The inhibitory effect of Isoliquiritigenin on the proliferation of human arterial smooth muscle cell

Dynamin-related protein 1 mediates the therapeutic effect of isoliquiritigenin in diabetic intimal hyperplasia via regulation of mitochondrial fission

Phenotypic shift of vascular smooth muscle cells (VSMCs) plays a key role in intimal hyperplasia, especially in patients with diabetes mellitus (DM). This study aimed to investigate the role of dynamin-related protein 1 (DRP1) in mitochondrial fission-mediated VSMC phenotypic shift and to clarify whether DRP1 is the therapeutic target of isoliquiritigenin (ISL). Wire injury of carotid artery or platelet-derived growth factor treatment was performed in DM mice or high-glucose cultured human aortic smooth muscle cells (HASMCs), respectively. The effects of DRP1 silencing on DM-induced intimal hyperplasia were investigated both in vivo and in vitro. Phenotypic shift of HASMCs was evaluated by detection of reactive oxygen species (ROS) generation, cell viability, and related protein expressions. The effects of ISL on DM-induced intimal hyperplasia were evaluated both in vivo and in vitro. DRP1 silencing and ISL treatment attenuated DM-induced intimal hyperplasia with reduced ROS generation, cell viability, and VSMC dedifferentiation. The GTPase domain of DRP1 protein played a critical role in mitochondrial fission in DM-induced VSMC phenotypic shift. Cellular experiments showed that ISL inhibited mitochondrial fission and reduced the GTPase activity of DRP1, which was achieved by the directly binding to K216 of the DRP1 GTPase domain. ISL attenuated mouse intimal hyperplasia by reducing GTPase activity of DRP1 and inhibiting mitochondrial fission in vivo. In conclusion, increased GTPase activity of DRP1 aggregated DM-induced intimal hyperplasia by increasing mitochondrial fission-mediated VSMC phenotypic shift. ISL attenuated mouse intimal hyperplasia by reducing DRP1 GTPase activity and inhibiting mitochondrial fission of VSMCs.

Therapeutic Intervention in Cancer by Isoliquiritigenin from Licorice: A Natural Antioxidant and Redox Regulator

Oxidative stress could lead to a variety of body dysfunctions, including neurodegeneration and cancer, which are closely associated with intracellular signal transducers such as reactive oxygen species (ROS). It has been suggested that ROS is the upstream regulator of autophagy, and that it provides a negative feedback regulation to remove oxidative damage. Defects in the ROS-autophagic redox homeostasis could lead to the increased production of ROS and the accumulation of damaged organelles that in turn promote metabolic reprogramming and induce tumorigenesis. One significant characteristic of pancreatic cancer is the reprogramming of cellular energy metabolism, which facilitates the rapid growth, invasiveness, and the survival of cancer cells. Thus, the rectification of metabolic dysfunction is essential in therapeutic cancer targeting. Isoliquiritigenin (ISL) is a chalcone obtained from the plant Glycyrrhiza glabra, which is a powdered root licorice that has been consumed for centuries in different regions of the world. ISL is known to be a natural antioxidant that possesses diversified functions, including redox regulation in cells. This review contains discussions on the herbal source, biological properties, and anticancer potential of ISL. This is the first time that the anticancer activities of ISL in pancreatic cancer has been elucidated, with a coverage of the involvement of antioxidation, metabolic redox regulation, and autophagy in pancreatic cancer development. Furthermore, some remarks on related compounds of the isoflavonoid biosynthetic pathway of ISL will also be discussed.

