Acetylbritannilactone Inhibits Neointimal Hyperplasia after Balloon Injury of Rat Artery by Suppressing Nuclear Factor-{kappa}B Activation

Britannilactone 1-O-acetate induced ubiquitination of NLRP3 inflammasome through TRIM31 as a protective mechanism against reflux esophagitis-induced esophageal injury

BACKGROUND

Reflux esophagitis (RE) is a disease in which inflammation of the esophageal mucosa owing to the reflux of gastric contents into the esophagus results in cytokine damage. Britannilactone 1-O-acetate (Brt) has anti-inflammatory effects, significantly inhibiting the activation of the NLRP3 inflammasome, leading to a decrease in inflammatory factors including IL-1 β, IL-6, and TNF-α. However, the mechanism underlying its protective effect against RE-induced esophageal injury remains unclear. In the present study, we investigated the protective mechanism of TRIM31 against NLRP3 ubiquitination-induced RE both in vivo and in vitro.

METHODS

A model of RE was established in vivo in rats by the method of "4.2 mm pyloric clamp + 2/3 fundoplication". In vitro, the mod was constructed by using HET-1A (esophageal epithelial cells) and exposing the cells to acid, bile salts, and acidic bile salts. The 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay was used to screen the concentration of administered drugs, and the viability of HET-1A cells in each group. HE staining was used to assess the degree of pathological damage in esophageal tissues. Toluidine blue staining was used to detect whether the protective function of the esophageal epithelial barrier was damaged and restored. The enzyme-linked immunosorbent assay (ELISA) was used to detect the levels of IL-1 β, IL-6, and TNF-α factors in serum. Immunohistochemistry (IHC) was used to detect the expression level of NLRP3 in esophageal tissues. The molecular docking and Co-immunoprecipitation assay (Co-IP assay) were used to detect the TRIM31 interacts with NLRP3. Western blotting detected the Claudin-4, Claudin-5, The G-protein-coupled receptor calcium-sensitive receptor (CaSR), NLRP3, TRIM31, ASC, C-Caspase1, and Caspase1 protein expression levels.

RESULTS

Brt could alleviate RE inflammatory responses by modulating serum levels of IL-1 β, IL-6, and TNF-α. It also activated the expression of NLRP3, ASC, Caspase 1, and C-Caspase-1 in HET-1A cells. Brt also attenuated TRIM31/NLRP3-induced pathological injury in rats with RE through a molecular mechanism consistent with the in vitro results.

CONCLUSIONS

Brt promotes the ubiquitination of NLRP3 through TRIM31 and attenuates esophageal epithelial damage induced by RE caused by acidic bile salt exposure. This study provides valuable insights into the mechanism of action of Brt in the treatment of RE and highlights its promising application in the prevention of NLRP3 inflammatory vesicle-associated inflammatory pathological injury.

The natural sesquiterpene lactone inulicin suppresses the production of pro-inflammatory mediators via inhibiting NF-κB and AP-1 pathways in LPS-activated macrophages

OBJECTIVE

Inulicin is a sesquiterpene lactone in Inulae Flos which is clinically used for the treatment of inflammatory diseases, such as cough, sputum production and vomit. This study aimed to demonstrate the anti-inflammatory activity and the underlying mechanism of inulicin by using LPS-induced in vitro and in vivo models.

METHODS

LPS-stimulated RAW264.7 macrophages and mouse peritoneal macrophages (MPMs) were used for evaluating the in vitro anti-inflammatory activity of inulicin, while endotoxemia mice were used for evaluating its in vivo action. Cytokines' levels were determined by ELISA. RT-qPCR and western blot were used for assaying the mRNA and protein levels of target genes. RAW264.7 macrophages transfected with reporter plasmid pNFκB-TA-luc or pAP1-TA-luc were used for assaying the activation of NF-κB or AP-1 signaling.

RESULTS

Inulicin significantly inhibited LPS-induced production of NO, IL-6, c-c motif chemokine ligand 2 (CCL2) and IL-1β in both RAW264.7 cells and MPMs. Mechanism study indicated that it could suppress inducible nitric oxide synthase (iNOS), IL-6, CCL2 and IL-1β mRNA levels in LPS-stimulated RAW264.7 cells. Moreover, inulicin inhibited IκBα phosphorylation and prevented the nuclear translocation of p65, thereby inactivating NF-κB signaling. Concurrently, it also inhibited AP-1 signaling through reducing the phosphorylation of JNK and ERK. In endotoxemia mice, a single intraperitoneal administration of inulicin could decrease the production of pro-inflammatory cytokines in serum and peritoneal lavage fluid.

