PI3Kγ Inhibitors Research Articles

Integration of Consensus‐Based Pharmacophore Mapping and Molecular Docking in Sequential Virtual Screening: Toward the Discovery of Novel PI3Kγ Inhibitors

AbstractNumerous research studies have demonstrated the significant correlation of phosphatidylinositol‐3 kinase gamma (PI3Kγ) with the onset and progression of various human diseases, highlighting PI3Kγ as a promising therapeutic target. However, PI3Kγ demonstrates considerable similarity with other isoforms in the PI3K family, presenting significant challenges in the creation of PI3Kγ inhibitors. This study presents an ensemble‐based virtual screening approach to discover novel inhibitors targeting PI3Kγ. Eganelisib (IPI‐549) is the sole selective PI3Kγ inhibitor that has progressed to clinical trials, making it a significant model for the advancement of novel PI3Kγ inhibitors. Initially, common feature pharmacophore and receptor–ligand pharmacophore models were independently developed using IPI‐549 and its potent derivatives, in conjunction with the crystal complex of PI3Kγ/IPI‐549. Both qualitative pharmacophore models proved highly effective at distinguishing between active and inactive compounds. Then, four widely utilized docking programs were chosen for assessment, where the Glide_SP mode demonstrated superior predictive accuracy in sampling ligand conformations during binding, effectively distinguishing between PI3Kγ inhibitors and noninhibitors. Finally, a virtual screening protocol was conducted to screen the ChEMBL database, utilizing similarity search, consensus‐based pharmacophore mapping, and sequential molecular docking. This process resulted in the identification of multiple molecules exhibiting notable promise as potent PI3Kγ inhibitors.

Expanding the therapeutic horizon in acute myeloid leukemia: The role of phosphoinositide-3-kinase-γ inhibition

Abstract Acute myeloid leukemia (AML) remains a formidable challenge due to its high relapse rate and limited therapeutic options. This study investigates the role of phosphoinositide-3-kinase-γ (PI3Kγ) in AML and explores the therapeutic potential of the PI3Kγ inhibitor, eganelisib, in preclinical models. Using genome-wide CRISPR interference screening, we identified PI3Kγ as a critical survival pathway in certain AML subsets. We demonstrated that inhibition of PI3Kγ with eganelisib disrupts oxidative phosphorylation, thereby impeding AML cell survival and proliferation. Notably, the combination of eganelisib with cytarabine showed enhanced efficacy, suggesting a synergistic interaction that improves treatment outcomes. These findings indicate that PI3Kγ is a viable therapeutic target in AML and that PI3Kγ inhibitors could be pivotal in overcoming treatment resistance and reducing relapse.

PI3Kγ inhibition circumvents inflammation and vascular leak in SARS-CoV-2 and other infections.

Virulent infectious agents such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and methicillin-resistant Staphylococcus aureus (MRSA) induce tissue damage that recruits neutrophils, monocyte, and macrophages, leading to T cell exhaustion, fibrosis, vascular leak, epithelial cell depletion, and fatal organ damage. Neutrophils, monocytes, and macrophages recruited to pathogen-infected lungs, including SARS-CoV-2-infected lungs, express phosphatidylinositol 3-kinase gamma (PI3Kγ), a signaling protein that coordinates both granulocyte and monocyte trafficking to diseased tissues and immune-suppressive, profibrotic transcription in myeloid cells. PI3Kγ deletion and inhibition with the clinical PI3Kγ inhibitor eganelisib promoted survival in models of infectious diseases, including SARS-CoV-2 and MRSA, by suppressing inflammation, vascular leak, organ damage, and cytokine storm. These results demonstrate essential roles for PI3Kγ in inflammatory lung disease and support the potential use of PI3Kγ inhibitors to suppress inflammation in severe infectious diseases.

Designing Small Molecule PI3Kγ Inhibitors: A Review of Structure-Based Methods and Computational Approaches.

The PI3K/AKT/mTOR pathway plays critical roles in a wide array of biological processes. Phosphatidylinositol 3-kinase gamma (PI3Kγ), a class IB PI3K family member, represents a potential therapeutic opportunity for the treatment of cancer, inflammation, and autoimmunity. In this Perspective, we provide a comprehensive overview of the structure, biological function, and regulation of PI3Kγ. We also focus on the development of PI3Kγ inhibitors over the past decade and emphasize their binding modes, structure-activity relationships, and pharmacological activities. The application of computational technologies and artificial intelligence in the discovery of novel PI3Kγ inhibitors is also introduced. This review aims to provide a timely and updated overview on the strategies for targeting PI3Kγ.

