Phosphatidylinositol 3-kinase Pathway Research Articles

Perilipin2-dependent lipid droplets accumulation promotes metastasis of oral squamous cell carcinoma via epithelial-mesenchymal transition

Emerging evidence shows that lipid metabolic reprogramming plays a vital role in tumor metastasis. The effect and mechanism of fatty acids and lipid droplets (LDs), the core products of lipid metabolism, on the metastasis of oral squamous cell carcinoma (OSCC), need further exploration. In this study, the influence of palmitic acid (PA) and oleic acid (OA) on the migration and invasion ability of OSCC cells was determined by in vitro experiments. Genetic manipulation of PLIN2 was performed to explore its effect on the accumulation of LDs and OSCC metastasis. Possible mechanisms of these biological effects were clarified by detecting the levels of epithelial-mesenchymal transition (EMT) markers and phosphatidylinositol 3-kinase (PI3K) pathway proteins as well as conducting various bioinformatics analyses. The results indicated that PA/OA promoted the migration and invasion of OSCC cells and induced PLIN2-dependent LDs accumulation in vitro. Knockdown of PLIN2 inhibited the LDs accumulation and the migration and invasion of OSCC cells in vitro, while overexpression of PLIN2 enhanced those of OSCC cells in vitro and also promoted the metastasis of OSCC in vivo. Besides, PLIN2 up-regulation activated the PI3K pathway and subsequently enhanced EMT in OSCC cells in vitro. OSCC patients with higher PLIN2 expression possessed poorer prognosis and higher sensitivity to chemotherapy drugs (1S,3 R)-RSL3 and ML-210. In conclusion, PLIN2-dependent LDs accumulation could promote the metastasis of OSCC cells by regulating EMT. PLIN2 might be a potential therapeutic target for OSCC patients, especially those with obesity.

Abstract A013: Shikonin, a strong inhibitor of Phosphoinositide 3-Kinase (PI3K) and Mitogen-Activated Protein (MAP) Kinase pathways, induces cell death in UV-B irradiated B16F10 melanoma cells

Abstract Ultraviolet (UV) radiation-induced skin damage plays a pivotal role in the pathogenesis of melanoma, a highly aggressive and fatal form of skin cancer. Shikonin, naturally occurring nathoquinone , is well-known for its inhibitory effects on phosphoinositide 3-kinase (PI3K) and mitogen-activated protein (MAP) kinase signaling pathways. It has previously been demonstrated to exert effects against various non-melanoma skin cancers. In this study, we investigated the effects of Shikonin treatment on UVB-irradiated B16F10 melanoma cells, revealing a dose-dependent reduction in cell viability and an enhancement of apoptosis. Invitro findings indicate that the pro-apoptotic effects of shikonin in UVB-exposed B16F10 cells are mediated by several mechanisms, including the generation of reactive oxygen species (ROS), modulation of the antioxidant defense response, and mitochondrial membrane potential (ΔΨM) depolarization. Further supporting the apoptotic role of Shikonin, we observed DNA fragmentation, caspase activation, poly(ADP-ribose) polymerase (PARP) cleavage, and an increase in sub-G2 cell populations. Shikonin treatment also significantly attenuated MEK-ERK signaling, influenced the PI3K/Akt pathway, and potentially inhibited UVB-induced nuclear translocation of NF-κB. Additionally, co-treatment with UVB and Shikonin led to a decrease in the Bcl-2/Bax ratio and upregulated the expression of pro-apoptotic proteins Bax and caspases. Collectively, these data suggest that Shikonin may act as a potential therapeutic agent for melanoma when combined with UVB exposure, providing a novel avenue for future treatment strategies. Citation Format: Aalim Maqsood Bhat, Sheikh Tasduq Abdullah. Shikonin, a strong inhibitor of Phosphoinositide 3-Kinase (PI3K) and Mitogen-Activated Protein (MAP) Kinase pathways, induces cell death in UV-B irradiated B16F10 melanoma cells. [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Translating Targeted Therapies in Combination with Radiotherapy; 2025 Jan 26-29; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2025;31(2_Suppl):Abstract nr A013.