CONCLUSIONS

The present study demonstrates that inulicin possesses anti-inflammatory effects in vitro and in vivo, which suggests that inulicin might be a promising candidate for the treatment of inflammatory diseases.

Acetylbritannilactone attenuates contrast-induced acute kidney injury through its anti-pyroptosis effects

Contrast-induced acute kidney injury (CI-AKI) is a severe complication caused by intravascular applied radial contrast media (CM). Pyroptosis is a lytic type of cell death inherently associated with inflammation response and the secretion of pro-inflammatory cytokines following caspase-1 activation. The aim of the present study was to investigate the protective effects of acetylbritannilactone (ABL) on iopromide (IOP)-induced acute renal failure and reveal the underlying mechanism. In vivo and in vitro, IOP treatment caused renal damage and elevated the caspase-1 (+) propidium iodide (PI) (+) cell count, interleukin (IL)-1β and IL-18 levels, lactate dehydrogenase (LDH) release, and the relative expression of nucleotide-binding domain, leucine-rich repeat containing protein 3 (NLRP3), apoptosis-associated speck-like protein (ASC), and gasdermin D (GSDMD), suggesting that IOP induces AKI via the activation of pyroptosis. Furthermore, the pretreatment of ABL partly mitigated the CI-AKI, development of pyroptosis, and subsequent kidney inflammation. These data revealed that ABL partially prevents renal dysfunction and reduces pyroptosis in CI-AKI, which may provide a therapeutic target for the treatment of CM-induced AKI.

The role and mechanism of β‑arrestins in cancer invasion and metastasis (Review)

β-arrestins are a family of adaptor proteins that regulate the signaling and trafficking of various G protein-coupled receptors (GPCRs). They consist of β-arrestin1 and β-arrestin2 and are considered to be scaffolding proteins. β-arrestins regulate cell proliferation, promote cell invasion and migration, transmit anti-apoptotic survival signals and affect other characteristics of tumors, including tumor growth rate, angiogenesis, drug resistance, invasion and metastatic potential. It has been demonstrated that β-arrestins serve roles in various physiological and pathological processes and exhibit a similar function to GPCRs. β-arrestins serve primary roles in cancer invasion and metastasis via various signaling pathways. The present review assessed the function and mechanism of β-arrestins in cancer invasion and metastasis via multiple signaling pathways, including mitogen-activated protein kinase/extracellular signal regulated kinase, Wnt/β-catenin, nuclear factor-κB and phosphoinositide-3 kinase/Akt.

The ubiquitin-activating enzyme E1 as a novel therapeutic target for the treatment of restenosis

AIMS

The ubiquitin-activating enzyme E1 (UBA1, E1), the apex of the ubiquitin proteasome pathway, plays a critical role in protein degradation and in pathological processes. Whether UBA1 participates the development of vascular restenosis remains unknown. This study aims to determine the role of UBA1 in the development of balloon injury induced neointimal formation.

METHODS AND RESULTS

Immunostaining and western blots were used to examine the expression of the ubiquitinated protein in the injured carotid after angioplasty. Higher levels of ubiquitinated protein were observed in the neointima. Local delivery of potent chemical UBA1 inhibitor PYR-41 (100 μM) and UBA1 shRNA lentivirus both resulted in a substantial decrease in intimal hyperplasia at 2 weeks and 4 weeks after balloon injury. UBA1 inhibition also reduced Ki-67 positive cell percentage and inflammatory response in the carotid artery wall. We further determined that in vitro UBA1 inhibition was able to ameliorate TNF-α-induced nuclear factor-kappa B (NF-κB) activation by reducing IκB degradation in vascular smooth muscle cells (VSMCs). UBA1 inhibition also led to the accumulation of short-lived proteins such as p53, p21 and c-jun, which may account for the UBA1 inhibition-induced cell cycle delay. Thus, VSMCs proliferation was blocked.

CONCLUSIONS

UBA1 inhibition effectively suppresses neointimal thickening through its anti-proliferative and anti-inflammatory effects. Our results provide further evidence that the ubiquitin-proteasome system is a potential new target for the prevention of vascular restenosis.

