Frequent loss of expression of the pro-apoptotic protein Bim in renal cell carcinoma: evidence for contribution to apoptosis resistance

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Item Type:	Article
Title:	Frequent loss of expression of the pro-apoptotic protein Bim in renal cell carcinoma: evidence for contribution to apoptosis resistance
Creators Name:	Zantl, N., Weirich, G., Zall, H., Seiffert, B.M., Fischer, S.F., Kirschnek, S., Hartmann, C., Fritsch, R.M., Gillissen, B., Daniel, P.T. and Haecker, G.
Abstract:	Renal cell carcinoma (RCC) is resistant to chemotherapy, and this resistance is mirrored by a high apoptosis resistance of many RCC lines in vitro. Here, we report the loss of the pro-apoptotic BH3-only protein Bim in a large part of clinical RCC cases and provide evidence for a functional relevance of this loss. Immunohistochemistry of clear cell renal cell carcinoma cases and corresponding normal kidney showed strong Bim reactivity in renal tubules of all cases but loss of Bim in 35 of 45 RCC samples. Out of nine RCC cell lines investigated, six showed strongly diminished or undetectable levels of Bim protein by western blotting. Four RCC lines of varying apoptosis sensitivity were analysed further. Bcl-2, Bcl-x(L), Mcl-1, Bax and Bak expression did not correlate with apoptosis sensitivity. All cell lines underwent apoptosis upon forced expression of Bax and Bim, suggesting an upstream difference. In all four lines, adriamycin induced p53 but not its targets Puma or Noxa. However, apoptosis sensitivity correlated with levels of Bim protein. Bim siRNA reduced apoptosis sensitivity in a susceptible cell line. Furthermore, inhibition of histone deacetylation restored Bim expression in cell lines. These data suggest that Bim has a function as a tumor suppressor in RCC.
Keywords:	Renal Cell Carcinoma, Apoptosis, Bim, Bcl-2, Expression, Animals, Rabbits
Source:	Oncogene
ISSN:	0950-9232
Publisher:	Nature Publishing Group
Volume:	26
Number:	49
Page Range:	7038-7048
Date:	25 October 2007
Official Publication:	https://doi.org/10.1038/sj.onc.1210510
PubMed:	View item in PubMed

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