Compound C inhibits in vitro angiogenesis and ameliorates thrombin-induced endothelial barrier failure

Intrinsic endothelial hyperresponsiveness to inflammatory mediators drives acute episodes in models of Clarkson disease

Clarkson disease, or monoclonal gammopathy-associated idiopathic systemic capillary leak syndrome (ISCLS), is a rare, relapsing-remitting disorder featuring the abrupt extravasation of fluids and proteins into peripheral tissues, which in turn leads to hypotensive shock, severe hemoconcentration, and hypoalbuminemia. The specific leakage factor(s) and pathways in ISCLS are unknown, and there is no effective treatment for acute flares. Here, we characterize an autonomous vascular endothelial defect in ISCLS that was recapitulated in patient-derived endothelial cells (ECs) in culture and in a mouse model of disease. ISCLS-derived ECs were functionally hyperresponsive to permeability-inducing factors like VEGF and histamine, in part due to increased endothelial nitric oxide synthase (eNOS) activity. eNOS blockade by administration of N(γ)-nitro-l-arginine methyl ester (l-NAME) ameliorated vascular leakage in an SJL/J mouse model of ISCLS induced by histamine or VEGF challenge. eNOS mislocalization and decreased protein phosphatase 2A (PP2A) expression may contribute to eNOS hyperactivation in ISCLS-derived ECs. Our findings provide mechanistic insights into microvascular barrier dysfunction in ISCLS and highlight a potential therapeutic approach.

Compound C Inhibits Ovarian Cancer Progression via PI3K-AKT-mTOR-NFκB Pathway

Epithelial Ovarian cancer (OvCa) is the leading cause of death from gynecologic malignancies in the United States, with most patients diagnosed at late stages. High-grade serous cancer (HGSC) is the most common and lethal subtype. Despite aggressive surgical debulking and chemotherapy, recurrence of chemo-resistant disease occurs in ~80% of patients. Thus, developing therapeutics that not only targets OvCa cell survival, but also target their interactions within their unique peritoneal tumor microenvironment (TME) is warranted. Herein, we report therapeutic efficacy of compound C (also known as dorsomorphin) with a novel mechanism of action in OvCa. We found that CC not only inhibited OvCa growth and invasiveness, but also blunted their reciprocal crosstalk with macrophages, and mesothelial cells. Mechanistic studies indicated that compound C exerts its effects on OvCa cells through inhibition of PI3K-AKT-NFκB pathways, whereas in macrophages and mesothelial cells, CC inhibited cancer-cell-induced canonical NFκB activation. We further validated the specificity of the PI3K-AKT-NFκB as targets of compound C by overexpression of constitutively active subunits as well as computational modeling. In addition, real-time monitoring of OvCa cellular bioenergetics revealed that compound C inhibits ATP production, mitochondrial respiration, and non-mitochondrial oxygen consumption. Importantly, compound C significantly decreased tumor burden of OvCa xenografts in nude mice and increased their sensitivity to cisplatin-treatment. Moreover, compound C re-sensitized patient-derived resistant cells to cisplatin. Together, our findings highlight compound C as a potent multi-faceted therapeutic in OvCa.

Dapagliflozin Inhibits Ventricular Remodeling in Heart Failure Rats by Activating Autophagy through AMPK/mTOR Pathway

Objective

Heart failure (HF) is the end stage of heart disease caused by various factors which mainly involves ventricular remodeling (VR). In HF patients with reduced ejection fraction, dapagliflozin (DAPA) reduced the risk of worsening HF or cardiovascular death. Thus, we attempted to clarify the specific role of DAPA underlying HF progression.

Methods

The HF rat model was established to mimic characteristics of HF in vivo. HE staining assessed histopathological changes in left ventricular myocardial tissue of rats in each group. ELISA measured plasma ANP and BNP levels of rats in each group. M-mode echocardiography detected cardiac function of rats in each group. TUNEL staining detected apoptosis of infarct margin cells in myocardial tissue of rats in each group. Western blot detected levels of apoptosis-related proteins, autophagy-related proteins, and AMPK/mTOR-related proteins in myocardial tissue of rats in each group. Immunohistochemical staining detected caspase-3 or LC3B level in myocardial tissue of rats in each group. The HF cellular model was established to mimic characteristics of HF in vitro. Flow cytometry detected H9C2 cell apoptosis under different conditions. Western blot detected levels of apoptosis-related proteins, autophagy-related proteins, and AMPK/mTOR-related proteins in H9C2 cells under different conditions. Immunofluorescence detected caspase-3 or LC3B level in H9C2 cells under different conditions.