Lipid Emulsion Mitigates the Cardiotoxic Effects of Labetalol in Rat Cardiomyoblasts

Lipid emulsion has recently emerged as an effective agent for improving the cardiotoxicity of highly lipophilic drugs. However, its effect on cardiotoxicity induced by labetalol, a nonselective beta-blocker, remains unknown. In this study, we investigated the effects of lipid emulsion on the cardiotoxicity of labetalol in rat cardiomyoblasts and tried to decipher the underlying mechanisms. The effects of lipid emulsion on labetalol-induced changes in cell viability, expression of Bax/Bcl-2, cleaved caspase-3, and cleaved caspase-9, and phosphorylation of GSK-3β, Akt, and PI3K were examined. Lipid emulsion inhibited labetalol-induced decrease in cell viability, whereas LY294002, MK2206, and SB216763, the inhibitors of phosphoinositide 3-kinase (PI3K), Akt, glycogen synthase kinase-3β (GSK-3β), respectively, partially attenuated this restoration of cell viability. Lipid emulsion reversed the increase in expression of cleaved caspase-3, cleaved caspase-9, and Bax/Bcl-2 and decrease in the phosphorylation of GSK-3β, Akt, and PI3K by labetalol. Lipid emulsion and cyclosporin, a mitochondrial permeability transition pore (MPTP) inhibitor, reduced the labetalol-induced increase in the number of TUNEL-positive cells and promoted late-stage apoptosis. Overall, lipid emulsion inhibited apoptotic cell death caused by labetalol toxicity via the inhibition of intrinsic apoptotic pathway and MPTP in rat cardiomyoblasts, which appears to involve PI3K, Akt, and GSK-3β signaling pathways.

Exploring the regulatory impact of insulin on type I collagen synthesis in hepatic stellate cells through α5β1 integrin

In the present study by Dodig and colleagues, published in Metabolism and Target Organ Damage , the authors investigate the role of insulin in promoting type I collagen synthesis in hepatic stellate cells (HSCs) through α5β1 integrin signaling. Using L-SACC1 transgenic mice, which exhibit hyperinsulinemia and insulin resistance without fasting hyperglycemia, the researchers demonstrate that elevated insulin levels significantly increase type I collagen production in HSCs. This effect is mediated by α5β1 integrin signaling rather than the PI3 kinase pathway. These findings suggest that chronic hyperinsulinemia may preprogram HSCs for enhanced fibrogenesis following liver injury, contributing to advanced fibrosis associated with metabolic disorders such as metabolic dysfunction-associated steatosis liver disease (MASLD) and type 2 diabetes. It further suggests that chronic hyperinsulinemia increases the risk of significant fibrosis burden in chronic liver disease. In this commentary, the strengths and limitations of this study are discussed, along with the potential impact of these findings on current treatment strategies for insulin resistance, endogenous hyperinsulinemia, and exogenous hyperinsulinemia in the development of MASLD and disease progression to fibrosis, cirrhosis, and hepatocellular carcinoma.

High Frequency of PIK3R1 Alterations in Ovarian Cancers: Clinicopathological and Molecular Associations.

The phosphoinositide 3-kinase (PI3K) pathway is activated in multiple cancers. However, the significance of PIK3R1 encoding the PI3K regulatory subunit, an inhibitor of the PI3K catalytic subunit encoded by PIK3CA, in ovarian cancer development is largely unknown. Here, we investigated PIK3R1 genomic alterations and gene expression by direct sequencing and qPCR methods in 197 ovarian cancers. The results were correlated with clinicopathological and molecular variables and patient outcomes. In addition to mutations (3.5%) and allelic losses (28.4%), we observed a very high frequency of decreased PIK3R1 mRNA levels in ovarian carcinomas (95.8%). Tumors with PIK3R1 mutations mostly represented low-stage cancers of endometrioid and clear-cell type. Tumors with PIK3R1 deletion and underexpression shared similar phenotypes of high-grade carcinomas (p = 0.003 and p = 0.025, respectively). Allelic loss was also associated with advanced stages (p = 0.003) and high-grade serous histotypes (p = 0.004). The PIK3R1 copy number correlated with mRNA levels (p = 0.009). PIK3R1 mutations coexisted with PTEN mutations (p = 0.041), whereas PIK3R1 deletion and underexpression were linked to PIK3CA amplification (p = 0.038 and p = 0.033, respectively). Low PIK3R1 expression diminished the probability of a complete response (OR 0.07, p = 0.03) in patients treated with platinum-based regimens. PIK3R1 alterations may contribute to the development of ovarian cancers with different malignant potential and molecular changes. The high frequency of PIK3R1 aberrations suggests their importance in PI3K pathway deregulation, and they may potentially serve as an alternative to PIK3CA markers for therapy with these pathway inhibitors.

Foxk2 Enhances Adipogenic Differentiation by Relying on the Transcriptional Activation of Peroxisome Proliferator-Activated Receptor Gamma.

