Expression and Prognostic Significance of a Panel of Tissue Hypoxia Markers in Head-and-Neck Squamous Cell Carcinomas

Abstract

To investigate the expression pattern of hypoxia-induced proteins identified as being involved in malignant progression of head-and-neck squamous cell carcinoma (HNSCC) and to determine their relationship to tumor pO(2) and prognosis. We performed immunohistochemical staining of hypoxia-induced proteins (carbonic anhydrase IX [CA IX], BNIP3L, connective tissue growth factor, osteopontin, ephrin A1, hypoxia inducible gene-2, dihydrofolate reductase, galectin-1, IkappaB kinase beta, and lysyl oxidase) on tumor tissue arrays of 101 HNSCC patients with pretreatment pO(2) measurements. Analysis of variance and Fisher's exact tests were used to evaluate the relationship between marker expression, tumor pO(2), and CA IX staining. Cox proportional hazard model and log-rank tests were used to determine the relationship between markers and prognosis. Osteopontin expression correlated with tumor pO(2) (Eppendorf measurements) (p = 0.04). However, there was a strong correlation between lysyl oxidase, ephrin A1, and galectin-1 and CA IX staining. These markers also predicted for cancer-specific survival and overall survival on univariate analysis. A hypoxia score of 0-5 was assigned to each patient, on the basis of the presence of strong staining for these markers, whereby a higher score signifies increased marker expression. On multivariate analysis, increasing hypoxia score was an independent prognostic factor for cancer-specific survival (p = 0.015) and was borderline significant for overall survival (p = 0.057) when adjusted for other independent predictors of outcomes (hemoglobin and age). We identified a panel of hypoxia-related tissue markers that correlates with treatment outcomes in HNSCC. Validation of these markers will be needed to determine their utility in identifying patients for hypoxia-targeted therapy.