Expression of IGF system genes during T-antigen driven pituitary tumorigenesis

Expression of IGF-I, IGF-II, the Type-I IGF receptor and six IGF binding pr oteins were examined in three different T-ag-driven mouse tumors. Unlike th e widespread expression of IGF-II in pancreatic p-cell tumors, IGF-II was n ot widely expressed in the two different pituitary tumors examined indicati ng that a mechanism independent of focal IGF-II expression can also drive T -antigen tumorigenesis. In addition, multiple IGF binding proteins were exp ressed in all three tumor types. This expression, however, was generally he terogeneous with no specific changes to indicate a required role for any IG F binding protein in T-antigen tumorigenesis.