Exacerbation of psoriatic skin lesions in a patient with Alzheimer disease receiving gamma-secretase inhibitor

Promising therapeutic targets for tumor treatment: Cleaved activation of receptors in the nucleus

A new fate of cell surface receptors, cleaved activation in the nucleus, is summarized. The intracellular domain (ICD) of cell surface receptors, cleaved by enzymes like γ-secretase, translocates to the nucleus to form transcriptional complexes participating in the onset and development of tumors. The fate is clinically significant, as inhibitors of cleavage enzymes have shown effectiveness in treating advanced tumors by reducing tumorigenic ICDs. Additionally, the construction of synthetic receptors also conforms with the fate mechanism. This review details each step of cleaved activation in the nucleus, elucidates tumorigenic mechanisms, explores application in antitumor therapy, and scrutinizes possible limitations.

Recent Advancements in Strategies for Abnormal Protein Clearance in Alzheimer's Disease

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Alzheimer's disease (AD) is a intricate neurodegenerative disease with chronic and progressive development whose typical neuropathological features encompasses senile plaques and neurofibrillary tangles respectively formed by the extracellular deposition of amyloid-beta (Aβ) and the intracellular accumulation of hyperphosphorylated tau protein in the brain, particularly in limbic and cortical regions. The pathological changes are considered to be caused by the loss of Aβ and tau protein clearance mechanisms under pathological conditions, which leads to an imbalance between the rates of clearance and production. Consequently, the main strategies for treating AD aim to reduce the production of Aβ and hyperphosphorylated tau protein in the brain, inhibit their accumulation, or accelerate their clearance. Although drugs utilizing these therapeutic strategies have been studied successively, their therapeutic effects have generally been less than ideal. Fortunately, recent advances have been made in clearance strategies for these abnormally expressed proteins, including immunotherapies and nanomedicines targeting Aβ or tau, which could represent an important breakthrough for treating AD. Here, we review recent development of the strategies for the removal of abnormal proteins and provide new ideas and methods for treating AD.

Evaluation of PSEN1 subunit of the γ-secretase gene in patients with psoriasis vulgaris: a pilot study

Introduction

Psoriasis is a chronic autoimmune inflammatory disease, the prevalence of which is 1–3% in the Polish population. Genome testing using single nucleotide polymorphisms revealed more than 50 regions associated with the risk of psoriasis, and most of these genes are associated with the immune system.

Aim

To assess the presence of PSEN1 subunits of the γ-secretase gene polymorphisms in patients with psoriasis and comparison of results with a healthy control group.

Material and methods

We used polymerase chain reaction – restriction fragment length polymorphism (PCR RFLP) method to assess polymorphisms. The starting material for analysis was peripheral blood obtained from the patient.

Results

PSEN1a-positivity was found in 2/52 (2.78%) of patients with psoriasis and 1/36 (3.85%) of healthy controls. PSEN1b positivity was seen in 3/52 (5.77%) of patients with psoriasis and 1/36 (3.85%) of control individuals. Only 3 patients with psoriasis but none of healthy volunteers had a presence of PSEN1c. Four patients were excluded from further statistical analysis.

Conclusions

We have not shown a relationship between PSEN1 polymorphism and the clinical occurrence of psoriasis but now we start the assessment of other subunits of the γ-secretase gene – PSENEN and NCSTN.

DAPT, a γ-Secretase Inhibitor, Suppresses Tumorigenesis, and Progression of Growth Hormone-Producing Adenomas by Targeting Notch Signaling