Comparative Pharmacokinetics of Seven Major Compounds in Normal and Atherosclerosis Mice after Oral Administration of Simiao Yong'an Decoction

Simiao Yong'an decoction (SMYAD), a classic traditional Chinese medicine formula, has been used to treat atherosclerosis (AS) in clinical in China, but its therapeutic mechanism and pharmacodynamic material basis are not clear. In this study, the AS model was caused by a high-fat diet and perivascular carotid collar placement (PCCP), and SMYAD was orally administered to the model and normal mice. A rapid, sensitive, selective, and reliable method using ultrahigh-performance liquid chromatography (UHPLC) system combined with a Q Exactive HF-X mass spectrometer (UHPLC-Q Exactive HF-X MS) was established and validated for the simultaneous determination of seven compounds, including harpagide, chlorogenic acid, swertiamarin, sweroside, angoroside C, liquiritin, and isoliquiritigenin in the plasma of normal and AS mice. The specificity, linearity, precision, accuracy, recovery, and stability of the method were all within the acceptable criteria. The results showed that some pharmacokinetic behaviors of harpagide, chlorogenic acid, and isoliquiritigenin were significantly different among the two groups of mice. The specific parameter changes were harpagide (AUC_0–t and AUC_0–∞ were 11075.09 ± 2132.38 and 16221.95 ± 5622.42 ng·mL⁻¹·h, respectively; CLz/F was 2.45 ± 0.87 L/h/mg), chlorogenic acid (t_1/2 was 21.59 ± 9.16 h; AUC_0–∞ was 2637.51 ± 322.54 ng·mL⁻¹·h; CLz/F was 13.49 ± 1.81 L/h/mg) and isoliquiritigenin (AUC_0–t and AUC_0–∞ were 502.25 ± 165.65 and 653.68 ± 251.34 ng·mL⁻¹·h, respectively; CLz/F was 62.16 ± 23.35 L/h/mg) were altered under the pathological status of AS. These differences might be partly ascribed to the changes in gastrointestinal microbiota, nonspecific drug transporters, and cytochrome P450 activity under the AS state, providing research ideas and experimental basis for pharmacological effects and pharmacodynamic material basis.

Circ-CHFR modulates the proliferation, migration, and invasion of ox-LDL-induced human aorta vascular smooth muscle cells through the miR-214-3p/PAPPA axis

Circular RNAs (circRNAs) are associated with the pathogenesis of human diseases, including atherosclerosis. Here, we undertook to investigate the biological role and mechanism of circRNA E3 ubiquitin-protein ligase (circ-CHFR) in atherosclerosis. The expression levels of circ-CHFR, miR-214-3p, and pregnancy-associated plasma protein A (PAPPA) were measured by real-time quantitative polymerase chain reaction (RT-qPCR) and western blot in human aorta vascular smooth muscle cells (HA-VSMCs) exposed to oxidized low-density lipoprotein (ox-LDL). Cell proliferation, migration, and invasion capabilities were assessed by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl-2H-tetrazol-3-ium bromide (MTT), and transwell assays, respectively. The relationship between miR-214-3p and circ-CHFR or PAPPA was confirmed by dual-luciferase reporter and RNA immunoprecipitation (RIP) assays. Our data showed that circ-CHFR was upregulated in HA-VSMCs after stimulation with ox-LDL. Downregulation of circ-CHFR inhibited the proliferation, migration, and invasion of HA-VSMCs exposed to ox-LDL. Mechanistically, circ-CHFR acted as a miR-214-3p sponge, and miR-214-3p was a molecular mediator of circ-CHFR regulation in ox-LDL-stimulated HA-VSMCs. PAPPA was a miR-214-3p target, and circ-CHFR regulated the expression of PAPPA by sponging miR-214-3p. Moreover, overexpression of miR-214-3p repressed the proliferation, migration, and invasion of ox-LDL-induced HA-VSMCs by decreasing PAPPA expression. Our findings suggest that the circ-CHFR/miR-214-3p/PAPPA axis regulates ox-LDL-induced proliferation, migration, and invasion in HA-VSMCs.

