Mast Cells Positive to Tryptase Correlate with Angiogenesis in Early Breast Cancer.

Abstract

Abstract Background: Literature data indicate that mast cells (MCs) are involved in tumor angiogenesis due to the release of several pro-angiogenetic factor among which tryptase, a serine protease stored in MCs granules, is one of the most active. In benign breast lesions and in primary breast cancer, tryptase-positive MCs are more numerous as compared to chymase-positive MCs. Recently, it has been demonstrated that tryptase-positive MCs are involved in angiogenesis in sentinel lymph nodes with micrometastases from patients with breast cancer. However no data has been published regarding the correlations between MCs positive to tryptase and angiogenesis in primary breast cancer tissue. In the present study, we have evaluated the correlations between the number of MCs positive to tryptase (MCDPT), the area occupied by MCs positive to tryptase (MCAPT), microvascular density (MVD) and endothelial area (EA) in a series of T1-3, N0-2, MO female breast cancer, by means of immunohistochemistry and image analysis methods.Material and Methods: Bioptic specimens were collected from 88 female breast cancer patients who had undergone breast cancer surgery. For the evaluation of MCDPT, MCAPT, MVD and EA, a three layer biotin-avidin-peroxidase system was utilized. Briefly, six-micrometers thick serial sections of formalin-fixed and paraffin-embedded bioptic tumor samples were obtained. Then sections were microwaved at 500 W for 10 min. and treated with a 3% hydrogen peroxide solution. Sections were incubated with human-specific monoclonal antibodies anti-CD34 (QB-END 10; Bio-Optica Milan, Italy) diluted 1:50 for 1h at room temperature and anti-tryptase (clone AA1; Dako, Glostrup, Denmark) diluted 1:100 for 1h at room temperature. The bound antibody was visualised using biotinylated secondary antibody, avidin-biotin peroxidase complex, and and 3-amino-9-ethylcarbazole. The five most vascularized areas ("hot spot") were selected at low magnification and both individual vessels were counted at x 400 magnification. In serial sections each single tryptase-positive MC was counted. Single brown stained endothelial cells and red MCs positive to tryptase were also evaluated in terms of immunostained area at x 400 magnification.Results: Our data demonstrated a significantly (r= ranging from 0.78 to 0.89; p: ranging from 0.001 to 0.002 by Pearson's analysis respectively) correlation between MCDPT, MCAPT, MVD, EA each to other, whereas no correlation concerning MCDPT, MCAPT, MVD, EA and the main clinical pathological features was found.Discussion: These preliminary results suggest that tryptase-positive MC play a key role in breast cancer angiogenesis and that inhibition of tryptase may be a new antiangiogenic strategy for the treatment of breast cancer. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 2159.