Cathepsin B-like proteinase as a marker for metastatic tumor cell variants

Serial transplantation of a spontaneous BDX rat tumor, classified as an anaplastic sarcoma, gives rise to two variants; a rapidly growing nonmetastatic line (AS) and a slowly growing, invasive, and highly metastatic variant (ASML). The availability of two cell lines of the same origin but with markedly differing metastatic potential offers an ideal model for the identification of the cellular properties involved in invasive and/or metastatic behavior. The present work focuses on the pattern of various proteinases in the two tumor cell variants. The findings disclosed one major consistent difference which relates to a cathepsin B-like cysteine proteinase. The metastatic ASML variant manifests exceedingly high intracellular cathepsin B-like activity; in the nonmetastatic AS variant, the activity of this proteinase is significantly lower. Other proteinases, in particular elastase-like, chymotrypsin-like, collagenase-like enzymes and plasminogen activator, showed low, essentially comparable activity patterns. Thus, cathepsin B-like proteinase is a marker enzyme of the metastatic ASML tumor cell variant.