Advances in the understanding of growth hormone-producing adenomas (GHomas) are ongoing, but current therapy is limited by moderate and variable efficacy and in need of life-long treatment. In this study, the molecular signaling pathway related to GHoma was investigated by proteomics and transcriptomics. The differentially expressed proteins and genes were significantly enriched in Extracellular Matrix-Receptor Interactions, Notch Signaling, Basal Cell Carcinoma Signaling, JAK-STAT3, Wnt Signaling, and Glioblastoma Multiforme Signaling by Ingenuity Pathway Analysis. Furthermore, the Notch2/Delta-like canonical Notch ligand (DLL) signaling pathway was identified to be associated with tumorigenesis and invasiveness of GHoma. In 76 patients, Notch2 and DLL3 were upregulated in invasive compared to those in non-invasive GHoma (p < 0.05). Disease-free survival was significantly longer in patients with low, compared with high, DLL3 expression (p = 0.027). Notch 2 knockdown inhibited cell migration in both GH3 cells and primary GHoma cells, along with downregulation of the mRNA expression of related genes. DAPT, a γ-secretase inhibitor, inhibited tumor growth and invasion in vivo and in vitro and suppressed the release of growth hormone in primary GHoma cells. The involvement of Notch2/DLL3 signaling in GHoma progression warrants additional study of Notch inhibitor, DAPT, as a potential GHoma treatment.

Inhibition of gamma-secretase in Notch1 signaling pathway as a novel treatment for ovarian cancer

Epithelial ovarian cancer (EOC) is the leading cause of death for gynecological cancer. Most patients are not diagnosed until the cancer is at an advanced stage with poor prognosis. Notch1 signaling pathway plays an oncogenic role in EOC. There have been few studies on enzymatic activity of γ-secretase and the mechanism of how γ-secretase inhibitor works on cancer cell. Here, we show that Jagged1 and NICD were highly expressed in ovarian carcinoma. The expressions of Notch1, Jagged1 and NICD in Notch1 pathway did not correlate with outcome in ovarian cancer. The enzymatic activity of γ-secretase in ovarian cancer cell lines SKOV3, CAOV3 and ES2 is significantly higher than in normal ovarian epithelial cell line T29. DAPT (a γ-secretase inhibitor) reduced the enzymatic activity of γ-secretase, inhibited the proliferation, and increased the apoptosis in ovarian cancer cell lines. Hence, γ-secretase inhibitor may become a highly promising novel therapeutic strategy against ovarian cancer in the field of precision medicine.

Notch Signaling: Linking Embryonic Lung Development and Asthmatic Airway Remodeling

Lung development is mediated by assorted signaling proteins and orchestrated by complex mesenchymal-epithelial interactions. Notch signaling is an evolutionarily conserved cell-cell communication mechanism that exhibits a pivotal role in lung development. Notably, both aberrant expression and loss of regulation of Notch signaling are critically linked to the pathogenesis of various lung diseases, in particular, pulmonary fibrosis, lung cancer, pulmonary arterial hypertension, and asthmatic airway remodeling; implying that precise regulation of intensity and duration of Notch signaling is imperative for appropriate lung development. Moreover, evidence suggests that Notch signaling links embryonic lung development and asthmatic airway remodeling. Herein, we summarized all-recent advances associated with the mechanistic role of Notch signaling in lung development, consequences of aberrant expression or deletion of Notch signaling in linking early-impaired lung development and asthmatic airway remodeling, and all recently investigated potential therapeutic strategies to treat asthmatic airway remodeling.

Improved Neuroprotection Provided by Drug Combination in Neurons Exposed to Cell-Derived Soluble Amyloid-β Peptide

Oligomeric amyloid-β (Aβ) peptide contributes to impaired synaptic connections and neurodegenerative processes, and as such, represents a primary therapeutic target for Alzheimer's disease (AD)-modifying approaches. However, the lack of efficacy of drugs that inhibit production of Aβ demonstrates the need for a better characterization of its toxic effects, both on synaptic and neuronal function. Here, we used conditioned medium obtained from recombinant HEK-AβPP cells expressing the human amyloid-β protein precursor (Aβ-CM), to investigate Aβ-induced neurotoxic and synaptotoxic effects. Characterization of Aβ-CM revealed that it contained picomolar amounts of cell-secreted Aβ in its soluble form. Incubation of primary cortical neurons with Aβ-CM led to significant decreases in synaptic protein levels as compared to controls. This effect was no longer observed in neurons incubated with conditioned medium obtained from HEK-AβPP cells grown in presence of the γ-secretase inhibitor, Semagacestat or LY450139 (LY-CM). However, neurotoxic and pro-apoptotic effects of Aβ-CM were only partially prevented using LY-CM, which could be explained by other deleterious compounds related to chronic oxidative stress that were released by HEK-AβPP cells. Indeed, full neuroprotection was observed in cells exposed to LY-CM by additional treatment with the antioxidant resveratrol, or with the pluripotent n-3 polyunsaturated fatty acid docosahexaenoic acid. Inhibition of Aβ production appeared necessary but insufficient to prevent neurodegenerative effects associated with AD due to other neurotoxic compounds that could exert additional deleterious effects on neuronal function and survival. Therefore, association of various types of protective agents needs to be considered when developing strategies for AD treatment.

