Inhibitors in AKTion: ATP-competitive vs allosteric

Scaffold Hopping Method for Design and Development of Potential Allosteric AKT Inhibitors

Targeting AKT is a practical strategy for cancer therapy in many cancer types. Targeted inhibitors of AKT are attractive solutions for inhibiting the interconnected signaling pathways, like PI3K/Akt/mTOR. Allosteric inhibitors are more desirable among different classes of AKT inhibitors as they could be more specific with fewer off-target proteins. In this study, a ligand/structure-based pipeline was developed to design new allosteric AKT inhibitors by employing the core hopping method. Triciribine, a traditional allosteric AKT inhibitor was used as the template, and the FDA-approved kinase inhibitors for cancer treatment were considered as the cores. The allosteric site in the crystal structure of AKT1 was used to screen the designed compounds. The results were further evaluated using molecular docking, ADME/T analysis, molecular dynamics (MD) simulation, and binding free energy calculations. The outcomes introduced 24 newly designed inhibitors, amongst which three compounds C6, C20, and C16 showed remarkable binding affinity to AKT1. While the docking scores for triciribine was around - 8.6 kcal/mol, the docking scores of these compounds were about - 11 to - 13 kcal/mol. The MD results indicated that designed compounds target the essential residues of the PH domain and kinase domain of AKT, such as Trp80, Thr211, Tyr272, Asp274, and Asp292. Scaffold hopping is a tremendous tool for designing novel anti-cancer agents by improving already known and potential drug compounds. The designed compounds are worth to be examined by experimental investigation in vitro and in vivo.

Targeting the RAS upstream and downstream signaling pathway for cancer treatment

Cancer often involves the overactivation of RAS/RAF/MEK/ERK (MAPK) and PI3K-Akt-mTOR pathways due to mutations in genes like RAS, RAF, PTEN, and PIK3CA. Various strategies are employed to address the overactivation of these pathways, among which targeted therapy emerges as a promising approach. Directly targeting specific proteins, leads to encouraging results in cancer treatment. For instance, RTK inhibitors such as imatinib and afatinib selectively target these receptors, hindering ligand binding and reducing signaling initiation. These inhibitors have shown potent efficacy against Non-Small Cell Lung Cancer. Other inhibitors, like lonafarnib targeting Farnesyltransferase and GGTI 2418 targeting geranylgeranyl Transferase, disrupt post-translational modifications of proteins. Additionally, inhibition of proteins like SOS, SH2 domain, and Ras demonstrate promising anti-tumor activity both in vivo and in vitro. Targeting downstream components with RAF inhibitors such as vemurafenib, dabrafenib, and sorafenib, along with MEK inhibitors like trametinib and binimetinib, has shown promising outcomes in treating cancers with BRAF-V600E mutations, including myeloma, colorectal, and thyroid cancers. Furthermore, inhibitors of PI3K (e.g., apitolisib, copanlisib), AKT (e.g., ipatasertib, perifosine), and mTOR (e.g., sirolimus, temsirolimus) exhibit promising efficacy against various cancers such as Invasive Breast Cancer, Lymphoma, Neoplasms, and Hematological malignancies. This review offers an overview of small molecule inhibitors targeting specific proteins within the RAS upstream and downstream signaling pathways in cancer.

The impact of E3 ligase choice on PROTAC effectiveness in protein kinase degradation

Proteolysis targeting chimera (PROTACs) provide a novel therapeutic approach that is revolutionizing drug discovery. The success of PROTACs largely depends on the combination of their three fragments: E3 ligase ligand, linker and protein of interest (POI)-targeting ligand. We summarize the pivotal significance of the precise combination of the E3 ligase ligand with the POI-recruiting warhead, which is crucial for the successful execution of cellular processes and achieving the desired outcomes. Therefore, the key to our selection was the use of at least two ligands recruiting two different ligases. This approach enables a direct comparison of the impacts of the specific ligases on target degradation.

