The relation between hypoxia-inducible factor (HIF)-1alpha and HIF-2alpha expression with anemia and outcome in surgically treated head and neck cancer

Abstract

Background: Hypoxia promotes tumorigenesis through the hypoxia-inducible factor (HIF) pathway. There are 2 main homologues of the regulatory proteins, HIF-1alpha and HIF-2alpha, which have different effects in genetic knock-out experiments. Anemia may contribute to hypoxia by reducing oxygen delivery, but it is not known whether this influences HIF-alpha expression in tumors.

Methods: The expression of HIF-1alpha, HIF-2alpha, carbonic anhydrase-9 (CA-9), and peripheral hemoglobin (Hb) levels in 151 patients who underwent surgery for head and neck squamous cell carcinoma (HNSCC) were analyzed and related to outcome.

Results: High HIF-1alpha was expressed in 45 of 140 tumors (30%), HIF-2alpha was expressed in 21 of 139 tumors (14%), and CA-9 was expressed in 56 of 149 tumors (62%). There was a positive correlation between HIF-1alpha expression and HIF-2alpha expression (P =.0001). HIF-1alpha alone was associated with a worse disease-specific survival (DSS) (P =.05) and disease-free survival (DFS) (P = .03) in multivariate analyses. Nine percent of tumors expressed both high HIF-1alpha and high HIF-2alpha. High HIF-1alpha/high HIF-2alpha expression was an independent prognostic factors in DSS (P = .04) and DFS (P =.005) in multivariate analyses. There was no correlation noted between Hb and HIF-1alpha, HIF-2alpha, or CA-9.

Conclusions: HIF-1alpha alone was correlated with DSS and DFS. The additive effect of HIF-2alpha on poor prognosis suggested that different pathways may be regulated by HIF-2alph. Anemia that was not related to HIF-alpha expression suggests that tumor intrinsic factors regulate HIF-alpha therefore, anemia may be a surrogate marker for other factors that affect outcome.