Proper differentiation of bone marrow stromal cells (BMSCs) into adipocytes is crucial for maintaining skeletal homeostasis. However, the underlying regulatory mechanisms remain incompletely understood, posing a challenge for the treatment of age-related osteopenia and osteoporosis. Here, through comprehensive gene expression analysis during BMSC differentiation into adipocytes, we identified the forkhead transcription factor Foxk2 as a key regulator of this process. Foxk2 expression was significantly higher in the inguinal and epididymal white adipose tissues of db/db mice compared to non-obese db/m controls and was induced in BMSCs, C3H/10 T1/2, and ST2 cells following adipogenic stimulation. Overexpression of Foxk2 promoted adipogenic differentiation of C3H/10 T1/2, ST2, and BMSCs, accompanied by increased expression of lipogenic factors. Conversely, Foxk2 silencing inhibited adipogenic differentiation. Moreover, Foxk2 also facilitated lipogenesis of C3H/10 T1/2 and ST2 cells. Adipogenic stimuli triggered the nuclear translocation of Foxk2 through PI3-kinase and mTOR signalling pathways. Once in the nucleus, Foxk2 is directly bound to the promoters of Pparγ1 and Pparγ2, thereby enhancing their transcriptional activity. Notably, PPARγ1 and PPARγ2 reciprocally augmented the transcriptional activity of the Foxk2 promoter, indicating the presence of a Foxk2-PPARγ positive feedback loop that drives adipogenesis.

Report of the Italian Cohort with Activated Phosphoinositide 3-Kinase δ Syndromein the Target Therapy Era.

Activated Phosphoinositide 3-Kinase (PI3K) δ Syndrome (APDS), an inborn error of immunity due to upregulation of the PI3K pathway, leads to recurrent infections and immune dysregulation (lymphoproliferation and autoimmunity). Clinical and genetic data of 28 APDS patients from 25 unrelated families were collected from fifteen Italian centers. Patients were genetically confirmed with APDS-1 (n = 20) or APDS-2 (n = 8), with pathogenic mutations in the PIK3CD or PIK3R1 genes. The median age at diagnosis was 15.5 years, with a median follow-up of 74 months (range 6-384). The main presenting symptoms were respiratory tract infections alone (57%) or associated with lymphoproliferation (17%). Later, non-clonal lymphoproliferation was the leading clinical sign (86%), followed by respiratory infections (79%) and gastrointestinal complications (43%). Malignant lymphoproliferative disorders, all EBV-encoding RNA (EBER)-positive at the histological analysis, occurred in 14% of patients aged 17-19 years, highlighting the role of EBV in lymphomagenesis in this disorder. Diffuse large B-cell lymphoma was the most frequent. Immunological work-up revealed combined T/B cell abnormalities in most patients. Treatment strategies included immunosuppression and PI3K/Akt/mTOR inhibitor therapy. Rapamycin, employed in 36% of patients, showed efficacy in controlling lymphoproliferation, while selective PI3Kδ inhibitor leniolisib, administered in 32% of patients, was beneficial on both infections and immune dysregulation. Additionally, three patients underwent successful HSCT due to recurrent infections despite ongoing prophylaxis or lymphoproliferation poorly responsive to Rapamycin. This study underscores the clinical heterogeneity and challenging diagnosis of APDS, highlighting the importance of multidisciplinary management tailored to individual needs and further supporting leniolisib efficacy.

Oncogenic PIK3CA corrupts growth factor signaling specificity.

Technical limitations have prevented understanding of how growth factor signals are encoded in distinct activity patterns of the phosphoinositide 3-kinase (PI3K)/AKT pathway, and how this is altered by oncogenic pathway mutations. We introduce a kinetic, single-cell framework for precise calculations of PI3K-specific information transfer for different growth factors. This features live-cell imaging of PI3K/AKT activity reporters and multiplexed CyTOF measurements of PI3K/AKT and RAS/ERK signaling markers over time. Using this framework, we found that the PIK3CAH1047R oncogene was not a simple, constitutive activator of the pathway as often presented. Dose-dependent expression of PIK3CAH1047R in human cervical cancer and induced pluripotent stem cells corrupted the fidelity of growth factor-induced information transfer, with preferential amplification of epidermal growth factor receptor (EGFR) signaling responses compared to insulin-like growth factor 1 (IGF1) and insulin receptor signaling. PIK3CAH1047R did not only shift these responses to a higher mean but also enhanced signaling heterogeneity. We conclude that oncogenic PIK3CAH1047R corrupts information transfer in a growth factor-dependent manner and suggest new opportunities for tuning of receptor-specific PI3K pathway outputs for therapeutic benefit.

