Expression of Sialyl Lewis X, Sialyl Lewis a, E-Cadherin and Cathepsin-D in Human Breast Cancer: Immunohistochemical Analysis in Mammary Carcinoma In Situ, Invasive Carcinomas and their Lymph Node Metastasis

Abstract

Objective: Breast cancer cells can invade and generate metastasis via either lymphatic or blood vessels. Sialyl Lewis X (SLe^X) and Sialyl Lewis a (SLe^a) are carbohydrate molecules that mediate the adhesion between tumor cells and the endothelium. These antigens are not expressed on normal breast tissue. Overexpression of SLe^X and SLe^a is combined with poor prognosis and malignant relapse. E-cadherin mediates tumor cell-tumor cell adhesion. Partial or complete loss of E-cadherin expression has also been found to correlate with poor prognosis in breast cancer patients. Another factor involved in metastasis is Cathepsin-D, a lysosomal protease. Cathepsin-D plays a role in cell proliferation and inhibition of tumor cell adhesion. In this study, we analysed the combined expression of SLe^X, SLe^a, Cathepsin-D and E-cadherin in breast carcinoma in situ, invasive carcinomas without metastasis and invasive carcinomas with lymph node metastasis. Materials and Methods: Slides of paraffin-embedded tissue of carcinoma in situ (8 DCIS, 2 CLIS), invasive carcinomas without metastasis (9 ductal, 1 lobular) and carcinomas (7 ductal, 2 lobular, 1 mucinous) with their lymph node metastasis (10 cases) were used. Breast cancer tissue was fixed and incubated with monoclonal antibodies against SLe^X (IgM) and SLe^a (IgM), Cathepsin-D (IgG) and E-cadherin (IgG). Staining reaction was performed with the ABC reagent. The intensity of immunohistochemical reaction on digital images of the slides was analyzed using a computeraided detection system. Results: We found a weak expression of both Sialyl Lewis antigens, a strong expression of E-cadherin and a moderate expression of Cathepsin-D in carcinoma in situ. The expression of both Sialyl Lewis antigens, E-cadherin and Cathepsin-D was moderate in invasive carcinomas without metastases. However, a strong expression of both Sialyl Lewis antigens and a very weak expression of E-cadherin was detected in primary carcinoma with lymph node metastases. The expression of Cathepsin-D was moderate in this tissue. E-cadherin expression was elevated whereas SLe^X and Cathepsin-D expression was reduced in lymph node metastases compared to the primary tumor. Conclusion: Combined analysis of tumor antigens involved in adhesion of breast cancer cells showed a negative correlation between Sialyl Lewis antigens and E-cadherin as the risk of metastasis progresses. Furthermore, there were significant differences of expression of the Sialyl Lewis antigens, E-cadherin and Cathepsin-D in primary breast cancer cells and their metastases. Evaluation of a panel of markers involved in cell adhesion could be a useful method for defining the metastatic risk in breast cancer patients.