Dietary polyphenols suppress chronic inflammation by modulation of multiple inflammation-associated cell signaling pathways

The high failure rate of the reductionist approach to discover effective and safe drugs to treat chronic inflammatory diseases has led scientists to seek alternative ways. Recently, targeting cell signaling pathways has been utilized as an innovative approach to discover drug leads from natural products. Cell signaling mechanisms have been identified playing key role in diverse diseases by inducing proliferation, cell survival and apoptosis. Phytochemicals are known to be able to modulate the cellular and molecular networks which are associated to chronic diseases including cancer-associated inflammation. In this review, the roles of dietary polyphenols (apigenin, kaempferol, quercetin, curcumin, genistein, isoliquiritigenin, resveratrol and gallic acid) in modulating multiple inflammation-associated cell signaling networks are deliberated. Scientific databases on suppressive effects of the polyphenols on chronic inflammation via modulation of the pathways especially in the recent five years are gathered and critically analyzed. The polyphenols are able to modulate several inflammation-associated cell signaling pathways, namely nuclear factor-kappa β, mitogen activated protein kinases, Wnt/β-catenin and phosphatidylinositol 3-kinase and protein kinase B via selective actions on various components of the networks. The suppressive effects of the polyphenols on the multiple cell signaling pathways reveal their potential use in prevention and treatment of chronic inflammatory disorders. Understanding the mechanistic effects involved in modulation of the signaling pathways by the polyphenols is necessary for lead identification and development of future functional foods for prevention and treatment of chronic inflammatory diseases.

Isoliquiritigenin Attenuates Monocrotaline-Induced Pulmonary Hypertension via Inhibition of the Inflammatory Response and PASMCs Proliferation

Pulmonary hypertension (PH) is a progressive and serious disease, where exacerbated inflammatory response plays a critical role. Isoliquiritigenin (ISL), an important flavonoid isolated from Glycyrrhizae radix, exhibits a wide range of pharmacological actions including anti-inflammation. Previously we found ISL alleviated hypoxia-induced PH; in the present study, to extend this, we evaluated the effects of ISL on monocrotaline (MCT)-induced PH and the relevant mechanisms. Rats received a single intraperitoneal injection of MCT, followed by intragastric treatments with ISL (10 mg/kg/d or 30 mg/kg/d) once a day for 28 days. The MCT administration increased the right ventricular systolic pressure (RVSP) (p < 0.001), the median width of pulmonary arteries (p < 0.01), and the weight ratio of the right ventricular wall/left ventricular wall plus septum (Fulton index) (p < 0.01) in rats; however, these changes were inhibited by both doses of ISL (p < 0.05). In addition, treatment with ISL suppressed the upregulated production of serum interleukin-6 (p < 0.01) and tumor necrosis factor-α (p < 0.05) by MCT and reversed the increases in the numbers of proliferating cell nuclear antigen (PCNA)-positive cells (p < 0.01) in the medial wall of pulmonary arteries. In in vitro experiments, ISL (10 μM, 30 μM, and 100 μM) inhibited excessive proliferation of cultured primary pulmonary artery smooth muscle cells (PASMCs) (p < 0.05, p < 0.01, and p < 0.001) in a dose-dependent manner and prevented an increase in the expressions of PCNA (p < 0.01) and phospho-Akt (p < 0.05) in PASMCs induced by hypoxia. These results suggest that ISL can attenuate MCT-induced PH via its anti-inflammatory and antiproliferative actions.

Nucleolin promotes Ang II‑induced phenotypic transformation of vascular smooth muscle cells via interaction with tropoelastin mRNA

