Selective targeting of HDAC1/2 elicits anticancer effects through Gli1 acetylation in preclinical models of SHH Medulloblastoma.

SHH Medulloblastoma (SHH-MB) is a pediatric brain tumor characterized by an inappropriate activation of the developmental Hedgehog (Hh) signaling. SHH-MB patients treated with the FDA-approved vismodegib, an Hh inhibitor that targets the transmembrane activator Smoothened (Smo), have shown the rapid development of drug resistance and tumor relapse due to novel Smo mutations. Moreover, a subset of patients did not respond to vismodegib because mutations were localized downstream of Smo. Thus, targeting downstream Hh components is now considered a preferable approach. We show here that selective inhibition of the downstream Hh effectors HDAC1 and HDAC2 robustly counteracts SHH-MB growth in mouse models. These two deacetylases are upregulated in tumor and their knockdown inhibits Hh signaling and decreases tumor growth. We demonstrate that mocetinostat (MGCD0103), a selective HDAC1/HDAC2 inhibitor, is a potent Hh inhibitor and that its effect is linked to Gli1 acetylation at K518. Of note, we demonstrate that administration of mocetinostat to mouse models of SHH-MB drastically reduces tumor growth, by reducing proliferation and increasing apoptosis of tumor cells and prolongs mouse survival rate. Collectively, these data demonstrate the preclinical efficacy of targeting the downstream HDAC1/2-Gli1 acetylation in the treatment of SHH-MB

"Shock and kill" effects of class I-selective histone deacetylase inhibitors in combination with the glutathione synthesis inhibitor buthionine sulfoximine in cell line models for HIV-1 quiescence

Latently infected, resting memory CD4+ T cells and macrophages represent a major obstacle to the eradication of HIV-1. For this purpose, "shock and kill" strategies have been proposed (activation of HIV-1 followed by stimuli leading to cell death). Histone deacetylase inhibitors (HDACIs) induce HIV-1 activation from quiescence, yet class/isoform-selective HDACIs are needed to specifically target HIV-1 latency. We tested 32 small molecule HDACIs for their ability to induce HIV-1 activation in the ACH-2 and U1 cell line models. In general, potent activators of HIV-1 replication were found among non-class selective and class I-selective HDACIs. However, class I selectivity did not reduce the toxicity of most of the molecules for uninfected cells, which is a major concern for possible HDACI-based therapies. To overcome this problem, complementary strategies using lower HDACI concentrations have been explored. We added to class I HDACIs the glutathione-synthesis inhibitor buthionine sulfoximine (BSO), in an attempt to create an intracellular environment that would facilitate HIV-1 activation. The basis for this strategy was that HIV-1 replication decreases the intracellular levels of reduced glutathione, creating a pro-oxidant environment which in turn stimulates HIV-1 transcription. We found that BSO increased the ability of class I HDACIs to activate HIV-1. This interaction allowed the use of both types of drugs at concentrations that were non-toxic for uninfected cells, whereas the infected cell cultures succumbed more readily to the drug combination. These effects were associated with BSO-induced recruitment of HDACI-insensitive cells into the responding cell population, as shown in Jurkat cell models for HIV-1 quiescence. The results of the present study may contribute to the future design of class I HDACIs for treating HIV-1. Moreover, the combined effects of class I-selective HDACIs and the glutathione synthesis inhibitor BSO suggest the existence of an Achilles' heel that could be manipulated in order to facilitate the "kill" phase of experimental HIV-1 eradication strategies

Epigenetic Regulation of a Murine Retrotransposon by a Dual Histone Modification Mark

Large fractions of eukaryotic genomes contain repetitive sequences of which the vast majority is derived from transposable elements (TEs). In order to inactivate those potentially harmful elements, host organisms silence TEs via methylation of transposon DNA and packaging into chromatin associated with repressive histone marks. The contribution of individual histone modifications in this process is not completely resolved. Therefore, we aimed to define the role of reversible histone acetylation, a modification commonly associated with transcriptional activity, in transcriptional regulation of murine TEs. We surveyed histone acetylation patterns and expression levels of ten different murine TEs in mouse fibroblasts with altered histone acetylation levels, which was achieved via chemical HDAC inhibition with trichostatin A (TSA), or genetic inactivation of the major deacetylase HDAC1. We found that one LTR retrotransposon family encompassing virus-like 30S elements (VL30) showed significant histone H3 hyperacetylation and strong transcriptional activation in response to TSA treatment. Analysis of VL30 transcripts revealed that increased VL30 transcription is due to enhanced expression of a limited number of genomic elements, with one locus being particularly responsive to HDAC inhibition. Importantly, transcriptional induction of VL30 was entirely dependent on the activation of MAP kinase pathways, resulting in serine 10 phosphorylation at histone H3. Stimulation of MAP kinase cascades together with HDAC inhibition led to simultaneous phosphorylation and acetylation (phosphoacetylation) of histone H3 at the VL30 regulatory region. The presence of the phosphoacetylation mark at VL30 LTRs was linked with full transcriptional activation of the mobile element. Our data indicate that the activity of different TEs is controlled by distinct chromatin modifications. We show that activation of a specific mobile element is linked to a dual epigenetic mark and propose a model whereby phosphoacetylation of histone H3 is crucial for full transcriptional activation of VL30 elements

