Syndecan-1 expression is diminished in acantholytic cutaneous squamous cell carcinoma

Syndecan-1 is a cell surface proteoglycan predominantly expressed on the su rface of adult epithelial cells, and is normally present in all epidermal l ayers except for the most superficial terminally differentiated cells, Synd ecan-1 mediates cell-cell and cell-extracellular matrix adhesion, thereby i nfluencing cell morphology and growth characteristics. In addition, in vitr o studies have shown that expression of syndecan-1 on tumor cells inhibits their invasion into the extracellular matrix, A total of 23 cutaneous biops ies of squamous cell carcinoma, including acantholytic squamous cell carcin oma, invasive squamous cell carcinoma which was not acantholytic, and squam ous cell carcinoma in situ were examined for syndecan-1 immunoreactivity. T he level of syndecan-1 expression was related to the degree of squamous cel l dyshesion, with expression being greatest in the in situ lesions and leas t in the acantholytic lesions. The loss of syndecan-1 expression with incre asing dyshesion of squamous cell carcinoma may be a mechanism for loosening of intercellular and cell-extracellular matrix attachments, thereby promot ing the invasion of neoplastic cells into the dermis.