Advancements in clinical research and emerging therapies for triple-negative breast cancer treatment.

Triple-negative breast cancer (TNBC), defined by the lack of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor 2 (HER2) expression, is acknowledged as the most aggressive form of breast cancer (BC), comprising 15%-20% of all primary cases. Despite the prevalence of TNBC, effective and well-tolerated targeted therapies remain limited, with chemotherapy continuing to be the mainstay of treatment. However, the horizon is brightened by recent advancements in immunotherapy and antibody-drug conjugates (ADCs), which have garnered the U.S. Food and Drug Administration (FDA) approval for various stages of TNBC. Poly (ADP-ribose) polymerase inhibitors (PARPi), particularly for TNBC with BRCA mutations, present a promising avenue, albeit with the challenge of resistance that must be addressed. The success of phosphoinositide-3 kinase (PI3K) pathway inhibitors in hormone receptor (HR)-positive BC suggests potential applicability in TNBC, spurring optimism within the research community. This review endeavors to offer a comprehensive synthesis of both established and cutting-edge targeted therapies for TNBC. We delve into the specifics of PARPi, androgen receptor (AR) inhibitors, Cancer stem cells (CSCs), PI3K/Protein Kinase B (AKT)/mammalian target of rapamycin (mTOR), the transforming growth factor-beta (TGF-β), Ntoch, Wnt/β-catenin, hedgehog (Hh) pathway inhibitors, Epigenetic target-mediated drug delivery, ADCs, immune checkpoint inhibitors (ICIs)and novel immunotherapeutic solutions, contextualizing TNBC within current treatment paradigms. By elucidating the mechanisms of these drugs and their prospective clinical applications, we aim to shed light on the challenges and underscore the beacon of hope that translational research and innovative therapies represent for the oncology field.

Duvelisib with docetaxel for patients with anti-PD-1 refractory, recurrent or metastatic head and neck squamous cell carcinoma.

Treatments after anti-PD-1 therapy for patients with recurrent, metastatic (R/M) head and neck squamous cell carcinoma (HNSCC) are limited. Blocking phosphatidylinositol 3-kinase (PI3K) signaling may lead to tumor immunomodulation and enhanced taxane sensitivity. This phase 2 trial evaluated dual, selective PI3Kδ/γ inhibition with docetaxel in patients with anti-PD-1 refractory R/M HNSCC. Patients received duvelisib (25 mg orally twice daily) with docetaxel (75 mg/m2 IV) every 21-days. The primary endpoint was overall response rate (ORR) (RECISTv1.1), employing a Simon two-stage design. Secondary endpoints: safety, progression-free survival (PFS), overall survival (OS); exploratory endpoints: correlating immunologic and genomic parameters with outcomes. From 11/1/21 to 10/10/23, 26 patients enrolled (median age: 64, 96% men, 54% with HPV+ disease; primary site: 12 oropharynx, 11 oral cavity, 3 larynx/hypopharynx. Best ORR was 19% (5/26) (95%CI: 6.8-40.7%), all were partial responses (median duration: 5.1 months [0.7-15.5]); 46% (12/26) exhibited stable disease and 32% (8/26) progression (1 unevaluable). Two patients remain on-treatment at data cutoff; 25% (6/24) came off for toxicity. Grade 3+ treatment-related adverse events were observed in 50% (13/26), most often elevated liver function tests (6, 23%). No deaths were treatment related. At median follow-up of 6.5 months (0.7-26), median PFS: 2.8 months (95%CI: 1.9-7.0); 17/26 patients had died. Median OS: 10.2 months (95%CI: 6.7-15.9), favoring HPV-negative patients. Greater tumor CD3+/CD8+ T cell infiltration trended with improved outcomes. We report a favorable response rate when combining a selective PI3K pathway inhibitor and taxane in patients with anti-PD-1 refractory HNSCC. gov: NCT05057247.

Fhl1, a new spatially specific protein, regulates vein graft neointimal hyperplasia.