The current study aimed to clarify the role of nucleolin in the phenotypic transformation of vascular smooth muscle cells (VSMCs) and to preliminarily explore its underlying mechanism. The spatial and temporal expression patterns of nucleolin, and the effects of angiotensin II (Ang II) on the expression of VSMC phenotypic transformation markers, α‑smooth muscle‑actin, calponin, smooth muscle protein 22α and osteopontin were investigated. The effects of nucleolin on VSMC phenotypic transformation and the expression of phenotypic transformation‑associated genes, tropoelastin, epiregulin and fibroblast growth factor 2 (b‑FGF), were determined. Protein‑RNA co‑immunoprecipitation was used to investigate the potential target genes regulated by the nucleolin in phenotypic transformation of VSMCs. Finally, the stability of tropoelastin mRNA and the effects of nucleolin on the expression of tropoelastin were assayed. The results revealed that Ang II significantly promoted the phenotypic transformation of VSMCs. The expression of nucleolin was gradually upregulated in VSMCs treated with Ang II at different concentrations for various durations. Ang II induced nucleolin translocation from the nucleus to cytoplasm. Additionally, Ang II significantly promoted the phenotypic transformation of VSMCs. Overexpression and silencing of nucleolin regulated the expressions of tropoelastin, epiregulin and b‑FGF. There was an interaction between tropoelastin mRNA and nucleolin protein, promoting the stability of tropoelastin mRNA and enhancing the expression of tropoelastin at the protein level. Upregulation of nucleolin had an important role in Ang II‑induced VSMC phenotypic transformation, and its underlying mechanism may be through interacting with tropoelastin mRNA, leading to its increased stability and protein expression. The findings provide a new perspective into the regulatory mechanism of VSMC phenotypic transformation.

The dietary flavonoid isoliquiritigenin is a potent cytotoxin for human neuroblastoma cells

Neuroblastoma (NB) is the most common extracranial solid tumor of early childhood; it accounts for approximately 8–10% of all childhood cancers and is the most common cancer in children in the first year of life. Patients in the high-risk group have a poor prognosis, with relapses being common and often refractory to drug treatment in those that survive. Moreover, the drug treatment itself can lead to a range of long-term sequelae. Therefore, there is a critical need to identify new therapeutics for NB. Isoliquiritigenin (ISLQ) is a naturally-occurring, dietary chalcone-type flavonoid with a range of biological effects that depend on the cell type and context. ISLQ has potential as an anticancer agent. Here we show that ISLQ has potent cytotoxic effects on SK-N-BE(2) and IMR-32 human NB cells, which carry amplification of the MYCN gene, the main prognostic marker of poor survival in NB. ISLQ was found to increase cellular reactive oxygen species (ROS). The cytotoxic effect of ISLQ was blocked by small molecule inhibitors of oxidative stress-induced cell death, and by the antioxidant N-acetyl-l-cysteine (NAC). Combined treatment of either SK-N-B-E(2) or IMR-32 cells with ISLQ and the anticancer agent cisplatin resulted in loss of cell viability that was greater than that induced by cisplatin alone. This study provides proof-of-principle that ISLQ is a potent cytotoxin for MYCN-amplified human NB cells. This is an important first step in rationalizing the further study of ISLQ as a potential adjunct therapy for high-risk NB.

Minimally modified low-density lipoprotein upregulates the ETB and α1 receptors in mouse mesenteric arteries in vivo by activating the PI3K/Akt pathway

OBJECTIVES

The current study aimed to explore whether minimally modified low-density lipoprotein (mmLDL) via tail vein injection upregulates the ET_B and α₁ receptors in mouse mesenteric arteries by activating the PI3K/Akt pathway.

METHODS

The contraction curves of the mesenteric arteries caused by sarafotoxin 6c (S6c, ET_B receptor agonist) and phenylephrine (PE, α₁ receptor agonist) were measured by a myograph system. Serum oxLDL was detected using enzyme-linked immunosorbent assays. The levels of the ET_B receptor, the α₁ receptor, PI3K, p-PI3K and p-Akt were detected using real-time polymerase chain reaction and Western blot analyses.

KEY FINDINGS

Minimally modified low-density lipoprotein noticeably enhanced the contraction effect curves of S6c and PE, with significantly increased E_max values (P < 0.01), compared to those of the control group. This treatment significantly increased the mRNA expression and protein levels of the ET_B and α₁ receptors and the protein levels of p-PI3K and p-Akt in the vessel wall (P < 0.01). LY294002 inhibited the effect of mmLDL.

CONCLUSIONS

An increase in mmLDL activated the PI3K/Akt pathway, which upregulated the expression of the ET_B and α₁ receptors and enhanced the ET_B and α_1- receptor-mediated contractile function.