Results

DAPA attenuated left VR and improved cardiac function in HF rats. DAPA attenuated cardiomyocyte apoptosis in HF rats. DAPA facilitated cardiomyocyte autophagy in HF rats via the AMPK/mTOR pathway. DAPA repressed hypoxia-induced H9C2 cell apoptosis by facilitating autophagy. DAPA repressed hypoxia-induced H9C2 cell apoptosis via the AMPK/mTOR pathway.

Conclusion

DAPA suppresses ventricular remodeling in HF through activating autophagy via AMPK/mTOR pathway, which provides a potential novel insight for seeking therapeutic plans of HF.

Role of PI3K/Akt and MEK/ERK Signalling in cAMP/Epac-Mediated Endothelial Barrier Stabilisation

Background and Aims

Activation of the cAMP/Epac signalling stabilises endothelial barrier function. Moreover, its activation is accompanied by an activation of PI3K/Akt and MEK/ERK signalling in diverse cell types but their impact on endothelial barrier function is largely unknown. Here the role of PI3K/Akt and MEK/ERK signalling in cAMP/Epac-mediated endothelial barrier stabilisation was analysed.

Methods

Endothelial barrier function was analysed in cultured human umbilical vein endothelial cells (HUVECs) by measuring flux of albumin. A modified cAMP analogue 8-pCPT-2′-O-Me-cAMP (Epac agonist) was used to specifically activate cAMP/Epac signalling.

Results

Epac agonist reduces the basal and attenuates thrombin-induced endothelial hyperpermeability accompanied by an activation of PI3K/Akt and MEK/ERK signalling. The qPCR data demonstrate HUVECs express PI3Kα, PI3Kβ, and PI3Kγ but not PI3Kδ isoforms. The western blot data demonstrate Epac agonist activates PI3Kα and PI3Kβ isoforms. Inhibition of MEK/ERK but not PI3K/Akt pathway potentiates the endothelial barrier protective effects of cAMP/Epac signalling. Inhibition of MEK/ERK signalling in the presence of Epac agonist induces a reorganisation of actin cytoskeleton to the cell periphery, enhanced VE-cadherin localisation at cell-cell junctions, and dephosphorylation of myosin light chains (MLC) but not inhibition of RhoA/Rock signalling. Moreover, Epac agonist promotes endothelial cell (EC) survival via reduction in activities of pro-apoptotic caspases in a PI3K/Akt and MEK/ERK signalling-dependent manner.

Conclusion

Our data demonstrate that the Epac agonist simultaneously activates diverse signalling pathways in ECs, which may have differential effects on endothelial barrier function. It activates PI3K/Akt and MEK/ERK signalling which mainly govern its pro-survival effects on ECs. Inhibition of MEK/ERK but not PI3K/Akt signalling enhances barrier stabilising and barrier protective effects of cAMP/Epac activation.

Chemical Compounds Used In This Study

8-pCPT-2′-O-Me-cAMP (PubChem CID: 9913268); Akt inhibitor VIII (PubChem CID: 10196499); AS-252424 (PubChem CID: 11630874); IC-87114 (PubChem CID: 9908783); PD 98059 (PubChem CID: 4713); PIK-75 (PubChem CID: 10275789); TGX-221 (PubChem CID: 9907093); Thrombin (PubChem CID: 90470996); U0126 (PubChem CID: 3006531); Wortmannin (PubChem CID: 312145).

Kudinoside-D, a triterpenoid saponin derived from Ilex kudingcha suppresses adipogenesis through modulation of the AMPK pathway in 3T3-L1 adipocytes

The leaves of Ilex Kudingcha, locally named "Kudingcha" in China, has been traditionally applied for treating obesity. Studies have demonstrated that the ethanol extract of Ilex kudingcha have anti-adipogenic effects. However, the constituent which was responsible for its anti-obesity and its underlying molecular mechanism has not yet been elucidated. This research explored the anti-obesity effect of kudinoside-D which was a main natural component of triterpenoid saponin from the ethanol extract of Ilex kudingcha, on lipid accumulation and the potential mechanism of action of adipogenesis in 3T3-L1 adipocytes. The adipocytes were treated with various concentrations of kudinoside D (0 to 40μM) during differentiation. The image-based Oil Red O staining analyses revealed that KD-D, dose dependently reduced cytoplasmic lipid droplet in 3T3-L1 adipocytes with the IC₅₀ is 59.49μM. Meanwhile, major adipogenic transcription factor peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer binding protein-α (C/EBPα) and sterol regulatory element-binding protein 1c (SREBP-1c) were significantly repressed as well as their target genes. The phosphorylation of AMP-activated protein kinase (AMPK) and its downstream target phosphorylated-acetyl CoA carboxylase (ACC) expression were also increased. In addition, the inhibitory effects of KD-D on the expressions of PPARγ and C/EBPα were weakened when cells were cotreated with AMPK inhibitor Compound C. These results indicated KD-D exerts anti-adipogenic effects through modulation of adipogenic transcription factors via AMPK signaling pathway. And the current findings demonstrated that KD-D was a potential therapeutic candidate for alleviating obesity and hyperlipidemia.