Vein grafts are commonly employed in revascularisation surgery for multivessel coronary artery disease, yet neointimal hyperplasia (NIH) remains a critical impediment to the long-term patency of these grafts. Despite this, effective methods to precisely identify and target interventions for the neointima are still inadequate. In this study, Sprague-Dawley (SD) rats were used to establish an external jugular vein transplantation model, and the NIH pathophysiological process was tracked across 11 time points (0-35 days) using various histological stains. Spatial transcriptomics was performed on normal veins and 19-day grafts to explore gene expression in neointimal regions. Immunohistochemical analysis identified neointima-specific markers, while NIH progression was assessed in SD rats with four and a half LIM domains protein 1 (Fhl1) knockout and in human saphenous veins (HSV) with adenovirus-mediated Fhl1 overexpression. Typical neointimal formation commenced by day 11 postgrafting and peaked at day 19. Neointimal cells originated from newly generated α-SMA(+) repair cells located outside the grafted vein, displaying a hybrid fibroblast-smooth muscle cell phenotype. Spatial transcriptomics identified stable and sustained Fhl1 expression within the neointima throughout the entire NIH phase. Systemic knockout of Fhl1 in SD rats via the phosphoinositide 3-kinase pathway exacerbated graft inflammation, heightened cell proliferation, and accelerated NIH. Conversely, FHL1 overexpression in cultured HSV suppressed NIH. These findings indicate that, following grafting into the arterial system, the newly formed repair cells external to the grafted vein play a pivotal role in NIH, with neointimal cells exhibiting stable and continuous Fhl1 expression. Fhl1 serves as a protective factor against NIH both in vivo and in HSV, likely due to its anti-inflammatory and anti-proliferative effects. This study firstly used spatial transcriptomics technique to analyse the neointima and generated a specific neointimal transcriptomic atlas. Fhl1 exhibits specific and stable expression in the spatial region of the neointima. It has thus far the highest enrichment of expression in the neointima in NIH phases, suggesting that it is a prominent molecular biomarker of neointima. We generated rats with a Fhl1 deletion and found that insufficient Fhl1 expression caused an increase in the severity of vascular inflammation and proliferation during neointimal hyperplasia. Adenovirus-mediated FHL1 overexpression in human saphenous vein have beneficial effects in preventing neointimal hyperplasia. These highlight its potential as a therapeutic target for mitigating vein graft failure associated with cardiovascular procedures. Spatial transcriptomics profiles and morphological observations demonstrated that a newly generated cell population outside the grafted vein with hybrid phenotype between SMCs and fibroblasts contributes to neointimal formation.

Cholesterol overload in macrophages drives metabolic dysfunction-associated steatohepatitis via inhibiting 7-dehydrocholesterol reductase in mice

BackgroundDietary cholesterol promotes metabolic dysfunction-associated steatohepatitis (MASH), with hepatic macrophages central to disease pathology. However, the mechanisms by which cholesterol-loaded macrophages influence MASH remain unclear.MethodsIn this study, mice were fed a cholesterol-rich choline-deficient, L-amino acid-defined, high-fat diet (CDAHFD). Hepatic cholesterol levels, inflammatory markers, and pro-inflammatory macrophage polarization were assessed. In vitro studies examined the impact of cholesterol on macrophage polarization, identifying 7-dehydrocholesterol reductase (DHCR7) as a key cholesterol- and inflammation-responsive enzyme. DHCR7 expression in macrophages from MASH patients and model mice was evaluated. Functional studies involving in vitro knockdown and overexpression experiments, were complemented using myeloid-specific DHCR7 knockout mice. RNA sequencing was performed on liver tissues from wild-type and DHCR7 knockout mice to identify affected signaling pathways.ResultsCDAHFD-fed mice exhibited local cholesterol accumulation and a pro-inflammatory macrophage phenotype in the liver. Cholesterol overload in vitro promoted M1 polarization and liver inflammation, reversible by simvastatin. DHCR7 expression, responded to cholesterol and polarization state, was downregulated in M1-polarized and hepatic macrophages from MASH patients and mice. DHCR7 suppression promoted pro-inflammatory phenotype, while its overexpression showed anti-inflammatory effects. Myeloid-specific DHCR7 deficiency in CDAHFD-fed mice worsened liver inflammation and pro-inflammatory macrophage infiltration. RNA sequencing identified the phosphoinositide 3-kinase (PI3K) pathway in DHCR7-regulated effects, with DHCR7-PI3K axis activation mitigating cholesterol-driven inflammation.ConclusionsThese findings unveil novel mechanistic insights into MASH pathogenesis, suggesting targeting macrophage-specific DHCR7 activation may offer a promising therapeutic strategy for MASH.

