Expression of hypoxia-inducible factor-1α in oligodendrogliomas

Abstract

Hypoxia-inducible factor (HIF)1α is considered to play a key role in the adaptation of cells to hypoxia by stimulating angiogenesis via regulation of vascular endothelial growth factor and by metabolic adaptation to O₂ deprivation. Expression of HIF-1α protein and p53 was investigated by immunohistochemistry in 51 specimens of supratentorial pure oligodendrogliomas. Microvessels density (MVD) was determined by anti-CD34 immunostaining. The influence of HIF-1α expression on survival was investigated using univariate and multivariate analysis. Strong expression of HIF-1α was observed in 12 (23.5%) specimens, moderate in 21 (41.2%) specimens, and weak in 8 (15.7%) cases, and no expression was found in 10 samples (19.6%). There was no correlation of HIF-1α expression with histologic grading (P = 0.428, Mann–Whitney test). Hypoxia-inducible factor–1α expression and MVD showed a strong correlation (P < 0.001, r = 0.735, Spearman coefficient of correlation). Overexpression of p53 was observed in only two cases. Patients with strong or moderate expression of HIF-1α had a significantly shorter overall survival rate compared with those with low or no expression in univariate (P = 0.0434; log-rank test) and multivariate analysis (P = 0.0187). Overexpression of HIF-1α indicates a diminished prognosis in oligodendrogliomas, independent of p53 status. This finding may be explained by the strong vascularization of these tumors that prevents hypoxia and allows O₂ diffusion and henceforth tumor progression. Cancer 2001;92:165–171. © 2001 American Cancer Society.