Isoliquiritigenin protects against blood‑brain barrier damage and inhibits the secretion of pro-inflammatory cytokines in mice after traumatic brain injury

Traumatic brain injury (TBI) caused by an external mechanical force acting on the brain is a serious neurological condition. Inflammation plays an important role in prolonging secondary tissue injury after TBI, leading to neuronal cell death and dysfunction. Isoliquiritigenin (ILG) is a flavonoid monomer with anti-inflammatory characteristic. Thus, we had investigated the potential protective effects of ILG on TBI-induced injuries and identified the mechanisms underlying it. Here, we have demonstrated that ILG preserves blood brain barrier (BBB) integrity in vivo, suppresses the activation of microglia and inflammatory responses in mice after TBI, consequently leading to neurofunctional deficits, brain oedema, structural damage, and macrophage infiltration. In vitro, ILG exerts anti-inflammatory effect, and upregulates tight junction proteins 120‑β‑catenin and occludin in SH‑SY5Y cells under oxygen glucose deprivation/reoxygenation (OGD/D) condition. Additionally, we found that PI3K/AKT/GSK‑3β signalling pathway is involved in ILG treatment for TBI. To further confirm it, we had used SC79 (ethyl 2‑amino‑6‑chloro‑4‑(1‑cyano‑2‑ethoxy‑2‑oxoethyl)‑4H‑chromene‑3‑carboxylate), an Akt specific activator, to activate Akt, we found that SC79 partially reduces the protective effect of ILG for TBI. Overall, our current study reveals the neuroprotective role of ILG on TBI-induced BBB damage, downregulated tight junction proteins via PI3K/AKT/GSK‑3β signalling pathway. Furthermore, ILG suppresses the secretion of pro-inflammatory cytokines after TBI through inhibiting the PI3K/AKT/GSK‑3β/NF‑κB signalling pathway. Our findings suggest that GSK‑3β is a key regulatory factor during TBI-induced secretion of inflammatory cytokines, neuronal apoptosis and destruction of BBB.

Isoliquiritigenin inhibits proliferation and metastasis of MKN28 gastric cancer cells by suppressing the PI3K/AKT/mTOR signaling pathway

Isoliquiritigenin (ISL) is a flavonoid extracted from licorice root, which is known to serve important antitumor roles in numerous types of cancers; however, its effect on gastric cancer remains to be elucidated. The present study aimed to explore the roles and underlying mechanisms of ISL in MKN28 gastric cancer cells. MKN28 cell proliferation was measured using the Cell Counting Kit‑8 (CCK8) assay. A Transwell assay was used to determine the effects of ISL on the migration and invasion of MKN28 cells. Apoptosis was assessed by flow cytometry, and the expression levels of apoptosis‑, autophagy‑ and signaling pathway‑related proteins were detected by western blot analysis. The results of the CCK8 assay demonstrated that ISL significantly inhibited the proliferation of MKN28 cells (P<0.05). Transwell assays demonstrated that the migration and invasion of MKN28 cells were significantly inhibited following treatment with ISL (P<0.05). Flow cytometric analysis indicated that ISL induced apoptosis of MKN28 cells. In addition, western blot analysis revealed that the ratio of microtubule‑associated proteins 1A/1B light chain 3B (LC3)II/LC3I was upregulated, as was Beclin 1 expression; however, p62 was downregulated following ISL pretreatment, thus suggesting that ISL triggered autophagy in MKN28 cells. In addition, the phosphorylation levels of protein kinase B (AKT) and mammalian target of rapamycin (mTOR) were significantly reduced following ISL treatment. These results indicated that ISL may influence apoptosis and autophagy in MKN28 cells by suppressing the phosphoinositide 3‑kinase/AKT/mTOR signaling pathway. In conclusion, the findings of the present study suggested that ISL may inhibit MKN28 cell proliferation, migration and invasion by inducing apoptosis and autophagy, implying potential as a therapeutic agent for gastric cancer.