Identification of allosteric inhibitor against AKT1 through structure-based virtual screening

AKT (serine/threonine protein kinase) is a potential therapeutic target for many types of cancer as it plays a vital role in cancer progression. Many AKT inhibitors are already in practice under single and combinatorial therapy. However, most of these inhibitors are orthosteric / pan-AKT that are non-selective and non-specific to AKT kinase and their isoforms. Hence, researchers are searching for novel allosteric inhibitors that bind in the interface between pH and kinase domain. In this study, we performed structure-based virtual screening from the afroDB (a diverse natural compounds library) to find the potential inhibitor targeting the AKT1. These compounds were filtered through Lipinski, ADMET properties, combined with a molecular docking approach to obtain the 8 best compounds. Then we performed molecular dynamics simulation for apoprotein, AKT1 with 8 complexes, and AKT1 with the positive control (Miransertib). Molecular docking and simulation analysis revealed that Bianthracene III (hit 1), 10-acetonyl Knipholonecyclooxanthrone (hit 2), Abyssinoflavanone VII (hit 5) and 8-c-p-hydroxybenzyldiosmetin (hit 6) had a better binding affinity, stability, and compactness than the reference compound. Notably, hit 1, hit 2 and hit 5 had molecular features required for allosteric inhibition.

Inhibitors of phosphoinositide 3-kinase (PI3K) and phosphoinositide 3-kinase-related protein kinase family (PIKK)

Phosphoinositide 3-kinases (PI3K) and phosphoinositide 3-kinase-related protein kinases (PIKK) are two structurally related families of kinases that play vital roles in cell growth and DNA damage repair. Dysfunction of PIKK members and aberrant stimulation of the PI3K/AKT/mTOR signalling pathway are linked to a plethora of diseases including cancer. In recent decades, numerous inhibitors related to the PI3K/AKT/mTOR signalling have made great strides in cancer treatment, like copanlisib and sirolimus. Notably, most of the PIKK inhibitors (such as VX-970 and M3814) related to DNA damage response have also shown good efficacy in clinical trials. However, these drugs still require a suitable combination therapy to overcome drug resistance or improve antitumor activity. Based on the aforementioned facts, we summarised the efficacy of PIKK, PI3K, and AKT inhibitors in the therapy of human malignancies and the resistance mechanisms of targeted therapy, in order to provide deeper insights into cancer treatment.

Fc Epsilon RI-Neuroimmune Interplay in Pruritus Triggered by Particulate Matter in Atopic Dermatitis Patients

Atopic dermatitis (AD) is the most common chronic relapsing neuroinflammatory skin disease that is characterized by a complex and multifactorial pathophysiology. It reflects a profound interplay between genetic and environmental factors, and a recently disclosed neuroimmune dysregulation that drives skin barrier disruption, pruritus, and microbial imbalance. In terms of the key external environmental players that impact AD, air quality and itch severity linkage have been thoroughly researched. The impact of ambient air pollutants including particulate matter (PM) and AD pruritic exacerbation has been recorded despite reductions in air pollution levels in in developed countries. The developing countries have, on the contrary, experienced significant urbanization and industrialization with limited environmental protection standards in the past decades. This unprecedented construction, petrochemical industry utilization, and increment in population counts has been paired with consistent exposure to outdoor PM. This may present a key cause of AD pruritic exacerbation supported by the fact that AD prevalence has intensified globally in the past 50 years, indicating that environmental exposure may act as a trigger that could flare up itch in vulnerable persons. At the molecular level, the impact of PM on severe pruritus in AD could be interpreted by the toxic effects on the complex neuroimmune pathways that govern this disease. AD has been recently viewed as a manifestation of the disruption of both the immune and neurological systems. In light of these facts, this current review aims to introduce the basic concepts of itch sensory circuits in the neuroimmune system. In addition, it describes the impact of PM on the potential neuroimmune pathways in AD pathogenesis with a special focus on the Fc Epsilon RI pathway. Finally, the review proposes potential treatment lines that could be targeted to alleviate pruritus based on immune mediators involved in the Fc Epsilon signaling map.

Computer-Aided Identification of Kinase-Targeted Small Molecules for Cancer: A Review on AKT Protein

AKT (also known as PKB) is a serine/threonine kinase that plays a pivotal regulatory role in the PI3K/AKT/mTOR signaling pathway. Dysregulation of AKT activity, especially its hyperactivation, is closely associated with the development of various human cancers and resistance to chemotherapy. Over the years, a wide array of AKT inhibitors has been discovered through experimental and computational approaches. In this regard, herein we present a comprehensive overview of AKT inhibitors identified using computer-assisted drug design methodologies (including docking-based and pharmacophore-based virtual screening, machine learning, and quantitative structure-activity relationships) and successfully validated small molecules endowed with anticancer activity. Thus, this review provides valuable insights to support scientists focused on AKT inhibition for cancer treatment and suggests untapped directions for future computer-aided drug discovery efforts.

