Decreased expression of CD80 is a marker for increased tumorigenicity ln anew murine model of oral squamous-cell carcinoma

We established a new syngeneic murine model of oral squamous-cell carcinoma (SCC) to analyze the potential role of immune recognition determinants in the early development of oral cancer. In this study, we examined whether SC C that undergo transformation and development in the absence of specific im munity exhibit differences in tumorigenicity that relate to differences in expression of CD80, CD86 or MHC class I. Mucosal keratinocytes from BALB/c mice were transformed in vitro with 4-nitroquinolone-1-oxide (4-NQO) and in oculated into SCID mice to obtain tumorigenic cell lines. Five SCC cell lin es were re-isolated from tumors, and 4 retained cytokeratin and beta 4-inte grin markers of epithelial origin. Their growth was compared in BALB/c and in congenic SCID mice to establish whether the cell lines exhibit differenc es in immunogenicity. Three lines that showed slower growth or completely r egressed when implanted in immune competent hosts retained or developed inc reased expression of CD80 during development in SCID mice. Conversely, 2 SC C lines that lost expression of CD80 after passage in vivo grew progressive ly in immune-competent hosts. MHC-class-l and CD86 expression did not corre late with tumorigenicity. These observations provide evidence that decrease d expression of CD80 may serve as a marker for increased tumorigenicity dur ing early development of oral SCC. The development of this new murine oral SCC model should prove useful in determining the potential effects of CD80 expression on the immune pathogenesis and therapy of SCC. Int. J. Cancer 82 :377-384, 1999. (C) 1999 Wiley-Liss, Inc.