Abstract 1957: OPM-116, a highly potent and specific PI3Kγ inhibitor to enhance antitumor immunity

Abstract Tumor-associated macrophages are an integral part of the tumor microenvironment. They play a crucial role in cancer initiation and progression by orchestrating tumor proliferation, angiogenesis, extracellular matrix remodeling, metastasis, immunosuppression, and resistance to checkpoint blockade immunotherapy and chemotherapy (Gao J, 2022). On the other hand, when properly stimulated, macrophages can effectively interact with the innate and adaptive immune systems arms, promoting cancer cell phagocytosis and tumor destruction by T cell-mediated cytotoxicity (Mantovani A, 2022). PI3Kγ has a unique pattern of expression and biological function, and it has been investigated for a long time as a therapeutic target for different disorders, including cancer. Inhibition of PI3Kγ reprograms M2 macrophages into M1 cells in the tumor microenvironment which translates into the expansion of activated T cells by relieving macrophage suppression. Recent clinical data indicates the compelling role of PI3Ky in combination with PDL1 in anti-tumor activity, irrespective of PDL1 status (Hamilton E, 2021). PI3Ky selectivity has been difficult to achieve due to the high sequence homology across the class 1 PI3K isoforms (Drew SL, 2020). Macrocyclization of small molecules with a linear structure strongly reduces their conformational flexibility and alters a variety of their physicochemical and biological characteristics. The unexpected selectivity these compounds can exhibit, even amongst closely similar target molecules, is explained by the conformationally limited structure (Ma J, 2022). Here, we describe the discovery of a potent and selective, ATP-competitive inhibitor of PI3Kγ. OPM-116, macrocyclic compound display >300-fold selectivity for PI3Kγ over the other class I isoforms. Its selectivity in biochemical and cellular assays as well as in human PBMC assays is presented. In vitro, OPM-116 can inhibit the IL-4-induced polarization of M2 macrophages. Pharmacodynamic analysis performed in animals that received oral compound administration confirmed the absolute selectivity and good PK profiles of the drug. OPM-116 is a highly selective, PI3Kγ inhibitor that displays high potency and specificity and represents a promising step toward the identification of a clinical candidate. Drew S.L., et al. Discovery of potent and selective PI3Kγ inhibitors. J. Med. Chem. 2020. Ma J., et al. Development of small macrocyclic kinase inhibitors. Futur. Med. Chem. 2022. Gao J., et al. Shaping polarization of tumor-associated macrophages in cancer immunotherapy. Front. Immunol. 2022. Mantovani A, et al. Macrophages as tools and targets in cancer therapy. Nat Rev Drug Discovery. 2022. Hamilton E, et al. Mario-3 phase II study safety run-in evaluating a novel triplet combination of eganelisib, atezolizumab, and nab-paclitaxel as first-line therapy for locally advanced or metastatic TNBC. AACR, Cancer Res 2021. Citation Format: Kenji Shoji, Petra Blom, Maria Eugenia Riveiro, Jan Hoflack. OPM-116, a highly potent and specific PI3Kγ inhibitor to enhance antitumor immunity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1957.

Defining a Targetable Leukemia Intrinsic Dependency on Noncanonical PI3Kgamma Signaling