Molecular docking appraisal of Dysphania ambrosioides phytochemicals as potential inhibitor of a key triple-negative breast cancer driver gene

Triple-negative breast cancer (TNBC) is a lethal and aggressive breast cancer subtype. It is characterized by the deficient expression of the three main receptors implicated in breast cancers, making it unresponsive to hormone therapy. Hence, an existing need to develop a targeted molecular therapy for TNBC. The PI3K/AKT/mTOR signaling pathway mediates critical cellular processes, including cell proliferation, survival, and angiogenesis. It is activated in approximately 10-21% of TNBCs, emphasizing the importance of this intracellular target in TNBC treatment. AKT is a prominent driver of the PI3K/AKT/mTOR pathway, validating it as a promising therapeutic target. Dysphania ambrosioides is an important ingredient of Nigeria's traditional herbal recipe for cancer treatment. Thus, our present study explores its anticancer properties through a structure-based virtual screening of 25 biologically active compounds domiciled in the plant. Interestingly, our molecular docking study identified several potent inhibitors of AKT 1 and 2 isoforms from D. ambrosioides. However, cynaroside and epicatechin gallate having a binding energy of - 9.9 and - 10.2 kcal/mol for AKT 1 and 2, respectively, demonstrate considerable drug-likeness than the reference drug (capivasertib), whose respective binding strengths for AKT 1 and 2 are - 9.5 and - 8.4 kcal/mol. Lastly, the molecular dynamics simulation experiment showed that the simulated complex systems of the best hits exhibit structural stability throughout the 50 ns run. Together, our computational modeling analysis suggests that these compounds could emerge as efficacious drug candidates in the treatment of TNBC. Nevertheless, further experimental, translational, and clinical research is required to establish an empirical clinical application.

Graphical Abstract

A structure-based virtual screening and simulation of Dysphania ambrosioides phytochemicals in the active pocket of AKT 1 and 2 isoforms.

N-(2-ozoazepan-3-yl)-pyrrolidine-2-carboxamide, a novel Octopus vulgaris ink-derived metabolite, exhibits a pro-apoptotic effect on A549 cancer cell line and inhibits pro-inflammatory markers

This research aimed to chemically synthesize and evaluate the antiproliferative and anti-inflammatory potential of ozopromide (OPC), a novel compound recently isolated from O. vulgaris ink. After chemical synthesis, OPC structural characterization was confirmed by COSY2D, FTIR, and C-/H-NMR. OPC inhibited the growth of human breast (MDA-MB-231), prostate (22Rv1), cervix (HeLa), and lung (A549) cancerous cells, being the highest effect on the latter (IC₅₀: 53.70 μM). As confirmed by flow cytometry, OPC induced typical apoptosis-derived morphological features on A549 cells, mostly at early and late apoptosis stages. OPC generated a dose-dependent effect inhibiting IL-6 and IL-8 on LPS-stimulated peripheral mononuclear cells (PBMCs). A major affinity of OPC to Akt-1 and Bcl-2 proteins in silico agreed with the observed pro-apoptotic mechanisms. Results suggested that OPC has the potential to alleviate inflammation and be further studied for anticancer activity. Marine-derived food products such as ink contains bioactive metabolites exhibiting potential health benefits.

Novel Synthetic Derivative of Renieramycin T Right-Half Analog Induces Apoptosis and Inhibits Cancer Stem Cells via Targeting the Akt Signal in Lung Cancer Cells

Akt is a key regulatory protein of cancer stem cells (CSCs) and is responsible for cancer aggressiveness and metastasis. Targeting Akt is beneficial for the development of cancer drugs. renieramycin T (RT) has been reported to have Mcl-1 targeting activity, and the study of the structure-activity relationships (SARs) demonstrated that cyanide and the benzene ring are essential for its effects. In this study, novel derivatives of the RT right-half analog with cyanide and the modified ring were synthesized to further investigate the SARs for improving the anticancer effects of RT analogs and evaluate CSC-suppressing activity through Akt inhibition. Among the five derivatives, a compound with a substituted thiazole structure (DH_25) exerts the most potent anticancer activity in lung cancer cells. It has the ability to induce apoptosis, which is accompanied by an increase in PARP cleavage, a decrease in Bcl-2, and a diminishment of Mcl-1, suggesting that residual Mcl-1 inhibitory effects exist even after modifying the benzene ring to thiazole. Furthermore, DH_25 is found to induce CSC death, as well as a decrease in CSC marker CD133, CSC transcription factor Nanog, and CSC-related oncoprotein c-Myc. Notably, an upstream member of these proteins, Akt and p-Akt, are also downregulated, indicating that Akt can be a potential target of action. Computational molecular docking showing a high-affinity interaction between DH_25 and an Akt at the allosteric binding site supports that DH_25 can bind and inhibit Akt. This study has revealed a novel SAR and CSC inhibitory effect of DH_25 via Akt inhibition, which may encourage further development of RT compounds for cancer therapy.

