Hypoxia-inducible factor 1α is closely linked to an aggressive phenotype in breast cancer

Abstract

Purpose The aim of this study is to clarify characteristics of invasive breast cancer with expression of Hypoxia-induced factor 1α (HIF-1α) which is induced by hypoxia and signal transduction of growth factors. Experimental Design We examined, by immunohistochemical analysis, the expression of HIF-1α in normal breast tissue, benign disorders and breast cancer. In invasive breast cancer, we investigated the correlation between expression of HIF-1α and clinicopathological and biological factors. We also studied the prognostic value of HIF-1α in breast cancer. Results HIF-1α was mainly detected in tumor cell nuclei. In the 171 cases of invasive breast cancer examined, nuclear HIF-1α expression was detected in 63 (36.8%) cases. Immunoreactive nuclear HIF-1α was correlated with tumor size (p = 0.0013), lymph node metastasis (p = 0.0005), tumor stage (p = 0.0031) and histological grade (p = 0.0074). Elevated HIF-1α levels was also associated with hormone receptor negativity (p = 0.0025), HER2 overexpression (p = 0.0053), high Ki67 labeling index (p = 0.0002), increased levels of VEGF (p < 0.0001), COX-2 overexpression (p = 0.0029) and increased nuclear p53 (p = 0.0048). In terms of the possible use of HIF-1α as a prognostic indicator, patients who had increased HIF-1α levels in their tumor showed shorter disease-free survival (DFS) (p < 0.0001) and overall survival (OS) (p = 0.0002) than those lacking HIF-1α in univariate analysis. In multivariate analysis of DFS and OS, HIF-1α was identified an independent prognostic factor. Conclusions These findings suggest that HIF-1α was closely linked to an aggressive phenotype in breast cancer. It may be useful to study the expression of HIF-1α using immunohistochemical analysis for better understanding of the tumor characteristics of breast cancer.