Bcl3-dependent stabilization of CtBP1 is crucial for the inhibition of apoptosis and tumor progression in breast cancer.

Abstract

B-cell lymphoma 3 (Bcl3) is a proto-oncogene upregulated in a wide range of cancers, including breast cancer. Although Bcl3 is known to promote cell proliferation and inhibit apoptosis, the molecular mechanisms underlying the proto-oncogenic function of Bcl3 have not been completely elucidated. To gain insight into the oncogenic role of Bcl3, we applied a proteomic approach, which led to the identification of C-terminal binding protein 1 (CtBP1) as a binding partner of Bcl3. A PXDLS/R motif embedded in Bcl3 was found to mediate the interaction between Bcl3 and CtBP1, which caused the stabilization of CtBP1 by blocking proteasome-dependent degradation. Apoptotic stimuli-induced degradation of CtBP1 was significantly abolished by the upregulation of Bcl3, leading to the sustained repression of pro-apoptotic gene expression and subsequent inhibition of apoptosis. Intriguingly, a strong positive correlation between the protein levels of Bcl3 and CtBP1 was detected in breast cancer patient samples. Our study reveals a novel combinatorial role for Bcl3 and CtBP1, providing an explanation for the acquisition of resistance to apoptosis in cancer cells, which is a major requirement for cancer development.

DOI: 10.1016/j.bbrc.2010.08.084

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@article{Choi2010Bcl3dependentSO, title={Bcl3-dependent stabilization of CtBP1 is crucial for the inhibition of apoptosis and tumor progression in breast cancer.}, author={Hee June Choi and Ji Min Lee and HyunKyung Kim and Hye Jin Nam and Hi-Jai R. Shin and Dongha KimDongha Kim and Enyoung Ko and Dong-Young Noh and Keun Il Kim and Jung H. Kim and Sung Hee Baek}, journal={Biochemical and biophysical research communications}, year={2010}, volume={400 3}, pages={396-402} }