Combined treatments with AZD5363, AZD8542, curcumin or resveratrol induce death of human glioblastoma cells by suppressing the PI3K/AKT and SHH signaling pathways

Glioblastoma (GBM) is a very aggressive tumor that presents vascularization, necrosis and is resistant to chemotherapy and radiotherapy. Current treatments are not effective eradicating GBM, thus, there is an urgent need to develop novel therapeutic strategies against GBM. AZD5363, AZD8542, curcumin and resveratrol, are widely studied for the treatment of cancer and in the present study we explored the effects of the administration of combined treatments with AZD5363, AZD8542, curcumin or resveratrol on human GBM cells. We found that the combined treatments with AZD5363+AZD8542+Curcumin and AZD8542+Curcumin+Resveratrol inhibit the PI3K/AKT and SHH survival pathways by decreasing the activity of AKT, the reduction of the expression of SMO, pP70S6k, pS6k, GLI1, p21 and p27, and the activation of caspase-3 as a marker of apoptosis. These results provide evidence that the combined treatments AZD5363+AZD8542+Curcumin and AZD8542+Curcumin+Resveratrol have the potential to be an interesting option against GBM.

Safety Profile of Ipatasertib Plus Abiraterone vs Placebo Plus Abiraterone in Metastatic Castration-resistant Prostate Cancer

PURPOSE

Adding ipatasertib to abiraterone and prednisone/prednisolone significantly improved radiographic progression-free survival for patients with metastatic castration-resistant prostate cancer (mCRPC) with PTEN-loss tumours by immunohistochemistry in the IPATential150 trial (NCT03072238). Here we characterise the safety of these agents in subpopulations and assess manageability of key adverse events (AEs).

MATERIALS AND METHODS

In this randomised, double-blind, phase 3 trial, patients with previously untreated asymptomatic or mildly symptomatic mCRPC were randomised 1:1 to receive ipatasertib-abiraterone or placebo-abiraterone (all with prednisone/prednisolone). AEs were analysed, focusing on key AEs of diarrhoea, hyperglycaemia, rash and transaminase increased.

RESULTS

1097 patients received study medication and were assessed for safety (47% with PTEN-loss tumours by immunohistochemistry and 20% were Asian). Ipatasertib was associated with increased Grade 3/4 AEs and AEs leading to treatment discontinuation vs placebo. The rate of discontinuation of ipatasertib was 18% in patients with PTEN-loss and 21% overall. The frequencies of all-grade, Grade 3/4 and serious AEs were similar between the PTEN-loss and overall populations. Diarrhoea, hyperglycaemia, rash and transaminase elevation were more frequent in ipatasertib-treated patients, appearing rapidly after treatment initiation (median onset: 8-43 days for ipatasertib arm and 56-104 days for placebo). The ipatasertib discontinuation rate was 32% and 18% in Asian and non-Asian patients, respectively, despite similar baseline characteristics and Grade 3/4 AE frequencies between groups.

CONCLUSIONS

Ipatasertib plus abiraterone had an overall tolerable safety profile consistent with known toxicities. More AEs leading to drug discontinuation were observed with ipatasertib than placebo, but incidence would likely be lessened with prophylactic measures.

