title: Role of aldo-keto reductases and other doxorubicin pharmacokinetic genes in doxorubicin resistance, DNA binding, and subcellular localization.
abstract: BACKGROUND
  Since proteins involved in chemotherapy drug pharmacokinetics and pharmacodynamics have a strong impact on the uptake, metabolism, and efflux of such drugs, they likely play critical roles in resistance to chemotherapy drugs in cancer patients.
  
  
  METHODS
  To investigate this hypothesis, we conducted a whole genome microarray study to identify difference in the expression of genes between isogenic doxorubicin-sensitive and doxorubicin-resistant MCF-7 breast tumour cells. We then assessed the degree of over-representation of doxorubicin pharmacokinetic and pharmacodynamic genes in the dataset of doxorubicin resistance genes.
  
  
  RESULTS
  Of 27,958 Entrez genes on the array, 7.4 per cent or 2,063 genes were differentially expressed by ≥ 2-fold between wildtype and doxorubicin-resistant cells. The false discovery rate was set at 0.01 and the minimum p value for significance for any gene within the "hit list" was 0.01. Seventeen and 43 per cent of doxorubicin pharmacokinetic genes were over-represented in the hit list, depending upon whether the gene name was identical or within the same gene family, respectively. The most over-represented genes were within the 1C and 1B families of aldo-keto reductases (AKRs), which convert doxorubicin to doxorubicinol. Other genes convert doxorubicin to other metabolites or affect the influx, efflux, or cytotoxicity of the drug. In further support of the role of AKRs in doxorubicin resistance, we observed that, in comparison to doxorubicin, doxorubincol exhibited dramatically reduced cytotoxicity, reduced DNA-binding activity, and strong localization to extra nuclear lysosomes. Pharmacologic inhibition of the above AKRs in doxorubicin-resistant cells increased cellular doxorubicin levels, restored doxorubicin cytotoxicity and re-established doxorubicin localization to the nucleus. The properties of doxorubicinol were unaffected.
  
  
  CONCLUSIONS
  These findings demonstrate the utility of using curated pharmacokinetic and pharmacodynamic knowledge bases to identify highly relevant genes associated with doxorubicin resistance. The induction of one or more of these genes was found to be correlated with changes in the drug's properties, while inhibiting one specific class of these genes (the AKRs) increased cellular doxorubicin content and restored drug DNA binding, cytotoxicity, and subcellular localization.
authors.affiliation: Graduate Program in Biology, Laurentian University, Sudbury, ON, Canada.
authors.forename: Allan D
authors.initials: AD
authors.lastname: Heibein
authors.forename: Baoqing
authors.initials: B
authors.lastname: Guo
authors.forename: Jason A
authors.initials: JA
authors.lastname: Sprowl
authors.forename: David A
authors.initials: DA
authors.lastname: Maclean
authors.forename: Amadeo M
authors.initials: AM
authors.lastname: Parissenti
mesh_terms: D015089:20-Hydroxysteroid Dehydrogenases / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D015096:3-Hydroxysteroid Dehydrogenases / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D000449:Aldehyde Reductase / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism*; D000074425:Aldo-Keto Reductase Family 1 Member C3; D000074408:Aldo-Keto Reductases; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000235:genetics* / Q000378:metabolism; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D002793:Cholic Acids / Q000494:pharmacology; D016572:Cyclosporine / Q000494:pharmacology; D004273:DNA, Neoplasm / Q000378:metabolism; D004317:Doxorubicin / Q000031:analogs & derivatives* / Q000493:pharmacokinetics* / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm; D020869:Gene Expression Profiling; D006801:Humans; D006911:Hydroxyprostaglandin Dehydrogenases / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D061986:MCF-7 Cells; D020411:Oligonucleotide Array Sequence Analysis
chemical_list: D002793:Cholic Acids; D004273:DNA, Neoplasm; D004317:Doxorubicin; D016572:Cyclosporine; D015096:3-Hydroxysteroid Dehydrogenases; D015089:20-Hydroxysteroid Dehydrogenases; C115140:3 alpha-beta, 20 beta-hydroxysteroid dehydrogenase; C120471:AKR1B10 protein, human; D000074408:Aldo-Keto Reductases; D006911:Hydroxyprostaglandin Dehydrogenases; C484670:AKR1B1 protein, human; D000449:Aldehyde Reductase; C487341:AKR1C3 protein, human; D000074425:Aldo-Keto Reductase Family 1 Member C3; C010013:adriamycinol; C007036:cholanic acid