Epithelial and stromal syndecan-1 and -2 are distinctly expressed in oral- and cutaneous squamous cell carcinomas

Oral squamous cell carcinoma (OSCC) and cutaneous squamous cell carcinoma (CSCC) are epithelial neoplasms of which OSCC has worse survival and higher risk of metastasis than CSCC. The aim of this study was to explore the differences of immunoexpressions between syndecan-1 and -2 in OSCC and head and neck CSCC.

A total of 35 patients diagnosed with OSCC and 25 with CSCC, presented T1 and T2 tumors and treated at Helsinki University Central Hospital between years 2001 and 2009, were selected into this study. The levels and locations of syndecan-1 and -2 immunostainings were analyzed using formalin-fixed and paraffin-embedded tissue samples of OSCC and CSCC cases together with clinical data.

Cell membrane epithelial syndecan-1 expression decreased significantly compared to normal tissue in both cancer types. Cell membrane syndecan-1 expression in the invasive front had negative correlation with invasion depth of both tumors (OSCC, r = -0.339, P = 0.025; CSCC, r = -0.469, P = 0.004). In cancers over 4-mm invasion depth, the number of stromal syndecan-1-positive collagen fibers and inflammatory cells were higher in OSCC than in CSCC. Syndecan-2 expression in non-malignant stroma was higher in CSCC than in OSCC tumors. In addition, unlike syndecan-1, syndecan-2 was more often and more intensively expressed in the tumor inflammatory cells in CSCC than in OSCC.

Our results suggest that variable stromal expression of syndecan-1 and -2 in OSCC compared to CSCC may at least partially explain the differences in their clinical behavior.