Acetylbritannilactone Modulates Vascular Endothelial Growth Factor Signaling and Regulates Angiogenesis in Endothelial Cells

The present study was conducted to determine the effects of 1-O-acetylbritannilactone (ABL), a compound extracted from Inula britannica L., on vascular endothelial growth factor (VEGF) signaling and angiogenesis in endothelial cells (ECs). We showed that ABL promotes VEGF-induced cell proliferation, growth, migration, and tube formation in cultured human ECs. Furthermore, the modulatory effect of ABL on VEGF-induced Akt, MAPK p42/44, and p38 phosphorylation, as well as on upstream VEGFR-2 phosphorylation, were associated with VEGF-dependent Matrigel angiogenesis in vivo. In addition, animals treated with ABL (26 mg/kg/day) recovered blood flow significantly earlier than control animals, suggesting that ABL affects ischemia-mediated angiogenesis and arteriogenesis in vivo. Finally, we demonstrated that ABL strongly reduced the levels of VEGFR-2 on the cell surface, enhanced VEGFR-2 endocytosis, which consistent with inhibited VE-cadherin, a negative regulator of VEGF signaling associated with VEGFR-2 complex formation, but did not alter VE-cadherin or VEGFR-2 expression in ECs. Our results suggest that ABL may serve as a novel therapeutic intervention for various cardiovascular diseases, including chronic ischemia, by regulating VEGF signaling and modulating angiogenesis.

Gingerol Inhibits Serum-Induced Vascular Smooth Muscle Cell Proliferation and Injury-Induced Neointimal Hyperplasia by Suppressing p38 MAPK Activation

Purpose:

Gingerol inhibits growth of cancerous cells; however, its role in vascular smooth muscle cell (VSMC) proliferation is not known. The present study investigated the effect of gingerol on VSMC proliferation in cell culture and during neointima formation after balloon injury.

Method and Results:

Rat VSMCs or carotid arteries were harvested at 15 minutes, 30 minutes, 1, 6, 12, and 24 hours of fetal bovine serum (FBS; 10%) stimulation or balloon injury, respectively. Gingerol prevented FBS (10%)-induced proliferation of VSMCs in a dose-dependent manner (50 μmol/L-400 μmol/L). The FBS-induced proliferating cell nuclear antigen (PCNA) upregulation and p27Kip1 downregulation were also attenuated in gingerol (200 μmol/L) pretreated cells. Fetal bovine serum-induced p38 mitogen-activated protein kinase (MAPK) activation, PCNA upregulation, and p27Kip1 downregulation were abrogated in gingerol (200 μmol/L) and p38 MAPK inhibitor (SB203580, 10 μmol/L) pretreated cells. Balloon injury induced time-dependent p38 MAPK activation in the carotid artery. Pretreatment with gingerol (200 μmol/L) significantly attenuated injury-induced p38 MAPK activation, PCNA upregulation, and p27Kip1 downregulation. After 14 days of balloon injury, intimal thickening, neointimal proliferation, and endothelial dysfunction were significantly prevented in gingerol pretreated arteries. In isolated organ bath studies, gingerol (30 nmol/L-300 μmol/L) inhibited phenylephrine-induced contractions and induced dose-dependent relaxation of rat thoracic aortic rings in a partially endothelium-dependent manner.

Conclusion:

Gingerol prevented FBS-induced VSMC proliferation and balloon injury-induced neointima formation by regulating p38 MAPK. Vasodilator effect of gingerol observed in the thoracic aorta was partially endothelium dependent. Gingerol is thus proposed as an attractive agent for modulating VSMC proliferation, vascular reactivity, and progression of vascular proliferative diseases.

Acetylbritannilactone Modulates MicroRNA-155-Mediated Inflammatory Response in Ischemic Cerebral Tissues

