Manuela Rodriquez

Histone deacetylase inhibitors in the treatment of cancer: overview and perspectives

Histone deacetylase inhibitors (HDACis) are one of the last frontiers in pharmaceutical research. Several classes of HDACi have been identified. Although more than 20 HDACi are under preclinical and clinical investigation as single agents and in combination therapies against different cancers, just two of them were approved by the US FDA: Zolinza(®) and Istodax(®), both licensed for the treatment of cutaneous T-cell lymphoma, the latter also of peripheral T-cell lymphoma. Since HDAC enzymes act by forming multiprotein complexes (clusters), containing cofactors, the main problem in designing new HDACi is that the inhibition activity evaluated on isolated enzyme isoforms does not match the in vivo outcomes. In the coming years, the research will be oriented toward a better understanding of the functioning of these protein complexes as well as the development of new screening assays, with the final goal to obtain new drug candidates for the treatment of cancer.

Chemistry and biology of chromatin remodeling agents: state of art and future perspectives of HDAC inhibitors.

Chromatin remodeling is a fundamental phenomenon in the life of eukaryotic cells, bearing implications to numerous physiological and pathological phenomena. This review outlines the chemistry of natural and synthetic agents endowed with the ability to interfere with such biological function, with a particular emphasis on histone deacetylase (HDAC) inhibitors. Other aspects covered in this article comprise structure activity relationships (SAR) and modes of action at molecular level, including the description of crystal structures of enzyme-inhibitor complexes.

Skeletally diverse small molecules using a build/couple/pair strategy.

Intermolecular couplings of simple building blocks using catalytic, stereoselective cross-Mannich reactions followed by intramolecular functional group-pairing reactions of easily accessed variants of the Mannich products are explored as a route to skeletally diverse small molecules. The synthetic pathway yields products having 12 different skeletons using only three steps and has the potential to enable substantial stereochemical diversification in the future.

Effects of FR235222, a novel HDAC inhibitor, in proliferation and apoptosis of human leukaemia cell lines: Role of Annexin A1

FR235222, a novel histone deacetylase inhibitor (HDACi), at 50nM caused accumulation of acetylated histone H4, inhibition of cell proliferation and G1 cycle arrest accompanied by increase of p21 and down-regulation of cyclin E in human promyelocytic leukaemia U937 cells. The compound was also able to increase the protein and mRNA levels of annexin A1 (ANXA1) without effects on apoptosis. Similar effects were observed in human chronic myelogenous leukaemia K562 cells and human T cell leukaemia Jurkat cells. Cycle arrest and ANXA1 expression, without significant effects on apoptosis, were also induced by different HDACi like suberoylanilide hydroxamic acid (SAHA) and trichostatin-A (TSA). FR235222 at 0.5 microM stimulated apoptosis of all leukaemia cell lines associated to an increased expression of the full-length (37kDa) protein and the appearance of a 33kDa N-terminal cleavage product in both cytosol and membrane. These results suggest that ANXA1 expression may mediate cycle arrest induced by low doses FR235222, whereas apoptosis induced by high doses FR235222 is associated to ANXA1 processing.

Molecular modeling studies toward the structural optimization of new cyclopeptide-based HDAC inhibitors modeled on the natural product FR235222

The natural cyclopeptide FR235222 is a potent HDAC inhibitor displaying relevant multiple anticancer effects and is considered an attractive lead compound for the generation of new and more effective antitumor therapeutics. Recently, we have synthesized a small collection of FR235222 simplified analogues which showed interesting biological activities. These results encouraged us to further explore the structural determinants responsible for the activity of this class of HDAC inhibitors in order to gain guidelines for the rational design of new derivatives with putative higher affinity for this target. In the present paper, we report the results obtained, docking these ligands in the binding pocket of HDLP, an HDAC homologue.

Design and synthesis of cyclopeptide analogues of the potent histone deacetylase inhibitor FR235222.

Various structurally modified analogues of FR235222 (1), a natural tetrapeptide inhibitor of mammalian histone deacetylases, were prepared in a convergent approach. The design of the compounds was aimed to investigate the effect of structural modifications of the tetrapeptide core involved in enzyme binding in order to overcome some synthetic difficulties connected with the natural product 1. The modifications introduced could also help identify key structural features involved in the mechanism of action of these compounds. The prepared molecules were subjected to in vitro pharmacological tests, and their potency was tested on cultured cells. Two of the components of the array were found to be more potent than the parent compound 1 and almost as efficient as trichostatin A (TSA). These results demonstrate that it is possible to synthesize highly active cyclic tetrapeptides using commercially available amino acids (with the exception of 2‐amino‐8‐oxodecanoic acid, Ahoda). The nature of the residue in the second position of the cyclic peptide and the stereochemistry of the Ahoda tail are important for the inhibitory activity of this class of cyclic tetrapeptide analogues.

