Cancer Therapy: Preclinical CPTH6, a Thiazole Derivative, Induces Histone Hypoacetylation and Apoptosis in Human Leukemia Cells Daniela Trisciuoglio 1 , Ylenia Ragazzoni 1 , Andrea Pelosi 2 , Marianna Desideri 1 , Simone Carradori 4 , Chiara Gabellini 1,3 , Giovanna Maresca 7 , Riccardo Nescatelli 5 , Daniela Secci 4 , Adriana Bolasco 4 , Bruna Bizzarri 4 , Chiara Cavaliere 5 , Igea D'Agnano 7 , Patrizia Filetici 6 , Lucia Ricci-Vitiani 8 , Maria Giulia Rizzo 2 , and Donatella Del Bufalo 1 Abstract Purpose: We previously identified novel thiazole derivatives able to reduce histone acetylation and histone acetyltransferase (HAT) activity in yeast. Among these compounds, 3-methylcyclopentylidene- [4-(4 0 -chlorophenyl)thiazol-2-yl]hydrazone (CPTH6) has been selected and used throughout this study. Experimental Design: The effect of CPTH6 on histone acetylation, cell viability and differentiation, cell- cycle distribution, and apoptosis in a panel of acute myeloid leukemia and solid tumor cell lines has been evaluated. Results: Here, we showed that CPTH6 leads to an inhibition of Gcn5 and pCAF HAT activity. Moreover, it inhibits H3/H4 histones and a-tubulin acetylation of a panel of leukemia cell lines. Concentration- and time-dependent inhibition of cell viability, paralleled by accumulation of cells in the G 0 /G 1 phase and depletion from the S/G 2 M phases, was observed. The role of mitochondrial pathway on CPTH6-induced apoptosis was shown, being a decrease of mitochondrial membrane potential and the release of cytochrome c, from mitochondria to cytosol, induced by CPTH6. Also the involvement of Bcl-2 and Bcl-xL on CPTH6- induced apoptosis was found after overexpression of the two proteins in leukemia cells. Solid tumor cell lines from several origins were shown to be differently sensitive to CPTH6 treatment in terms of cell viability, and a correlation between the inhibitory efficacy on H3/H4 histones acetylation and cytotoxicity was found. Differentiating effect on leukemia and neuroblastoma cell lines was also induced by CPTH6. Conclusions: These results make CPTH6 a suitable tool for discovery of molecular targets of HAT and, potentially, for the development of new anticancer therapies, which warrants further investigations. Clin Cancer Res; 18(2); 475–86. Ó2011 AACR. Introduction Epigenetic changes, including histone modifications, often occur in cancer (1). Among the post-translational modifications of histones, one regards the acetylation of specific lysine e-amino groups in the N-terminal tail of the core chromosomal histones H2A, H2B, H3, and H4. His- tone acetylation increases accessibility of several factors to the chromatin at specific genes or over vast regions of the genome (2, 3), and it is involved in the regulation of several cell functions, such as gene transcription (4, 5), DNA repair (6), and replication (7). Histone acetyltransferases (HAT) are the enzymes responsible for histone acetylation, which can be reversed by the activity of histone deacetylases (HDAC), enzymes that hydrolyze the acetyl groups (8). The histone acetylation–deacetylation balance is accurately maintained through an equilibrium of HAT and HDAC enzymatic activities in normal cells. On the contrary, irreg- ular pattern of histone acetylation is often found associated with cancer, and it has been hypothesized to modulate the expression of oncogenes and tumor suppressor genes (9–12). Therefore, both protein acetylation and deacetyla- tion pathways represent attractive targets for cancer therapy. High hyperacetylation of histones in oral squamous and hepatocellular carcinoma patient samples has been reported (13, 14). Translocation of HAT genes (15), muta- tion of the HAT p300 (16), overexpression of AIB-1, a HAT coactivator of a nuclear hormone receptor (17), represent Authors' Affiliations: 1 Experimental Chemotherapy Laboratory and 2 Molecular Oncogenesis Laboratory, Regina Elena National Cancer Insti- tute; Departments of 3 Anatomy, Histology, Forensic Medicine, Orthope- dics, Section of Histology and Medical Embryology, 4 Chemistry and Pharmaceutical Technologies, 5 Chemistry and 6 Institute of Molecular Biol- ogy and Pathology, CNR, "Sapienza" University; 7 Institute of Cell Biology and Neurobiology-CNR Santa Lucia Foundation-IRCCS; and 8 Department of Hematology, Oncology, and Molecular Medicine, Istituto Superiore di Sanit a, Rome, Italy Note: Supplementary data for this article are available at Clinical Cancer Research Online (http://clincancerres.aacrjournals.org/). Corresponding Author: Donatella Del Bufalo, Experimental Chemother- apy Laboratory, Regina Elena National Cancer Institute, Via delle Messi d'Oro 156, 00158 Rome, Italy. Phone: 39-06 5266 2575; Fax: 39-06 5266 2592; E-mail: delbufalo@ifo.it doi: 10.1158/1078-0432.CCR-11-0579 Ó2011 American Association for Cancer Research. Clinical Cancer Research www.aacrjournals.org 475 Downloaded from http://aacrjournals.org/clincancerres/article-pdf/18/2/475/2007168/475.pdf by guest on 24 June 2022