Phosphatidylinositol 3-kinase Pathway Research Articles

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

Abstract Phosphoinositide-3-kinase (PI3K) pathway function is crucial to normal development, differentiation and function of immune cells including B, T and NK cells. Following the description of two cohorts of patients with a 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-functions variants in PIK3R1 and PTEN have also been linked to APDS. Importantly, the availability of small molecules that inhibit the PI3K pathway have enabled targeted treatment of APDS patients. In this review, we define (1) the PI3K pathway and its role in inborn errors of immunity; (2) the clinical and immunological presentation of APDS1 (PIK3CD GOF), APDS2 (PIK3R1 LOF) and related disorders; (3) Diagnostic approaches to identify and functionally validate the genetic causes of disease; (4) therapeutic interventions to target PI3K hyperactivation; and finally (5) 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.

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.

Regulation of PI3K signaling in cancer metabolism and PI3K-targeting therapy.

The phosphatidylinositol-3-kinase (PI3K) signaling plays a key role in various cellular functions and is frequently activated in cancer, making it an attractive therapeutic target. The PI3K signaling pathway influencing glucose metabolism, lipid synthesis, nucleotide production, and protein synthesis, all of which contribute to cancer cell proliferation and survival. It enhances glucose uptake through the activation of glucose transporters and glycolysis, while also promoting lipid synthesis via downstream factors like mTORC1. This pathway boosts nucleotide synthesis by regulating transcription factors like MYC, activating key enzymes for purine and pyrimidine production. Additionally, due to its essential role in cancer cell growth, the PI3K pathway is a key target for anticancer therapies. However, treatment using PI3K inhibitors alone has limitations, including drug resistance and significant side effects such as hyperglycemia, fatigue, and liver dysfunction. Clinical trials have led to the development of isoform-specific PI3K inhibitors to reduce toxicity. Combining PI3K inhibitors with other treatments, such as hormone therapy or surgery, may improve efficacy and minimize side effects. Further research is needed to fully understand the mechanisms of PI3K inhibitors and improve individualized treatment approaches. In this review, we introduce the characteristic of three classes of PI3Ks, discuss the regulation of cancer metabolism including the control of glucose uptake, glycolysis, de novo lipid synthesis, nucleotide synthesis and protein synthesis, and review the current statuses of different PI3K inhibitors therapy.

Bioinformatics analysis of G protein subunit gamma transduction protein 2-autophagy axis in CD11b+ dendritic cells as a potential regulator to skew airway neutrophilic inflammation in asthma endotypes.

Asthma is a heterogeneous inflammatory disease with two main clinical endotypes: type 2 (T2) high and low asthma. The plasticity and autophagy in dendritic cells (DCs) influence T helper (Th)2 or Th17 differentiation to regulate asthma endotypes. Enhanced autophagy in DCs fosters Th2 differentiation in allergic environments, while reduced autophagy favors Th17 cell differentiation in sensitized and infected environments. Autophagy regulation in DCs involves interaction with various pathways like G protein-coupled receptor (GPCR), mammalian target of rapamycin (mTOR), or phosphoinositide 3-kinase (PI3K) pathway. However, specific molecules within DCs influencing asthma endotypes remain unclear. Gene expression data series (GSE) 64896, 6858, 2276, and 55247 were obtained from gene expression omnibus (GEO) database. Differentially expressed genes (DEGs) between CD103+ and CD11b+ DCs after induction by ovalbumin (OVA) and lipopolysaccharide (LPS) were analyzed using GEO2R. DEGs were examined through Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and protein-protein interaction (PPI) analyses. The hub gene network was construct with STRING database and Cytoscape. Autophagy differences in DCs and the selected hub gene in GSE6858, GSE2276, and GSE55247 were evaluated using student t tests. Our analysis identified 635 upregulated and 360 downregulated genes in CD11b+ DCs, compared to CD103+ DCs. These DEGs were associated with "PI3K-AKT signaling pathway," "Ras signaling pathway," and so forth. Thirty-five hub genes were identified, in which G protein subunit gamma transduction protein 2 (Gngt2) in CD11b+ DCs exhibited a relatively specific increase in expression associated with autophagy defects under the induction environment similar to T2 low asthma model. No significant difference was found in lung Gngt2 expression between T2 high asthma model and control group. Our analysis suggested Gngt2 acted as an adapter molecule that inhibited autophagy, promoting Th17-mediated airway inflammation via the GPCR pathway in a T2 low asthma mice model. Targeting this pathway provides new asthma treatment strategies in preclinical research.

