therapy combining IFN-alpha and 5-FU.
authors.affiliation: Department of Urology, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
authors.forename: Donghao
authors.initials: D
authors.lastname: Shang
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Ito
authors.forename: Jun
authors.initials: J
authors.lastname: Watanabe
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Awakura
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Nishiyama
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Kamoto
authors.forename: Osamu
authors.initials: O
authors.lastname: Ogawa
mesh_terms: D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D002292:Carcinoma, Renal Cell / Q000188:drug therapy* / Q000235:genetics*; D045744:Cell Line, Tumor; D005472:Fluorouracil / Q000008:administration & dosage; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D016898:Interferon-alpha / Q000008:administration & dosage; D009154:Mutation; D016896:Treatment Outcome; D016159:Tumor Suppressor Protein p53 / Q000235:genetics* / Q000378:metabolism
chemical_list: D016898:Interferon-alpha; D016159:Tumor Suppressor Protein p53; D005472:Fluorouracil