title: Selecting control genes for RT-QPCR using public microarray data.
abstract: BACKGROUND
  Gene expression analysis has emerged as a major biological research area, with real-time quantitative reverse transcription PCR (RT-QPCR) being one of the most accurate and widely used techniques for expression profiling of selected genes. In order to obtain results that are comparable across assays, a stable normalization strategy is required. In general, the normalization of PCR measurements between different samples uses one to several control genes (e.g. housekeeping genes), from which a baseline reference level is constructed. Thus, the choice of the control genes is of utmost importance, yet there is not a generally accepted standard technique for screening a large number of candidates and identifying the best ones.
  
  
  RESULTS
  We propose a novel approach for scoring and ranking candidate genes for their suitability as control genes. Our approach relies on publicly available microarray data and allows the combination of multiple data sets originating from different platforms and/or representing different pathologies. The use of microarray data allows the screening of tens of thousands of genes, producing very comprehensive lists of candidates. We also provide two lists of candidate control genes: one which is breast cancer-specific and one with more general applicability. Two genes from the breast cancer list which had not been previously used as control genes are identified and validated by RT-QPCR. Open source R functions are available at http://www.isrec.isb-sib.ch/~vpopovic/research/
  
  
  CONCLUSIONS
  We proposed a new method for identifying candidate control genes for RT-QPCR which was able to rank thousands of genes according to some predefined suitability criteria and we applied it to the case of breast cancer. We also empirically showed that translating the results from microarray to PCR platform was achievable.
authors.affiliation: Bioinformatics Core Facility, Swiss Institute of Bioinformatics, CH-1015 Lausanne, Switzerland. vlad.popovici@isb-sib.ch
authors.forename: Vlad
authors.initials: V
authors.lastname: Popovici
authors.forename: Darlene R
authors.initials: DR
authors.lastname: Goldstein
authors.forename: Janine
authors.initials: J
authors.lastname: Antonov
authors.forename: Rolf
authors.initials: R
authors.lastname: Jaggi
authors.forename: Mauro
authors.initials: M
authors.lastname: Delorenzi
authors.forename: Pratyaksha
authors.initials: P
authors.lastname: Wirapati
mesh_terms: D001943:Breast Neoplasms / Q000175:diagnosis / Q000235:genetics; D055088:Early Detection of Cancer; D005260:Female; D020869:Gene Expression Profiling / Q000379:methods*; D006801:Humans; D020411:Oligonucleotide Array Sequence Analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods*