Sen T, Sen N, Huang Y, Sinha D, Luo ZG, Ratovitski E, Sidransky D

Tumor protein (TP)-p53 family members often play pro-apoptotic roles, while nuclear factor kappaB (NF-κB) functions as a pro-apoptotic and anti-apoptotic regulator depending of cellular environment. We previously showed that the NF-κΒ activation leads to the reduction of the TP63 isoform, ΔNp63α, thereby rendering the cells susceptible to cell death upon ...

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DNA damage. However, the functional relationship between TP63 isotypes and NF-κB is poorly understood. Here, we report that the TAp63 regulates NF-κB transcription and protein stability subsequently leading to the cell death phenotype. We found that TAp63α induced the expression of the p63 subunit of NF-κB (RELA), and target genes involved in cell cycle arrest or apoptosis, thereby triggering cell death pathways in MCF10A cells. RELA was shown to concomitantly modulate specific cell survival pathways, making it indispensable for the TAp63α-dependent regulation of cell death. We showed that TAp63α and RELA formed protein complexes resulted in their mutual stabilization, and inhibition of the RELA ubiquitination. Finally, we showed that TAp63α directly induced RelA transcription by binding to and activating of its promoter and, in turn, leading to activation of the NF-κB-dependent cell death genes. Overall our data defined the regulatory feedback loop between TAp63α and NF-κB involved in the activation of cell death process of cancer cells.

Date: Oct. 20, 2011

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