ISOLATION OF TISSUE-TYPE PLASMINOGEN-ACTIVATOR, CATHEPSIN-H, AND NONSPECIFIC CROSS-REACTING ANTIGEN FROM SK-PC-1 PANCREAS CANCER-CELLS USING SUBTRACTIVE HYBRIDIZATION

We have used subtractive hybridization to isolate cDNAs overexpressed in SK-PC-1 pancreas cancer cells. Forty-five independent clones corres ponding to 11 genes were identified. Their expression in cultured panc reas cancer cells, normal pancreas tissue, and normal exocrine pancrea s cultures was examined by Northern blotting. cDNA clones can be group ed into two broad categories: (1) those corresponding to genes express ed at high levels both in tumor cell lines and in primary cultures of normal pancreas, but not in normal tissue (i.e. thymosin beta 4(3), cy tokeratin 18, beta-actin, pyruvate kinase and mitochondrial genes); an d (2) those corresponding to genes expressed at high levels in pancrea s cancer cultures hut not in normal pancreas tissue or cultured cells (i.e. tissue-type plasminogen activator and cathepsin H). The overexpr ession of these proteases in pancreas cancers suggests that they play a role in the aggressive biological behavior of this tumor.