Hypoxia inducible factor-1α correlates with VEGF-C expression and lymphangiogenesis in breast cancer

The transcription factor Hypoxia inducible factor-1 alpha (HIF-1 alpha) plays a crucial role in tumor progression by regulating angiogenesis, cell survival and drug resistance. HIF-1 alpha is also implicated in biological functions under normoxic conditions and recent data provide evidence for a possible role in tumor lymphangiogenesis by regulating the lymphatic vascular endothelial growth factor-C (VEGF-C). In breast cancer, lymphatic vessel invasion (LVI) by tumor cells and subsequent metastasis to axillary lymph nodes is a critical point in progression of the disease with severe therapeutical and prognostic implications. Aim of this study is to investigate the role of HIF-1 alpha in VEGF-C expression, lymphangiogenesis, and LVI in lymph node positive breast cancer. Lymphatic microvessel density (LMVD), LVI, HIF-1 alpha and VEGF-C protein-expression were evaluated by immunohistochemistry in 119 cases of lymph node positive invasive breast cancer. There was a significant correlation between HIF-1 alpha and VEGF-C (p = 0.026, r = 0.204, Spearman's coefficient of correlation). Further a significant association between HIF-1 alpha-expression and the amount of peritumoral lymphangiogenesis LMVD was seen (p = 0.014, Mann-Whitney test). LMVD correlated significantly with LVI (p < 0.001, Mann-Whitney test). HIF-1 alpha was an independent prognostic factor for overall and disease free survival in uni- and multivariate analysis (p = 0.027, 0.029, 0.025, respectively, Cox regression). Our data provide evidence for a possible role of HIF-1 alpha as regulator of tumor-associated lymphangiogenesis in human breast cancer and emphasizes the promising status of HIF-1 alpha as a therapeutical target against tumor progression and metastasis.