There are overlapping clinical and pathologic characteristics between poor prognosis subsets of acute myeloid leukemia (AML) and blastic plasmacytoid dendritic cell neoplasm (BPDCN), but common dependencies are ill-defined. We hypothesized that identifying novel shared targets and biomarkers could elucidate biology and nominate new therapies for both malignancies. We performed genome-wide CRISPR interference in BPDCN cells and identified 327 dependency genes, which were then analyzed informatically and functionally in AML, ALL, and BPDCN cells and patient-derived xenografts (PDXs). We defined a leukemia subset characterized by PIK3R5 activation and sensitivity to phosphoinositide 3-kinase gamma (PI3Kγ) inhibition via a noncanonical downstream pathway. The PI3Kγ complex includes an enzymatic subunit p110γ encoded by PIK3CG and a regulatory subunit p101 encoded by PIK3R5. Intriguingly, despite elevation of both p110γ and p101 proteins in this leukemia subset, only the PIK3R5 mRNA is overexpressed. To investigate this disconnection, we measured protein half-life and found that p110γ stability is positively regulated by PIK3R5/p101, associated with reduced p110γ ubiquitination. This suggested that increased expression of PIK3R5/p101 leads to posttranslational p110γ elevation by protecting it from ubiquitin proteasome-mediated degradation. To identify the upstream activator of PIK3R5, we analyzed RNA-seq data in >200 leukemia PDXs and found that AMLs with activated PIK3R5 are enriched for an innate immune response signature (IIRS). Supporting this model and indicating potential clinical relevance, analysis of TCGA AML patients revealed that the IIRS, which includes PIK3R5, was associated with M4/M5 monocytic AML and poor prognosis, independent of age, cytogenetics, or somatic mutations. Furthermore, in cells with low baseline expression, PIK3R5 was induced by the Toll-like receptor agonist resiquimod, showing that PIK3R5 is activated by inflammatory signaling and consistent with a monocytic/dendritic lineage association. By integrated analysis of ATAC-seq and ChIP-seq in PIK3R5 high vs low leukemias, as well as gene dependency scores, we identified the transcription factor PU.1 as responsible for PIK3R5 activation. Treatment with resiquimod enhanced the interaction between PU.1 and the PIK3R5 promoter, while depletion of PU.1 nullified the ability of resiquimod to activate PIK3R5. To elucidate molecular events downstream of p101/PI3Kγ, we studied consequences of pathway inactivation using PIK3R5 interference or the PI3Kγ-selective inhibitor eganelisib. Surprisingly, there was no effect of PI3Kγ inactivation on AKT phosphorylation or canonical PI3K-AKT-mTOR mRNA targets. Therefore, we performed phosphoproteomics and found that PAK1 S144, a phosphorylation site not previously associated with PI3K signaling, was suppressed by PIK3R5/PI3Kγ inhibition ( panel a). Selective inhibitors of PAK1, but not AKT, replicated the effect of eganelisib. Furthermore, introduction of constitutively active PAK1, but not inactive PAK1, eliminated sensitivity of leukemias to eganelisib, supporting the functional relationship between PAK1 phosphorylation and PI3Kγ dependency. PI3Kγ inhibitors are being tested in solid tumor trials to repolarize macrophages and potentiate immune checkpoint blockade, but their cancer cell-intrinsic role has not been explored. To assess PI3Kγ inhibition in vivo, we first performed intradermal xenografting assays using BPDCN derived from a patient's skin tumor. Eganelisib achieved comparable efficacy to cytarabine chemotherapy and the combination of eganelisib and cytarabine exerted significant synergy (combination index=0.63, p<0.0001). Next, we measured the effect of PI3Kγ inhibition on survival in disseminated PDX models. As predicted, single agent eganelisib significantly prolonged survival in AML, ALL, and BPDCN with high PIK3R5, while having no benefit in cases with low PIK3R5. To our surprise, the combination of eganelisib/cytarabine synergistically increased survival in all cases, regardless of baseline PIK3R5 ( panel b). We conclude that inflammatory signaling-activated PIK3R5 is a biomarker for sensitivity to PI3Kγ inhibition via an unappreciated PI3Kγ-PAK1 axis. Synergy with cytarabine unmasked eganelisib sensitivity in additional leukemias, expanding the therapeutic potential of targeting PI3Kγ.

Development of PI3Kγ selective inhibitors: the strategies and application.

The γ isoform of Class I PI3Ks (PI3Kγ) is primarily found in leukocytes and is essential for the function of myeloid cells, as it regulates the migration, differentiation, and activation of myeloid-lineage immune cells. Thus, PI3Kγ has been identified as a promising drug target for the treatment of inflammation, autoimmune disease, and immuno-oncology. Due to the high incidence of serious adverse events (AEs) associated with PI3K inhibitors, in the development of PI3Kγ inhibitors, isoform selectivity was deemed crucial. In this review, an overview of the development of PI3Kγ selective inhibitors in the past years is provided. The isoform selectivity of related drugs was achieved by different strategies, including inducing a specificity pocket by a propeller-shape structure, targeting steric differences in the solvent channel, and modulating the conformation of the Asp-Phe-Gly DFG motif, which have been demonstrated feasible by several successful cases. The insights in this manuscript may provide a potential direction for rational drug design and accelerate the discovery of PI3Kγ selective inhibitors.