In silico drug screen reveals potential competitive MTHFR inhibitors for clinical repurposing

MTHFR (Methylenetetrahydrofolate reductase) is a pivotal enzyme involved in one-carbon metabolism, which is critical for the proliferation of cancer cells. In line with this, published literature showed that MTHFR knockdown caused impaired growth of multiple types of cancer cells. Moreover, higher MTHFR expression levels were linked to shorter overall survival in hepatocellular carcinoma, adrenocortical carcinoma, and low-grade glioma, bringing the need to design MTHFR inhibitors as a possible treatment option. No competitive inhibitors of MTHFR have been reported as of today. This study aimed to identify potential competitive MTHFR inhibitor candidates using an in silico drug screen. A total of 30470 molecules containing biogenic compounds, FDA-approved drugs, and those in clinical trials were screened against the catalytic pocket of MTHFR in the presence and absence of cofactors. Binding energy and ADMET analysis revealed that Vilanterol (β2-adrenergic agonist), Selexipag (prostacyclin receptor agonist), and Ramipril Diketopiperazine (ACE inhibitor) are potential competitive inhibitors of MTHFR. Molecular dynamics analyses and MM-PBSA calculations with these compounds particularly revealed the amino acids between 285-290 for ligand binding and highlighted Vilanterol as the strongest candidate for MTHFR inhibition. Our results could guide the development of novel MTHFR inhibitor compounds, which could be inspired by the drugs brought into the spotlight here. More importantly, these potential candidates could be quhickly tested as a repurposing strategy in pre-clinical and clinical studies of the cancers mentioned above.Communicated by Ramaswamy H. Sarma.

Targeting the PI3K/AKT/mTOR Signaling Pathway in the Treatment of Human Diseases: Current Status, Trends, and Solutions

The phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathway is one of the most important intracellular pathways involved in cell proliferation, growth, differentiation, and survival. Therefore, this route is a prospective biological target for treating various human diseases, such as tumors, neurodegenerative diseases, pulmonary fibrosis, and diabetes. An increasing number of clinical studies emphasize the necessity of developing novel molecules targeting the PI3K/AKT/mTOR pathway. This review focuses on recent advances in ATP-competitive inhibitors, allosteric inhibitors, covalent inhibitors, and proteolysis-targeting chimeras against the PI3K/AKT/mTOR pathway, and highlights possible solutions for overcoming the toxicities and acquired drug resistance of currently available drugs. We also provide recommendations for the future design and development of promising drugs targeting this pathway.

From Serendipity to Rational Identification of the 5,6,7,8-Tetrahydrobenzo[4,5]thieno[2,3-d]pyrimidin-4(3H)-one Core as a New Chemotype of AKT1 Inhibitors for Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is a heterogeneous hematopoietic malignancy whose prognosis is globally poor. In more than 60% of AML patients, the PI3K/AKTs/mTOR signaling pathway is aberrantly activated because of oncogenic driver alterations and further enhanced by chemotherapy as a mechanism of drug resistance. Against this backdrop, very recently we have started a multidisciplinary research project focused on AKT1 as a pharmacological target to identify novel anti-AML agents. Indeed, the serendipitous finding of the in-house compound T187 as an AKT1 inhibitor has paved the way to the rational identification of new active small molecules, among which T126 has emerged as the most interesting compound with IC₅₀ = 1.99 ± 0.11 μM, ligand efficiency of 0.35, and a clear effect at low micromolar concentrations on growth inhibition and induction of apoptosis in AML cells. The collected results together with preliminary SAR data strongly indicate that the 5,6,7,8-tetrahydrobenzo[4,5]thieno[2,3-d]pyrimidin-4(3H)-one derivative T126 is worthy of future biological experiments and medicinal chemistry efforts aimed at developing a novel chemical class of AKT1 inhibitors as anti-AML agents.

Novel therapeutic approaches in GEP-NETs based on genetic and epigenetic alterations

Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are heterogeneous malignancies with distinct prognosis based on primary tumor localization, grade, stage and functionality. Surgery remains the only curative option in localized tumors, but systemic therapy is the mainstay of treatment for patients with advanced disease. For decades, the therapeutic landscape of GEP-NETs was limited to chemotherapy regimens with low response rates. The arrival of novel agents such as somatostatin analogues, peptide receptor radionuclide therapy, tyrosine kinase inhibitors or mTOR-targeted drugs, has changed the therapeutic paradigm of GEP-NETs. However, the efficacy of these agents is limited in time and there is scarce knowledge of optimal treatment sequencing. In recent years, massive parallel sequencing techniques have started to unravel the genomic intricacies of these tumors, allowing us to better understand the mechanisms of resistance to current treatments and to develop new targeted agents that will hopefully start an era for personalized treatment in NETs. In this review we aim to summarize the most relevant genomic aberrations and signaling pathways underlying GEP-NET tumorigenesis and potential therapeutic strategies derived from them.

