Class I histone deacetylases regulate p53/NF-?B crosstalk in cancer cells.

The transcription factors NF-?B and p53 as well as their crosstalk determine the fate of tumor cells upon therapeutic interventions. Replicative stress and cytokines promote signaling cascades that lead to the co-regulation of p53 and NF-?B. Consequently, nuclear p53/NF-?B signaling complexes activate NF-?B-dependent survival genes. The 18 histone deacetylases (HDACs) are epigenetic modulators that fall into four classes (I-IV). Inhibitors of histone deacetylases (HDACi) become increasingly appreciated as anti-cancer agents. Based on their effects on p53 and NF-?B, we addressed whether clinically relevant HDACi affect the NF-?B/p53 crosstalk. The chemotherapeutics hydroxyurea, etoposide, and fludarabine halt cell cycle progression, induce DNA damage, and lead to DNA fragmentation. These agents co-induce p53 and NF-?B-dependent gene expression in cell lines from breast and colon cancer and in primary chronic lymphatic leukemia (CLL) cells. Using specific HDACi, we find that the class I subgroup of HDACs, but not the class IIb deacetylase HDAC6, are required for the hydroxyurea-induced crosstalk between p53 and NF-?B. HDACi decrease the basal and stress-induced expression of p53 and block NF-?B-regulated gene expression. We further show that class I HDACi induce senescence in pancreatic cancer cells with mutant p53.     «

The transcription factors NF-?B and p53 as well as their crosstalk determine the fate of tumor cells upon therapeutic interventions. Replicative stress and cytokines promote signaling cascades that lead to the co-regulation of p53 and NF-?B. Consequently, nuclear p53/NF-?B signaling complexes activate NF-?B-dependent survival genes. The 18 histone deacetylases (HDACs) are epigenetic modulators that fall into four classes (I-IV). Inhibitors of histone deacetylases (HDACi) become increasingly appr...     »