Antiproliferative and proapoptotic activities of 4-hydroxybenzoic acid-based inhibitors of histone deacetylases Carole Seidel a , Michael Schnekenburger a , Mario Dicato a , Marc Diederich a,b,⇑ a Laboratoire de Biologie Moléculaire et Cellulaire du Cancer, Hôpital Kirchberg, 9, rue Edward Steichen, L-2540 Luxembourg, Luxembourg b Department of Pharmacy, College of Pharmacy, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul 151-742, Republic of Korea article info Article history: Received 13 July 2013 Received in revised form 14 September 2013 Accepted 23 September 2013 Keywords: Acetylation HDAC inhibitor Cell cycle arrest Apoptosis Leukemia Cancer abstract Histone acetyltransferases (HATs) and histone deacetylases (HDACs) regulate cellular processes by mod- ifying the acetylation status of many proteins. Pathologically altered HDAC activity contributes to cancer development and thus characterization of novel acetylation modulators is important for future anti-can- cer therapies. In this study, we identified three novel 4-hydroxybenzoic acid derivatives as pan-HDAC inhibitors that increased protein acetylation levels, arrested cell cycle progression and triggered apoptotic cell death, without affecting viability of normal cells. Our data support the potential of 4-hydroxybenzoic acid deriv- atives as pan-HDAC inhibitors with anticancer properties. Ó 2013 Elsevier Ireland Ltd. All rights reserved. 1. Introduction Lysine acetylation is a major post-translational modification regulating function, activity, subcellular localization and protein- protein interaction. Histone acetylation controls gene expression together with other histone modifications and epigenetic mecha- nisms including DNA methylation. Enzymes responsible for addi- tion and removal of histone acetylation were identified as histone acetyltransferases (HATs) and histone deacetylases (HDACs), respectively [6]. As altered acetylation profiles were associated to tumor devel- opment, HDACs became an interesting target for anticancer ther- apy [8,22,27]. HDAC family comprises 18 members, subdivided in four classes (Class I: HDACs 1, 2, 3 and 8; class II: HDACs 4, 5, 6, 7, 9 and 10; class IV: HDAC11; class III, also called sirtuins (SIRT): SIRT1 to 7) based on activity, sequence similarity and cellular localization. To date, numerous proteins were reported as HDAC targets: Class I HDACs maintain proliferation and survival of cancer cells by inhibiting p53 or p21 expression [33]. HDAC5 and 9 repress transcriptional activity of myocyte enhancer factor 2 (MEF2) and Yin Yang 1 (YY1) that prevent cardiac hypertrophy [4,30]. HDAC6 deacetylates a-tubulin and cortactin, which contribute to the poly- merization of microtubule and actin filaments, thus affecting cellu- lar mobility and division [12,35]. Inhibition of HDAC activity became an interesting therapeutic target for patients relapsing or refractory to classical chemother- apy [8,22,27]. HDAC inhibitors (HDACi) lead to hyper-acetylation of histone and non-histone proteins inducing differentiation, inhi- bition of cell cycle progression and/or apoptotic cell death. HDACi target many cancer cell models with moderate effects on normal cells [9,28]. HDACi inhibit aberrant cell cycle progression by induc- ing cyclin-dependent kinase inhibitor 1A (CDKN1A, p21) and by inhibiting cyclin E [7,11,20]. In addition, HDACi induce cell death by inducing or inhibiting transcription of pro-apoptotic (e.g. Bim) or anti-apoptotic (e.g. survivin) proteins [3,34]. Accordingly, over the last decades, numerous natural and syn- thetic HDACi were identified. So far, Food and Drug Administration approved Vorinostat (suberoylanilide hydroxamic acid, SAHA) against zinc-dependent HDACs and Romidepsin (FK228, FR901228) against class I HDACs for the treatment of cutaneous T-cell lymphoma [10,21]. However, improved HDACi are required for increased specificity and reduced side effects. Here, we describe novel 4-hydroxybenzoic acid (4-HBA)-based compounds with HDAC inhibitory properties. Biological activities on proliferation, cell cycle progression and apoptotic cell death were characterized in both normal and cancer cells. 0304-3835/$ - see front matter Ó 2013 Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.canlet.2013.09.026 ⇑ Corresponding author. Address: Department of Pharmacy, College of Pharmacy, Seoul National University, Building 20, Room 303, 599 Gwanak-ro, Gwanak-gu, Seoul 151-742, Republic of Korea. Tel.: +82 2 880 8919. E-mail address: marcdiederich@snu.ac.kr (M. Diederich). Cancer Letters 343 (2014) 134–146 Contents lists available at ScienceDirect Cancer Letters journal homepage: www.elsevier.com/locate/canlet