Targeting Akt/PKB in pediatric tumors: A review from preclinical to clinical trials

The serine/threonine kinase Akt is a major player in the phosphoinositide 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) signaling pathway, and its modulation impacts multiple cellular processes such as growth, proliferation, and survival. Several abnormalities in this pathway have been documented over the years, and these alterations were shown to have great implications in tumorigenesis and resistance to chemotherapy. Thus, multiple Akt inhibitors have been developed and tested in adult tumors, and some of them are currently undergoing phase I, II, and III clinical trials for distinct cancers that arise during adulthood. Despite that, the impact of these inhibitors is still not fully understood in pediatric tumors, and Akt-specific targeting seems to be a promising approach to treat children affected by cancers. This review summarizes recent available evidence of Akt inhibitors in pediatric cancers, from both preclinical and clinical studies. In short, we demonstrate the impact that Akt inhibition provides in tumorigenesis, and we suggest targeting the PI3K/Akt/mTOR signaling pathway, alone or in combination with other inhibitors, is a feasible tool to achieve better outcomes in pediatric tumors.

Studies on Biological and Molecular Effects of Small-Molecule Kinase Inhibitors on Human Glioblastoma Cells and Organotypic Brain Slices

Glioblastoma is the most common and aggressive primary brain tumor. Multiple genetic and epigenetic alterations in several major signaling pathways—including the phosphoinositide 3-kinases (PI3K)/AKT/mTOR and the Raf/MEK/ERK pathway—could be found. We therefore aimed to investigate the biological and molecular effects of small-molecule kinase inhibitors that may interfere with those pathways. For this purpose, patient-derived glioblastoma cells were challenged with dactolisib, ipatasertib, MK-2206, regorafenib, or trametinib. To determine the effects of the small-molecule kinase inhibitors, assays of cell proliferation and apoptosis and immunoblot analyses were performed. To further investigate the effects of ipatasertib on organotypic brain slices harboring glioblastoma cells, the tumor growth was estimated. In addition, the network activity in brain slices was assessed by electrophysiological field potential recordings. Multi-kinase inhibitor regorafenib and both MK-2206 and dactolisib were very effective in all preclinical tumor models, while with respect to trametinib, two cell lines were found to be highly resistant. Only in HROG05 cells, ipatasertib showed anti-tumoral effects in vitro and in organotypic brain slices. Additionally, ipatasertib diminished synchronous network activity in organotypic brain slices. Overall, our data suggest that ipatasertib was only effective in selected tumor models, while especially regorafenib and MK-2206 presented a uniform response pattern.

TIRAP/Mal Positively Regulates TLR8-Mediated Signaling via IRF5 in Human Cells

Toll-like receptor 8 (TLR8) recognizes single-stranded RNA of viral and bacterial origin as well as mediates the secretion of pro-inflammatory cytokines and type I interferons by human monocytes and macrophages. TLR8, as other endosomal TLRs, utilizes the MyD88 adaptor protein for initiation of signaling from endosomes. Here, we addressed the potential role of the Toll-interleukin 1 receptor domain-containing adaptor protein (TIRAP) in the regulation of TLR8 signaling in human primary monocyte-derived macrophages (MDMs). To accomplish this, we performed TIRAP gene silencing, followed by the stimulation of cells with synthetic ligands or live bacteria. Cytokine-gene expression and secretion were analyzed by quantitative PCR or Bioplex assays, respectively, while nuclear translocation of transcription factors was addressed by immunofluorescence and imaging, as well as by cell fractionation and immunoblotting. Immunoprecipitation and Akt inhibitors were also used to dissect the signaling mechanisms. Overall, we show that TIRAP is recruited to the TLR8 Myddosome signaling complex, where TIRAP contributes to Akt-kinase activation and the nuclear translocation of interferon regulatory factor 5 (IRF5). Recruitment of TIRAP to the TLR8 signaling complex promotes the expression and secretion of the IRF5-dependent cytokines IFNβ and IL-12p70 as well as, to a lesser degree, TNF. These findings reveal a new and unconventional role of TIRAP in innate immune defense.

Covalent Allosteric Inhibitors of Akt Generated Using a Click Fragment Approach

Akt is a protein kinase that has been implicated in the progression of cancerous tumours. A number of covalent allosteric Akt inhibitors are known, and based on these scaffolds, a small library of novel potential covalent allosteric imidazopyridine-based inhibitors was designed. The envisaged compounds were synthesised, with click chemistry enabling a modular approach to a number of the target compounds. The binding modes, potencies and antiproliferative activities of these synthesised compounds were explored, thereby furthering the structure activity relationship knowledge of this class of Akt inhibitors. Three novel covalent inhibitors were identified, exhibiting moderate activity against Akt1 and various cancer cell lines, potentially paving the way for future covalent allosteric inhibitors with improved properties.

