α-Tocopheryl succinate inhibits malignant mesothelioma by disrupting the Fibroblast Growth Factor Autocrine Loop: Mechanism and the role of oxidative stress
MetadataShow full item record
We have studied the potential effect against human malignant mesotheliomas (MM) of a-tocopheryl succinate (a-TOS), a redox-silent vitamin E analog with strong pro-apoptotic and anti-cancer activity. a-TOS at sub-apoptotic levels inhibited proliferation of MM cell lines, while being nontoxic to nonmalignant mesothelial cells. Because MM cells are typified by a highly metastatic phenotype, we investigated the effect of a-TOS on genes playing a major role in MM progression. Of these, a-TOS down regulated fibroblast growth factor (FGF)-1 and, in particular, FGF-2 on the transcriptional level in MM cells, and this was not observed in their nonmalignant counterparts. FGF-2 short interfering RNA suppressed proliferation of MM cells. Down-regulation of FGF-2 was likely because of inhibition of the egr-1 transcription activity that was decreased in MM cells via oxidative stress induced by a-TOS, as evidenced by EPR spectroscopy, whereas nonmalignant cells did not show this response. Treatment of MM cells with egr-1 short interfering RNA suppressed proliferation, which was overridden by exogenously added recombinant FGF-1 and, in particular, FGF-2. An analog of coenzyme Q targeted to mitochondria and superoxide dismutase overrode inhibition ofMMcell proliferation by a-TOS as well as a-TOS-induced inhibition of egr-1-dependent transactivation. Finally, a-TOS significantly suppressed experimental MM in immunocompromised mice. Our data suggest that a-TOS suppresses MM cell proliferation by disrupting the FGF-FGF receptor autocrine signaling loop by generating oxidative stress and point to the agent as a selective drug against thus far fatal mesotheliomas.
Journal of Biological Chemistry
© 2005 American Society for Biochemistry and Molecular Biology. Reproduced in accordance with the copyright policy of the publisher. This journal is available online, use hypertext links.