PDF《Oncogene (2009) 28, 243–256》

ORIGINAL ARTICLE HDAC4 represses p21WAF1/Cip1 expression in human cancer cells through a Sp1-dependent, p53-independent mechanism D Mottet1,2 , S Pirotte1 , V Lamour1 , M Hagedorn3 , S Javerzat3 , A Bikfalvi3 , A Bellahce ` ne1 , E Verdin2 and V Castronovo1

1 Metastasis Research Laboratory, GIGA-Cancer (Center for Experimental Cancer Research), University of Lie `ge, Lie `ge, Belgium;

2 Gladstone Institute of Virology and Immunology, University of California, San Francisco, CA, USA and

3 ELAT (European Laboratory for Angiogenesis and Translational Research), Institut National de la Sante ? et de la Recherche Me ?dical INSERM U920 (ex E0113), University of Bordeaux I, Talence, France Cancer cells have complex, unique characteristics that distinguish them from normal cells, such as increased growth rates and evasion of anti-proliferative signals.

Global inhibition of class I and II histone deacetylases (HDACs) stops cancer cell proliferation in vitro and has proven effective against cancer in clinical trials, at least in part, through transcriptional reactivation of the p21WAF1/Cip1 gene. The HDACs that regulate p21WAF1/Cip1 are not fully identi?ed. Using small interfering RNAs, we found that HDAC4 participates in the repression of p21WAF1/Cip1 through Sp1/Sp3-, but not p53-binding sites. HDAC4 interacts with Sp1, binds and reduces histone H3 acetylation at the Sp1/Sp3 binding site-rich p21WAF1/Cip1 proximal promoter, suggesting a key role for Sp1 in HDAC4-mediated repression of p21WAF1/Cip1 . Induction of p21WAF1/Cip1 mediated by silencing of HDAC4 arrested cancer cell growth in vitro and inhibited tumor growth in an in vivo human glioblastoma model. Thus, HDAC4 could be a useful target for new anti-cancer therapies based on selective inhibition of speci?c HDACs. Oncogene (2009) 28, 243C256;

doi:10.1038/onc.2008.371;

published online

13 October

2008 Keywords: histone deacetylase;

p21WAF1/Cip1 ;

Sp1;

siRNA;

cancer Introduction Histone deacetylases (HDACs) regulate gene transcrip- tion by modifying the acetylation level of histones and non-histone proteins such as transcription factors. Mammalian HDACs are usually subdivided into three classes based on their similarity to yeast HDACs. Class I members (HDAC1, 2, 3,

8 and 11) are homologous to the yeast RPD3 protein. Class II HDACs (HDAC4, 5, 6, 7,

9 and 10) have similarities to yeast HDA1. The third class, the sirtuin proteins, are homologous to the yeast SIR2 protein, require nicotinamide adenine dinucleotide as a cofactor and are insensitive to HDAC inhibitors (de Ruijter et al., 2003;

Glozak et al., 2005;

Hildmann et al., 2007;

Yang and Seto, 2008). Global inhibition of HDAC activity has anti-tumor effects in vitro, and numerous HDAC inhibitors are being tested in clinical trials. The recent FDA approval of SAHA (Zolinza) for treatment of cutaneous T-cell lymphoma (Duvic and Vu, 2007a, b) validates the concept of HDAC inhibition in the treatment of cancer. HDAC inhibitors exert multiple and desirable anti- cancer effects by modulating the expression of the subset of genes involved in the inhibition of tumor cell proliferation, and differentiation, induction of apoptosis and inhibition of angiogenesis (Marks et al., 2004;

McLaughlin and La Thangue, 2004;

Acharya et al., 2005;

Kelly and Marks, 2005;

Bolden et al., 2006;

Minucci and Pelicci, 2006;

Dokmanovic et al., 2007;

Rasheed et al., 2007;

Xu et al., 2007). Among the genes that are consistently upregulated in cancer cells treated with HDAC inhibitors is the cell cycle mediator p21WAF1/Cip1 (Nakano et al., 1997;