Objective: To identify changes associated with P-cadherin expression in bladder cancer and evaluate the potential role of such events in determining the clinical outcome and cell behaviour, as the function of P-cadherin in normal epithelium is unknown, as is its potential role in neoplastic progression in different cancers.
Materials and methods: In all, 536 bladder tumour specimens from 408 patients were assembled in seven tissue microarrays. Paraffin sections from each array were processed for immunohistochemistry to assess the expression of P-cadherin. The expression of P-cadherin was forced using lipofectin, followed by an assessment of migration and invasion potential using standard in vitro assays.
Results: The absence of P-cadherin staining was associated with muscle-invasive disease, grade 3 (P < 0.001) and nodal disease (P = 0.009). Similar results were obtained when considering cytoplasmic and unrestricted localization of P-cadherin (P < 0.001), except for nodal involvement. The group with cytoplasmic location of P-cadherin showed a shorter cancer-specific survival than the group with membrane location of P-cadherin (P = 0.03). Forced expression of P-cadherin in EJ and UM-UC-3 cells, that constitutively lack P-cadherin expression, resulted in modulation of catenin expression and enhanced migration of EJ and UM-UC-3/P-cadherin transfectants (>200%).
Conclusions: These results showed that loss of expression, cytoplasmic relocation or unrestricted tissue location of P-cadherin was associated with a poor clinical outcome and prognosis in bladder cancer. From the in vitro work it is evident that P-cadherin plays a role in regulating the migration potential of bladder carcinoma cells.