Ornithine Decarboxylase- and ras-Induced Cell Transformations: Reversal by Protein Tyrosine Kinase Inhibitors and Role of pp130^CAS

Abstract

We have found that overexpression of human ornithine decarboxylase (ODC) induces cell transformation in NIH 3T3 and Rat-1 cells (M. Auvinen, A. Paasinen, L. C. Andersson, and E. Hölttä, Nature (London) 360:355-358, 1992). The ODC-transformed cells display increased levels of tyrosine phosphorylation, in particular of a cluster of 130-kDa proteins. Here we show that one of the proteins with enhanced levels of tyrosine phosphorylation in ODC-overexpressing cells is the previously described p130 substrate of pp60v-src, known to associate also with v-Crk and designated p130CAS. We also studied the role of protein tyrosine phosphorylation in the ODC-induced cell transformation by exposing the cells to herbimycin A, a potent inhibitor of Src-family kinases, and to other inhibitors of protein tyrosine kinases. Treatment with the inhibitors reversed the phenotype of ODC-transformed cells to normal, with an organized, filamentous actin cytoskeleton. Coincidentally, the tyrosine hyperphosphorylation of p130 was markedly reduced, while the level of activity of ODC remained highly elevated. A similar reduction in pp130 phosphorylation and reversion of morphology by herbimycin A were observed in v-src- and c-Ha-ras-transformed cells. In addition, we show that expression of antisense mRNA for p130CAS resulted in reversion of the transformed phenotype of all these cell lines. An increased level of tyrosine kinase activity, not caused by c-Src or c-Abl, was further detected in the cytoplasmic fraction of ODC-transformed cells. Preliminary characteristics of this kinase are shown. These data indicate that p130CAS is involved in cell transformation by ODC, c-ras, and v-src oncogenes, raise the intriguing possibility that p130CAS may be generally required for transformation, and imply that there is at least one protein tyrosine kinase downstream of ODC that is instrumental for cell transformation.

Altered regulation of Src tyrosine kinase by transforming growth factor ?1 in a human hepatoma cell line

“…4). Pretreatment with 0.5 µg/mL of herbimycin A, a potent inhibitor of protein tyrosine kinases, particularly of the Src family, [32][33][34] decreased Src kinase activity below detectable levels and inhibited tyrosine phosphorylation of these 120-to 130-kd proteins in TGF-␤ 1 -treated Mahlavu cells (data not shown).…”

Anti-tumor activity of antizyme which targets the ornithine decarboxylase (ODC) required for cell growth and transformation

“…ODC also has been shown to be a critical component in cell transformation (Auvinen et al, 1992;Moshier et al, 1993). More recent work has shown that ODC expression induces enhanced level of tyrosine phosphorylation, in particular of p130 cas (Auvinen et al, 1995), suggesting that there is a protein tyrosine kinase(s) acting downstream of ODC either dependent or independent of its catalytic activity. The elevation of cellular polyamine levels induces antizyme production by a unique translational frameshifting mechanism (Rom and Matsufuji et al, 1995.…”

“…It is also notable that c-myc and c-fos proto-oncogenes have been found to be transcriptional activators of ODC (Bello et al, 1993;Wrighton et al, 1993). More recently, it was reported that ODC expression induces an enhanced level of tyrosine phosphorylation, in particular of p130 cas (Auvinen et al, 1995), suggesting that there is a protein tyrosine kinase(s) acting downstream of ODC either dependent or independent of its catalytic activity. Thus, ODC and polyamines appear to play pivotal functions in the cellular signaling pathway for cell growth.…”

Functions of the adapter protein Cas: signal convergence and the determination of cellular responses

“…The ability of activated Src to induce morphological transformation and anchorage-independent growth was restored when wild type Cas was ectopically expressed in the Cas-null cells. Furthermore, Auvinen et al (1995) demonstrated that expression of antisense Cas constructs could partially reverse cellular transformation induced by ornithine decarboxylase, Ha-Ras and v-Src, indicating that Cas plays a direct role in cellular transformation.…”

“…Multiple proapoptotic stimuli have been shown to induce Cas cleavage, including Eschericia coli lipopolysaccharide (LPS), nocodazole, etoposide, adenosine and UV irradiation (Bannerman et al, 1998;Chan et al, 1999;Harrington et al, 2001;Kook et al, 2000a,b). Cas dephosphorylation, Cas cleavage and apoptosis are also induced by overexpression of the receptor-like PTPase LAR (Weng et al, 1999).…”