Discovery of a dual Ras and ARF6 inhibitor from a GPCR endocytosis screen

Structural insights, regulation, and recent advances of RAS inhibitors in the MAPK signaling cascade: a medicinal chemistry perspective

The MAPK pathway has four main components: RAS, RAF, MEK, and ERK. Among these, RAS is the most frequently mutated protein and the leading cause of cancer. The three isoforms of the RAS gene are HRAS, NRAS, and KRAS. The KRAS gene is characterized by two splice variants, K-Ras4A and K-Ras4B. The occurrence of cancer often involves a mutation in both KRAS4A and KRAS4B. In this study, we have elucidated the mechanism of the RAS protein complex and the movement of switches I and II. Only two RAS inhibitors, sotorasib and adagrasib, have been approved by the FDA, and several are in clinical trials. This review comprises recent developments in synthetic RAS inhibitors, their unique properties, their importance in inhibiting RAS mutations, and the current challenges in developing new RAS inhibitors. This review will undoubtedly help researchers design novel RAS inhibitors.

Nucleolin in the cell membrane promotes Ang II-mediated VSMC phenotypic switching by regulating the AT1R internalization function : Nucleolin promotes Ang II-mediated VSMC phenotypic switching

BACKGROUND

Nucleolin (NCL) plays an important regulatory role in angiotensin II (Ang II)-induced phenotypic switching of vascular smooth muscle cells (VSMCs). The aim of this study was to discuss its potential regulatory mechanisms.

RESULTS

We investigated if the pathways involving Ang II type 1 receptor (AT1R) and PKC/MAPK are responsible for Ang II's effects on VSMC phenotypic switching. Ang II upregulated NCL expression and activated the PKC/MAPK signaling pathway to induce VSMC phenotypic switching. In addition, Ang II promoted the translocation of NCL from the nucleus to the cell membrane. NCL was shown to bind to AT1R, whereas the binding of NCL to AT1R was greatly attenuated after the deletion of the GAR region. In addition, when peptide-N-glycosidase F (PNGase F) was applied, the N-glycosylation of NCL protein and the phenotypic switching of VSMC were inhibited. Ang II-induced AT1R internalization, whereas overexpression of NCL delayed Ang II-induced AT1R internalization by inhibiting AT1R phosphorylation and recruited Rab4 and Rab11 to promote recycling, and knockdown of NCL showed the opposite effect and reversal of AT1R binding by the use of rasarfin reversed the effects of sh-NCL. In in vivo experiments, knockdown of NCL expression inhibited Ang II-induced blood pressure rise and vasculopathy.

CONCLUSIONS

Our study demonstrates that NCL promotes Ang II-mediated phenotypic switching of VSMCs by regulating AT1R internalization function.

In silico approaches for drug repurposing in oncology: a scoping review

Introduction: Cancer refers to a group of diseases characterized by the uncontrolled growth and spread of abnormal cells in the body. Due to its complexity, it has been hard to find an ideal medicine to treat all cancer types, although there is an urgent need for it. However, the cost of developing a new drug is high and time-consuming. In this sense, drug repurposing (DR) can hasten drug discovery by giving existing drugs new disease indications. Many computational methods have been applied to achieve DR, but just a few have succeeded. Therefore, this review aims to show in silico DR approaches and the gap between these strategies and their ultimate application in oncology. Methods: The scoping review was conducted according to the Arksey and O'Malley framework and the Joanna Briggs Institute recommendations. Relevant studies were identified through electronic searching of PubMed/MEDLINE, Embase, Scopus, and Web of Science databases, as well as the grey literature. We included peer-reviewed research articles involving in silico strategies applied to drug repurposing in oncology, published between 1 January 2003, and 31 December 2021. Results: We identified 238 studies for inclusion in the review. Most studies revealed that the United States, India, China, South Korea, and Italy are top publishers. Regarding cancer types, breast cancer, lymphomas and leukemias, lung, colorectal, and prostate cancer are the top investigated. Additionally, most studies solely used computational methods, and just a few assessed more complex scientific models. Lastly, molecular modeling, which includes molecular docking and molecular dynamics simulations, was the most frequently used method, followed by signature-, Machine Learning-, and network-based strategies. Discussion: DR is a trending opportunity but still demands extensive testing to ensure its safety and efficacy for the new indications. Finally, implementing DR can be challenging due to various factors, including lack of quality data, patient populations, cost, intellectual property issues, market considerations, and regulatory requirements. Despite all the hurdles, DR remains an exciting strategy for identifying new treatments for numerous diseases, including cancer types, and giving patients faster access to new medications.

