Phosphoinositide Conversion Inactivates R-RAS and Drives Metastases in Breast Cancer

Breast cancer is the most prevalent cancer and a major cause of death in women worldwide. Although early diagnosis and therapeutic intervention significantly improve patient survival rate, metastasis still accounts for most deaths. Here it is reported that, in a cohort of more than 2000 patients with breast cancer, overexpression of PI3KC2α occurs in 52% of cases and correlates with high tumor grade as well as increased probability of distant metastatic events, irrespective of the subtype. Mechanistically, it is demonstrated that PI3KC2α synthetizes a pool of PI(3,4)P2 at focal adhesions that lowers their stability and directs breast cancer cell migration, invasion, and metastasis. PI(3,4)P2 locally produced by PI3KC2α at focal adhesions recruits the Ras GTPase activating protein 3 (RASA3), which inactivates R-RAS, leading to increased focal adhesion turnover, migration, and invasion both in vitro and in vivo. Proof-of-concept is eventually provided that inhibiting PI3KC2α or lowering RASA3 activity at focal adhesions significantly reduces the metastatic burden in PI3KC2α-overexpressing breast cancer, thereby suggesting a novel strategy for anti-breast cancer therapy

Surexpression cardiac de PDE4B1 à l'aide d'un virus adéno-associé

Activation of the β-adrenergic pathway results in an increase in cAMP which plays a key role in the regulation of cardiac contraction. While an acute stimulation of the β-adrenergic receptors (β-ARs) improves cardiac function, their chronic activation in heart failure (HF) is detrimental to the heart, as it promotes deregulation of intracellular calcium handling and maladaptive remodeling. Multiple phosphodiesterases (PDEs) are responsible for cAMP degradation and compartmentation, and therefore finely tune β-AR responses. We showed previously that PDE4B is decreased in pathological cardiac hypertrophy and PDE4B ablation in mice exacerbates β-AR stimulation of the L-type Ca2+ current and the propensity to cardiac arrhythmias. Since long term treatment with PDE inhibitors increases mortality in HF, we hypothesized that decreasing cAMP levels could have a therapeutic effect in this disease. To address this hypothesis we used two different models: transgenic overexpression of the PDE using the cardiac specific promoter α-MHC, and PDE-encoding adeno-associated virus targeting the heart in adult mice. We explored whether transgenic or serotype 9 adeno-associated viral vectors (AAV9) mediated cardiac overexpression of PDE4B could prevent maladaptive hypertrophy in a mouse model of chronic isoproterenol (Iso) infusion (60 µg/g/day during 2 weeks). Echocardiography allowed cardiac function exploration. PDE4B protein expression in heart extracts was measured by western blot. Heart sections (10 µm thick) were cut from paraffin-embedded specimens and stained with Masson’s trichrome to quantify fibrosis. A ten-fold and five-fold increase in PDE4B protein levels was measured in transgenic and AAV9, respectively. In transgenic mice, constitutive PDE4B overexpression caused a mild hypertrophy in adult mice. In control mice, either wild-type or injected with a AAV9 encoding for (1x1012 vp), chronic Iso treatment induced cardiac hypertrophy, fibrosis, and decreased ejection fraction (EF) measured by echocardiography. Overexpression of PDE4B did not prevent cardiac hypertrophy induced by Iso, but abolished the increase in fibrosis. More importantly, EF was preserved when PDE4B was overexpressed in this pathological model. Altogether, these results suggest that gene therapy with AAV9 encoding PDEs is a potential therapeutic approach for cardiac maladaptive hypertrophy.L'activation de la voie β-adrénergique entraîne une augmentation de l'AMPc qui joue un rôle clé dans la régulation de la contraction cardiaque. Alors qu'une stimulation aiguë des récepteurs β-adrénergiques (β-AR) améliore la fonction cardiaque, leur activation chronique dans l'insuffisance cardiaque (IC) est préjudiciable au cœur, car elle favorise la dérégulation du calcium intracellulaire et le remodelage pathologique du cœur. Les phosphodiestérases (PDE) sont responsables de la dégradation de l'AMPc et de la compartimentation, et donc ajustent finement les réponses β-AR. Nous avons montré précédemment que la PDE4B est diminuée dans l'hypertrophie cardiaque pathologique et que l'ablation de PDE4B chez la souris exacerbe la stimulation β-AR du courant Ca2+ de type L et la propension aux arythmies cardiaques. Étant donné qu'un traitement à long terme par des inhibiteurs de la PDE augmente la mortalité dans l'HF, nous avons supposé que la diminution des taux d'AMPc pourrait avoir un effet thérapeutique dans cette maladie. Nous avons exploré si la surexpression cardiaque médiée par les vecteurs viraux adéno-associés sérotype 9 (AAV9) ou à l’aide d’un système transgénique de PDE4B pourrait prévenir une hypertrophie dans un modèle murin d'infusion chronique d'isoprotérénol (Iso) (60 μg / g / jour pendant 2 semaines). L'échocardiographie a permis l'exploration de la fonction cardiaque. L'expression de la protéine PDE4B dans les extraits de coeur a été mesurée par western blot. Des coupes de cœur (10 μm d'épaisseur) ont été prélevées sur des échantillons inclus en paraffine et colorées avec le trichrome de Masson pour quantifier la fibrose. Une augmentation de dix fois et cinq fois des niveaux de protéines PDE4B a été mesurée dans les transgéniques et les AAV9, respectivement. Chez les souris transgéniques adulte, la surexpression constitutive de la PDE4B a provoqué une légère hypertrophie. Chez les souris témoins, de type sauvage ou ayant reçu un AAV9 codant pour la Luciferase(1x1012 particules virales), le traitement par Iso chronique a induit une hypertrophie cardiaque, une fibrose et une diminution de la fraction d'éjection (EF) mesurée par échocardiographie. La surexpression de PDE4B n'a pas empêché l'hypertrophie cardiaque induite par Iso, mais a aboli l'augmentation de la fibrose. Plus important encore, l’EF a été préservé lorsque PDE4B a été surexprimé dans ce modèle pathologique. Au total, ces résultats suggèrent que la thérapie génique avec des AAV9 codant pour PDE est une approche thérapeutique potentielle pour le traitement de l'hypertrophie cardiaque inadaptée

