Relationships between heparanase activity and increasing metastatic potential of fibroblasts transfected with various oncogenes

Abstract

We have examined the effects of transformation by activated H-ras and other transforming oncogenes on the activity of the enzyme, heparanase. Degradation of 3H-N-acetylated-partially N-desulfated heparan sulfate by cellular extracts of the transformants was assessed by gel permation chromatography. More extensive degradation was observed with 10T 1 2 mouse embryo fibroblasts transfected with an activated H-ras oncogene. The cells having the highest metastatic potential (CIRAS-3) were shown to contain the greatest heparanase activity, giving 49% higher levels of activity than parental cells (P < 0.0002). Furthermore, the enzyme activity produced by a series of H-ras transformed cell lines increased progressively with metastatic potential (non-parametric rank correlation coefficient r = 0.96). Transfection of NIH 3T3 fibroblasts with activated H-ras, v-src or v-fes oncogenes, which induced the metastatic phenotype, did not lead to large increases in heparanase activities. Also, inhibition of rasinduced malignancy by cotransfection of rat REF cells with the Ad2 E1a oncogene did not produce significant declines in heparanase activities. These results are consistent with the view that modifications in heparanase activity can play a role in the complex process of metastasis in some, but not all situations.