Polymorphonuclear myeloid-derived suppressor cells and phosphatidylinositol-3 kinase gamma are critical to tobacco-mimicking oral carcinogenesis in mice

BackgroundOral squamous cell carcinoma (OSCC) is a devastating disease most often associated with tobacco consumption that induces a field of mutations from which a tumor arises. Identification of ways to...

TNFSF14/LIGHT promotes cardiac fibrosis and atrial fibrillation vulnerability via PI3Kγ/SGK1 pathway-dependent M2 macrophage polarisation

BackgroundTumour necrosis factor superfamily protein 14 (TNFSF14), also called LIGHT, is an important regulator of immunological and fibrosis diseases. However, its specific involvement in cardiac fibrosis and atrial fibrillation (AF) has not been fully elucidated. The objective of this study is to examine the influence of LIGHT on the development of myocardial fibrosis and AF.MethodsPCR arrays of peripheral blood mononuclear cells (PBMCs) from patients with AF and sinus rhythm was used to identify the dominant differentially expressed genes, followed by ELISA to evaluate its serum protein levels. Morphological, functional, and electrophysiological changes in the heart were detected in vivo after the tail intravenous injection of recombinant LIGHT (rLIGHT) in mice for 4 weeks. rLIGHT was used to stimulate bone marrow-derived macrophages (BMDMs) to prepare a macrophage-conditioned medium (MCM) in vitro. Then, the MCM was used to culture mouse cardiac fibroblasts (CFs). The expression of relevant proteins and genes was determined using qRT-PCR, western blotting, and immunostaining.ResultsThe mRNA levels of LIGHT and TNFRSF14 were higher in the PBMCs of patients with AF than in those of the healthy controls. Additionally, the serum protein levels of LIGHT were higher in patients with AF than those in the healthy controls and were correlated with left atrial reverse remodelling. Furthermore, we demonstrated that rLIGHT injection promoted macrophage infiltration and M2 polarisation in the heart, in addition to promoting atrial fibrosis and AF inducibility in vivo, as detected with MASSON staining and atrial burst pacing respectively. RNA sequencing of heart samples revealed that the PI3Kγ/SGK1 pathway may participate in these pathological processes. Therefore, we confirmed the hypothesis that rLIGHT promotes BMDM M2 polarisation and TGB-β1 secretion, and that this process can be inhibited by PI3Kγ and SGK1 inhibitors in vitro. Meanwhile, increased collagen synthesis and myofibroblast transition were observed in LIGHT-stimulated MCM-cultured CFs and were ameliorated in the groups treated with PI3Kγ and SGK1 inhibitors.ConclusionLIGHT protein levels in peripheral blood can be used as a prognostic marker for AF and to evaluate its severity. LIGHT promotes cardiac fibrosis and AF inducibility by promoting macrophage M2 polarisation, wherein PI3Kγ and SGK1 activation is indispensable.

Developing new PI3Kγ inhibitors by combining pharmacophore modeling, molecular dynamic simulation, molecular docking, fragment-based drug design, and virtual screening

Since dysregulation of the phosphatidylinositol 3-kinase gamma (PI3Kγ) signaling pathway is associated with the pathogenesis of cancer, inflammation, and autoimmunity, PI3Kγ has emerged as an attractive target for drug development. IPI-549 is the only selective PI3Kγ inhibitor that has advanced to clinical trials, thus, IPI-549 could serve as a promising template for designing novel PI3Kγ inhibitors. In this present study, a modeling strategy consisting of common feature pharmacophore modeling, receptor-ligand pharmacophore modeling, and molecular dynamics simulation was utilized to identify the key pharmacodynamic characteristic elements of the target compound and the key residue information of the PI3Kγ interaction with the inhibitors. Then, 10 molecules were designed based on the structure-activity relationships, and some of them exhibited satisfactory predicted binding affinities to PI3Kγ. Finally, a hierarchical multistage virtual screening method, involving the developed common feature and receptor-ligand pharmacophore model and molecular docking, was constructed for screening the potential PI3Kγ inhibitors. Overall, we hope these findings would provide some guidance for the development of novel PI3Kγ inhibitors.

