title: Effects of warm ischemic time on gene expression profiling in colorectal cancer tissues and normal mucosa.
abstract: BACKGROUND
  Genome-wide gene expression analyses of tumors are a powerful tool to identify gene signatures associated with biologically and clinically relevant characteristics and for several tumor types are under clinical validation by prospective trials. However, handling and processing of clinical specimens may significantly affect the molecular data obtained from their analysis. We studied the effects of tissue handling time on gene expression in human normal and tumor colon tissues undergoing routine surgical procedures.
  
  
  METHODS
  RNA extracted from specimens of 15 patients at four time points (for a total of 180 samples) after surgery was analyzed for gene expression on high-density oligonucleotide microarrays. A mixed-effects model was used to identify probes with different expression means across the four different time points. The p-values of the model were adjusted with the Bonferroni method.
  
  
  RESULTS
  Thirty-two probe sets associated with tissue handling time in the tumor specimens, and thirty-one in the normal tissues, were identified. Most genes exhibited moderate changes in expression over the time points analyzed; however four of them were oncogenes, and two confirmed the effect of tissue handling by independent validation.
  
  
  CONCLUSIONS
  Our results suggest that a critical time point for tissue handling in colon seems to be 60 minutes at room temperature. Although the number of time-dependent genes we identified was low, the three genes that already showed changes at this time point in tumor samples were all oncogenes, hence recommending standardization of tissue-handling protocols and effort to reduce the time from specimen removal to snap freezing accounting for warm ischemia in this tumor type.
authors: Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.
authors: Valeria
authors: V
authors: Musella
authors: Paolo
authors: P
authors: Verderio
authors: James Francis
authors: JF
authors: Reid
authors: Sara
authors: S
authors: Pizzamiglio
authors: Manuela
authors: M
authors: Gariboldi
authors: Maurizio
authors: M
authors: Callari
authors: Massimo
authors: M
authors: Milione
authors: Milione
authors: M
authors: Massimo
authors: Loris
authors: L
authors: De Cecco
authors: Silvia
authors: S
authors: Veneroni
authors: Marco Alessandro
authors: MA
authors: Pierotti
authors: Maria Grazia
authors: MG
authors: Daidone
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis / Q000235:genetics*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy; D015179:Colorectal Neoplasms / Q000175:diagnosis / Q000235:genetics*; D005260:Female; D015870:Gene Expression; D020869:Gene Expression Profiling; D006801:Humans; D008297:Male; D008875:Middle Aged; D020411:Oligonucleotide Array Sequence Analysis; D015513:Oncogene Proteins / Q000235:genetics*; D011446:Prospective Studies; D012334:RNA, Neoplasm / Q000235:genetics*; D013048:Specimen Handling / Q000592:standards*; D013997:Time Factors; D052096:Warm Ischemia / Q000592:standards*
chemical_list: D015513:Oncogene Proteins; D012334:RNA, Neoplasm