Gains and losses of CD44 expression during breast carcinogenesis and tumour progression

Aims This study was performed to investigate whether the CD44 immunophenotype of breast lesions correlates with the clinical evolution and prognosis of breast cancer. Methods and results One-hundred and fifty-two routinely processed normal, benign and malignant breast tissue samples were investigated by the following monoclonal antibodies: CD44 s (F10–44–2), CD44v3 (3G5), CD44v4 (11.10), CD44v5 (VFF-8), CD44v6 (VFF-18), CD44v7 (VFF-9), CD44v9 (11–24) after wet autoclave pretreatment for antigen retrieval. We found that: (1) in normal breast tissues luminal epithelial cells lacked detectable CD44 in contrast to basal cells, which constitutionally expressed CD44 s, v3, v5 v6 and v9 isoforms; (2) in the intraductal compartment of benign hyperplastic lesions, there was scattered or focal staining for CD44 s, v5, v6, v7 and v9 isoforms; (3) in neoplastic lesions restricted neo-expression of CD44v3 and v4 was detected; and (4) the CD44 immunophenotype of invasive breast carcinomas was influenced largely by differentiation grade, steroid receptor status of the tumours and significantly correlated with metastatic involvement of the axillary lymph nodes. Conclusions Qualitative and quantitative changes of CD44 expression are implicated in early stages of breast carcinogenesis. The restricted neo-expression of certain CD44 isoforms in breast neoplasias suggests that CD44 might be a potential target for future antibody-based tumour therapy.