Expression of the CD44 cell adhesion molecule in urinary bladder transitional cell carcinoma

CD44 cell adhesion molecule (PgP-1, ECM III, Hermes antigen) is a polymorphic integral membrane glycoprotein associated with cell matrix adhesion, lymphocyte activation, recirculation, and homing. CD44 expression has been reported in in malignant lymphoma and in a variety of epithelial human cancers but has not been studied as a prognostic marker in urinary bladder transitional cell carcinoma. CD44s (standard 85- to 95-kDa macromolecule) expression was measured by qualitative and image analysis-quantitated immunohistochemical techniques using the A3D8 monoclonal antibody. CD44v6 (a splice variant exon of CD44s) expression was measured by qualitative immunohistochemical techniques using the 2F10 monoclonal antibody. The results of CD44s and CD44v6 expression were compared with tumor grade, pathologic stage, and DNA content analysis on Feulgen-stained tissue sections in 44 cases of urinary bladder transitional cell carcinoma. The mean percentage-positive area of staining intensity for CD44s expression in Grade 1 tumors was 61%, compared with 30% for the Grade 3 tumors (P < 0.001). Non-invasive tumors featured a 59%-positive area of staining intensity, compared with the 30% staining percentage for the deeply invasive tumors (P < 0.001). There was significant correlation of aneuploid DNA content with loss of CD44s staining (P < 0.05). The staining results for CD44v6 paralleled those for the CD44s, with a significant loss of staining in high-grade and high-stage aggressive tumors in comparison with the low-grade nonaggressive tumors (P < 0.01). In urinary bladder transitional cell carcinoma, CD44s and CD44v6 expression parallels that for other cell adhesion molecules, such as E-cadherin, that feature a significant progressive loss of immunoreactivity in association with tumor dedifferentiation, advancing pathologic stage, and abnormal DNA content.