A slow but steady nanoLuc: R162A mutation results in a decreased, but stable, nanoLuc activity

NanoLuc (NLuc) luciferase has found extensive application in designing a range of biological assays, including gene expression analysis, protein-protein interaction, and protein conformational changes due to its enhanced brightness and small size. However, questions related to its mechanism of interaction with the substrate, furimazine, as well as bioluminescence activity remain elusive. Here, we combined molecular dynamics (MD) simulation and mutational analysis to show that the R162A mutation results in a decreased but stable bioluminescence activity of NLuc in living cells and in vitro. Specifically, we performed multiple, all-atom, explicit solvent MD simulations of the apo and furimazine-docked (holo) NLuc structures revealing differential dynamics of the protein in the absence and presence of the ligand. Further, analysis of trajectories for hydrogen bonds (H-bonds) formed between NLuc and furimazine revealed substantial H-bond interaction between R162 and Q32 residues. Mutation of the two residues in NLuc revealed a decreased but stable activity of the R162A, but not Q32A, mutant NLuc in live cell and in vitro assays performed using lysates prepared from cells expressing the proteins and with the furimazine substrate. In addition to highlighting the role of the R162 residue in NLuc activity, we believe that the mutant NLuc will find wide application in designing in vitro assays requiring extended monitoring of NLuc bioluminescence activity. SIGNIFICANCE: Bioluminescence has been extensively utilized in developing a variety of biological and biomedical assays. In this regard, engineering of brighter bioluminescent proteins, i.e. luciferases, has played a significant role. This is acutely exemplified by the engineering of the NLuc luciferase, which is small in size and displays much enhanced bioluminescence and thermal stability compared to previously available luciferases. While enhanced bioluminescent activity is desirable in a multitude of biological and biomedical assays, it would also be useful to develop variants of the protein that display a prolonged bioluminescence activity. This is specifically relevant in designing assays that require bioluminescence for extended periods, such as in the case of biosensors designed for monitoring slow enzymatic or cellular signaling reactions, without necessitating multiple rounds of luciferase substrate addition or any specialized reagents that result in increased assay costs. In the current manuscript, we report a mutant NLuc that possesses a stable and prolonged bioluminescence activity, albeit lower than the wild-type NLuc, and envisage a wider application of the mutant NLuc in designing biosensors for monitoring slower biological and biomedical events.

Membrane trafficking alterations in breast cancer progression

Breast cancer (BC) is the most common type of cancer in women, and remains one of the major causes of death in women worldwide. It is now well established that alterations in membrane trafficking are implicated in BC progression. Indeed, membrane trafficking pathways regulate BC cell proliferation, migration, invasion, and metastasis. The 22 members of the ADP-ribosylation factor (ARF) and the >60 members of the rat sarcoma (RAS)-related in brain (RAB) families of small GTP-binding proteins (GTPases), which belong to the RAS superfamily, are master regulators of membrane trafficking pathways. ARF-like (ARL) subfamily members are involved in various processes, including vesicle budding and cargo selection. Moreover, ARFs regulate cytoskeleton organization and signal transduction. RABs are key regulators of all steps of membrane trafficking. Interestingly, the activity and/or expression of some of these proteins is found dysregulated in BC. Here, we review how the processes regulated by ARFs and RABs are subverted in BC, including secretion/exocytosis, endocytosis/recycling, autophagy/lysosome trafficking, cytoskeleton dynamics, integrin-mediated signaling, among others. Thus, we provide a comprehensive overview of the roles played by ARF and RAB family members, as well as their regulators in BC progression, aiming to lay the foundation for future research in this field. This research should focus on further dissecting the molecular mechanisms regulated by ARFs and RABs that are subverted in BC, and exploring their use as therapeutic targets or prognostic markers.

Arf6 as a therapeutic target: Structure, mechanism, and inhibitors

ADP-ribosylation factor 6 (Arf6), a small G-protein of the Ras superfamily, plays pivotal roles in multiple cellular events, including exocytosis, endocytosis, actin remodeling, plasma membrane reorganization and vesicular transport. Arf6 regulates the progression of cancer through the activation of cell motility and invasion. Aberrant Arf6 activation is a potential therapeutic target. This review aims to understand the comprehensive function of Arf6 for future cancer therapy. The Arf6 GEFs, protein structure, and roles in cancer have been summarized. Comprehending the mechanism underlying Arf6-mediated cancer cell growth and survival is essential. The structural features of Arf6 and its efforts are discussed and may be contributed to the discovery of future novel protein-protein interaction inhibitors. In addition, Arf6 inhibitors and mechanism of action are listed in the table. This review further emphasizes the crucial roles in drug resistance and attempts to offer an outlook of Arf6 in cancer therapy.

