title: Impact of warm ischemia on phosphorylated biomarkers in head and neck squamous cell carcinoma.
abstract: OBJECTIVE
  To quantitatively and visually characterize changes in phosphorylated biomarker expression in head and neck squamous cell carcinoma specimens from excision through 90 minutes of warm ischemia.
  
  
  METHODS
  Tissue biospecimens were procured prospectively. Head and neck squamous cell carcinoma specimens from 5 patients were subdivided into three parts upon excision, exposed to warm ischemia of 15, 30, or 90 minutes, and routinely biobanked. Relative change in biomarker expression of p-Akt, p-ERK, and p-Stat3 was measured by immunoblot densitometry. Immunofluorescent stains were performed to visually supplement the quantitative analysis.
  
  
  RESULTS
  From 15 to 30 minutes of ex vivo ischemia, there was a significant decrease in p-Akt (p = 0.045) as the mean intensity fell by 44.9%. This decrease in p-Akt remained significant at the 90 minute time point (p = 0.015). From 15 to 30 minutes of ischemia, there was a trend toward a decline in p-ERK, which became significant by 90 minutes of ex vivo warm ischemia (p = 0.008). These changes were supported by qualitative differences in p-ERK fluorescence at 0 and 90 minutes warm ischemia.
  
  
  CONCLUSIONS
  Some phosphorylated biomarkers of HNSCC remain highly dynamic during the period of ex vivo warm ischemia after surgical excision but before biobanking. These findings have critical implications for studies that attempt to correlate protein phosphorylation with clinical outcome. We conclude that ex vivo warm ischemia time is a major determinant of tissue quality that may explain inconsistent results from biomarker research in head and neck squamous cell carcinoma.
authors.affiliation: Section of Otolaryngology-Head and Neck Surgery, Department of Surgery, The University of Chicago Chicago, IL 60637, USA.
authors.forename: Jacob I
authors.initials: JI
authors.lastname: Tower
authors.affiliation: Department of Pathology, The University of Chicago Chicago, IL 60637, USA.
authors.forename: Mark W
authors.initials: MW
authors.lastname: Lingen
authors.affiliation: Comprehensive Cancer Center, The University of Chicago Chicago, IL 60637, USA.
authors.forename: Tanguy Y
authors.initials: TY
authors.lastname: Seiwert
authors.affiliation: Section of Otolaryngology-Head and Neck Surgery, Department of Surgery, The University of Chicago Chicago, IL 60637, USA.
authors.forename: Alexander
authors.initials: A
authors.lastname: Langerman
keywords: Biobanking; biomarkers; head and neck squamous cell carcinoma; phosphorylated biomarkers; warm ischemia