title: Synergy of irofulven in combination with other DNA damaging agents: synergistic interaction with altretamine, alkylating, and platinum-derived agents in the MV522 lung tumor model.
abstract: OBJECTIVE
  Irofulven (MGI 114, NSC 683863) is a semisynthetic derivative of illudin S, a natural product present in the Omphalotus illudins (Jack O'Lantern) mushroom. This novel agent produces DNA damage, that in contrast to other agents, is predominately ignored by the global genome repair pathway of the nucleotide excision repair (NER)(2) system. The aim of this study was to determine the antitumor activity of irofulven when administered in combination with 44 different DNA damaging agents, whose damage is in general detected and repaired by the genome repair pathway.
  
  
  METHODS
  The human lung carcinoma MV522 cell line and its corresponding xenograft model were used to evaluate the activity of irofulven in combination with different DNA damaging agents.
  
  
  RESULTS
  Two main classes of DNA damaging agents, platinum-derived agents, and select bifunctional alkylating agents, demonstrated in vivo synergistic or super-additive interaction with irofulven. DNA helicase inhibiting agents also demonstrated synergy in vitro, but an enhanced interaction with irofulven could not be demonstrated in vivo. There was no detectable synergistic activity between irofulven and agents capable of inducing DNA cleavage or intercalating into DNA.
  
  
  CONCLUSIONS
  These results indicate that the antitumor activity of irofulven is enhanced when combined with platinum-derived agents, altretamine, and select alkylating agents such as melphalan or chlorambucil. A common factor between these agents appears to be the production of intrastrand DNA crosslinks. The synergistic interaction between irofulven and other agents may stem from the nucleotide excision repair system being selectively overwhelmed at two distinct points in the pathway, resulting in prolonged stalling of transcription forks, and subsequent initiation of apoptosis.
authors.affiliation: University of California San Diego, San Diego, CA 92103, USA. mkelner@ucsd.edu
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Kelner
authors.forename: Trevor C
authors.initials: TC
authors.lastname: McMorris
authors.forename: Rafael J
authors.initials: RJ
authors.lastname: Rojas
authors.forename: Leita A
authors.initials: LA
authors.lastname: Estes
authors.forename: Pharnuk
authors.initials: P
authors.lastname: Suthipinijtham
mesh_terms: D006585:Altretamine / Q000008:administration & dosage / Q000494:pharmacology; D000818:Animals; D018906:Antineoplastic Agents, Alkylating / Q000008:administration & dosage / Q000494:pharmacology; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D017209:Apoptosis / Q000187:drug effects; D002277:Carcinoma / Q000188:drug therapy* / Q000235:genetics; D004249:DNA Damage / Q000187:drug effects*; D004273:DNA, Neoplasm / Q000187:drug effects*; D004357:Drug Synergism; D005260:Female; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000235:genetics; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009944:Organoplatinum Compounds / Q000008:administration & dosage / Q000494:pharmacology; D011897:Random Allocation; D012717:Sesquiterpenes / Q000008:administration & dosage / Q000494:pharmacology; D014158:Transcription, Genetic / Q000187:drug effects; D023041:Xenograft Model Antitumor Assays
chemical_list: D018906:Antineoplastic Agents, Alkylating; D004273:DNA, Neoplasm; D009944:Organoplatinum Compounds; D012717:Sesquiterpenes; C102714:irofulven; D006585:Altretamine