Discovery of 1-Hydroxypyridine-2(1H)-thione-6-carboxylic Acid as a First-in-Class Low-Cytotoxic Nanomolar Metallo β-Lactamase Inhibitor

VIM-2 is one of the most common carbapenem-hydrolyzing metallo β-lactamases (MBL) found in many drug-resistant Gram-negative bacterial strains. Currently, there is a lack of effective lead compounds with optimal therapeutic potential within our drug development pipeline. Here we report the discovery of 1-hydroxypyridine-2(1H)-thione-6-carboxylic acid (3) as a first-in-class metallo β-lactamase inhibitor (MBLi) with a potent inhibition Ki of 13 nm against VIM-2 that corresponds to a remarkable 0.99 ligand efficiency. We further established that 3 can restore the antibiotic activity of amoxicillin against VIM-2-producing E. coli in a whole cell assay with an EC50 of 110 nm. The potential mode of binding of 3 from molecular modeling provided structural insights that could corroborate the observed changes in the biochemical activities. Finally, 3 possesses a low cytotoxicity (CC50 ) of 97 μm with a corresponding therapeutic index of 880, making it a promising lead candidate for further optimization in combination antibacterial therapy.

The Role of Neurotrophin Signaling in Gliomagenesis: A Focus on the p75 Neurotrophin Receptor (p75NTR/CD271)

The p75 neurotrophin receptor (p75^NTR, a.k.a. CD271), a transmembrane glycoprotein and a member of the tumor necrosis family (TNF) of receptors, was originally identified as a nerve growth factor receptor in the mid-1980s. While p75^NTR is recognized to have important roles during neural development, its presence in both neural and nonneural tissues clearly supports the potential to mediate a broad range of functions depending on cellular context. Using an unbiased in vivo selection paradigm for genes underlying the invasive behavior of glioma, a critical characteristic that contributes to poor clinical outcome for glioma patients, we identified p75^NTR as a central regulator of glioma invasion. Herein we review the expanding role that p75^NTR plays in glioma progression with an emphasis on how p75^NTR may contribute to the treatment refractory nature of glioma. Based on the observation that p75^NTR is expressed and functional in two critical glioma disease reservoirs, namely, the highly infiltrative cells that evade surgical resection, and the radiation- and chemotherapy-resistant brain tumor-initiating cells (also referred to as brain tumor stem cells), we propose that p75^NTR and its myriad of downstream signaling effectors represent rationale therapeutic targets for this devastating disease. Lastly, we provide the provocative hypothesis that, in addition to the well-documented cell autonomous signaling functions, the neurotrophins, and their respective receptors, contribute in a cell nonautonomous manner to drive the complex cellular and molecular composition of the brain tumor microenvironment, an environment that fuels tumorigenesis.

Impairment of blood brain barrier is related with the neuroinflammation induced peripheral immune status in intracerebroventricular colchicine injected rats: An experimental study with mannitol

The neurodegeneration in AD patients may be associated with changes of peripheral immune responses. Some peripheral immune responses are altered due to neuroinflammation in colchicine induced AD (cAD) rats. The leaky blood brain barrier (BBB) in cAD-rats may be involved in inducing peripheral inflammation, though there is no report in this regard. Therefore, the present study was designed to investigate the role of BBB in cADrats by altering the BBB in a time dependent manner with injection (i.v.) of mannitol (BBB opener). The inflammatory markers in the brain and serum along with the peripheral immune responses were measured after 30 and 60min of mannitol injection in cAD rats. The results showed higher inflammatory markers in the hippocampus and serum along with alterations in peripheral immune parameters in cAD rats. Although the hippocampal inflammatory markers did not further change after mannitol injection in cAD rats, the serum inflammatory markers and peripheral immune responses were altered and these changes were greater after 60min than that of 30min of mannitol injection. The present study shows that the peripheral immune responses in cAD rats after 30 and 60min of mannitol injection are related to magnitude of impairment of BBB in these conditions. It can be concluded from this study that impairment of BBB in cAD rats is related to the changes of peripheral immune responses observed in that condition.