Galvanotactic Migration of Glioblastoma and Brain Metastases Cells

Galvanotaxis, the migration along direct current electrical fields, may contribute to the invasion of brain cancer cells in the tumor-surrounding tissue. We hypothesized that pharmacological perturbation of the epidermal growth factor (EGF) receptor and downstream phosphatidylinositol 3-kinase (PI3K)/AKT pathway prevent galvanotactic migration. In our study, patient-derived glioblastoma and brain metastases cells were exposed to direct current electrical field conditions. Velocity and direction of migration were estimated. To determine the effects of EGF receptor antagonist afatinib and AKT inhibitor capivasertib, assays of cell proliferation, apoptosis and immunoblot analyses were performed. Both inhibitors attenuated cell proliferation in a dose-dependent manner and induced apoptosis. We found that most of the glioblastoma cells migrated preferentially in an anodal direction, while brain metastases cells were unaffected by direct current stimulations. Afatinib presented only a mild attenuation of galvanotaxis. In contrast, capivasertib abolished the migration of glioblastoma cells without genetic alterations in the PI3K/AKT pathway, but not in cells harboring PTEN mutation. In these cells, an increase in the activation of ERK1/2 may in part substitute the inhibition of the AKT pathway. Overall, our data demonstrate that glioblastoma cells migrate in the electrical field and the PI3K/AKT pathway was found to be highly involved in galvanotaxis.

The role of PI3'-lipid signalling in melanoma initiation, progression and maintenance

Phosphatidylinositol-3'-kinases (PI3Ks) are a family of lipid kinases that phosphorylate the 3' hydroxyl (OH) of the inositol ring of phosphatidylinositides (PI). Through their downstream effectors, PI3K generated lipids (PI3K-lipids hereafter) such as PI(3,4,5)P3 and PI(3,4)P2 regulate myriad biochemical and biological processes in both normal and cancer cells including responses to growth hormones and cytokines; the cell division cycle; cell death; cellular growth; angiogenesis; membrane dynamics; and autophagy and many aspects of cellular metabolism. Engagement of receptor tyrosine kinase by their cognate ligands leads to activation of members of the Class I family of PI3'-kinases (PI3Kα, β, δ & γ) leading to accumulation of PI3K-lipids. Importantly, PI3K-lipid accumulation is antagonized by the hydrolytic action of a number of PI3K-lipid phosphatases, most notably the melanoma suppressor PTEN (lipid phosphatase and tensin homologue). Downstream of PI3K-lipid production, the protein kinases AKT1-3 are believed to be key effectors of PI3'-kinase signalling in cells. Indeed, in preclinical models, activation of the PI3K→AKT signalling axis cooperates with alterations such as expression of the BRAFV600E oncoprotein kinase to promote melanoma progression and metastasis. In this review, we describe the different classes of PI3K-lipid effectors, and how they may promote melanomagenesis, influence the tumour microenvironment, melanoma maintenance and progression to metastatic disease. We also provide an update on both FDA-approved or experimental inhibitors of the PI3K→AKT pathway that are currently being evaluated for the treatment of melanoma either in preclinical models or in clinical trials.

Aurora A and AKT Kinase Signaling Associated with Primary Cilia

Dysregulation of kinase signaling is associated with various pathological conditions, including cancer, inflammation, and autoimmunity; consequently, the kinases involved have become major therapeutic targets. While kinase signaling pathways play crucial roles in multiple cellular processes, the precise manner in which their dysregulation contributes to disease is dependent on the context; for example, the cell/tissue type or subcellular localization of the kinase or substrate. Thus, context-selective targeting of dysregulated kinases may serve to increase the therapeutic specificity while reducing off-target adverse effects. Primary cilia are antenna-like structures that extend from the plasma membrane and function by detecting extracellular cues and transducing signals into the cell. Cilia formation and signaling are dynamically regulated through context-dependent mechanisms; as such, dysregulation of primary cilia contributes to disease in a variety of ways. Here, we review the involvement of primary cilia-associated signaling through aurora A and AKT kinases with respect to cancer, obesity, and other ciliopathies.

