Expression of varying portions of the adenovirus 12 early region 1 in transformed cells affects tumorigenicity and interaction with extracellular matrix components.

Seven syngeneic rat cell lines transformed with the EcoRI-C (0 to 16.5 map units), SalI-C (0 to 10.3 map units), HindIII-G (0 to 6.8 map units), or AccI-H (0 to 4.7 map units) DNA fragments of highly oncogenic adenovirus 12 were tested for their tumorigenicity in syngeneic hosts and for their interaction with extracellular matrix components. Three of the cell lines (RFC1, EcoC-3, and SalC) were highly tumorigenic and induced tumors with a short latency period; two cell lines (HindG-2 and AccH-1) were also tumorigenic, but the latency period was significantly longer. The HindG-3 and AccH-4 cell lines were nontumorigenic. Collagen attachment preference was analyzed. All five tumorigenic cell lines showed a striking preference for type IV versus type I collagen in attachment assays. The nontumorigenic cell lines showed no preference for either type of collagen. Immunofluorescence analysis of the glycoprotein attachment factors laminin and fibronectin revealed a positive correlation between tumorigenicity, expression of the adenovirus 12 E1 region, and the amount of cell surface laminin. All of the cell lines displayed similar amounts of fibronectin on their surfaces. A similar correlation was observed with the laminin and fibronectin that was secreted into the culture medium. The highly tumorigenic cell lines secreted the greatest amount of laminin, while the nontumorigenic cell lines secreted the least. All of the cell lines secreted comparable amounts of fibronectin into the medium. The results suggest that preference for type IV collagen as well as the presence of cell surface laminin and its secretion are properties associated with expression of the E1 region of highly oncogenic adenovirus 12 in tumorigenic transformed cells.