Abstract 639: Prevention of pancreatitis and subsequent pancreatic cancer and fibrosis development by PI3Kγ inhibition

Abstract Anti-inflammatory, immunosuppressive macrophages play significant roles in promoting both tumorigenesis and fibrosis. Wound-healing type macrophages accumulate in sites of tissue injury, such as the cirrhotic liver, where they can induce oxidative damage and secrete immunosuppressive and pro-fibrotic factors that lead to oncogenesis. These innate immune cells are also major cellular producers of PDGFB and TGF-β1, which stimulate fibroblasts to secrete extracellular matrix proteins, such as collagen, and which also promote metastatic progression of neoplastic diseases. Chronic liver and pancreatic inflammation are significant risk factors for the development of hepatocellular carcinoma (HCC) and pancreatic ductal adenocarcinoma (PDAC), respectively. We have determined that the myeloid cell specific PI3K isoform PI3Kγ promotes the accumulation of myeloid cells and their immune suppressive polarization within the tumor microenvironment (TME), and that this kinase thereby promotes tumor growth in animal models of cancer, including PDAC. Genetic and pharmacological inhibition of PI3Kγ suppresses tumor growth and reduces fibrosis that is associated with PDAC and other tumors. Targeting immune suppressive myeloid cells represent an emerging approach within the field of cancer immunotherapy and fibrosis treatment; indeed, inhibition of PI3Kγ by the therapeutic eganelisib has shown beneficial effects, including increased overall and progression-free survival in clinical trials for melanoma, head and neck carcinoma, urothelial carcinoma and triple negative breast carcinoma. In this project, we are exploringWe examined the effect of whether PI3Kγ inhibition can in cancer prevention using mouse models of prevent cancer development by suppressing damaging chronic hepatic and pancreatic inflammation, associated fibrosis, and progression towards tumorigenesis using models of HCC and PDAC. We found that PI3Kγ inhibition prevented prevents acute and chronic inflammation and that promotes normal tissue loss and development of fibrosis in mouse models of chronic pancreatitis and liver inflammation. Studies are underway to determine iOur studies indicate thatf PI3Kγ inhibition can also prevent the development of pancreatic and liver carcinoma that results fromin response to chronic inflammation and fibrosis. Our These studies thus far suggest the a potential role of for PI3Kγ inhibition in the prevention of cancer development by preventing the chronic inflammation that leads towards fibrosis and carcinogenesis. The results of these studies could be applied to the future design of clinical trials with using clinical PI3Kγ inhibitors. Citation Format: Anghesom Ghebremedhin, Judith Varner, Marc Paradise. Prevention of pancreatitis and subsequent pancreatic cancer and fibrosis development by PI3Kγ inhibition [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 639.

Melanoma-associated macrophages-from molecular signals to therapeutic application

Macrophages are an important component of the innate immune system. They are abbreviated as Mφ, MΦ, or MP. The name is derived from Greek: large eaters, μακρóς (makrós) = large, φαγεῖν (phagein) = to eat, because they engulf and digest pathogens. Tumor-associated macrophages (TAMs) are associated with drug resistance in cancers, including melanoma, and targeting them may improve cancer treatment. The purpose of this article is to examine the role of TAMs in cancer, particularly in melanoma. The relationship between TAM and treatment resistance and their potential application in the treatment of melanoma are discussed. A literature search in PubMed and Google Scholar databases for TAM and melanoma was performed. Clinical trials were searched via clinicaltrials.gov and graphical representations were created using BioRender. In melanoma, macrophages are among the most abundant immune cells in the tumor microenvironment (TME). TAMs are associated with poor prognosis and resistance. They are involved in tumorigenesis and metastasis development. M2 is the predominant type of TAM and the M2 markers CD163 and CD204 are unfavorable prognostic biomarkers. Therapeutic approaches aim to decrease their recruitment, modulate their function, or reprogram them. Treatment using chimeric antigen receptor (CAR)-M cells and nanoparticles are currently being investigated. Drugs being tested for melanoma include signal transducer and activator of transcription 3 (STAT3) inhibitors, macrophage colony-stimulating factor (M-CSF) antagonists, interferons (IFN), talimogene laherparepvec (TVEC), histone deacetylase (HDAC) inhibitors, indoleamine 2,3-dioxygenase (IDO) inhibitors, colony-stimulating factor1 receptor (CSF-1R) antagonists, CD40 agonists, arginase1 (ARG-1) inhibitors, and phosphoinositide 3‑kinase γ (PI3K-γ) inhibitors. TAMs participate in developing resistance to current melanoma therapies. Treatment directed against them may help reduce the development of resistance and improve survival.