Black raspberry extract stimulates glucose uptake via adenosine monophosphate‐activated protein kinase and phosphatidylinositol‐3 kinase pathways in skeletal muscle cells

AbstractBlack raspberry (Rubus occidentalis) shows beneficial health effects, such as antioxidant, anti‐inflammatory, chemopreventive, antiproliferative, and antihyperglycemic activities. The present study investigated the antihyperglycemic activity of black raspberry extract (BRE) and potential mechanisms in skeletal muscle cells. Differentiated C2C12 myotubes were treated with the BRE (1–1000 μg/mL) or metformin (1 mM). The protein levels of various insulin signaling targets were measured by western blot analysis. BRE significantly increased glucose uptake by upregulated insulin receptor and phosphatidylinositol‐3 kinase (PI3K) in C2C12 cells, leading to enhanced translocation of glucose transporter 4 (GLUT4) to the plasma membrane. The expression of phosphorylated (p)‐adenosine monophosphate‐activated protein kinase (AMPK) was also enhanced by treatment with BRE, this resulting in stimulation of GLUT4 translocation to the plasma membrane and hence glucose uptake in skeletal muscles. These results suggest that BRE has an antihyperglycemic effect by stimulating GLUT4 translocation to the plasma membrane via activating the PI3K and AMPK pathways in skeletal muscle cells, thereby upregulating glucose uptake. Black raspberry is a potential functional food and has important implications for preventing and treating type‐2 diabetes. In addition, our study found that the flavonoids fraction is the main contributor fraction to promote glucose uptake in C2C12 cells.

Single molecule Lipid Biosensors Mitigate Inhibition of Endogenous Effector Proteins.

Genetically encoded lipid biosensors are essential cell biological tools. They are the only technique that provide real time, spatially resolved kinetic data for lipid dynamics in living cells. Despite clear strengths, these tools also carry significant drawbacks; most notably, lipid molecules bound to biosensors cannot engage with their effectors, causing inhibition. Here, we show that although PI 3-kinase (PI3K)-mediated activation of Akt is not significantly reduced in a cell population transfected with a PH-Akt1 PIP3/PI(3,4)P2 biosensor, single cells expressing the PH-Akt at visible levels (used for live-cell imaging) have no activated Akt at all. Tagging endogenous AKT1 with neonGreen at its genomic locus reveals its EGF-mediated translocation to the plasma membrane, accumulating at densities of ~0.3 molecules/μm2. Co-transfection with the PH-Akt biosensor or other PIP3 biosensors completely blocks this translocation, despite robust recruitment of the biosensors. A partial inhibition is even observed with PI(3,4)P2-selective biosensor. However, we found that expressing lipid biosensors at low levels, comparable with those of endogenous AKT, produced no such inhibition. Helpfully, these single-molecule biosensors revealed improved dynamic range and kinetic fidelity compared with over-expressed biosensor. This approach represents a less invasive way to probe spatiotemporal dynamics of the PI3K pathway in living cells.

MiR-24-3p modulates cardiac function in doxorubicin -induced heart failure via the Sp1/PI3K signaling pathway