Inflammatory responses play a critical role in ischemic brain injury. MicroRNA-155 (miR-155) induces the expression of inflammatory cytokines, and acetylbritannilactone (ABL) exerts potent antiinflammatory actions by inhibiting expression of inflammation-related genes. However, the functions of miR-155 and the actual relationship between ABL and miR-155 in ischemia-induced cerebral inflammation remain unclear. In this study, cerebral ischemia of wild-type (WT) and miR-155(-/-) mice was induced by permanent middle cerebral artery occlusion (MCAO). pAd-miR-155 was injected into the lateral cerebral ventricle 24 h before MCAO to induce miR-155 overexpression. MCAO mice and oxygen-glucose deprivation (OGD)-treated BV2 cells were used to examine the effects of ABL and miR-155 overexpression or deletion on the expression of proinflammatory cytokines. We demonstrated that ABL treatment significantly reduced neurological deficits and cerebral infarct volume by inhibiting tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) expression in ischemic cerebral tissue and OGD-treated BV2 cells. Mechanistic studies suggested that the observed decrease in TNF-α and IL-1β expression was attributable to the ABL-induced suppression of the expression of nuclear factor-kappa B (NF-κB) and Toll-like receptor 4 (TLR4). We further found that miR-155 promoted TNF-α and IL-1β expression by upregulating TLR4 and downregulating the expression of suppressor of cytokine signaling 1 (SOCS1) and myeloid differentiation primary response gene 88 (MyD88), while ABL exerted an inhibitory effect on miR-155-mediated gene expression. In conclusion, miR-155 mediates inflammatory responses in ischemic cerebral tissue by modulating TLR4/MyD88 and SOCS1 expression, and ABL exerts its antiinflammatory action by suppressing miR-155 expression, suggesting a novel miR-155-based therapy for ischemic stroke.

The genus Inula and their metabolites: from ethnopharmacological to medicinal uses

ETHNOPHARMACOLOGICAL RELEVANCE

The genus Inula comprises more than one hundred species widespread in temperate regions of Europe and Asia. Uses of this genus as herbal medicines have been first recorded by the Greek and Roman ancient physicians. In the Chinese Pharmacopoeia, from the 20 Inula spp. distributed in China, three are used as Traditional Chinese medicines, named Tumuxiang, Xuanfuhua and Jinfeicao. These medicines are used as expectorants, antitussives, diaphoretics, antiemetics, and bactericides. Moreover, Inula helenium L. which is mentioned in Minoan, Mycenaean, Egyptian/Assyrian pharmacotherapy and Chilandar Medical Codex, is good to treat neoplasm, wound, freckles and dandruff. Many other Inula spp. are used in Ayurvedic and Tibetan traditional medicinal systems for the treatment of diseases such as bronchitis, diabetes, fever, hypertension and several types of inflammation. This review is a critical evaluation of the published data on the more relevant ethnopharmacological and medicinal uses of Inula spp. and on their metabolites biological activities. This study allows the identification of the ethnopharmacological knowledge of this genus and will provide insight into the emerging pharmacological applications of Inula spp. facilitating the prioritirization of future investigations. The corroboration of the ethnopharmacological applications described in the literature with proved biological activities of Inula spp. secondary metabolites will also be explored.

MATERIALS AND METHODS

The major scientific databases including ScienceDirect, Medline, Scopus and Web of Science were queried for information on the genus Inula using various keyword combinations, more than 180 papers and patents related to the genus Inula were consulted. The International Plant Name Index was also used to confirm the species names.

RESULTS

Although the benefits of Inula spp. are known for centuries, there are insufficient scientific studies to certify it. Most of the patents are registered by Chinese researchers, proving the traditional use of these plants in their country. Although a total of sixteen Inula species were reported in the literature to have ethnopharmacological applications, the species Inula cappa (Buch.-Ham. ex D.Don) DC., Inula racemosa Hook.f., Inula viscosa (L.) Aiton [actually the accepted name is Dittrichia viscosa (L.) Greuter], Inula helenium, Inula britannica L. and Inula japonica Thunb. are the most frequently cited ones since their ethnopharmacological applications are vast. They are used to treat a large spectrum of disorders, mainly respiratory, digestive, inflammatory, dermatological, cancer and microbial diseases. Fifteen Inula spp. crude extracts were investigated and showed interesting biological activities. From these, only 7 involved extracts of the reported spp. used in traditional medicine and 6 of these were studied to isolate the bioactive compounds. Furthermore, 90 bioactive compounds were isolated from 16 Inula spp. The characteristic compounds of the genus, sesquiterpene lactones, are involved in a network of biological effects, and in consequence, the majority of the experimental studies are focused on these products, especially on their cytotoxic and anti-inflammatory activities. The review shows the chemical composition of the genus Inula and presents the pharmacological effects proved by in vitro and in vivo experiments, namely the cytotoxic, anti-inflammatory (with focus on nitric oxide, arachidonic acid and NF-κB pathways), antimicrobial, antidiabetic and insecticidal activities.

