title: Retinoic acid and the histone deacetylase inhibitor trichostatin a inhibit the proliferation of human renal cell carcinoma in a xenograft tumor model.
abstract: OBJECTIVE
  Therapy for advanced renal cell carcinoma (RCC) is ineffective in the majority of patients. We have previously reported that retinoid-induced up-regulation of retinoic acid receptor beta (RARbeta) correlated with antitumor effects in RCCs. Recent studies show that there is a reduction in the level of RARbeta2 expression in cancer cells due in part to histone hypoacetylation. Therefore, we tested whether combining histone deacetylase inhibitors with retinoic acid (RA) would restore RARbeta2 receptor expression, leading to increased growth inhibition in RCC cells.
  
  
  METHODS
  Cell proliferation, Western blot, and reverse transcription-PCR analyses of two RA-resistant RCC cell lines, SK-RC-39 and SK-RC-45, were assessed in the presence of all-trans retinoic acid (ATRA), trichostatin A (TSA), or the combination of ATRA and TSA. Analysis of apoptosis was also done on SK-RC-39 cells treated with these combinations. Additionally, a xenograft tumor model (SK-RC-39) was used in this study to investigate the efficacy of a liposome-encapsulated, i.v. form of ATRA (ATRA-IV) plus TSA combination therapy.
  
  
  RESULTS
  Enhanced inhibition of the proliferation of RCC cell lines and of tumor growth in a xenograft model was observed with the combination of ATRA plus TSA. Reactivation of RARbeta2 mRNA expression was observed in SK-RC-39 and SK-RC-45 cells treated with TSA alone or TSA in combination with ATRA. A partial G0-G1 arrest and increased apoptosis were observed with SK-RC-39 cells on treatment with ATRA and TSA.
  
  
  CONCLUSIONS
  The combination of ATRA and the histone deacetylase inhibitor TSA elicits an additive inhibition of cell proliferation in RCC cell lines. These results indicate that ATRA and histone deacetylase inhibitor therapies should be explored for the treatment of advanced RCC.
authors.affiliation: Department of Pharmacology, Weill Medical College of Cornell University, New York, New York 10021, USA.
authors.forename: Sue Ellen
authors.initials: SE
authors.lastname: Touma
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Goldberg
authors.forename: Paul
authors.initials: P
authors.lastname: Moench
authors.forename: Xiaojia
authors.initials: X
authors.lastname: Guo
authors.forename: Satish K
authors.initials: SK
authors.lastname: Tickoo
authors.forename: Lorraine J
authors.initials: LJ
authors.lastname: Gudas
authors.forename: David M
authors.initials: DM
authors.lastname: Nanus
mesh_terms: D000107:Acetylation / Q000187:drug effects; D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000494:pharmacology; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D015153:Blotting, Western; D002292:Carcinoma, Renal Cell / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D056572:Histone Deacetylase Inhibitors; D006657:Histones / Q000378:metabolism; D006801:Humans; D006877:Hydroxamic Acids / Q000008:administration & dosage / Q000494:pharmacology*; D007680:Kidney Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D051379:Mice; D008819:Mice, Nude; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018168:Receptors, Retinoic Acid / Q000235:genetics; D000072482:Retinoic Acid Receptor alpha; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014212:Tretinoin / Q000008:administration & dosage / Q000494:pharmacology*; D023041:Xenograft Model Antitumor Assays; D000097768:Retinoic Acid Receptor gamma
chemical_list: D000970:Antineoplastic Agents; D056572:Histone Deacetylase Inhibitors; D006657:Histones; D006877:Hydroxamic Acids; D012333:RNA, Messenger; D018168:Receptors, Retinoic Acid; D000072482:Retinoic Acid Receptor alpha; D014212:Tretinoin; D000097768:Retinoic Acid Receptor gamma; C000607071:RARA protein, human; C000607072:Rara protein, mouse; C082925:retinoic acid receptor beta; C012589:trichostatin A