The Tumor Suppressor p53 and Histone Deacetylase 1 Are Antagonistic Regulators of the Cyclin-Dependent Kinase Inhibitor p21/WAF1/CIP1 Gene

Abstract

The cyclin-dependent kinase inhibitor p21/WAF1/CIP1 is an important regulator of cell cycle progression, senescence, and differentiation. Genotoxic stress leads to activation of the tumor suppressor p53 and subsequently to induction of p21 expression. Here we show that the tumor suppressor p53 cooperates with the transcription factor Sp1 in the activation of the p21 promoter, whereas histone deacetylase 1 (HDAC1) counteracts p53-induced transcription from the p21 gene. The p53 protein binds directly to the C terminus of Sp1, a domain which was previously shown to be required for the interaction with HDAC1. Induction of p53 in response to DNA-damaging agents resulted in the formation of p53-Sp1 complexes and simultaneous dissociation of HDAC1 from the C terminus of Sp1. Chromatin immunoprecipitation experiments demonstrated the association of HDAC1 with the p21 gene in proliferating cells. Genotoxic stress led to recruitment of p53, reduced binding of HDAC1, and hyperacetylation of core histones at the p21 promoter. Our findings show that the deacetylase HDAC1 acts as an antagonist of the tumor suppressor p53 in the regulation of the cyclin-dependent kinase inhibitor p21 and provide a basis for understanding the function of histone deacetylase inhibitors as antitumor drugs.The tumor suppressor p53 can induce cell cycle arrest or apoptosis in response to a variety of stress signals, such as DNA damage, oncogenic stimuli, or hypoxia (reviewed in reference 49). Activation of p53 occurs by several mechanisms including protein stabilization and modification of the protein by phosphorylation and acetylation. p53 is a transcription factor that recognizes specific binding sites within numerous target genes including mdm2, cyclin G, bax, and p21/WAF1/CIP1 (for reviews see references 5 and 12). While multiple downstream targets are involved in the mediation of apoptotic effects, the main target for p53-induced cell cycle arrest seems to be the p21 gene. p21 has been identified by virtue of its activation by p53 (13), its association with cyclin/cyclin-dependent kinase (CDK) complexes (23, 66), and its up-regulation during senescence (47). Furthermore, the p21 protein was shown previously to interact with the proliferating cell nuclear antigen (PCNA), thereby preventing DNA replication (10). Induction of p21 expression by genotoxic stress and its role during terminal differentiation of various cell types have been investigated intensively. While p21 is activated by p53-dependent mechanisms in response to DNA damage to ensure cell cycle arrest and repair, a variety of agents that promote differentiation, like phorbol ester or okadaic acid, can up-regulate p21 independently of p53 (for a review see reference 16). Similarly, the p21 gene can be activated by transforming growth factor ␤, Ca 2ϩ , lovastatin, or nerve growth factor (16).Recently, a number of reports demonstrated the induction of p21 by inhibitors of histone deacetylases (HDACs), such as sodium butyrate (46), trichostatin A (TSA) (56), suberoylanilide hydroxamic a...

R306465 is a novel potent inhibitor of class I histone deacetylases with broad-spectrum antitumoral activity against solid and haematological malignancies

“…R306465, however, was found to inhibit angiogenesis potently, presumably through its antiproliferative effects on primary human endothelial cells rather than effects on cell migration. Analysis of xenograft tumours from R306465-treated mice revealed events consistent with HDAC1 inhibition (Lagger et al, 2003). R306465 administration resulted in p21 waf1, cip1 gene activation in both the central and peripheral tumour region, pointing at a rapid distribution of the compound throughout the tumour tissue.…”

HDAC4 represses p21WAF1/Cip1 expression in human cancer cells through a Sp1-dependent, p53-independent mechanism

“…HDAC4 represses p21 WAF1/Cip1 in cancer cells in vitro in a Sp1-dependent manner Although most reports demonstrated that HDAC inhibitors induced p21 WAF1/Cip1 expression in an Sp1/Sp3-dependent manner Sowa et al, 1997Sowa et al, , 1999Han et al, 2001;Wilson et al, 2006), a role for p53 in HDAC-associated p21 WAF1/Cip1 expression has also been reported in several human cancer cell lines (Lagger et al, 2003;Luo et al, 2004;Roy et al, 2005;Zhao et al, 2006).…”

“…To date, the most common model for p21 WAF1/Cip1 repression in cancer cells is the recruitment of HDACs by Sp1/-Sp3 transcription factors in the proximal promoter region encompassing the Sp1/Sp3 binding sites, which in turn repress p21 WAF1/Cip1 transcription by deacetylating histones H3 and H4. However, a role for p53 in HDAC-associated p21 WAF1/Cip1 expression has also been reported in several human cancer cell lines (Lagger et al, 2003;Luo et al, 2004;Roy et al, 2005;Zhao et al, 2006).…”

The role of histone acetylation versus DNA damage in drug-induced senescence and apoptosis

“…14,15 As changes in chromatin conformation may affect the binding of transcription factors and repair enzymes to DNA, the possibility exists that, whether DNA is damaged or not, gene expression may not be allowed unless chromatin is in its active state. 16 Histone acetylation at the promoter region of tumor suppressor genes has been shown to induce their expression leading to the inhibition of cellular proliferation 17 often through the induction of the same antiproliferative pathways that are activated by DNA damage. 18 However, the question of whether chromatin remodeling and DNA damage occur concurrently or in response to different stress levels has not yet been adequately addressed.…”