Digital Twins in Radiology

A digital twin is a virtual model developed to accurately reflect a physical thing or a system. In radiology, a digital twin of a radiological device enables developers to test its characteristics, make alterations to the design or materials, and test the success or failure of the modifications in a virtual environment. Innovative technologies, such as AI and -omics sciences, may build virtual models for patients that are continuously adjustable based on live-tracked health/lifestyle parameters. Accordingly, healthcare could use digital twins to improve personalized medicine. Furthermore, the accumulation of digital twin models from real-world deployments will enable large cohorts of digital patients that may be used for virtual clinical trials and population studies. Through their further refinement, development, and application into clinical practice, digital twins could be crucial in the era of personalized medicine, revolutionizing how diseases are detected and managed. Although significant challenges remain in the development of digital twins, a structural modification to the current operating models is occurring, and radiologists can guide the introduction of such technology into healthcare

Preparation of 7-nitro-2,1,3-benzoxadiazole derivatives for antitumor therapy

The invention relates to benzoxazole derivs. of formula I [R is (un)substituted alkyl, Ph, or phenylalkyl] for use in antitumor therapy owing to their potent inhibitory activity with respect to glutathione S-transferase (GST). Thus, I (R = CH2C6H4CO2Et-p) was prepd. by reaction of Et 4-(bromoethyl)benzoate with potassium Et xanthogenate, followed by treatment with EtONa in EtOH and 4-chloro-7-nitro-2,1,3-benzoxadiazole. The product showed IC50 = 1.19 and 0.007 vs. enzymes GSTP1-1 and GSTM2-2, resp. [on SciFinder(R)

Histone deacetylase inhibitors may reduce pathogenicity and virulence in Candida albicans

Candida albicans is able to establish mucosal and invasive diseases by means of different virulence factors that are frequently regulated by epigenetic mechanisms, including the acetylation-deacetylation of histones and of other regulatory proteins. The focus of our work was on understanding the possible effects of several histone deacetylase inhibitors (HDACi) on the expression of phenotypes that are associated with virulence and pathogenicity in C. albicans, such as adhesion to epithelial cells and the yeast to hypha transition. Some of the HDACi used for experiments caused a 90% reduction in the adherence of C. albicans to human cultured pneumocytes and significantly inhibited serum-induced germination. Inhibition of germination was correlated with a significant reduction in transcription of EFG1. Inhibition appeared less evident when an HDA1-deficient strain was tested. These results suggest that selective and specific HDACi could prove to be a valid approach for selected at-risk patients in the combined treatment of infections caused by C. albicans. © 2007 Federation of European Microbiological Societies

Non-cancer uses of histone deacetylase inhibitors: effects on infectious diseases and β-hemoglobinopathies

After the approval of suberoylanilide hydroxamic acid (SAHA, vorinostat, Zolinza) for the treatment of cutaneous T cell lymphoma (CTCL), a number of HDAC inhibitors (HDACi) are currently in Phase II or III clinical trials (alone or in combination) for the treatment of a great number of tumors. In addition to these cancer uses, HDACi can be successfully used in non-cancer diseases. In this review we focused on the uses of HDACi in some infectious diseases and beta-hemoglobinopaties. In C. albicans cultures, HDACi increased the frequency of cell switching (a relevant virulence trait) in the white-to-opaque transition, reduced the azole trailing effect through reduction in azole-dependent upregulation of CDR and ERG genes, and inhibited the fluconazole-dependent resistance induction. Moreover, they inhibited germination in several strains, and caused 90% reduction in the adherence of C. albicans to human cultured pneumocytes. In HIV-1-infected cells, the treatment with HDACi reactivates the HIV-1 expression in latent cellular reservoirs. Thus, the use of HDACi as adjuvant to highly active antiretroviral therapy (HAART) can represent a new potential therapeutic strategy to eradicate the viral infection. A number of HDACi have been reported as active against P. falciparum infection. Two recent papers show some 2-aminosuberic acid-based compounds as well as a series of phenylthiazolyl suberoyl hydroxamates as very potent and selective antimalarial agents. Among the many agents capable to perform post-natal reactivation of fetal hemoglobin production, HDACi for their capacity to de-repress gamma-globin gene expression in adult red cell, are presently considered promising molecules for personalized therapy of beta-hemoglobinopathies