title: Effect of hyperthermia on the cytotoxicity of 4 chemotherapeutic agents currently used for the treatment of transitional cell carcinoma of the bladder: an in vitro study.
abstract: OBJECTIVE
  Hyperthermia combined with chemotherapy is not a novel cancer treatment. However, the working mechanism of this combination therapy is not fully understood. In the current in vitro study we investigated the differences in cytotoxicity of 4 chemotherapeutic agents at 37C or 43C.
  
  
  METHODS
  The human transitional cell carcinoma cell lines used were RT4, RT112, 253J and T24. Cells were seeded in 96-well microtiter plates. After 24 hours cells were treated for 60 minutes with increasing concentrations of mitomycin C, epirubicin, gemcitabine and EO9 at a temperature of 37C or 43C. After treatment cells were rinsed 3 times and left for 24 hours in the incubator at 37C. The influence of chemotherapy and temperature on cell survival was determined by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide) assay.
  
  
  RESULTS
  Decreased cell proliferation with increasing concentrations of chemotherapeutic agents was demonstrated. EO9 proved to be the most potent agent at each temperature. Hyperthermia alone did not demonstrate decreased cell proliferation. However, a synergistic effect on decreased cell proliferation was demonstrated in all cell lines and chemotherapeutic agents used, although each had a maximum at a different chemotherapy concentration and to a different extent. Synergism was most obvious in cell lines treated with low dose epirubicin.
  
  
  CONCLUSIONS
  Synergism with hyperthermia and chemotherapy was clearly demonstrated for epirubicin, EO9, mitomycin C and to a lesser extent gemcitabine. Hyperthermia alone did not cause decreased cell proliferation. Synergism was most prominent with low drug doses and the most potent drug used in this in vitro study was EO9.
authors.affiliation: Department of Urology, University Medical Centre Nijmegen, Nijmegen, The Netherlands.
authors.forename: Antoine G
authors.initials: AG
authors.lastname: van der Heijden
authors.forename: Gerald
authors.initials: G
authors.lastname: Verhaegh
authors.forename: Cornelius F J
authors.initials: CF
authors.lastname: Jansen
authors.forename: Jack A
authors.initials: JA
authors.lastname: Schalken
authors.forename: J Alfred
authors.initials: JA
authors.lastname: Witjes
mesh_terms: D000903:Antibiotics, Antineoplastic / Q000008:administration & dosage; D000964:Antimetabolites, Antineoplastic / Q000008:administration & dosage; D000970:Antineoplastic Agents / Q000008:administration & dosage; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D001388:Aziridines / Q000008:administration & dosage; D002295:Carcinoma, Transitional Cell / Q000188:drug therapy / Q000473:pathology / Q000628:therapy*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004396:Coloring Agents; D003131:Combined Modality Therapy; D003841:Deoxycytidine / Q000008:administration & dosage / Q000031:analogs & derivatives*; D015251:Epirubicin / Q000008:administration & dosage; D006801:Humans; D006979:Hyperthermia, Induced; D045563:Indolequinones / Q000008:administration & dosage; D016685:Mitomycin / Q000008:administration & dosage; D013778:Tetrazolium Salts; D013844:Thiazoles; D001749:Urinary Bladder Neoplasms / Q000188:drug therapy / Q000473:pathology / Q000628:therapy*; D000093542:Gemcitabine
chemical_list: D000903:Antibiotics, Antineoplastic; D000964:Antimetabolites, Antineoplastic; D000970:Antineoplastic Agents; D001388:Aziridines; D004396:Coloring Agents; D045563:Indolequinones; D013778:Tetrazolium Salts; D013844:Thiazoles; D003841:Deoxycytidine; D015251:Epirubicin; D016685:Mitomycin; C022616:thiazolyl blue; C060817:apaziquone; D000093542:Gemcitabine