Emergence of mTOR mutation as an acquired resistance mechanism to AKT inhibition, and subsequent response to mTORC1/2 inhibition

Acquired resistance to molecular targeted therapy is a significant challenge of the precision medicine era. The ability to understand these mechanisms of resistance may improve patient selection and allow for the development of rationally designed next-line or combination treatment strategies and improved patient outcomes. AKT is a critical effector of the phosphoinositide 3-kinase signaling cascade, one of the most commonly activated pathways in human cancer. Deregulation of signaling pathways, such as RAF/MEK/ERK are previously described mechanisms of resistance to AKT/PI3K inhibitors. Mutations in the mTOR gene, however, are exceedingly rare. We present a case of acquired mTOR resistance, following targeted AKT inhibition, and subsequent response to mTOR1/2 inhibitor in a patient with metastatic endometrial cancer, the first documented response to ATP-competitive mTOR inhibition in this setting. This case supports mTOR mutation as a mechanism of resistance, and underscores the importance of tumor molecular profiling, exemplifying precision medicine in action.

Clinical Development of AKT Inhibitors and Associated Predictive Biomarkers to Guide Patient Treatment in Cancer Medicine

The serine/threonine kinase AKT is a critical effector of the phosphoinositide 3-kinase (PI3K) signaling cascade and has a pivotal role in cell growth, proliferation, survival, and metabolism. AKT is one of the most commonly activated pathways in human cancer and dysregulation of AKT-dependent pathways is associated with the development and maintenance of a range of solid tumors. There are multiple small-molecule inhibitors targeting different components of the PI3K/AKT pathway currently at various stages of clinical development, in addition to new combination strategies aiming to boost the therapeutic efficacy of these drugs. Correlative and translational studies have been undertaken in the context of clinical trials investigating AKT inhibitors, however the identification of predictive biomarkers of response and resistance to AKT inhibition remains an unmet need. In this review, we discuss the biological function and activation of AKT, discuss its contribution to tumor development and progression, and review the efficacy and toxicity data from clinical trials, including both AKT inhibitor monotherapy and combination strategies with other agents. We also discuss the promise and challenges associated with the development of AKT inhibitors and associated predictive biomarkers of response and resistance.

Targeting Akt in cancer for precision therapy

Biomarkers-guided precision therapeutics has revolutionized the clinical development and administration of molecular-targeted anticancer agents. Tailored precision cancer therapy exhibits better response rate compared to unselective treatment. Protein kinases have critical roles in cell signaling, metabolism, proliferation, survival and migration. Aberrant activation of protein kinases is critical for tumor growth and progression. Hence, protein kinases are key targets for molecular targeted cancer therapy. The serine/threonine kinase Akt is frequently activated in various types of cancer. Activation of Akt promotes tumor progression and drug resistance. Since the first Akt inhibitor was reported in 2000, many Akt inhibitors have been developed and evaluated in either early or late stage of clinical trials, which take advantage of liquid biopsy and genomic or molecular profiling to realize personalized cancer therapy. Two inhibitors, capivasertib and ipatasertib, are being tested in phase III clinical trials for cancer therapy. Here, we highlight recent progress of Akt signaling pathway, review the up-to-date data from clinical studies of Akt inhibitors and discuss the potential biomarkers that may help personalized treatment of cancer with Akt inhibitors. In addition, we also discuss how Akt may confer the vulnerability of cancer cells to some kinds of anticancer agents.

Targeting the PI3K/AKT/mTOR Signaling Pathway in Lung Cancer: An Update Regarding Potential Drugs and Natural Products

Lung cancer is one of the most common cancers and has a high mortality rate. Due to its high incidence, the clinical management of the disease remains a major challenge. Several reports have documented a relationship between the phosphatidylinositol-3-kinase (PI3K)/ protein kinase B (AKT)/ mammalian target of rapamycin (mTOR) pathway and lung cancer. The recognition of this pathway as a notable therapeutic target in lung cancer is mainly due to its central involvement in the initiation and progression of the disease. Interest in using natural and synthetic medications to target these signaling pathways has increased in recent years, with promising results in vitro, in vivo, and in clinical trials. In this review, we focus on the current understanding of PI3K/AKT/mTOR signaling in tumor development. In addition to the signaling pathway, we highlighted the therapeutic potential of recently developed PI3K/AKT/mTOR inhibitors based on preclinical and clinical trials.