title: Microarray-analysis: a new approach to study the molecular mechanisms of thermo-chemotherapy.
abstract: BACKGROUND
  Experimental studies for the treatment of relapsed neuroblastoma include the use of hyperthermia in combination with chemotherapeutic drugs. Cytotoxic effects of alkylants and platinum compounds on tumor cells can be enhanced by hyperthermia in various in vitro models. However, the underlying molecular mechanisms are still largely unknown.
  
  
  METHODS
  In this study, we used microarray-analysis as a new biological approach to gain insight into the pharmacogenomics and possible target genes of thermochemotherapy. As a model, LAN 1 neuroblastoma cells were treated for 1 h with low doses of cisplatin alone, with simultaneous heating to 42 degrees C or with hyperthermia alone. Gene expression was analyzed at five time points 0 to 24 h after treatment using U95Av2 oligonucleotide arrays (Affymetrix Inc). Significant changes of gene expression levels were calculated by similarity metrices and Pearson correlation.
  
  
  RESULTS
  Only a few genes (n = 23) demonstrated altered expression following treatment of LAN 1 cells with cisplatin alone. Hyperthermia alone resulted in significant expression changes of 136 genes in comparison to untreated control cells. Combination therapy of cisplatin and hyperthermia resulted in expression changes of 251 genes, interestingly including 131 genes with unchanged expression under treatment with either cisplatin or hyperthermia alone. Significant changes of expression levels could be annotated to genes involved in heat shock response, protein degradation and apoptosis. These results are now being validated on mRNA- and protein levels by RT-PCR and Western Blot analysis.
  
  
  CONCLUSIONS
  Microarray-Analysis is a suitable new approach for the identification of target genes, which might play an important role for the synergistic effect of hyperthermia and chemotherapy in tumor cells.
authors.affiliation: University Children's Hospital of Essen, Germany.
authors.forename: J H
authors.initials: JH
authors.lastname: Schulte
authors.forename: A
authors.initials: A
authors.lastname: Schramm
authors.forename: T
authors.initials: T
authors.lastname: Pressel
authors.forename: L
authors.initials: L
authors.lastname: Klein-Hitpass
authors.forename: B
authors.initials: B
authors.lastname: Kremens
authors.forename: J
authors.initials: J
authors.lastname: Eils
authors.forename: W
authors.initials: W
authors.lastname: Havers
authors.forename: A
authors.initials: A
authors.lastname: Eggert
mesh_terms: D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000494:pharmacology*; D017209:Apoptosis; D015153:Blotting, Western; D002151:Calorimetry; D016923:Cell Death; D002460:Cell Line; D002945:Cisplatin / Q000008:administration & dosage / Q000494:pharmacology*; D003131:Combined Modality Therapy; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D006360:Heat-Shock Proteins; D006801:Humans; D006979:Hyperthermia, Induced; D009447:Neuroblastoma / Q000188:drug therapy / Q000235:genetics* / Q000628:therapy*; D020411:Oligonucleotide Array Sequence Analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D014407:Tumor Cells, Cultured
chemical_list: D000970:Antineoplastic Agents; D006360:Heat-Shock Proteins; D002945:Cisplatin