PurposeThe goal of this research was to explore the role of miR-24-3p in heart failure (HF), with a focus on its impact on the specificity protein 1 (Sp1)/phosphoinositide 3-kinase (PI3K) pathway. MethodsHF rat and HF cell models were established using doxorubicin(Dox). Cardiac function was assessed through echocardiography, while histological changes were observed via hematoxylin-eosin (HE) staining. To further investigate the underlying mechanisms, HF cell models were treated with either an Sp1 inhibitor or a PI3K inhibitor. Additionally, models with miR-24-3p overexpression or silencing were constructed. N-terminal pro-brain natriuretic peptide (NT-proBNP) levels were determined by ELISA. Cell apoptosis was evaluated using TUNEL staining, and lactate dehydrogenase (LDH) levels were measured by colorimetry. Reactive oxygen species (ROS) production was analyzed using flow cytometry. Related gene and protein expressions were assessed via qRT-PCR and Western blotting. Finally, the relationship between miR-24-3p and Sp1 was confirmed through dual-luciferase assays. ResultsDox treatment increased the left ventricular internal diameter (LVIDd) while decreasing ejection fraction (EF) and fractional shortening (FS), leading to disorganized cardiomyocyte arrangement, cellular edema, and necrosis in rats. In HF rats, NT-proBNP, Caspase-3, and miR-24-3p expression levels were elevated, whereas Sp1 and PI3K mRNA and protein expression levels were decreased. Similarly, Dox-induced damage in H9c2 cardiomyocytes resulted in increased NT-proBNP, apoptosis, Caspase-3, LDH, ROS, and miR-24-3p expression, along with decreased Sp1 and PI3K expression. Treatment with either Sp1 or PI3K inhibitors exacerbated the Dox-induced cardiomyocyte damage, further elevating NT-proBNP, apoptosis, Caspase-3, LDH, ROS, and miR-24-3p expression levels. Notably, Sp1 inhibition reduced PI3K expression, and PI3K inhibition, in turn, suppressed Sp1 expression. Overexpression of miR-24-3p worsened Dox-induced cardiomyocyte damage, characterized by increased NT-proBNP, apoptosis, Caspase-3, LDH, and ROS expression, alongside reduced Sp1 and PI3K expression. In contrast, silencing miR-24-3p mitigated these detrimental effects and increased Sp1 and PI3K expression. Dual-luciferase assays confirmed that miR-24-3p directly targets Sp1. ConclusionDox induces cardiomyocyte damage, impairs cardiac function, and promotes cardiomyocyte apoptosis and oxidative stress. Silencing miR-24-3p offers a protective effect by activating the Sp1/PI3K signaling pathway in heart failure.

IL-8 and PI3K pathway influence the susceptibility of TRAIL-sensitive colorectal cancer cells to TRAIL-induced cell death.

Tumour necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is an apoptosis inducer that exhibits an ideal therapeutic safety profile with less adverse effects than conventional chemotherapy. However, the occurrence of TRAIL resistance has been reported in various cancers including colorectal cancer (CRC). Substantial efforts have been channelled towards managing TRAIL resistance including identifying molecular targets. Interleukins (ILs) have been recently shown to play critical roles in modulating TRAIL sensitivity in cancer cells. This study investigated the roles of two ILs, IL-8 and IL⍺, in TRAIL resistance in CRC. TRAIL-resistant HT-29 and TRAIL-sensitive HCT 116 cells, were treated with human recombinant IL-8 and IL-1⍺. The results indicated that treatment with IL-8 (2.5 ng/mL) significantly protected TRAIL-sensitive HCT 116 cells from TRAIL-induced cell death (p < 0.05). However, IL-1⍺ did not play a role in modulating CRC cells' responses to TRAIL. Data from RT-qPCR and Western blotting revealed the molecular regulations of IL-8 on TRAIL decoy receptor genes (OPG) and autophagy-related genes (BECN1 and LC3B) expression. The activation of the phosphoinositide 3-kinase (PI3K) pathway was shown to counteract TRAIL-induced cell death. By inhibiting its activation with wortmannin, the protective role of IL-8 against TRAIL treatment was reversed, suggesting the involvement of the PI3K pathway. Collectively, findings from this study identified the role of IL-8 and PI3K in modulating CRC cells' sensitivity to TRAIL. Further validation of these two potential molecular targets is warranted to overcome TRAIL resistance in CRC.

Retraction Note: Oncolysis of pancreatic tumour cells by a γ34.5-deleted HSV-1 does not rely upon Ras-activation, but on the PI 3-kinase pathway.

Retraction Note: Oncolysis of pancreatic tumour cells by a γ34.5-deleted HSV-1 does not rely upon Ras-activation, but on the PI 3-kinase pathway.

Molecular mechanisms of PI3K isoform dependence in embryonic growth.

