Proteolysis targeting chimera extracellular vesicles for therapeutic development treating triple negative breast cancer.

Proteolysis targeting chimeras (PROTACs) are an emerging targeted cancer therapy approach, but wide-spread clinical use of PROTAC is limited due to poor cell targeting and penetration, and instability in vivo. To overcome such issues and enhance the in vivo efficacy of PROTAC drugs, microfluidic droplet-based electroporation (µDES) was developed as a novel extracellular vesicle (EVs) transfection system, which enables the high-efficient PROTAC loading and effective delivery in vivo. Our previously developed YX968 PROTAC drug had shown the selectively degradation of HDAC3 and 8, which effectively suppresses the growth of breast tumor cell lines, including MDA-MB-231 triple negative breast cancer (TNBC) line, via dual degradation without provoking a global histone hyperacetylation.

Discovery of a Highly Potent and Selective HDAC8 Degrader: Advancing the Functional Understanding and Therapeutic Potential of HDAC8.

HDAC8 plays crucial roles in biological processes, from gene regulation to cell motility, making it a highly desirable target for therapeutic intervention. HDAC8 also has deacetylase-independent activity which cannot be blocked by a conventional inhibitor. In this study, we report the discovery of YX862, a highly potent and selective hydrazide-based HDAC8-proteolysis targeting chimera (PROTAC) degrader.

HDAC3 and HDAC8 PROTAC dual degrader reveals roles of histone acetylation in gene regulation.

HDAC3 and HDAC8 have critical biological functions and represent highly sought-after therapeutic targets. Because histone deacetylases (HDACs) have a very conserved catalytic domain, developing isozyme-selective inhibitors remains challenging. HDAC3/8 also have deacetylase-independent activity, which cannot be blocked by conventional enzymatic inhibitors.

DAXX drives de novo lipogenesis and contributes to tumorigenesis.

Cancer cells exhibit elevated lipid synthesis. In breast and other cancer types, genes involved in lipid production are highly upregulated, but the mechanisms that control their expression remain poorly understood. Using integrated transcriptomic, lipidomic, and molecular studies, here we report that DAXX is a regulator of oncogenic lipogenesis.

CBP/p300: Critical Co-Activators for Nuclear Steroid Hormone Receptors and Emerging Therapeutic Targets in Prostate and Breast Cancers.

The CREB-binding protein (CBP) and p300 are two paralogous lysine acetyltransferases (KATs) that were discovered in the 1980s-1990s. Since their discovery, CBP/p300 have emerged as important regulatory proteins due to their ability to acetylate histone and non-histone proteins to modulate transcription. Work in the last 20 years has firmly established CBP/p300 as critical regulators for nuclear hormone signaling pathways, which drive tumor growth in several cancer types.

Pharmacological Inhibition of CBP/p300 Blocks Estrogen Receptor Alpha (ERα) Function through Suppressing Enhancer H3K27 Acetylation in Luminal Breast Cancer.

Estrogen receptor alpha (ER) is the oncogenic driver for ER+ breast cancer (BC). ER antagonists are the standard-of-care treatment for ER+ BC; however, primary and acquired resistance to these agents is common. CBP and p300 are critical ER co-activators and their acetyltransferase (KAT) domain and acetyl-lysine binding bromodomain (BD) represent tractable drug targets, but whether CBP/p300 inhibitors can effectively suppress ER signaling remains unclear.

Discovery of histone deacetylase 3 (HDAC3)-specific PROTACs.

Histone deacetylases (HDACs) are validated drug targets for cancer treatment. Increased HDAC isozyme selectivity and novel strategies to inhibit HDAC activity could lead to safer and more effective drug candidates. Nonetheless, it is quite challenging to develop isozyme-specific HDACi due to the highly conserved catalytic domain.

Assays for Validating Histone Acetyltransferase Inhibitors.

Lysine acetyltransferases (KATs) catalyze acetylation of lysine residues on histones and other proteins to regulate chromatin dynamics and gene expression. KATs, such as CBP/p300, are under intense investigation as therapeutic targets due to their critical role in tumorigenesis of diverse cancers. The development of novel small molecule inhibitors targeting the histone acetyltransferase (HAT) function of KATs is challenging and requires robust assays that can validate the specificity and potency of potential inhibitors.

DAXX in cancer: phenomena, processes, mechanisms and regulation.

DAXX displays complex biological functions. Remarkably, DAXX overexpression is a common feature in diverse cancers, which correlates with tumorigenesis, disease progression and treatment resistance. Structurally, DAXX is modular with an N-terminal helical bundle, a docking site for many DAXX interactors (e.

Inhibition of androgen receptor transactivation function by adenovirus type 12 E1A undermines prostate cancer cell survival.

Background: Mutations or truncation of the ligand-binding domain (LBD) of androgen receptor (AR) underlie treatment resistance for prostate cancer (PCa). Thus, targeting the AR N-terminal domain (NTD) could overcome such resistance.

Methods: Luciferase reporter assays after transient transfection of various DNA constructs were used to assess effects of E1A proteins on AR-mediated transcription.

Degradation of DAXX by adenovirus type 12 E1B-55K circumvents chemoresistance of ovarian cancer to cisplatin.

Adenovirus E1B 55-kilodalton (E1B-55K) mediated DAXX degradation represents a potential mechanism by which E1B-55K sensitizes cancer cells to chemotherapy. Here we report the effects of E1B-55K-mediated DAXX degradation in chemoresistant ovarian cancer cells on response to chemotherapy. Cells with E1B-55K expression were more sensitive to cisplatin than cells without E1B-55K expression.

βArrestin2 Mediates Renal Cell Carcinoma Tumor Growth.