Developing a Naïve Bayesian Classification Model with PI3Kγ structural features for virtual screening against PI3Kγ: Combining molecular docking and pharmacophore based on multiple PI3Kγ conformations

Phosphatidylinositol 3-kinase gamma (PI3Kγ) plays a critical role in immune signaling, thus identifying PI3Kγ as a potential therapeutic target. However, developing selective PI3Kγ inhibitors is hampered by the highly conserved structure of the ATP-binding pocket. Focused effort would be needed to improve upon the γ-subtype selectivity of the inhibitors; therefore, in the present study, a naïve Bayesian classification (NBC) model with PI3Kγ structural features that integrates molecular docking and pharmacophore based on multiple PI3Kγ conformations was developed for virtual screening against PI3Kγ to find novel selective PI3Kγ inhibitors. First, the active PI3Kγ inhibitors/decoy dataset was used to prove whether molecular docking or pharmacophore, integrating multiple PI3Kγ conformations always has higher prediction accuracy than that of any single conformation. Second, both internal cross-validation and external prediction revealed that the NBC model combining molecular docking and pharmacophore could significantly improve the enrichment of active PI3Kγ inhibitors. Then, an analog dataset based on JN-PK1 (a reference compound) was constructed and submitted to virtual screening using the optimal NBC model. Finally, a novel inhibitor with higher PI3Kγ inhibitory activity than JN-PK1 was identified through a series of biological assays, showing both good accuracy and significant reliability of the NBC model with the PI3Kγ structural features. We hope that the developed virtual screening strategy will provide valuable guidance for the discovery of novel selective PI3Kγ inhibitors.

Investigation into the anti-airway inflammatory role of the PI3Kγ inhibitor JN-PK1: An in vitro and in vivo study

Phosphatidylinositol 3-kinase gamma (PI3Kγ) has been proven to be a potential target for the treatment of inflammatory diseases of the airway; however, there are few reports of selective PI3Kγ inhibitors being used in the field of airway inflammation thus far. Herein, a study employing in vitro and in vivo methodologies was carried out to assess the anti-airway inflammatory effects of JN-PK1, a selective PI3Kγ inhibitor. In RAW264.7 macrophages, JN-PK1 inhibited PI3Kγ-dependent, cellular C5a-induced AKT Ser473 phosphorylation in a concentration- and time-dependent manner and had no significant effect on cell viability.Furthermore, JN-PK1 significantly suppressed LPS-induced, proinflammatory cytokine expression and nitric oxide production through inhibition of the PI3K signaling pathway in RAW264.7 cells. Then, a murine asthma model was established to evaluate the anti-airway inflammation effect of JN-PK1. BALB/c mice were sensitized and challenged with ovalbumin (OVA) to develop an inflammatory response, fibrosis formation, and other airway changes similar to the symptomatology of asthma in humans. Oral administration of JN-PK1 remarkably attenuated OVA-induced asthma in association with the inhibition of the PI3K signaling pathway. That is to say, the oral administration significantly inhibited increases in inflammatory cell counts and reduced T-helper type 2 cytokine production in bronchoalveolar lavage fluid. Pulmonary histological studies showed that oral administration of JN-PK1 not only reduced the infiltration of inflammatory cells but also retarded airway inflammation and fibration. Taken together, JN-PK1 could be developed as a promising candidate for inflammation therapy, and our findings support some potential for therapeutic inhibition of PI3Kγ to treat inflammatory airway diseases.

Identifying Active Compounds and Mechanisms of Citrus changshan-Huyou Y. B. Chang against URTIs-Associated Inflammation by Network Pharmacology in Combination with Molecular Docking

Purpose The ripe fruits of Citrus changshan-huyou, known as Quzhou Fructus Aurantii (QFA), have been commonly used for respiratory diseases. The purpose of this study was to investigate their active compounds and demonstrate their mechanism in the treatment of upper respiratory tract infections (URTIs) through network pharmacology and molecular docking. Methods The prominent compounds of QFA were acquired from TCMSP database. Their targets were retrieved from SwissTargetPrediction database, and target genes associated with URTIs were collected from DisGeNET and GeneCards databases. The target protein-protein interaction (PPI) network was constructed by using STRING database and Cytoscape. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) were enriched. Visual compound-target-pathway network was established with Cytoscape. The effects of compounds were verified on the inhibitory activities against phosphoinositide 3-kinases (PI3Ks). Finally, the molecular docking was carried out to confirm the binding affinity of the bioactive compounds and target proteins. Results Five important active compounds, naringenin (NAR), tangeretin (TAN), luteolin (LUT), hesperetin (HES), and auraptene (AUR), were obtained. The enrichment analysis demonstrated that the pathways associated with inflammation mainly contained PI3K/Akt signalling pathway, TNF signalling pathway, and so on. The most important targets covering inflammation-related proteins might be PI3Ks. In vitro assays and molecular docking exhibited that TAN, LUT, and AUR acted as PI3Kγ inhibitors. Conclusion The results revealed that QFA could treat URTIs through a multi-compound, multi-target, multi-pathway network, in which TAN, LUT, and AUR acted as PI3Kγ inhibitors, probably contributing to a crucial role in treatment of URTIs.

