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INTRODUCTION: Hypoxia-inducible factor (HIF)-1alpha levels in invasive breast carcinoma have been shown to be an adverse prognostic indicator. Cellular HIF-1alpha activity is regulated by factor-inhibiting hypoxia-inducible factor 1 (FIH-1). In hypoxia, FIH-1 hydroxylation of Asn803 within the C-terminal transactivation domain does not occur and HIF-1alpha forms a fully active transcriptional complex. The present study investigates the role of FIH-1 in invasive breast carcinoma and its correlation with hypoxia. METHODS: Microarrayed tissue cores from 295 invasive carcinomas were stained for FIH-1, for HIF-1alpha and for carbonic anhydrase 9. FIH-1 expression was correlated with standard clinicopathological parameters and with the expression of the surrogate hypoxic markers HIF-1alpha and carbonic anhydrase 9. RESULTS: FIH-1 was positive in 239/295 (81%) tumours, 42/295 (14%) exclusively in the nucleus and 54/295 (18%) exclusively in the cytoplasm. Exclusive nuclear FIH-1 expression was significantly inversely associated with tumour grade (P = 0.02) and risk of recurrence (P = 0.04), whereas exclusive cytoplasmic FIH-1 was significantly positively associated with tumour grade (P = 0.004) and carbonic anhydrase 9 expression (P = 0.02). Patients with tumours that excluded FIH-1 from the nucleus had a significantly shorter survival compared with those with exclusive nuclear expression (P = 0.02). Cytoplasmic FIH-1 expression was also an independent poor prognostic factor for disease-free survival. CONCLUSION: FIH-1 is widely expressed in invasive breast carcinoma. As with other HIF regulators, its association between cellular compartmentalization and the hypoxic response and survival suggests that tumour regulation of FIH-1 is an additional important mechanism for HIF pathway activation.

Original publication




Journal article


Breast Cancer Res

Publication Date





Adult, Aged, Aged, 80 and over, Antigens, Neoplasm, Biomarkers, Tumor, Breast Neoplasms, Carbonic Anhydrase IX, Carbonic Anhydrases, Cell Hypoxia, Cytoplasm, Female, Humans, Hypoxia-Inducible Factor 1, alpha Subunit, Immunohistochemistry, Middle Aged, Mixed Function Oxygenases, Neoplasm Invasiveness, Predictive Value of Tests, Prognosis, Repressor Proteins, Survival Analysis, Transcription Factors