Abstract B014: Novel dual BET/p300 bromodomain inhibitors therapeutically inhibit BRD4-NUT driven NUT Carcinomas

Introduction: NUT carcinoma (NC) is an aggressive subtype of squamous carcinoma whose growth is driven by the BRD4-NUT fusion oncoprotein. With a median survival of 6.7 months, NC is perhaps the most aggressive solid tumor in humans, and there exist no effective or standard treatment regimens. BRD4-NUT drives growth by blocking differentiation. BRD4-NUT binds chromatin through the acetyl-histone binding, dual bromodomains (BD) of BRD4. BET inhibitors are highly selective for the BDs of BET proteins and have demonstrated on-target activity in human NC patients, however toxicity has limited efficacy. BRD4-NUT forms hyperacetylated regions, termed megadomains, enriched with the NUT-interacting histone acetyltransferase, p300, that upregulate expression of key oncogenic targets, including MYC. Here we sought to determine the role of p300 in the blockade of differentiation and growth of NC cells. Next, we investigated whether inhibiting both BRD4 and p300, by blocking the BDs of BRD4 and p300 with a novel dual inhibitor class of compounds, termed ‘NEO’ (NEO2734 and NEO1132), might exhibit greater inhibition of NC growth than BET BD inhibition alone. Methods: We utilized in vitro reporter assays to map the minimal essential domain of NUT necessary for its interaction with p300. Using our NC cell derivative, 797TRex, which contains a single genomic FRT recombination site, and constitutively express tetracycline repressor (TR), allows for FLP-recombinase insertion of tet-inducible NUT or p300 constructs. Immunofluorescence, immunoblotting, cell-titer glo (Promega), and nascent RNAseq were used to evaluate effects of transgene induction and treatment with compounds. Tolerability and efficacy of various compounds were evaluated in vivo in a disseminated mouse NC xenograft model using the PER-403 human BRD4-NUT+ cell line. Results: We determined that a putative transcriptional activation domain (TAD1 (NUT390-482)) of NUT and the TAZ2 domain of p300 (p3001721-1837) bind directly. We found that inducing expression of TAD1 or TAZ2 in 797TRex cells results in rapid differentiation and promotes the dispersion of acetylated and p300-enriched BRD4-NUT megadomains/foci, indicating that p300 is required for the blockade of differentiation through its direct interaction with NUT. Preliminary data also suggest TAD1 (NUT390-482) expression in 797TRex cells decreases nascent transcription of BRD4-NUT-mediated oncogenic targets. Furthermore, our findings indicate that NEO compounds inhibit in vitro NC growth with IC50s = 44-225nM, which associated with the induction of squamous differentiation. Most strikingly, the lead clinical NEO compound completely abrogated NC tumor growth in our pilot disseminated xenograft mouse study, which greatly prolonged survival as compared to a lead clinical BET inhibitor (GSK762) or “standard” chemotherapy (cisplatin/etoposide) commonly used for NC. Conclusions: These data support our hypothesis that p300 recruitment is necessary for the oncogenic functions of BRD4-NUT and dual targeting of BET and p300 BDs represents a promising therapeutic option for NC patients. Future studies are necessary to determine the relative contribution of BET versus p300 BD inhibition to preventing NC growth by NEO compounds.

Citation Format: Chevaun D Morrison-Smith, Amy DiBona, Erica Walsh, Kristina Danga, Ivona Filic, Tatiana Knox, Adlai Grayson, Michael Cameron, Christopher French. Novel dual BET/p300 bromodomain inhibitors therapeutically inhibit BRD4-NUT driven NUT Carcinomas [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr B014. doi:10.1158/1535-7163.TARG-19-B014

Palm Fruit Bioactives modulate human astrocyte activity in vitro altering the cytokine secretome reducing levels of TNFα, RANTES and IP-10

