title: All-trans retinoic acid and interferon-alpha for treatment of human renal cell carcinoma multicellular tumor spheroids.
abstract: BACKGROUND
  Conventional preclinical investigations have strongly recommended to combine interferon-alpha (IFN-alpha) with 13-cis retinoic acid (13-cRA, isotretinoin) for treatment of renal cell carcinoma (RCC). However, a recent randomized controlled trial on the drug combination ultimately failed to demonstrate an increased tumor-specific survival of patients with metastatic RCC (MRCC). All-trans retinoic acid (ATRA, tretinoin) was suggested to provide stronger antineoplastic properties than 13-cRA in different other tumors.
  
  
  METHODS
  The present study aimed to compare ATRA with 13-cRA (0.1, 1, 10, 100 nM) alone or in combination with IFN-alpha (5, 400, 5,000, 25,000, 250,000 IU/ml) or 5-fluorouracil (5-FU; 0.1, 1, 10, 100 microg/ml). Multicellular tumor spheroids of human RCC cells (SN12C) were treated in order to facilitate the predictions of the model system.
  
  
  RESULTS
  ATRA decreased the mean volume of SN12C spheroids 10-20% more than 13-cRA. Both retinoids led to a super-additive growth inhibition in combination with IFN-alpha, but not with 5-FU. However, in this scenario the superior effect of ATRA compared to 13-cRA, although statistically significant, was not impressive (<10%).
  
  
  CONCLUSIONS
  ATRA provides a slightly stronger direct antineoplastic effect on human renal cancer cells than 13-cRA, and acts synergistically with IFN-alpha. However, ATRA, if at all, does not seem to be more suitable for treatment of patients with MRCC than 13-cRA.
authors.affiliation: Department of Urology, University of Aachen, Aachen, Germany. detlef.rohde@klinikum-darmstadt.de
authors.forename: Detlef
authors.initials: D
authors.lastname: Rohde
authors.forename: Drasko
authors.initials: D
authors.lastname: Brkovic
authors.forename: Inga
authors.initials: I
authors.lastname: Hönig d'Orville
mesh_terms: D000970:Antineoplastic Agents / Q000627:therapeutic use*; D002292:Carcinoma, Renal Cell / Q000188:drug therapy*; D006801:Humans; D016898:Interferon-alpha / Q000627:therapeutic use*; D007680:Kidney Neoplasms / Q000188:drug therapy*; D018874:Spheroids, Cellular / Q000187:drug effects*; D014212:Tretinoin / Q000627:therapeutic use*; D014407:Tumor Cells, Cultured
chemical_list: D000970:Antineoplastic Agents; D016898:Interferon-alpha; D014212:Tretinoin