Immunohistochemical detection for nuclear beta-catenin in sporadic basal cell carcinoma

Despite the increasing incidence of basal cell carcinoma (BCC), its pathogenesis has remained largely unknown. Recently, it was reported that genes involved in tissue morphogenesis, such as sonic hedgehog or patched, were found to be mutated in BCC, suggesting the involvement of those molecules in the pathogenesis of this tumour. Furthermore, there is evidence that the Wnt-mediated signalling pathway may be one of the downstream targets of sonic hedgehog-mediated signalling, which has led us to focus on molecular events on the Wnt pathway in BCC. Among the signal transducers involved in the Wnt pathway, it is clear that beta-catenin plays a pivotal role in the promotion of morphogenesis and cell growth. In respect to this, it has been reported that, in particular circumstances, as in colorectal cancers, beta-catenin migrates to the nuclei, where it exerts an ability to activate the transcription of various genes.

To investigate the cellular distribution of beta-catenin in skin tumours, in particular, in BCC.

Twenty skin biopsy specimens derived from BCC, 10 from inflammatory skin diseases and five from squamous cell carcinomas were immunostained with an antibody directed against beta-catenin.

Fourteen of the 20 BCC samples tested showed nuclear localization of beta-catenin, while none of the other samples gave rise to positive nuclear staining.

Nuclear localization of beta-catenin is a characteristic feature of BCC; this suggests its tumorigenic role in this tumour. This gives us a further insight into the molecular pathogenesis of BCC.