The phosphoinositide 3-kinase (PI3K) pathway is an important signaling mechanism for cell proliferation and metabolism. Mutations that activate PIK3CA may make cells p110α dependent, but when phosphatase tensin homolog (PTEN) is lost, the p110β isoform of PI3Ks becomes more important. However, the exact mechanism underlying the prevalence of p110s remains unclear. In this study, our aim was to elucidate the processes behind PI3K isoform dependency in a cellular model of embryonic development. In order to understand PI3K isoform prevalence, mouse embryonic fibroblasts (MEFs) were used and p110β, PTEN and Rac1 activity was modulated using retroviral plasmids. Expression levels and cellular growth were assessed by performing immunoblots and crystal violet assays. The levels of PTEN had only a partial effect on the prevalence of PI3K isoforms in MEFs. The dependency on p110α diminished when PTEN was depleted. Of note, when PTEN expression was repressed, there was no full transition in dependency from one PI3K isoform to the other. Interestingly, the viability of PTEN-depleted MEFs became less dependent on p110α and more dependent on p110β when p110β was overexpressed. Nevertheless, the overexpression of p110β in conjunction with PTEN knock-downs did not result in a complete shift of isoforms in PI3Ks. Finally, we investigated Rac1 activation with a mutant allele and determined a more potent increase in p110β prominence in MEFs. These findings suggest that multiple cellular parameters, including PTEN status, PI3K isoform levels, and Rac1 activity, combine to influence PI3K isoform prevalence, rather than a single determinant.

I told you to stop: obscurin's role in epithelial cell migration.

The giant cytoskeletal protein obscurin contains multiple cell signaling domains that influence cell migration. Here, we follow each of these pathways, examine how these pathways modulate epithelial cell migration, and discuss the cross-talk between these pathways. Specifically, obscurin uses its PH domain to inhibit phosphoinositide-3-kinase (PI3K)-dependent migration and its RhoGEF domain to activate RhoA and slow cell migration. While obscurin's effect on the PI3K pathway agrees with the literature, obscurin's effect on the RhoA pathway runs counter to most other RhoA effectors, whose activation tends to lead to enhanced motility. Obscurin also phosphorylates cadherins, and this may also influence cell motility. When taken together, obscurin's ability to modulate three independent cell migration pathways is likely why obscurin knockout cells experience enhanced epithelial to mesenchymal transition, and why obscurin is a frequently mutated gene in several types of cancer.

Targeted DNA Sequencing in Diagnosis of Malignant Phyllodes Tumors With Emphasis on Tumors With Keratin and p63 Expression

The differential diagnosis of malignant spindle cell neoplasms in the breast most frequently rests between malignant phyllodes tumor (MPT) and metaplastic carcinoma (MBC). Diagnosis of MPT can be challenging due to diffuse stromal overgrowth, keratin (CK) and/or p63 immunopositivity, and absent CD34 expression, which can mimic MBC, especially in core biopsies. Distinction of MPT from MBC has clinical implications, with differences in surgical approach, chemotherapy, and radiation. In this study, we evaluated MPTs (78 tumors, 64 patients) for stromal CK, p63, and CD34 expression and profiled a subset (n = 31) by targeted next-generation DNA sequencing, with comparison to MBC (n = 44). Most MPTs (71%) were CK+ and/or p63+, including 32% CK+ (25/77 focal) and 65% p63+ (32/66 focal, 10/66 patchy, and 1/66 diffuse). Thirty percent of MPTs expressed both CK and p63 (20/66), compared with 95% of MBCs (40/42, P < .001). CK and/or p63 were positive in CD34+ and CD34− MPTs. Recurrent genetic aberrations in MPTs involved TERT, TP53, MED12, CDKN2A, chromatin modifiers, growth factor receptors/ligands, and phosphoinositide-3 kinase (PI-3K) and MAPK pathway genes. Only MED12 (39%, 12/31) and SETD2 (13%, 4/31) were exclusively mutated in MPTs and not MBCs (P < .001 and P = .044, respectively), whereas PIK3R1 mutations were only found in MBCs (37%, 13/35, P < .001). Comparative literature review additionally identified ARID1B, EGFR, FLNA, NRAS, PDGFRB, RAD50, and RARA alterations enriched or exclusively in MPTs vs MBCs. MED12 was mutated in MPTs with diffuse stromal overgrowth (53%, 9/17), CD34− MPTs (41%, 7/17), and CK+ and/or p63+ MPTs (39%, 9/23), including 36% of CD34− MPTs with CK and/or p63 expression. Overall, MED12 mutation and/or CD34 expression were observed in 68% (21/31) MPTs, including 61% (14/23) of CK+ and/or p63+ tumors. Our results emphasize the prevalence of CK and p63 expression in MPTs and demonstrate the diagnostic utility of next-generation DNA sequencing, especially in MPTs with confounding factors that can mimic MBC.