Class II PI3Ks at the Intersection between Signal Transduction and Membrane Trafficking

Phosphorylation of inositol phospholipids by the family of phosphoinositide 3-kinases (PI3Ks) is crucial in controlling membrane lipid composition and regulating a wide range of intracellular processes, which include signal transduction and vesicular trafficking. In spite of the extensive knowledge on class I PI3Ks, recent advances in the study of the three class II PI3Ks (PIK3C2A, PIK3C2B and PIK3C2G) reveal their distinct and non-overlapping cellular roles and localizations. By finely tuning membrane lipid composition in time and space among different cellular compartments, this class of enzymes controls many cellular processes, such as proliferation, survival and migration. This review focuses on the recent developments regarding the coordination of membrane trafficking and intracellular signaling of class II PI3Ks through the confined phosphorylation of inositol phospholipids

PI3K Signaling in Mechanisms and Treatments of Pulmonary Fibrosis Following Sepsis and Acute Lung Injury

Pulmonary fibrosis is a pathological fibrotic process affecting the lungs of five million people worldwide. The incidence rate will increase even more in the next years due to the long-COVID-19 syndrome, but a resolving treatment is not available yet and usually prognosis is poor. The emerging role of the phosphatidylinositol 3-kinase (PI3K)/AKT signaling in fibrotic processes has inspired the testing of drugs targeting the PI3K/Akt pathway that are currently under clinical evaluation. This review highlights the progress in understanding the role of PI3K/Akt in the development of lung fibrosis and its causative pathological context, including sepsis as well as acute lung injury (ALI) and its consequent acute respiratory distress syndrome (ARDS). We further summarize current knowledge about PI3K inhibitors for pulmonary fibrosis treatment, including drugs under development as well as in clinical trials. We finally discuss how the design of inhaled compounds targeting the PI3K pathways might potentiate efficacy and improve tolerability

The Guareschi Pyridine Scaffold as a Valuable Platform for the Identification of Selective PI3K Inhibitors

A novel series of 4-aryl-3-cyano-2-(3-hydroxyphenyl)-6-morpholino-pyridines have been designed as potential phosphatidylinositol-3-kinase (PI3K) inhibitors. The compounds have been synthesized using the Guareschi reaction to prepare the key 4-aryl-3-cyano-2,6-dihydroxypyridine intermediate. A different selectivity according to the nature of the aryl group has been observed. Compound 9b is a selective inhibitor against the PI3K\u3b1 isoform, maintaining a good inhibitory activity. Docking studies were also performed in order to rationalize its profile of selectivity

Phosphoinositide 3-Kinase-C2α Regulates Polycystin-2 Ciliary Entry and Protects against Kidney Cyst Formation.

Signaling from the primary cilium regulates kidney tubule development and cyst formation. However, the mechanism controlling targeting of ciliary components necessary for cilium morphogenesis and signaling is largely unknown. Here, we studied the function of class II phosphoinositide 3-kinase-C2α (PI3K-C2α) in renal tubule-derived inner medullary collecting duct 3 cells and show that PI3K-C2α resides at the recycling endosome compartment in proximity to the primary cilium base. In this subcellular location, PI3K-C2α controlled the activation of Rab8, a key mediator of cargo protein targeting to the primary cilium. Consistently, partial reduction of PI3K-C2α was sufficient to impair elongation of the cilium and the ciliary transport of polycystin-2, as well as to alter proliferation signals linked to polycystin activity. In agreement, heterozygous deletion of PI3K-C2α in mice induced cilium elongation defects in kidney tubules and predisposed animals to cyst development, either in genetic models of polycystin-1/2 reduction or in response to ischemia/reperfusion-induced renal damage. These results indicate that PI3K-C2α is required for the transport of ciliary components such as polycystin-2, and partial loss of this enzyme is sufficient to exacerbate the pathogenesis of cystic kidney disease.SCOPUS: ar.jinfo:eu-repo/semantics/publishe