Post-marketing safety concern of PI3K inhibitors in the cancer therapies: an 8-year disproportionality analysis from the FDA Adverse Event Reporting System

ABSTRACT Background The Phosphoinositide 3-kinases (PI3Ks) family plays a crucial role in tumorigenesis. Alpelisib (inhibiting PI3Kα), copanlisib (inhibiting PI3Kα andPI3Kδ), duvelisib (inhibiting PI3Kδ and PI3Kγ), and idelalisib (inhibiting PI3Kδ) were developed to target the PI3K pathway. However, the toxicity limits their application to some extent. It’s necessary to investigate the adverse effects (AEs) of these inhibitors. Research design and methods We conducted a comparative analysis of the safety signals of AEs in PI3K inhibitors using disproportionality analysis in the FDA Adverse Event Reporting System database(FAERS). Results Our study identified significant safety signals for metabolic disorders with all PI3K inhibitors. Notable safety signals for gastrointestinal disorders were observed with most PI3K inhibitors, with the exception of copanlisib. Common AEs shared among all PI3K inhibitors included colitis and dehydration. Alpelisib displayed unique AEs associated with metabolic disorders, whereas copanlisib exhibited idiosyncratic AEs linked to cardiac and vascular disorders. Stevens-Johnson syndrome emerged as a common severe adverse event (SAE) among alpelisib, copanlisib, and idelalisib, while febrile neutropenia was prevalent among copanlisib, duvelisib, and idelalisib. Intestinal perforation was solely associated with alpelisib. Conclusions The safety profiles of the five PI3K inhibitors vary concerning adverse events. These findings could guide drug selection and inform future prospective research.

Hyperactivation of the PI3K pathway in inborn errors of immunity: current understanding and therapeutic perspectives.

The phosphoinositide-3-kinase (PI3K) pathway function is crucial to the normal development, differentiation, and function of immune cells including B, T, and NK cells. Following the description of two cohorts of patients with an inboirn error of immunity(also known as primary immunodeficiency) with gain-of-function variants in the PIK3CD gene a decade ago, the disease entity activated PI3K delta syndrome (APDS) was named. Since then, many more patients with PIK3CD variants have been described, and loss-of-function variants in PIK3R1 and PTEN have also been linked to APDS. Importantly, the availability of small molecules that inhibit the PI3K pathway has enabled targeted treatment of APDS patients. In this review, we define (i) the PI3K pathway and its role in inborn errors of immunity; (ii) the clinical and immunological presentation of APDS1 (PIK3CD GOF), APDS2 (PIK3R1 LOF), and related disorders; (iii) Diagnostic approaches to identify and functionally validate the genetic causes of disease; (iv) therapeutic interventions to target PI3K hyperactivation; and finally (v) current challenges and future perspectives that require attention for the optimal treatment of patients with APDS and APDS-L diseases.

Adolescent exposure to organophosphate insecticide malathion induces spermatogenesis dysfunction in mice by activating the HIF-1/MAPK/PI3K pathway

Chemical-caused reproductive dysfunction has emerged as a global public health concern. This study investigated the adverse effects of the organophosphorus pesticide malathion on reproductive function in adolescent male mice at environmentally relevant concentrations. The results indicated that eight-week malathion exposure reduced testis weight, caused sex and thyroid hormone disorders, and induced testicular spermatogenic epithelium damage and oxidative stress. Testicular RNA sequencing indicated that malathion significantly affected testicular energy metabolism, hypoxia-inducible factor 1 (HIF-1) signaling, and steroid hormone biosynthesis pathways. Malathion significantly increased the gene and protein expression of HIF-1α by upregulating key genes in the mitogen-activated protein kinase (MAPK) pathway (Map2k2, Mapk3, and Eif4e2) and the phosphatidylinositol 3-kinase (PI3K) pathway (Pik3r2 and Akt1). Furthermore, malathion downregulated HIF-1α degradation-regulating genes while upregulating anaerobic metabolism and inflammation-related genes, thereby inhibiting normoxia and promoting hypoxia processes. Testicular hypoxia subsequently induced steroid hormone biosynthesis disorders and spermatogenesis dysfunction. Molecular docking verified that malathion interfered with HIF-1α and steroid hormone synthases (CYP11A1, CYP17A1 and CYP19A1) by forming hydrogen bonds and hydrophobic interactions with these proteins. This study presents the first evidence that malathion triggers spermatogenesis dysfunction in mice through activating the HIF-1/MAPK/PI3K pathway, providing a comprehensive understanding of the reproductive toxicity risks associated with organophosphorus pesticides.

