[Cathepsins L and B and their endogenous inhibitors in embryonal fibroblasts transformed by different genes]

Expression of cysteine proteinases, cathepsins L and B, and their inhibitors was studied out in three model systems of rat embryo fibroblasts, sequentially immortalized and transformed by different genes. In Model I rat embryo fibroblasts were immortalized with DNA of early region of simian adenovirus SA7 (clone REF-1) and then transformed by c-Ha-ras oncogene (REF-2EJ; malignant transformation). In Model II and III, the immortalized fibroblasts (clone IE5) were obtained by transfection with the polyoma virus LT gene and the clone IE5 used lost this gene; the malignant transformation was achieved by transfection with the E7 gene (clone trF8; Model II) and E6/E7 genes ¿clone A5E5(pC7-1); Model III]¿ of human papilloma virus types 16 and 18 respectively. In Model I, the increase in the total cathepsin L and B activity was correlated with the stages of transformation, at the same time, in Models II and III, this activity in immortalized IE5 fibroblasts was higher than at transformation stage. The activity of cathepsin L in lysates of transformed fibroblasts--REF-2EJ, significantly exceeded this activity both in transformed cells trF8 and A5E5(pC7-1)(6- and 10-fold, respectively). In cell cultures of Models I and II, the increases in secreted activity of cathepsins L and B were correlated with the stages of fibroblasts transformation, but in cultures of Model III, this activity at the stage of malignant transformation was lower than that the stage of immortalization. Therefore, the activities of cathepsins L and B were expressed to varying degrees at different stages of oncogenic transformation and the expression of their activities were dependent on type of transforming gene. It was established that changes in proteolytic potential were correlated with differences in the transforming phenotype of cell clones. An endogenous inhibitor(s) of cysteine proteinases was found in conditioned media of all type cell cultures. Expression and inhibitory properties of this inhibitor(s) were different at distinct stages of transformation.