VEGF-C expressing tumor-associated macrophages in lymph node positive breast cancer: impact on lymphangiogenesis and survival.

BACKGROUND: The ability of malignant tumors to metastasize presents a severe challenge in cancer treatment. Lymphatic vessels provide one of the main routes for tumor-metastasis on the way to regional lymph nodes. Increasing evidence suggests that inflammatory cells play an important role in tumor-associated angiogenesis and lymphangiogenesis. Recent data show that a specialized sub fraction of tumor-associated macrophages (TAMs) expressing the lymphoangiogenic growth factors vascular endothelial growth factor-C and -D (VEGF-C/D) at the tumor site, is related to lymphangiogenesis, lymphovascular invasion, and lymph node metastasis. Aim of this study was to clear the role of VEGF-C/D expressing TAMs in invasive breast cancer. METHODS: One hundred-seven cases of lymph node positive invasive breast cancer were included into the study. Lymphatic microvessel density (LMVD), lymphovascular invasion (LVI), peritumoral inflammatory reaction (PI), and VEGF-C expression in tumors (VEGF-C(T)) and TAMs (VEGF-C(C)) were evaluated by immunohistochemistry and in situ hybridization. RESULTS: Significant associations were seen between LMVD and LVI, LMVD and VEGF-C(T), and between VEGF-C(T) and VEGF-C(C). Further significant correlations were evaluated between VEGF-C(C)/VEGF-C(T) and PI as well as between PI and LVI. LVI remained an independent prognostic factor for disease-free survival and overall survival. CONCLUSIONS: Our data provide evidence that the peritumoral inflammatory reaction and VEGF-C expressing TAMs may play an important role in tumor lymphangiogenesis and lymphovascular invasion in invasive breast cancer, implying new potential anti-tumor targets.

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

The transcription factor Hypoxia inducible factor-1alpha (HIF-1alpha) plays a crucial role in tumor progression by regulating angiogenesis, cell survival and drug resistance. HIF-1alpha 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-1alpha in VEGF-C expression, lymphangiogenesis, and LVI in lymph node positive breast cancer. Lymphatic microvessel density (LMVD), LVI, HIF-1alpha 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-1alpha and VEGF-C (p = 0.026, r = 0.204, Spearman's coefficient of correlation). Further a significant association between HIF-1alpha-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-1alpha 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-1alpha as regulator of tumor-associated lymphangiogenesis in human breast cancer and emphasizes the promising status of HIF-1alpha as a therapeutical target against tumor progression and metastasis.