Histone Deacetylase Inhibitors in the Treatment of Hematological Malignancies

Histone deacetylases (HDACs) play a central role in the epigenetic regulation of gene expression. Aberrant activity of HDACs has been found in several human cancers leading to the development of HDAC inhibitors (HDACi) as anti-tumors drugs. In fact, over the last years, a number of HDACi have been evaluated in clinical trials; these drugs have the common ability to hyperacetylate both histone and non-histone targets, resulting in a variety of effects on both cancer cells and immune responses. Clinical trials of HDACi conducted in solid tumors and hematological malignancies have shown a better clinical efficacy of these drugs in hematological malignancies. In this review, will be highlighted the mechanisms of action underlying the clinical responses obtained with these drugs and the doubts regarding the use of HDACi in cancer therapy.

Histone deacetylase inhibitor FR235222 sensitizes human prostate adenocarcinoma cells to apoptosis through up-regulation of Annexin A1

The reduction of Annexin A1 (ANXA1) expression, commonly associated with prostate cancer, could be due to elevated activity of histone deacetylases. We have investigated the mechanisms of apoptotic effects of FR235222 in LNCaP cell line and the role of ANXA1. We showed that treatment with FR235222 induced apoptosis through a caspase-dependent mechanism. FR235222 was able to increase the protein levels of ANXA1 at a transcriptional level. Finally, the inhibition of ANXA1 expression by siRNA leads to a partial reduction of FR235222-induced apoptosis. The results suggest that elevated activity of HDACs is responsible for the reduction of ANXA1, indicating that ANXA1 expression is a contributing factor to the proapoptotic effects in prostate cancer.

Downregulation of Hypoxia-related Responses by Novel Antitumor Histone Deacetylase Inhibitors in MDAMB231 Breast Cancer Cells

The tumor microenvironment is characterized by a poor circulation which results in the selection of neoplastic cells that can grow or survive under hypoxic conditions. The relationship between hypoxia and histone deacetylase (HDAC) inhibitors has been previously established. In this work we evaluated the effects of novel HDAC inhibitors (the natural peptide FR235222 and three tetrapeptide analogs) in the human breast cancer cell line MDAMB231, cultured under hypoxia (2% O2 ≉ 14 mmHg) or normoxia (20% O2 ≉ 140 mmHg). First, we found that the novel HDAC inhibitors reduced cell proliferation in MDAMB231 cells at an extent which was similar or even higher than that exerted by the classic HDAC inhibitors trichostatin-A and suberoylanilide hydroxamic acid. More interestingly, the antiproliferative effects of the novel HDAC inhibitors were, in general, significantly higher in hypoxic cells than in normoxic controls. Hypoxic MDAMB231 cells expressed high levels of the hypoxia-inducible factor (HIF)-1α and HIF-1α-related genes, such as vascular endothelial growth factor, Bcl-2/E1B 19 kDa interacting protein-3, glucose transporter-1, carbonic anhydrase IX, as determined by Western blot analysis and qRT-PCR. Finally, we found that HIF-1α and HIF-1α-related genes were significantly downregulated by FR235222 and analogs. In conclusion, the identification of novel effects exerted by the HDAC inhibitors, characterized by a strong efficacy in inhibiting the expression of HIF-1α and its related genes, may have important implications in the pharmacological control of several tumors, including breast cancer, characterized by the presence of hypoxia, angiogenesis and metabolic derangements.

β-Amyloid-acetylcholine molecular interaction: new role of cholinergic mediators in anti-Alzheimer therapy?

BACKGROUND For long time Alzheimers disease has been attributed to a cholinergic deficit. More recently, it has been considered dependent on the accumulation of the amyloid beta peptide (Aβ), which promotes neuronal loss and impairs neuronal function. Results/methodology: In the present study, using biophysical and biochemical experiments we tested the hypothesis that in addition to its role as a neurotransmitter, acetylcholine may exert its action as an anti-Alzheimer agent through a direct interaction with Aβ. CONCLUSION Our data provide evidence that acetylcholine favors the soluble peptide conformation and exerts a neuroprotective effect against the neuroinflammatory and toxic effects of Aβ. The present paper paves the way toward the development of new polyfunctional anti-Alzheimer therapeutics capable of intervening on both the cholinergic transmission and the Aβ aggregation.