Expression of the CD44 glycoprotein (lymphocyte-homing receptor) in untreated human breast cancer and its relationship to prognostic markers.

CD44 is a cell surface glycoprotein which has been suggested to be associated with aggressive histological features in breast cancer (BC). It has also been implicated in conferring metastatic potential to rat carcinoma cells. The aim of this study was to determine the potential value of CD44 as a prognostic/metastatic marker in BC by means of immunohistochemistry. The expression of the CD44 glycoprotein was investigated in tumours from 52 untreated female patients with BC, using the monoclonal antibody A3D8. 10 samples of normal breast tissue were randomly obtained and also investigated with respect to CD44 expression. DNA ploidy, the S-phase fraction (SPF) and oestrogen-(OR) and progesterone-receptor (PgR) contents in the tumours were determined and together with the prognostic markers of age, tumour size, tumour grade and lymph node status, correlated with CD44 expression in BC. Also, the distribution of CD44 tumour cell expression was compared with expression of the permeability drug resistance glycoprotein (P-gp) in this material. Expression of CD44 on carcinoma cells was observed in 21/52 cases (40%). Capillary endothelial reactivity of the tumours occurred in 42 cases (80%). Non-neoplastic epithelial breast tissue was positive in 2/10 (20%) samples and capillary vessels in 7/10 (70%). Carcinoma CD44 cell expression was not associated with age, tumour size, tumour grade, DNA ploidy, SPF, hormone-receptor contents or lymph node metastases. There was a statistical correlation between CD44 and P-gp expression in breast carcinoma cells which may suggest a connection between adhesion molecules and drug resistance. These findings do not support an association between CD44 expression and adverse prognostic features or lymph node metastases in BC. Capillary CD44 staining was a common feature in BC. There appeared to be an upward regulation in CD44 expression in BC compared with the normal breast tissue.