Loss of the proteasomal deubiquitinase USP14 induces growth defects and a senescence phenotype in colorectal cancer cells.

The proteasome-associated deubiquitinase USP14 is a potential drug target. Using an inducible USP14 knockout system in colon cancer cells, we found that USP14 depletion impedes cellular proliferation, induces cell cycle arrest, and leads to a senescence-like phenotype. Transcriptomic analysis revealed altered gene expression related to cell division and cellular differentiation.

Comprehensive Target Screening and Cellular Profiling of the Cancer-Active Compound b-AP15 Indicate Abrogation of Protein Homeostasis and Organelle Dysfunction as the Primary Mechanism of Action.

Dienone compounds have been demonstrated to display tumor-selective anti-cancer activity independently of the mutational status of TP53. Previous studies have shown that cell death elicited by this class of compounds is associated with inhibition of the ubiquitin-proteasome system (UPS). Here we extend previous findings by showing that the dienone compound b-AP15 inhibits proteasomal degradation of long-lived proteins.

Sensitivity of Acute Myelocytic Leukemia Cells to the Dienone Compound VLX1570 Is Associated with Inhibition of the Ubiquitin-Proteasome System.

Dienone compounds with a 1,5-diaryl-3-oxo-1,4-pentadienyl pharmacophore have been widely reported to show tumor cell selectivity. These compounds target the ubiquitin-proteasome system (UPS), known to be essential for the viability of tumor cells. The induction of oxidative stress, depletion of glutathione, and induction of high-molecular-weight (HMW) complexes have also been reported.

Identification of proteasome inhibitors using analysis of gene expression profiles.

Inhibitors of the 20S proteasome such as bortezomib (Velcade) and carfilzomib (Kypriolis) are in clinical use for the treatment of patients with multiple myeloma and mantle cell lymphoma. In an attempt to identify novel inhibitors of the ubiquitin-proteasome system (UPS) we used the connectivity map (CMap) resource, based on alterations of gene expression profiles by perturbagens, and performed COMPARE analyses of drug sensitivity patterns in the NCI panel. Cmap analysis identified a large number of small molecules with strong connectivity to proteasome inhibition, including both well characterized inhibitors of the 20S proteasome and molecules previously not described to inhibit the UPS.

Induction of ER Stress in Acute Lymphoblastic Leukemia Cells by the Deubiquitinase Inhibitor VLX1570.

The proteasome is a validated target of cancer therapeutics. Inhibition of proteasome activity results in the activation of the unfolded protein response (UPR) characterized by phosphorylation of eukaryotic initiation factor 2α (eIF2α), global translational arrest, and increased expression of the proapoptotic CHOP (C/EBP homologous protein) protein. Defects in the UPR response has been reported to result in altered sensitivity of tumor cells to proteasome inhibitors.

Author Correction: Cytotoxic unsaturated electrophilic compounds commonly target the ubiquitin proteasome system.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Analysis of determinants for in vitro resistance to the small molecule deubiquitinase inhibitor b-AP15.

Background: b-AP15/VLX1570 are small molecule inhibitors of the ubiquitin specific peptidase 14 (USP14) and ubiquitin carboxyl-terminal hydrolase 5 (UCHL5) deubiquitinases (DUBs) of the 19S proteasome. b-AP15/VLX1570 have been shown to be cytotoxic to cells resistant to bortezomib, raising the possibility that this class of drugs can be used as a second-line therapy for treatment-resistant multiple myeloma. Limited information is available with regard to potential resistance mechanisms to b-AP15/VLX1570.

Cytotoxic unsaturated electrophilic compounds commonly target the ubiquitin proteasome system.

A large number of natural products have been advocated as anticancer agents. Many of these compounds contain functional groups characterized by chemical reactivity. It is not clear whether distinct mechanisms of action can be attributed to such compounds.

Repurposing of auranofin: Thioredoxin reductase remains a primary target of the drug.

Auranofin is a gold (I)-containing compound used for the treatment of rheumatic arthritis. Auranofin has anticancer activity in animal models and is approved for clinical trials for lung and ovarian carcinomas. Both the cytosolic and mitochondrial forms of the selenoprotein thioredoxin reductase (TrxR) are well documented targets of auranofin.

Proteasome inhibitor b-AP15 induces enhanced proteotoxicity by inhibiting cytoprotective aggresome formation.

Proteasome inhibitors have been shown to induce cell death in cancer cells by triggering an acute proteotoxic stress response characterized by accumulation of poly-ubiquitinated proteins, ER stress and the production of reactive oxygen species. The aggresome pathway has been described as an escape mechanism from proteotoxicity by sequestering toxic cellular aggregates. Here we show that b-AP15, a small-molecule inhibitor of proteasomal deubiquitinase activity, induces poly-ubiquitin accumulation in absence of aggresome formation.

Acute lymphoblastic leukemia cells are sensitive to disturbances in protein homeostasis induced by proteasome deubiquitinase inhibition.