m6A demethylase ALKBH5 attenuates doxorubicin-induced cardiotoxicity via posttranscriptional stabilization of Rasal3

The clinical application of anthracyclines such as doxorubicin (DOX) is limited due to their cardiotoxicity. N6-methyladenosine (m⁶A) plays an essential role in numerous biological processes. However, the roles of m⁶A and m⁶A demethylase ALKBH5 in DOX-induced cardiotoxicity (DIC) remain unclear. In this research, DIC models were constructed using Alkbh5-knockout (KO), Alkbh5-knockin (KI), and Alkbh5-myocardial-specific knockout (ALKBH5^{flox/flox, αMyHC-Cre}) mice. Cardiac function and DOX-mediated signal transduction were investigated. As a result, both Alkbh5 whole-body KO and myocardial-specific KO mice had increased mortality, decreased cardiac function, and aggravated DIC injury with severe myocardial mitochondrial damage. Conversely, ALKBH5 overexpression alleviated DOX-mediated mitochondrial injury, increased survival, and improved myocardial function. Mechanistically, ALKBH5 regulated the expression of Rasal3 in an m⁶A-dependent manner through posttranscriptional mRNA regulation and reduced Rasal3 mRNA stability, thus activating RAS3, inhibiting apoptosis through the RAS/RAF/ERK signaling pathway, and alleviating DIC injury. These findings indicate the potential therapeutic effect of ALKBH5 on DIC.

Daily Brief Heat Therapy Reduces Seizures in A350V IQSEC2 Mice and Is Associated with Correction of AMPA Receptor-Mediated Synaptic Dysfunction

Purposeful induction of fever for healing, including the treatment of epilepsy, was used over 2000 years ago by Hippocrates. More recently, fever has been demonstrated to rescue behavioral abnormalities in children with autism. However, the mechanism of fever benefit has remained elusive due in large part to the lack of appropriate human disease models recapitulating the fever effect. Pathological mutations in the IQSEC2 gene are frequently seen in children presenting with intellectual disability, autism and epilepsy. We recently described a murine A350V IQSEC2 disease model, which recapitulates important aspects of the human A350V IQSEC2 disease phenotype and the favorable response to a prolonged and sustained rise in body core temperature in a child with the mutation. Our goal has been to use this system to understand the mechanism of fever benefit and then develop drugs that can mimic this effect and reduce IQSEC2-associated morbidity. In this study, we first demonstrate a reduction in seizures in the mouse model following brief periods of heat therapy, similar to what was observed in a child with the mutation. We then show that brief heat therapy is associated with the correction of synaptic dysfunction in neuronal cultures of A350V mice, likely mediated by Arf6-GTP.

The Application of High-Throughput Approaches in Identifying Novel Therapeutic Targets and Agents to Treat Diabetes

During the past decades, unprecedented progress in technologies has revolutionized traditional research methodologies. Among these, advances in high-throughput drug screening approaches have permitted the rapid identification of potential therapeutic agents from drug libraries that contain thousands or millions of molecules. Moreover, high-throughput-based therapeutic target discovery strategies can comprehensively interrogate relationships between biomolecules (e.g., gene, RNA, and protein) and diseases and significantly increase the authors' knowledge of disease mechanisms. Diabetes is a chronic disease primarily characterized by the incapacity of the body to maintain normoglycemia. The prevalence of diabetes in modern society has become a severe public health issue that threatens the well-being of millions of patients. Although a number of pharmacological treatments are available, there is no permanent cure for diabetes, and discovering novel therapeutic targets and agents continues to be an urgent need. The present review discusses the technical details of high-throughput screening approaches in drug discovery, followed by introducing the applications of such approaches to diabetes research. This review aims to provide an example of the applicability of high-throughput technologies in facilitating different aspects of disease research.

Aldosterone breakthrough from a pharmacological perspective

Aldosterone (Aldo) breakthrough is a well-known phenomenon that occurs in patients with long-term renin-angiotensin aldosterone system (RAAS) blockade using inhibitors of renin or angiotensin converting enzyme or angiotensin II type 1 receptor blockers. The blockade of the mineralocorticoid receptor (MR), an Aldo binding receptor, is effective in managing patients with resistant hypertension, defined as uncontrollable blood pressure despite the concurrent use of three antihypertensive drugs. In other words, MR inhibitors are not used as first-line antihypertensive drugs in most guidelines for hypertension management. Aldo breakthrough puts hypertensive patients at higher risk of cardiovascular disease and worsens future outcomes. This review discusses Aldo secretion and the mechanism of Aldo breakthrough, dependent or independent of the RAAS, with consideration of the pharmacological aspects of this phenomenon, as well as hypothetical views.