Neuroprotection by 4R-cembranoid against Gulf War Illness-related Chemicals is mediated by ERK, PI3K, and CaMKII pathways

Gulf War Illness (GWI) has been consistently linked to exposure to pyridostigmine (PB), N,N-Diethyl-meta-toluamide (DEET), permethrin (PER), and traces of sarin. In this study, diisopropylfluorophosphate (DFP, sarin surrogate) and the GWI-related chemicals were found to reduce the number of functionally active neurons in rat hippocampal slices. These findings confirm a link between GWI neurotoxicants and N-Methyl-D-Aspartate (NMDA)-mediated excitotoxicity, which was successfully reversed by Edelfosine (a phospholipase Cβ (PLCβ3) inhibitor) and Flupirtine (a Kv7 channel agonist).To test whether 4R-cembranoid (4R), a nicotinic α7 acetylcholinesterase receptor (α7AChR) modulator known for its neuroprotective properties, can restore hippocampal neurons from glutamate-induced neurotoxicity, we exposed rat hippocampal slices with DFP for 10 min followed by 60 min treatment with 4R. We investigated the 4R mechanisms of neuroprotection after preincubation with LY294002, PD98059, and KN-62. The inhibition of the phosphatidylinositol 3-kinase (PI3K), mitogen-activated protein kinase (MEK1/2), and calcium/calmodulin-dependent protein kinase (CaMKII) abrogated the protective effect of 4R against DFP-induced neurotoxicity. In separate experiments, after incubation with DFP, followed by 4R for 1 h, cellular extracts were prepared for Western blotting of phospho-Akt, phospho-GSK3β, phosphorylated extracellular signal-regulated kinase (ERK)1/2, CaMKII and cAMP response element-binding protein (CREB). Our results show that DFP induces neuronal dysfunction by dephosphorylation, while 4R restores the phosphorylation of Akt, GSK3, ERK1/2, CREB, and CaMKII. Moreover, our proteomics analysis supported the notion that 4R activates additional signaling pathways related to enhancing neuronal signaling, synaptic plasticity, and apoptotic inhibition to promote cell survival against DFP, offering biomarkers for developing treatment against GWI.

Conditional Pten inactivation in pituitary results in sex-specific prolactinoma formation

Pituitary tumors, including prolactinomas, present significant clinical challenges that require a deeper understanding of their molecular roots for improved diagnostics and therapies. Here, we investigate the role of the phosphatase and tensin homolog (PTEN)/phosphoinositide 3-kinase (PI3K) pathway in pituitary tumorigenesis using a mouse model. Conditional knockout of Pten in all pituitary cell lineages resulted in prolactinoma formation exclusively in female mice, demonstrating the critical role of PTEN in pituitary homeostasis. While Pten inactivation induced Akt activation in all pituitary cells, only prolactin-producing cells exhibited tumorigenic changes, suggesting specific cell-type effects. Histological and molecular analyses of prolactinomas revealed similarities with human pituitary tumors, such as decreased vascularization and cell adhesion proteins and increased accumulation of cell cycle proteins. Notably, prolactinomas displayed diminished levels of phosphorylated extracellular signal-regulated kinase (ERK), implicating downregulation of ERK in tumorigenesis. Finally, we analyzed PTEN/PI3K activation in a collection of human pituitary tumors. Overall, our study delineates the intricate interplay between the PTEN and ERK signaling pathways, providing insights into sex-specific mechanisms of pituitary tumorigenesis and potential therapeutic strategies for prolactinomas.

The protective effect of irisin against hemorrhagic injury is mediated by PI3K and p38 pathways in hemorrhage/resuscitation.

The objective of this study is to investigate whether PI3kinase (PI3K) and p38 mitogen-activated kinase contributes to the protection of irisin during hemorrhage/resuscitation. Experimental groups were divided by receiving the different treatments during resuscitation: I) Hemorrhage: Adult male CD-1 mice were subjected to hemorrhage at a mean arterial blood pressure of 35~45 mmHg for 60 min followed by 120 min of resuscitation (n=13); II) Hemorrhage + Irisin: receiving irisin (5µg/kg) (n=13); III) Hemorrhage + Irisin + PI3K inhibitor: receiving both Ly294002 (1mg/kg, i.v.) and irisin (n=6); IV) Hemorrhage + Irisin + p38 inhibitor: receiving SB202190 (1mg/kg, i.v.) and irisin (n=6). As compared to hemorrhage/resuscitation control, irisin improved the cardiac function and recovery of hemodynamics in association with the decreased systemic IL-1, IL-6, and TNF-α, which was completely abrogated by PI3K or p38 inhibitions. Furthermore, inhibition of PI3K or p38 abolished irisin-induced reduction of the infiltration of inflammatory cells and TUNEL-positive apoptosis in the cardiac and skeletal muscles. Irisin reduced TNF-α and IL6 expression in cardiac and skeletal muscle, which was abrogated by inhibition of PI3K or p38. Irisin-treated hemorrhage increases the phosphorylation of PI3K and p38 in both cardiac and skeletal muscle, which was mitigated by inhibition of PI3K or p38. Conclusion: PI3K and p38 play a critical role in modulating the protective effect of irisin during the hemorrhage/resuscitation. Significance Statement 1). This study has identified a critical pathway in regulation of trauma/hemorrhage by using a preclinical and reproducible model, in which Irisin, as a hormone factor, stimulates PI3K and p38 pathways to induce the protection against traumatic conditions. 2). The study holds promise to develop a new therapeutic strategy to target irisin and its pathway related to PI3K and p38 to treat trauma and its comorbidities to reduce mortality for clinical implication.