Therapeutic strategies for Alzheimer's disease in clinical trials

Alzheimer's disease (AD) is considered to be the most common cause of dementia and is an incurable, progressive neurodegenerative disorder. Current treatment of the disease, essentially symptomatic, is based on three cholinesterase inhibitors and memantine, affecting the glutamatergic system. Since 2003, no new drugs have been approved for treatment of AD. This article presents current directions in the search for novel, potentially effective agents for the treatment of AD, as well as selected promising treatment strategies. These include agents acting upon the beta-amyloid, such as vaccines, antibodies and inhibitors or modulators of γ- and β-secretase; agents directed against the tau protein as well as compounds acting as antagonists of neurotransmitter systems (serotoninergic 5-HT6 and histaminergic H3). Ongoing clinical trials with Aβ antibodies (solanezumab, gantenerumab, crenezumab) seem to be promising, while vaccines against the tau protein (AADvac1 and ACI-35) are now in early-stage trials. Interesting results have also been achieved in trials involving small molecules such as inhibitors of β-secretase (MK-8931, E2609), a combination of 5-HT6 antagonist (idalopirdine) with donepezil, inhibition of advanced glycation end product receptors by azeliragon or modulation of the acetylcholine response of α-7 nicotinic acetylcholine receptors by encenicline. Development of new effective drugs acting upon the central nervous system is usually a difficult and time-consuming process, and in the case of AD to-date clinical trials have had a very high failure rate. Most phase II clinical trials ending with a positive outcome do not succeed in phase III, often due to serious adverse effects or lack of therapeutic efficacy.

Emerging roles of the γ-secretase-notch axis in inflammation

γ-Secretase is a distinct proteolytic complex required for the activation of many transmembrane proteins. The cleavage of substrates by γ-secretase plays diverse biological roles in producing essential products for the organism. More than 90 transmembrane proteins have been reported to be substrates of γ-secretase. Two of the most widely known and studied of these substrates are the amyloid precursor protein (APP) and the Notch receptor, which are precursors for the generation of amyloid-β (Aβ) and the Notch intracellular domain (NICD), respectively. The wide spectrum of γ-secretase substrates has made analyses of the pathology of γ-secretase-related diseases and underlying mechanisms challenging. Inflammation is an important aspect of disease pathology that requires an in-depth analysis. γ-Secretase may contribute to disease development or progression by directly increasing and regulating production of pro-inflammatory cytokines. This review summarizes recent evidence for a role of γ-secretase in inflammatory diseases, and discusses the potential use of γ-secretase inhibitors as an effective future treatment option.

[(3) H]-L685,458 binding sites are abundant in multiple peripheral organs in rats: implications for safety assessment of putative γ-secretase targeting drugs

γ-Secretase is a multimeric enzyme complex that carries out proteolytic processing to a variety of cellular proteins. It is currently explored as a therapeutic target for Alzheimer's disease (AD) and cancer. Mechanism-based toxicity needs to be thoroughly evaluated for γ-secretase inhibitory and/or modulatory drugs. This study comparatively assessed putative γ-secretase catalytic sites in rat peripheral tissues relative to brain and explored an effort of its pharmacological inhibition on hair regeneration. Using [(3) H]-labelled L685,458, a potent γ-secretase inhibitor, as probe, we found more abundant presence of γ-secretase binding sites in the liver, gastrointestinal tract, hair follicle, pituitary gland, ovary and testis, as compared to the brain. Local application of L658,458 delayed vibrissal regrowth following whisker removal. These results suggest that γ-secretase may execute important biological functions in many peripheral systems, as in the brain. The development of γ-secretase inhibitors/modulators for AD and cancer therapy should include close monitoring of toxicological panels for hepatic, gastrointestinal, endocrinal and reproductive functions.