Neurodegenerative diseases, including Alzheimer's disease and Parkinson's disease, are becoming more prevalent and an increasing burden on society. Neurodegenerative diseases often arise in the milieu of neuro-inflammation of the brain. Reactive astrocytes are key regulators in the development of neuro-inflammation. This study describes the effects of Palm Fruit Bioactives (PFB) on the behavior of human astrocytes which have been activated by IL-1β. When activated, the astrocytes proliferate, release numerous cytokines/chemokines including TNFα, RANTES (CCL5), IP-10 (CXCL10), generate reactive oxygen species (ROS), and express specific cell surface biomarkers such as the Intercellular Adhesion Molecule (ICAM), Vascular Cellular Adhesion Molecule (VCAM) and the Neuronal Cellular Adhesion Molecule (NCAM). Interleukin 1-beta (IL-1β) causes activation of human astrocytes with marked upregulation of pro-inflammatory genes. We show significant inhibition of these pro-inflammatory processes when IL-1β-activated astrocytes are exposed to PFB. PFB causes a dose-dependent and time-dependent reduction in specific cytokines: TNFα, RANTES, and IP-10. We also show that PFB significantly reduces ROS production by IL-1β-activated astrocytes. Furthermore, PFB also reduces the expression of ICAM and VCAM, both in activated and naïve human astrocytes in vitro. Since reactive astrocytes play an essential role in the neuroinflammatory state preceding neurodegenerative diseases, this study suggests that PFB may have a potential role in their prevention and/or treatment.

Abstract 2655: Oncogenic chromatin factors drive cell type-specific transcription within megadomains in NUT midline carcinoma

NUT midline carcinoma (NMC), a subtype of squamous cell cancer, is one of the most aggressive human solid malignancies known. NMC is driven by the creation of a translocation oncoprotein, BRD4-NUT, which blocks differentiation and drives growth of NMC cells. BRD4-NUT forms distinctive nuclear foci in patient tumors, which we find correlate with ∼100 unprecedented, hyperacetylated expanses of chromatin that reach up to 2 Mb in size. These ‘megadomains’ appear to be the result of aberrant, feed-forward loops of acetylation and binding of acetylated histones. Megadomains drive transcription of underlying DNA in NMC patient cells and in naïve cells induced to express BRD4-NUT. Here we characterize the constituents of BRD4-NUT chromatin complexes using a crosslinking approach, BioTAP-XL. We find many transcriptional activating proteins known to associate with BRD4, along with novel interactors including p300/CBP and a previously uncharacterized BRD4-NUT Megadomain Associated Protein (BMAP1). BMAP1 is expressed in primary NMC tissue and a subset of more common head and neck squamous cell carcinomas (HNSQC). Concurrently, we discovered a patient-derived NMC harboring a novel BMAP1-NUT fusion. BMAP-NUT blocks differentiation, and like BRD4-NUT recruits p300 to form hyperacetylated megadomains, including at the MYC locus. Thus, our proteomic and genetic approaches have converged on a novel mechanism that involves reprogramming very large regulatory regions to drive oncogenic transcription.

Citation Format: Mitzi I. Kuroda, Artyom A. Alekseyenko, Erica M. Walsh, Xin Wang, Adlai Grayson, Peter T. Hsi, Peter V. Kharchenko, Christopher A. French. Oncogenic chromatin factors drive cell type-specific transcription within megadomains in NUT midline carcinoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2655.

Using tests of false belief with children with autism: how valid and reliable are they?

Twenty-two children with autism were given four tests of false belief understanding: the Sally-Anne task, two variants of the deceptive box task, and the three boxes task. The overall consistency of the children's performance was high, 77 percent of the participants either passing or failing all of the tasks. The convergent validity (across-task consistency) of the deceptive box and the three boxes paradigms was high, and the convergent validity of the three boxes and Sally-Anne tasks was also acceptable. However, a weaker level of convergent validity was found for the deceptive box and Sally-Anne tasks, suggesting that these paradigms test slightly different aspects of cognition. The reliability (within-child consistency) of the children's performances across two versions of the deceptive box task was high. These findings are discussed in terms of their practical implications for practitioners and researchers.

Can't or won't? Evidence relating to authorship in facilitated communication

Most experimental evaluations of Facilitated Communication (FC) provide no evidence that this technique is valid. Important as they are, controlled test-based studies have characteristically not done justice to the complexity of the issues which surround FC. This paper summarises a long term evaluation project involving various forms of data collection. In this study too, controlled testing has shown very little evidence for the validity of the technique. In contrast, other sources of data, including records of naturally occurring message passing and intensive video analysis have provided evidence that the communication skills of some FC users have been enhanced. An overview of the project is presented, and discussed in relation to the blurring of findings (observations of behaviour) and inferences (judgements of communicative competence) in the extant literature.

Evaluation of facilitated communication

Two case studies are presented to demonstrate the effectiveness of Facilitated Communication (FC). A wide variety of sources of data have been examined and consistent behaviour found within FC interactions. There are indications that changes in behaviour of both people resulted at least in part from the use of FC.