8359 Increased hepatic SGK1 activity promotes metabolic dysfunction-associated fatty liver disease in a sex-dependent manner

Abstract Disclosure: A. Vastola-Mascolo: None. G. Hernández: None. D. Alvarez de la Rosa: None. The serum and glucocorticoid-induced kinase 1 (SGK1) is a Ser/Thr kinase with key roles in fluid and electrolyte homeostasis, blood pressure regulation and energy metabolism. Its expression is controlled by steroid hormones such as glucocorticoids, mineralocorticoids and estrogen, in addition to other stimuli such as glucose. SGK1 activation mainly depends on the PI3 kinase pathway, implicating it in insulin signaling. Previous work from our laboratory demonstrated that a systemic increase in SGK1 activity exacerbates diet-induced development of metabolic syndrome in mouse, characterized by obesity, glucose intolerance, insulin resistance, dyslipidemia and hypertension. In addition, a high-fat diet rapidly led to the development of hepatic steatosis. We now test the hypothesis that at least part of the effects of increased systemic SGK1 activity promoting the development of metabolic syndrome are due to alterations in liver glucose or lipid handling. To that end we developed a mouse strain with hepatocyte-specific transgenic SKG1 expression and challenged it with high-fat or high-fat/high-sucrose diets. Our results show sex differences in the development of obesity, with a marked increase in body weight in female, but not male transgenic animals. Glucose homeostasis was normal in both sexes. Increased obesity in females correlated with increased lipid accumulation in the liver. However, liver fibrosis, inflammation and dyslipidemia were more marked in male animals, further suggesting an interaction between SGK1 and sex steroid hormone signaling. Our results demonstrate a key role of SGK1 in liver lipid metabolism and suggest a crosstalk between this signaling pathway and sex hormones, which determine a more negative outcome in male animals. Presentation: 6/1/2024

Hyperglycemia secondary to phosphatidylinositol-3 kinase (PI3K) inhibition.

Phosphatidylinositol-3 kinase (PI3K) is a critical intracellular pathway that regulates cell growth, metabolism, and survival and has been implicated in most human cancers. Targeting this pathway has been approved as a therapeutic option for breast cancer and lymphoma (e.g. alpelisib, idelalisib), and there are several clinical trials underway in additional types of cancer. However, PI3K is an important mediator of the action of insulin, and the use of PI3K inhibitors has been associated with hyperglycemia. We report the case of a 53-year-old female with metastatic breast cancer who developed acute grade 3 hyperglycemia from a novel PI3K inhibitor, inavolisib. We review the treatment options for PI3K inhibitor-associated hyperglycemia. Treatment strategies that minimize hyperinsulinemia may be preferable considering animal models have demonstrated that hyperinsulinemia may result in partial reactivation of the PI3K pathway and counter the anti-cancer effectiveness of PI3K inhibitors. Phosphatidylinositol-3 kinase (PI3K) is an intracellular pathway that regulates a range of physiological functions, including cell growth, metabolism, survival, and angiogenesis. Hyperactivation of the PI3K pathway is associated with almost all human cancers, and thus PI3K inhibition has been proposed as a treatment option for selected cancers. The action of insulin after binding to the insulin receptor on the cell surface (e.g. glucose uptake in skeletal muscle, inhibition of glycogenolysis and gluconeogenesis) is mediated by the intracellular PI3K pathway, and thus PI3K inhibition may lead to hyperinsulinemic hyperglycemia. All patients treated with PI3K inhibitors should receive pre-treatment screening for hyperglycemia, lifestyle advice, and a glucometer to measure fasting BGL and 2-h post-dinner BGL levels twice per week for at least the first 30 days of treatment. Insulin or insulin secretagogues (e.g. sulfonylurea) may inhibit the anti-tumor activity of PI3K inhibitors, and thus treatment of PI3K inhibitor-associated hyperglycemia should prefer alternative approaches such as a low carbohydrate diet, metformin, SGLT2i, or dose reduction of the PI3K inhibitor.