Expression of cell adhesion molecules, CD44s and E-cadherin, in infiltrating micropapillary versus tubular carcinomas of the breast

In contrast to the tow metastatic potential of tubular carcinoma, infiltrating micropapillary carcinoma of the breast has been associated with an extremely high incidence of metastases. The mechanism underlining this discrepancy in biological behavior is not well understood. Loss of intercellular adhesion molecules scuh as CD44 and E-cadherin has been correlated with a greater potential for invasion and metastatic spread. This study investigates the relationship between the expression of CD44s and E-cadherin and the metastatic potential of these two types of invasive breast cancer. Methods: Immunohistochemical studies were performed on formalin-fixed, paraffin-embedded archival tissue of 21 infiltrating tubular and 2.1 micropapillary carcinomas with monoclonal antibodies against the standard form of CD44 (CD44s, Dako) and E-cadherin (Zymed). A standard avidin-biotin-peroxidase method was used with prior antigen retrieval (microwave). Immunohistochemical reaction was scored as negative or positive. Results: Comparison of CD44s staining showed a significant difference in positivity between micropapillary carcinomas (14/23) and tubular carcinomas (20/21) (p<0.01). Tumors lacking CD44s expression were more frequently progesterone receptor negative or CerbB2 positive, although not statistically significant (p@0.06). All the infiltrating micropapillary carcinomas as well as tubular carcinomas demonstrated strong expression of E-cadherin. Conclusion: Loss of CD44s expression is associated with infiltrating micropapillary carcinoma but not tubular carcinoma, suggesting that it may play an important role in the metastatic potential of micropapillary carcinoma. On the contrary. E-cadherin is unlikely to be involved in such a process since no difference in expression is seen in these two types of carcinomas.