The non-genotoxic nature of proteasome inhibition makes it an attractive therapeutic option for the treatment of pediatric malignancies. We recently described the small molecule VLX1570 as an inhibitor of proteasome deubiquitinase (DUB) activity that induces proteotoxic stress and apoptosis in cancer cells. Here we show that acute lymphoblastic leukemia (ALL) cells are highly sensitive to treatment with VLX1570, resulting in the accumulation of polyubiquitinated proteasome substrates and loss of cell viability.

Tideglusib induces apoptosis in human neuroblastoma IMR32 cells, provoking sub-G0/G1 accumulation and ROS generation.

Neuroblastoma is the most common tumor amongst children amounting to nearly 15% of cancer deaths. This cancer is peculiar in its characteristics, exhibiting differentiation, maturation and metastatic transformation leading to poor prognosis and low survival rates among children. Chemotherapy, though toxic to normal cells, has shown to improve the survival of the patient with emphasis given more towards targeting angiogenesis.

The proteasome deubiquitinase inhibitor VLX1570 shows selectivity for ubiquitin-specific protease-14 and induces apoptosis of multiple myeloma cells.

Inhibition of deubiquitinase (DUB) activity is a promising strategy for cancer therapy. VLX1570 is an inhibitor of proteasome DUB activity currently in clinical trials for relapsed multiple myeloma. Here we show that VLX1570 binds to and inhibits the activity of ubiquitin-specific protease-14 (USP14) in vitro, with comparatively weaker inhibitory activity towards UCHL5 (ubiquitin-C-terminal hydrolase-5).

Inhibition of proteasome deubiquitinase activity: a strategy to overcome resistance to conventional proteasome inhibitors?

Although more traditionally associated with degradation and maintenance of protein homeostasis, the ubiquitin-proteasome system (UPS) has emerged as a critical component in the regulation of cancer cell growth and survival. The development of inhibitors that block the proteolytic activities of the proteasome have highlighted its suitability as a bona fide anti-cancer drug target. However, key determinants including the development of drug resistance and dose-limiting toxicity call for the identification of alternative components of the UPS for novel drug targeting.

Nanostructured delivery system for Suberoylanilide hydroxamic acid against lung cancer cells.

With the objective to provide a potential approach for the treatment of lung cancer, nanotechnology based Suberoylanilide hydroxamic acid (SAHA)-loaded Poly-d, l-lactide-co glycolide (PLGA) nanoparticles have been formulated using the nanoprecipitation technique. The acquired nanoparticles were characterized by various throughput techniques and the analyses showed the presence of smooth and spherical shaped SAHA-loaded PLGA nanoparticles, with an encapsulation efficiency of 44.8% and a particle size of 208nm.

Blocking NF-κB sensitizes non-small cell lung cancer cells to histone deacetylase inhibitor induced extrinsic apoptosis through generation of reactive oxygen species.

NF-κB signalling is one of the main cell survival pathways that attenuate the anticancer efficacy of therapeutic drugs. Previous studies demonstrated that the histone deacetylase (HDAC) inhibitor induces apoptosis in some malignancies through multiple mechanisms including up-regulation of death receptors, disruption of Hsp90 function and generation of reactive oxygen species (ROS). However, HDAC inhibitor also induces a cell survival signal through NF-κB activation.

Anticancer activity of Ficus religiosa engineered copper oxide nanoparticles.

The design, synthesis, characterization and application of biologically synthesized nanomaterials have become a vital branch of nanotechnology. There is a budding need to develop a method for environmentally benign metal nanoparticle synthesis, that do not use toxic chemicals in the synthesis protocols to avoid adverse effects in medical applications. Here, it is a report on an eco-friendly process for rapid synthesis of copper oxide nanoparticles using Ficus religiosa leaf extract as reducing and protecting agent.

Romidepsin induces cell cycle arrest, apoptosis, histone hyperacetylation and reduces matrix metalloproteinases 2 and 9 expression in bortezomib sensitized non-small cell lung cancer cells.

Histone deacetylase (HDAC) inhibitors have been proven to be effective therapeutic agents to kill cancer cells through inhibiting HDAC activity or altering the structure of chromatin. We recently reported that chemotherapy by the HDAC inhibitor, romidepsin activates the anti- apoptotic transcription factor NF-κB in A549 non-small cell lung cancer (NSCLC) cells and fails to induce significant levels of apoptosis. We also demonstrated that NF-κB inhibition with proteasome inhibitor bortezomib enhanced HDAC inhibitor induced mitochondrial injury and sensitize A549 NSCLC cells to apoptosis through the generation of reactive oxygen species.

Origanum vulgare mediated biosynthesis of silver nanoparticles for its antibacterial and anticancer activity.

In the present study, we achieved silver nanoparticles using the aqueous extract of Origanum vulgare (Oregano) by reducing 1mM silver nitrate (AgNO3) solution. The green synthesized silver nanoparticles were characterized by high throughput techniques like UV-vis spectroscopy, Fourier infrared spectroscopy (FT-IR), field emission-scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and dynamic light scattering measurements. Morphologically, the nanoparticles were found to be spherical with an average particle size distribution of 136±10.