Abstract 2056: PI3Kgamma inhibition reduces inflammation and promotes survival in cancer and SARS-CoV-2

Abstract Solid tumors are characterized by extensive immune suppressive inflammation, vascular leak, fibrosis and organ damage. Similarly, SARS-CoV-2 infections induce aberrant pulmonary and systemic inflammation, vascular leak, coagulation, fibrosis and fatal organ damage. We previously demonstrated that macrophages in solid tumors strongly expressed phosphatidylinositol 3-kinase gamma (PI3Kγ), a signaling protein that coordinately controls granulocyte and monocyte trafficking to tumors as well as wound-healing-type macrophage transcription in cancer and fibrosis. We also observed that macrophages in COVID-19 lungs strongly expressed PI3Kγ. To identify therapeutic strategies to suppress COVID-19-associated inflammation, we characterized lung tissue of COVID-19 patients using multiplex immunohistochemistry and tissue transcriptomics. Lungs of deceased patients exhibited substantial infiltration by neutrophils and wound-healing macrophages, fibrosis and alveolar type II cell depletion. In animal models of lung inflammation, bacterial infections, viral infection and SARS-CoV-2 infection, PI3Kγ deletion or inhibition with the cancer therapeutic IPI-549 (eganelisib) suppressed pulmonary and systemic inflammation, reduced lung damage, and promoted survival. These studies demonstrate the essential role of PI3Kγ in inflammatory diseases as well as cancer and support the use of PI3Kγ inhibitors such as eganelisib to suppress inflammation and promote survival in pulmonary infections like SARS-CoV-2 and cancer. Citation Format: Judith A. Varner, Anghesom Ghebremedhin. PI3Kgamma inhibition reduces inflammation and promotes survival in cancer and SARS-CoV-2 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2056.

Recombinant EGFL7 Mitigated Pressure Overload-Induced Cardiac Remodeling by Blocking PI3K /AKT/ Signaling in Macrophages.

Inflammation and endothelial dysfunction play an essential role in heart failure (HF). Epidermal growth factor-like protein 7 (EGFL7) is upregulated during pathological hypoxia and exerts a protective role. However, it is unclear whether there is a link between abnormal EGFL7 expression and inflammation in overload stress-induced heart failure. Our results showed that EGFL7 transiently increased during the early 4 weeks of TAC and in hypertensive patients without heart failure. However, it decreased to the basal line in the heart tissue 8 weeks post-transverse aortic constriction (TAC) or hypertensive patients with heart failure. Knockdown of EGFL7 with siRNA in vivo accelerated cardiac dysfunction, fibrosis, and macrophage infiltration 4 weeks after TAC. Deletion of macrophages in siRNA-EGFL7-TAC mice rescued that pathological phenotype. In vitro research revealed the mechanism. PI3K/AKT/N signaling in macrophages was activated by the supernatant from endothelial cells stimulated by siRNA-EGFL7+phenylephrine. More macrophages adhered to endothelial cells, but pretreatment of macrophages with PI3Kγ inhibitors decreased the adhesion of macrophages to endothelial cells. Ultimately, treatment with recombinant rmEGFL7 rescued cardiac dysfunction and macrophage infiltration in siRNA-EGFL7-TAC mice. In conclusion, EGFL7 is a potential inhibitor of macrophage adhesion to mouse aortic endothelial cells. The downregulation of EGFL7 combined with increased macrophage infiltration further promoted cardiac dysfunction under pressure overload stress. Mechanistically, EGFL7 reduced endothelial cell adhesion molecule expression and inhibited the PI3K/AKT/NFB signaling pathway in macrophages.

