Mechanism of action of azatyrosine: recent process
Monden, Y.; Shindo-Okada, N.; Nishimura, S.
Gan to Kagaku Ryoho. Cancer and ChemoTherapy 24(11): 1563-1570
1997
ISSN/ISBN: 0385-0684 PMID: 9309155 Document Number: 477899
Azatyrosine is known to convert ras, raf or c-erbB-2-transformed NIH3T3 cells to a normal phenotype. We attempted to identify the signal-transduction process triggered by oncogenic c-ErbB-2 that was inhibited by azatyrosine. Azatyrosine did not suppress activation of Ras induced by introduction of c-ErbB-2. However, it inhibited increases in phosphorylation of c-Raf-1 induced by oncogenic c-ErbB-2. Furthermore, azatyrosine inhibited activation of the 12-O-tetradecanoylphorbol-13-acetate (TPA) response element in response to stimulation by oncogenic c-ErbB-2. These results suggest that this agent acts downstream of Ras in signal transduction from oncogenic c-ErbB-2 to nuclear factors. Moreover, we found that azatyrosine was incorporated into proteins instead of tyrosine. The simultaneous presence of a high concentration of tyrosine inhibited the conversion to a normal phenotype of transformed cells by azatyrosine. These results strongly suggest that incorporation of azatyrosine into proteins might convert the transformed cells in to cells with a normal phenotype.