title: Real-time PCR-based assay to quantify the relative amount of human and mouse tissue present in tumor xenografts.
abstract: BACKGROUND
  Xenograft samples used to test anti-cancer drug efficacies and toxicities in vivo contain an unknown mix of mouse and human cells. Evaluation of drug activity can be confounded by samples containing large amounts of contaminating mouse tissue. We have developed a real-time quantitative polymerase chain reaction (qPCR) assay using TaqMan technology to quantify the amount of mouse tissue that is incorporated into human xenograft samples.
  
  
  RESULTS
  The forward and reverse primers bind to the same DNA sequence in the human and the mouse genome. Using a set of specially designed fluorescent probes provides species specificity. The linearity and sensitivity of the assay is evaluated using serial dilutions of single species and heterogeneous DNA mixtures. We examined many xenograft samples at various in vivo passages, finding a wide variety of human:mouse DNA ratios. This variation may be influenced by tumor type, number of serial passages in vivo, and even which part of the tumor was collected and used in the assay.
  
  
  CONCLUSIONS
  This novel assay provides an accurate quantitative assessment of human and mouse content in xenograft tumors. This assay can be performed on aberrantly behaving human xenografts, samples used in bioinformatics studies, and periodically for tumor tissue frequently grown by serial passage in vivo.
authors.affiliation: Biological Testing Branch, Developmental Therapeutics Program, Division of Cancer Treatment and Diagnosis, National Cancer Institute-Frederick, Frederick, MD, USA. alcosers@mail.nih.gov
authors.forename: Sergio Y
authors.initials: SY
authors.lastname: Alcoser
authors.forename: David J
authors.initials: DJ
authors.lastname: Kimmel
authors.forename: Suzanne D
authors.initials: SD
authors.lastname: Borgel
authors.forename: John P
authors.initials: JP
authors.lastname: Carter
authors.forename: Kelly M
authors.initials: KM
authors.lastname: Dougherty
authors.forename: Melinda G
authors.initials: MG
authors.lastname: Hollingshead
mesh_terms: D000818:Animals; D001483:Base Sequence; D045744:Cell Line, Tumor; D004247:DNA / Q000032:analysis*; D017931:DNA Primers; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D009369:Neoplasms / Q000235:genetics*; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods*; D013045:Species Specificity; D014183:Transplantation, Heterologous
chemical_list: D017931:DNA Primers; D004247:DNA