Exploring PI3Kγ binding preference with Eganelisib, Duvelisib, and Idelalisib via energetic, pharmacophore and dissociation pathway analyses

Phosphatidylinositol 3-kinase (PI3K) is the central regulator of cellular functions and is suggested as a target for various diseases; thus, effective PI3K inhibitors provide a promising opportunity for the pharmaceutical intervention of many diseases. Among them, PI3Kγ has received more attention because of its essential role in immune signaling. However, the development of novel selective PI3Kγ inhibitors is a major challenge due to the high sequence homology across the class I PI3K isoforms. Therefore, understanding the substrate specificity and receptor-ligand interaction of PI3Kγ would be an appropriate strategy for the rational design of potent γ-selective inhibitors. In this study, by combining various molecular modeling approaches (including classic and enhanced sampling molecular dynamics (MD) simulations, end-point binding free energy calculations, and pharmacophore models), three quinolinone core-containing inhibitors, Idelalisib/CAL-101, Duvelisib/IPI-145, and Eganelisib/IPI-549, were employed to reveal the selective binding mechanisms targeting PI3Kγ. The classic MD and free energy calculations highlight the significant interaction and some key residues for the selective binding against PI3Kγ. Furthermore, the dissociation pathway analysis based on umbrella sampling simulations reveals that hydrophobic interactions are dominant for binding of the three ligands during the dissociation processes, and cooperation between the P-loop and the ligands always exists in the binding/dissociation process. Finally, the pharmacophore model revealed that IPI-549 contains a unique hydrophobic feature, and PI3Kγ exhibits an important hydrogen bond donor feature of hydrogen amide. These findings may provide some important information for the rational design and optimization of PI3Kγ-selective inhibitors.

Synthesis and Bio-evaluation of 2-Alkyl Substituted Fluorinated Genistein Analogues against Breast Cancer.

Breast cancer is the leading cause of cancer death in women. The current methods of chemotherapy for breast cancer generally have strong adverse reactions and drug resistance. Therefore, the discovery of novel anti-breast cancer lead compounds is urgently needed. This study aimed to design and synthesize a series of 2-alkyl substituted fluorinated genistein analogues and evaluate their anti-breast cancer activity. Target compounds were obtained in a multistep reaction synthesis. The anti-tumor activity of compounds I-1~I-35 was evaluated with MCF-7, MDA-MB-231, MDA-MB-435, and MCF-10A cell lines in vitro, with tamoxifen as the positive control. Molecular docking was used to study the interaction between the synthesized compounds and PI3K-gamma. A series of 2-alkyl substituted fluorinated genistein analogues was designed, synthesized, and screened for their bioactivity. Most of the compounds displayed better selectivity toward breast cancer cell lines as compared to tamoxifen. Among these analogues, I-2, I-3, I-4, I-9, I-15, and I-17 have the strongest selective inhibition of breast cancer cells. Compounds I-10, I-13, I-15, I-17, and I- 33 were found to have significant inhibitory effects on breast cancer cells. Molecular docking studies have shown that these compounds may act as PI3Kγ inhibitors and may further exhibit anti-breast cancer effects. Most of the newly synthesized compounds could highly, selectively inhibit breast cancer cell lines. The experimental results indicate that the synthesized analogs may also have obvious selective inhibitory effects on other malignant proliferation cancer cells.

Development of New Thiophene-Containing Triaryl Pyrazoline Derivatives as PI3Kγ Inhibitors.

A series of new thiophene-containing triaryl pyrazoline derivatives, 3a–3t, were synthesized and evaluated regarding PI3K inhibition activity and anti-tumor potency based on a trial of introducing significant moieties, including pyrazoline and thiophene, and simplifying the parallel ring structures. Most of the tested compounds indicated potent PI3K inhibitory potency, with this series of compounds showing more potency for PI3Kγ than PI3Kα. The top hit 3s seemed more potent than the positive control LY294002 on inhibiting PI3Kγ (IC50 values: 0.066 μM versus 0.777 μM) and more selective from PI3Kα (Index values: 645 versus 1.74). It could be inferred that the combination of para- and meta-, as well as the modification of the electron-donating moieties, led to the improvement in potency. The anti-proliferation inhibitory activity and the enzymatic inhibition potency indicated consistent tendencies. The top hit 3s could inhibit the phosphorylation of Akt by inhibiting PI3K through the PI3K-Akt-mTOR pathway. The molecular docking simulation indicated that the binding pattern of 3s into PI3Kγ was preferable than that of PI3Kα, with more hydrogen bond, more π-involved interactions, and fewer π-sulfur interactions. The information in this work is referable for the further development of selective inhibitors for specific isoforms of PI3K.