Cell discohesion and multifocality of carcinoma in situ of the bladder: new insight from the adhesion molecule profile (e-cadherin, Ep-CAM, and MUC1).

Urothelial cell carcinoma in situ (CIS) of the bladder is a superficially diffusive and highly discohesive disease. The authors analyzed the expression of some adhesion molecules (e-cadherin and Ep-CAM) and MUC1 in 32 unifocal and multifocal bladder urothelial cell CIS in an attempt to clarify this discohesion. E-cadherin was strongly expressed, in more than 75% of the cases. The presence of methylation of the CDH1 e-cadherin promoter gene was also investigated, but methylation was found in only one case. Ep-CAM was present in all the cases with a heterogeneous staining pattern. Similarly, MUC1/episialin was variously present in 94% of the cases without a polarized staining pattern and was expressed more strongly in cases with multifocal disease. Because loss of MUC1 polarization leads to interference with cell-cell adhesion mechanisms mediated by cadherins, these findings help explain why bladder urothelial cell CIS often shows a discohesive morphology and multifocality despite a strongly expressed adhesion molecule profile. Finally, Ep-CAM expression might provide some support for future target therapy trials.