Investigation of P120catenin Expression in Human Basal Cell Carcinoma of the Skin

Background: P120(ctn) is a specific membranous adhesion protein, that maintains the stability of intercellular junctions. An altered expression of p120(ctn), either reduced in the cell membrane or increase in the cytoplasm, plays a crucial role in carcinogenesis. No research has analysed the expression of p120(ctn) in basal cell carcinoma (BCC) of the skin so far. Therefore, we immunohistochemically studied p120(ctn) in a set of cutaneous BCCs in order to determine, whether there is difference in the expression pattern related to the histologic subtypes and tumor growth characteristics. Material and Methods: The study group consisted of 38 BCCs cathegorized into low-risk (non-infiltrative) subroup (8 superficial and 12 nodular subtypes) and high-risk (infiltrative) subgroup (10 nodular-infiltrative and 8 infiltrative subtypes). Specific monoclonal antibody against p120(ctn) was used for staining. Results: Overall, there were 12 cases (31.6%) with normal preserved and 26 cases (68.4%) with abnormal p120(ctn) expression. In superficial, nodular, nodular-infiltrative and infiltrative subtypes, abnormal p120(ctn) immunoreactivity was found in 37.5% (3/8), 41.7% (5/12), 100% (10/10) and 100% (8/8), respectively. We have confirmed a strong correlation between the expression of p120(ctn) and both given, non-infiltrative and infiltrative BCC growth phenotypes. In the latter subgroup, almost all lesions showed diffusely reduced membranous staining, of which five also manifested an aberrant immunoreactivity in the cytoplasm. This cytoplasmic positivity occurred solely at the invasive front of the infiltrative tumor formations. Conclusion: Our results showed that decreased membranous expression of p120(ctn) was a frequent event in human cutaneous BCC and it was associated with infiltrative growth phenotype. Considering that nearly half of the BCCs with non-infiltrative growth pattern also exhibited reduced membranous expression, aberrant cytoplasmic immunoreactivity of p120(ctn), which was found exclusively in the high-risk BCC variants, can more reliably reflect and predict biological behaviour and malignant potential.