The expression of CD44 glycoprotein adhesion molecules in basal cell carcinomas is related to growth pattern and invasiveness

Basal cell carcinomas (BCCs) of the skin exhibit a wide range of histologic al growth patterns as well as a highly variable rate of invasiveness, A lar ge body of experimental and clinical studies supports a role for the CD44 g lycoprotein family in the latter process. In the present study, we explored the distribution and the level of expression of pan-CD44, CD44v3. CD44v5 a nd CD44v6 in BCCs. The use of paraffin sections, combined with an antigen r etrieval procedure, yielded far more detailed data than would have been pos sible with frozen sections. On average, the level of expression of the four CD44 isoforms studied appeared to differ relatively little. However, tumou rs or tumour areas consisting of thin tumour cell strands showed a signific antly stronger expression of all four isoforms than those consisting of sol id tumour cell groups. Furthermore, the highest CD44 expression was frequen tly observed in the smallest tumour cell strands in the tumour periphery In these strands, the label seemed to be located not only at the tumour cell- tumour cell interface, as in other tumour areas, but also on the tumour cel l surfaces facing the stroma, We are presently assessing the exact localiza tion of CD44 at the cellular level by immunoelectron microscopy. In most ca ses, different growth patterns with significantly different levels of CD44 expression were found side by side within individual tumours, CD44 expressi on is therefore not a static tumour cell characteristic but is correlated w ith tumour architecture and tumour-stroma interaction.