CATHEPSIN-B ACTIVITY IN B-16 MELANOMA-CELLS - A POSSIBLE MARKER FOR METASTATIC POTENTIAL

  • 1 January 1982
    • journal article
    • research article
    • Vol. 42  (3) , 980-986
Abstract
In solid s.c. tumors of a variant of the murine B16 melanoma with high metastatic potential (B16F10), there was a 2- to 7-fold elevation of lysosomal cathepsin B activity when compared to the B16F1 variant with low metastatic potential. The highest activities (based on either protein or DNA) of cathepsin B were found in tumors of < 1 g. When B16F1 and B16F10 melanoma variants were grown in tissue culture, the metastatic differential in cathepsin B activity was lost as the cells were subcultured. This differential in cathepsin B activity could be restored by reestablishing the cultured cells as s.c. tumors. The activities of 4 other lysosomal enzymes (cathepsin D, .beta.-N-acetylglucosaminidase, .beta.-glucuronidase and acid phosphatase) showed little evidence of a positive correlation with the metastatic potential of the B16 melanoma variants. Eighty to 90% of cathepsin B activity was localized to a fraction containing viable tumor cells which was isolated by centrifugal elutriation. In contrast, only 50% of cathepsin D activity was in the viable tumor cell fraction, and from 30-70% of .beta.-N-acetylglucosaminidase, .beta.-glucuronidase, and acid phosphatase. Elevated levels of cathepsin B in the high metastatic B16F10 variant are consistent with the idea that cathepsin B may play a direct or a regulatory role in tumor metastasis.