Low-Dose Lithium Stabilizes Human Endothelial Barrier by Decreasing MLC Phosphorylation and Universally Augments Cholinergic Vasorelaxation Capacity in a Direct Manner

Lithium at serum concentrations up to 1 mmol/L has been used in patients suffering from bipolar disorder for decades and has recently been shown to reduce the risk for ischemic stroke in these patients. The risk for stroke and thromboembolism depend not only on cerebral but also on general endothelial function and health; the entire endothelium as an organ is therefore pathophysiologically relevant. Regardless, the knowledge about the direct impact of lithium on endothelial function remains poor. We conducted an experimental study using lithium as pharmacologic pretreatment for murine, porcine and human vascular endothelium. We predominantly investigated endothelial vasorelaxation capacities in addition to human basal and dynamic (thrombin-/PAR-1 receptor agonist-impaired) barrier functioning including myosin light chain (MLC) phosphorylation (MLC-P). Low-dose therapeutic lithium concentrations (0.4 mmol/L) significantly augment the cholinergic endothelium-dependent vasorelaxation capacities of cerebral and thoracic arteries, independently of central and autonomic nerve system influences. Similar concentrations of lithium (0.2–0.4 mmol/L) significantly stabilized the dynamic thrombin-induced and PAR-1 receptor agonist-induced permeability of human endothelium, while even the basal permeability appeared to be stabilized. The lithium-attenuated dynamic permeability was mediated by a reduced endothelial MLC-P known to be followed by a lessening of endothelial cell contraction and paracellular gap formation. The well-known lithium-associated inhibition of inositol monophosphatase/glycogen synthase kinase-3-β signaling-pathways involving intracellular calcium concentrations in neurons seems to similarly occur in endothelial cells, too, but with different down-stream effects such as MLC-P reduction. This is the first study discovering low-dose lithium as a drug directly stabilizing human endothelium and ubiquitously augmenting cholinergic endothelium-mediated vasorelaxation. Our findings have translational and potentially clinical impact on cardiovascular and cerebrovascular disease associated with inflammation explaining why lithium can reduce, e.g., the risk for stroke. However, further clinical studies are warranted.

The flower of Edgeworthia gardneri (wall.) Meisn. suppresses adipogenesis through modulation of the AMPK pathway in 3T3-L1 adipocytes

ETHNOPHARMACOLOGICAL RELEVANCE

The flower of Edgeworthia gardneri (Wall.) Meisn., locally named "Lvluohua, ", has been widely used as Tibetan folk medicine for the treatment of metabolic diseases for a long time.

AIM OF THIS STUDY

To evaluate the anti-adipogenesis effect of ethyl acetate extract of the flower of E. gardneri (EEG extract) in 3T3-L1 adipocytes.

MATERIALS AND METHODS

Obesity-related parameters such as lipid accumulation and TG content were determined by Oil red O staining and enzymatic kit, respectively. Western blotting was used to determine the expressions of peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer-binding protein-α (C/EBPα), phosphorylated adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC). Moreover, main constituents of EEG extract were analyzed by high performance liquid chromatography (HPLC).

RESULTS

EEG extract decreased the lipid and triglyceride (TG) accumulations during the differentiation process and down-regulated the adipogenesis-related transcriptional factors PPARγ and C/EBPα. EEG extract treatment increased AMPK and ACC phosphorylation. In addition, pretreatment with AMPK inhibitor, weakened the inhibitory effects of EEG extract on the expressions of PPARγand C/EBPα. HPLC analysis indicated that tiliroside was the main constituent in EEG extract.

CONCLUSIONS

These results suggest that EEG extract may exert anti-adipogenic effects through modulation of the AMPK signaling pathway.