Background. Serine proteases have important roles in tumor invasion and metastasis, and their inhibitors, serine protease inhibitors (serpins), are attractive targets for therapeutic strategies. On chromosome 18q21, there is a cluster of serpins: maspin, headpin, and squamous cell carcinoma antigen 1 (SCCA1)/SCCA2. Others and we have reported that the expression of these serpins is downregulated in head and neck squamous cell carcinoma (HNSCC) cells compared with normal squamous epithelial cells. In this study, we hypothesized that expression of SCCA1 is biologically disadvantageous to HNSCC cells. Methods. HNSCC cell lines were transfected with a mammalian expression vector with SCCA1 cDNA. In vitro proliferation, migration, or invasive potential (matrigel assay) of the transfectants were assayed. In addition, the in vivo growth and invasion was analyzed using the floor-of-mouth model of nude mice. Results. SCCA1 expression did not alter the in vitro growth rate of established HNSCC cells. However, SCCA1 expression significantly inhibited the in vitro invasion in matrigel assays. Furthermore, the in vivo growth and invasion in nude mice was also inhibited by SCCA1 expression. Conclusions. Overexpression of SCCA1 in a HNSCC cell line inhibited its invasive potential. Loss of expression of the serpin SCCA1 may play a role in the malignant progression of HNSCC.
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