Renal Cell Carcinoma (RCC) is one of the most lethal urological cancers worldwide. The disease does not present early clinical symptoms and is commonly diagnosed at an advanced stage. Limited molecular drivers have been identified for RCC, resulting in the lack of effective treatment for patients with progressive disease.

CBP/p300 Bromodomain Mediates Amyloid Formation.

Bromodomains are protein domains that serve as "readers" of acetylated lysine marks and mediate DNA-templated processes. In this issue of Cell Chemical Biology, Olzscha et al. (2017) report that the CBP/p300 bromodomains mediate the formation of amyloid-like aggregates and that inhibitors specific to these bromodomains reduce the degree of protein aggregation and mitigate HDAC inhibitor-induced cytotoxicity.

Intrinsic cellular signaling mechanisms determine the sensitivity of cancer cells to virus-induced apoptosis.

Cancer cells of epithelial and mesenchymal phenotypes exhibit different sensitivities to apoptosis stimuli, but the mechanisms underlying this phenomenon remain partly understood. We constructed a novel recombinant adenovirus expressing Ad12 E1A (Ad-E1A12) that can strongly induce apoptosis. Ad-E1A12 infection of epithelial cancer cells displayed dramatic detachment and apoptosis, whereas cancer cells of mesenchymal phenotypes with metastatic propensity were markedly more resistant to this virus.

Profiling technologies for the identification and characterization of small-molecule histone deacetylase inhibitors.

Histone deacetylases (HDACs) are promising drug targets for treating cancer, neurologic, inflammatory and metabolic diseases. Four small molecule inhibitors of HDACs have gained regulatory approval for treating lymphomas and multiple myelomas. Highly sensitive in vitro and cell-based profiling technologies have been developed to discover HDAC inhibitors (HDACi) and characterize their inhibitory potency, target-binding specificity and kinetics.

Microarray gene expression profiling reveals potential mechanisms of tumor suppression by the class I HDAC-selective benzoylhydrazide inhibitors.

Histone deacetylase (HDAC) inhibitors (HDIs) have therapeutic potentials for treating cancer and other diseases. Modulation of gene expression by HDIs is a major mechanism underlying their therapeutic effects. A novel class of HDIs with a previously undescribed benzoylhydrazide scaffold has been discovered through a high throughput screening campaign.

Identification of histone deacetylase inhibitors with benzoylhydrazide scaffold that selectively inhibit class I histone deacetylases.

Inhibitors of histone deacetylases (HDACi) hold considerable therapeutic promise as clinical anticancer therapies. However, currently known HDACi exhibit limited isoform specificity, off-target activity, and undesirable pharmaceutical properties. Thus, HDACi with new chemotypes are needed to overcome these limitations.

Identification and characterization of small-molecule inhibitors of lysine acetyltransferases.

Lysine acetyltransferases (KATs) acetylate various proteins including histones, transcription factors, metabolic enzymes, and other cellular substrates. Protein acetylation significantly impacts protein stability and function. Certain KATs such as p300 (KAT3B) are overexpressed in cancer cells and are linked to tumor progression and drug resistance.

Overexpression of histone deacetylases in cancer cells is controlled by interplay of transcription factors and epigenetic modulators.

Histone deacetylases (HDACs) that deacetylate histone and nonhistone proteins play crucial roles in a variety of cellular processes. The overexpression of HDACs is reported in many cancer types and is directly linked to accelerated cell proliferation and survival. However, little is known about how HDAC expression is regulated in cancer cells.

p53 SUMOylation promotes its nuclear export by facilitating its release from the nuclear export receptor CRM1.

Chromosomal region maintenance 1 (CRM1) mediates p53 nuclear export. Although p53 SUMOylation promotes its nuclear export, the underlying mechanism is unclear. Here we show that tethering of a small, ubiquitin-like modifier (SUMO) moiety to p53 markedly increases its cytoplasmic localization.

Small-molecule inhibitors of acetyltransferase p300 identified by high-throughput screening are potent anticancer agents.

Acetyltransferase p300 (KAT3B) plays key roles in signaling cascades that support cancer cell survival and sustained proliferation. Thus, p300 represents a potential anticancer therapeutic target. To discover novel anticancer agents that target p300, we conducted a high-throughput screening campaign.

Downregulation of Mdm2 and Mdm4 enhances viral gene expression during adenovirus infection.

Successful viral replication entails elimination or bypass of host antiviral mechanisms. Here, we show that shRNA-mediated knockdown of murine double minute (Mdm2) and its paralog Mdm4 enhanced the expression of early and late viral gene products during adenovirus (HAdV) infection. Remarkably, whereas the expression of HAdV genes was low in p53-deficient mouse embryonic fibroblasts (p53KO MEFs), the HAdV early gene products were efficiently expressed in Mdm2/p53 double-knockout (DKO) and Mdm4/p53 DKO MEFs, and viral capsid proteins were produced in Mdm2/p53 DKO MEFs.

Inhibition of p53 by adenovirus type 12 E1B-55K deregulates cell cycle control and sensitizes tumor cells to genotoxic agents.

Adenovirus E1B-55K represses p53-mediated transcription. However, the phenotypic consequence of p53 inhibition by E1B-55K for cell cycle regulation and drug sensitivity in tumor cells has not been examined. In HCT116 cells with constitutive E1B-55K expression, the activation of p53 target genes such as the p21, Mdm2, and Puma genes was attenuated, despite markedly elevated p53 protein levels.

Emerging roles of the EBF family of transcription factors in tumor suppression.

Alterations in various developmental pathways are common themes in cancer. The early B-cell factors (EBF) are a family of four highly conserved DNA-binding transcription factors with an atypical zinc-finger and helix-loop-helix motif. They are involved in the differentiation and maturation of several cell lineages including B-progenitor lymphoblasts, neuronal precursors, and osteoblast progenitors.