Insulin enhances acid-sensing ion channel currents in rat primary sensory neurons

Insulin has been shown to modulate neuronal processes through insulin receptors. The ion channels located on neurons may be important targets for insulin/insulin receptor signaling. Both insulin receptors and acid-sensing ion channels (ASICs) are expressed in dorsal root ganglia (DRG) neurons. However, it is still unclear whether there is an interaction between them. Therefore, the purpose of this investigation was to determine the effects of insulin on the functional activity of ASICs. A 5 min application of insulin rapidly enhanced acid-evoked ASIC currents in rat DRG neurons in a concentration-dependent manner. Insulin shifted the concentration–response plot for ASIC currents upward, with an increase of 46.2 ± 7.6% in the maximal current response. The insulin-induced increase in ASIC currents was eliminated by the insulin receptor antagonist GSK1838705, the tyrosine kinase inhibitor lavendustin A, and the phosphatidylinositol-3 kinase antagonist wortmannin. Moreover, insulin increased the number of acid-triggered action potentials by activating insulin receptors. Finally, local administration of insulin exacerbated the spontaneous nociceptive behaviors induced by intraplantar acid injection and the mechanical hyperalgesia induced by intramuscular acid injections through peripheral insulin receptors. These results suggested that insulin/insulin receptor signaling enhanced the functional activity of ASICs via tyrosine kinase and phosphatidylinositol-3 kinase pathways. Our findings revealed that ASICs were targets in primary sensory neurons for insulin receptor signaling, which may underlie insulin modulation of pain.

Local keratinocyte-nociceptor interactions enhance obesity-mediated small fiber neuropathy via NGF-TrkA-PI3K signaling axis.

The pathology of diabetic small fiber neuropathy, characterized by neuropathic pain and axon degeneration, develops locally within the skin during the stages of obesity and pre-diabetes. However, the initiation and progression of morphological and functional abnormalities in skin sensory nerves remains elusive. To address this, we utilized ear skin from mice with diet-induced obesity (DIO), the mouse models for obesity and pre-type 2 diabetes. We evaluated pain-associated wiping behavior and conducted ex vivo live Ca2+ imaging of the DIO ear skin to detect sensory hypersensitivity. Our findings reveal sensory hypersensitivity in skin nociceptive axons followed by axon degeneration. Further mechanistic analysis identified keratinocytes as a major source of nerve growth factor (NGF) in DIO skin, which locally sensitizes nociceptors through NGF-mediated signaling. Indeed, the local inactivation of NGF and its receptor TrkA-mediated downstream signaling, including the phosphoinositide 3-kinases (PI3K) pathway, suppresses sensory hypersensitivity in DIO skin. Thus, targeting these local interactions between keratinocytes and nociceptors offers a therapeutic strategy for managing neuropathic pain, avoiding the adverse effects associated with systemic interventions.

Dual Inhibition of PI3 Kinase and MAP Kinase Signaling Pathways in Intrahepatic Cholangiocellular Carcinoma Cell Lines Leads to Proliferation Arrest but Not Apoptosis.

Cholangiocellular carcinoma (CCA) is the second most common primary liver cancer, with increasing incidence worldwide and inadequate therapeutic options. Intra- and extrahepatic bile ducts have distinctly different embryonic origins and developmental behavior, and accordingly, intra- and extrahepatic CCAs (ICC vs. ECC) are molecularly different. A promising strategy in oncotherapy is targeted therapy, targeting proteins that regulate cell survival and proliferation, such as the MAPK/ERK and PI3K/AKT/mTOR signaling pathways. Inhibitors of these pathways have been tested previously in CCA cell lines. However, these cell lines could not be clearly assigned to ICC or ECC, and the results indicated apoptosis induction by targeted therapeutics. We tested targeted therapeutics (selumetinib, MK2206) in three defined ICC cell lines (HuH28, RBE, SSP25). We observed additive effects of the dual inhibition of the two pathways, in accordance with the inhibition of phospho-AKT and phospho-ERK1/2 expression. Proliferation was blocked more effectively with dual inhibition than with each single inhibition, but cell numbers did not drop below baseline. Accordingly, we observed G1 phase arrest but not apoptosis or cell death (measured by cleaved caspase-3, AIFM1 regulation, sub-G0/G1 phase). We conclude that the dual inhibition of the MAPK/ERK and PI3K/AKT/mTOR pathways is highly effective to block the proliferation of ICC cell lines in vitro; however, potential clinical applications must be critically examined, as a proliferation block could also induce resistance to standard therapies.