Enhanced levels of cathepsin B mRNA in murine tumors

Abstract
Relative amounts of mRNA for cathepsin B were measured in normal murine liver and three murine tumors, an invasive liver tumor (hepatoma, Hepa cl 9) and two melanoma variants (B16‐F1 and B16 amelanotic melanoma, B16a). Using a human cDNA to the cathepsin B coding region as a hybridization probe, we detected two species of cathepsin B specific RNA transcripts (2.2 and 4.1 kb) in total RNA preparation of all four tissues. The concentrations of the 2.2 and 4.1 kb species were 3.6 and 2.7‐fold greater in the highly metastatic B16a melanoma than in normal liver. The concentration of the 2.2 kb species in the invasive hepatoma wa 1.7‐fold greater than in normal liver. The increased levels of the 2.2 kb message were reflected in increases in activity of cathepsin B in both Hepa cl 9 and B16a.