| First Author | Hiwasa T | Year | 1996 |
| Journal | J Biol Chem | Volume | 271 |
| Issue | 16 | Pages | 9181-4 |
| PubMed ID | 8621572 | Mgi Jnum | J:33449 |
| Mgi Id | MGI:80928 | Doi | 10.1074/jbc.271.16.9181 |
| Citation | Hiwasa T, et al. (1996) Synergistic induction of anchorage-independent growth of NIH3T3 mouse fibroblasts by cysteine proteinase inhibitors and a tumor promoter. J Biol Chem 271(16):9181-4 |
| abstractText | We have previously reported that Ras protein is a potent cysteine proteinase inhibitor. In order to examine whether the cysteine proteinase-inhibitory activity of Ras is involved in carcinogenesis, the effects of the following probes were investigated. Cystatin alpha is a cysteine proteinase-specific inhibitor and has some amino acid sequence homology with Ras. Ras has a CAAX motif (C, cysteine; A, aliphatic amino acid; X, any amino acid) at the carboxyl terminus, which is indispensable for the biological activity. Thus, cystatin alpha carrying a CAAX motif (cystatin alpha-CVLS) was examined. A v-Ha-Ras deletion mutant, Ras delta 42-49, has undetectable GTP binding activity, yet it retains a similar protease inhibitory activity to that of wild-type v-Ras. These genes were inserted into a eukaryotic inducible expression vector and transfected into NIH3T3 cells. The expression was effectively induced by treatment with a glucocorticoid hormone, dexamethasone. The expression of cystatin alpha-CVLS or Ras delta 42-49 alone induced neither transformation nor morphological changes. However, when their expression was induced in the presence of a tumor-promoting phorbol ester, a remarkable increase in the anchorage-independent growth was observed in cystatin alpha-CVLS- and Ras delta 42-49-transfected clones. These results suggest that cysteine proteinase inhibitors and a tumor promoter synergistically transformed NIH3T3 cells. It is thus possible that the cysteine proteinase-inhibitory activity of Ras might play a key role in the early stage of carcinogenesis. |
