Article type: Research Article
Authors: Ammar, Aula | Mohammed, Rabab A.A. | Salmi, Marko | Pepper, Michael | Paish, Emma C. | Ellis, Ian O. | Martin, Stewart G.
Affiliations: Department of Clinical Oncology, University of Nottingham, Nottingham, UK | MediCity Research Laboratory, Turku University, and Department of Bacterial and Inflammatory Diseases, National Public Health Institute, Turku, Finland | Unit for Advanced Studies, University of Pretoria, Lynnwood, South Africa | Department of Histopathology, University of Nottingham, Nottingham, UK
Note: [] Current address: Department of Pathology, Faculty of Medicine, Assiut University, Assiut, Egypt.
Note: [] Corresponding author: Dr Stewart G. Martin, Department of Clinical Oncology, School of Molecular Medical Sciences, University of Nottingham, Nottingham University Hospitals NHS Trust, City Hospital Campus, Nottingham NG5 1PB, UK. Tel.: +44 0115 823 1846; Fax: +44 0115 823 1849; E-mail: [email protected]
Abstract: Background: Mechanisms regulating breast cancer lymph node metastasis are unclear. Staining of CLEVER-1 (common lymphatic endothelial and vascular endothelial receptor-1) in human breast tumors was used, along with in vitro techniques, to assess involvement in the metastatic process. Methods: 148 sections of primary invasive breast cancers, with 10 yr follow-up, were stained with anti-CLEVER-1. Leukocyte infiltration was assessed, along with involvement of specific subpopulations by staining with CD83 (mature dendritic cells, mDC), CD209 (immature DC, iDC) and CD68 (macrophage, M�). In vitro expression of CLEVER-1 on lymphatic (LEC) and blood endothelial cells (BEC) was examined by flow cytometry. Results: In vitro results showed that although both endothelial cell types express CLEVER-1, surface expression was only evident on LEC. In tumour sections CLEVER-1 was expressed in blood vessels (BV, 61.4% of samples), lymphatic vessels (LV, 18.2% of samples) and in M�/DCs (82.4% of samples). However, only CLEVER-1 expression in LV was associated with LN metastasis (p = 0.027) and with M� indices (p = 0.021). Although LV CLEVER-1 was associated with LN positivity there was no significant correlation with recurrence or overall survival, BV CLEVER-1 expression was, however, associated with increased risk of recurrence (p = 0.049). The density of inflammatory infiltrate correlated with CLEVER-1 expression in BV (p < 0.001) and LV (p = 0.004). Conclusions: The associations between CLEVER-1 expression on endothelial vessels and macrophage/leukocyte infiltration is suggestive of its regulation by inflammatory conditions in breast cancer, most likely by macrophage-associated cytokines. Its upregulation on LV, related surface expression, and association with LN metastasis suggest that it may be an important mediator of tumor cell metastasis to LN.
Keywords: Breast cancer, lymph node metastasis, CLEVER-1, lymphatic, tumor cell adhesion
DOI: 10.3233/ACP-2011-0002
Journal: Analytical Cellular Pathology, vol. 34, no. 1-2, pp. 67-78, 2011
