Hypoxia-inducible factor-1α is associated with angiogenesis, and expression of bFGF, PDGF-BB, and EGFR in invasive breast cancer

Aims: Hypoxia-inducible factor-1 (HIF-1) is the key transcription factor regulating the cellular response to hypoxia, including angiogenesis. Growth factors play an important role in tumour growth and angiogenesis and some have been shown to be induced by HIF-1 in vitro. This study investigated if angiogenesis or growth factors or their receptors are associated with HIF-1α in invasive breast cancer. Methods and results: High levels of HIF-1α, detected by immunohistochemistry in 45 breast cancers, were positively associated with increased microvessel density (as a measure of angiogenesis) (P = 0.023). Furthermore, high levels of HIF-1α were associated with epithelial expression (≥ 10%) of epidermal growth factor receptor (EGFR) (P = 0.011), platelet-derived growth factor (PDGF)-BB (P < 0.001), and basic fibroblast growth factor (bFGF) (P = 0.045). A positive, yet insignificant, trend for HIF-1α to be associated with epithelial expression of transforming growth factor (TGF)-α (P = 0.081) and vascular endothelial growth factor (VEGF) (P = 0.109) was noticed as well as an inverse association with stromal expression of TGF-b-R1 (P = 0.070). Conclusions: In invasive breast cancer, HIF-1α is associated with angiogenesis, and expression of growth factors bFGF and PDGF-BB, and the receptor EGFR. Thus, agents targeting HIF-1 may combine different pathways of inhibiting breast cancer growth, including angiogenesis and growth factors