CONCLUSIONS

Although there are ca. 100 species in the genus Inula, only a few species have been investigated so far. Eight of the sixteen Inula spp. with ethnopharmacological application had been subjected to biological evaluations and/or phytochemical studies. Despite Inula royleana DC. and Inula obtusifolia A. Kerner are being used in traditional medicine, as far as we are aware, these species were not subjected to phytochemical or pharmacological studies. The biological activities exhibited by the compounds isolated from Inula spp., mainly anti-inflammatory and cytotoxic, support some of the described ethnopharmacological applications. Sesquiterpene lactone derivatives were identified as the most studied class, being britannilactone derivatives the most active ones and present high potential as anti-inflammatory drugs, although, their pharmacological effects, dose-response relationship and toxicological investigations to assess potential for acute or chronic adverse effects should be further investigated. The experimental results are promising, but the precise mechanism of action, the compound or extract toxicity, and the dose to be administrated for an optimal effect need to be investigated. Also human trials (some preclinical studies proved to be remarkable) should be further investigated. The genus Inula comprises species useful not only in medicine but also in other domains which makes it a high value-added plant.

Synthesis of 1-O-acetylbritannilactone analogues from Inula britannica and in vitro evaluation of their anticancer potential

A series of novel ABL analogues was synthesized by N/O-atom installing and aromatic ring esterifying, and 4a showed in vitro markedly anticancer activities against HeLa cells associated with induction of apoptosis, activation of caspase-3 and G2/M cell arrest.

HDAC2 phosphorylation-dependent Klf5 deacetylation and RARα acetylation induced by RAR agonist switch the transcription regulatory programs of p21 in VSMCs

Abnormal proliferation of vascular smooth muscle cells (VSMCs) occurs in hypertension, atherosclerosis and restenosis after angioplasty, leading to pathophysiological vascular remodeling. As an important growth arrest gene, p21 plays critical roles in vascular remodeling. Regulation of p21 expression by retinoic acid receptor (RAR) and its ligand has important implications for control of pathological vascular remodeling. Nevertheless, the mechanism of RAR-mediated p21 expression in VSMCs remains poorly understood. Here, we show that, under basal conditions, RARα forms a complex with histone deacetylase 2 (HDAC2) and Krüppel-like factor 5 (Klf5) at the p21 promoter to inhibit its expression. Upon RARα agonist stimulation, HDAC2 is phosphorylated by CK2α. Phosphorylation of HDAC2, on the one hand, promotes its dissociation from RARα, thus allowing the liganded-RARα to interact with co-activators; on the other hand, it increases its interaction with Klf5, thus leading to deacetylation of Klf5. Deacetylation of Klf5 facilitates its dissociation from the p21 promoter, relieving its repressive effect on the p21 promoter. Interference with HDAC2 phosphorylation by either CK2α knockdown or the use of phosphorylation-deficient mutant of HDAC2 prevents the dissociation of Klf5 from the p21 promoter and impairs RAR agonist-induced p21 activation. Our results reveal a novel mechanism involving a phosphorylation-deacetylation cascade that functions to remove the basal repression complex from the p21 promoter upon RAR agonist treatment, allowing for optimum agonist-induced p21 expression.

Celecoxib and acetylbritannilactone interact synergistically to suppress breast cancer cell growth via COX-2-dependent and -independent mechanisms

The use of celecoxib is associated with a significant decrease in breast cancer risk. However, the long-term use of high-dose celecoxib might be limited owing to cardiovascular side effects. In this study, we found that acetylbritannilactone (ABL), extract from a Chinese medicinal herb, could reduce celecoxib dose and potentiate the growth-inhibitory effect in breast cancer cells. ABL enhanced the apoptotic effect of celecoxib in COX-2-expressing cells, but had little effect in COX-2-negative cells. The apoptosis induced by the combination treatment disappeared when COX-2 was knocked down, whereas the lack of apoptotic effects in COX-2-negative cells was reversed after COX-2 transfection. However, the combination treatment induced a G(0)/G(1) phase arrest independent of whether or not the cells expressed COX-2. The G(0)/G(1) arrest was attributed to a decreased expression of cyclinD1, cyclinE, CDK2 and CDK6, especially the upregulation of p21. In addition, inhibition of Akt and p38 signaling pathways was required by the synergism, as the constitutively active Akt and p38 protected cells against apoptosis and cell cycle arrest induced by the combination treatment. In vivo, administration of celecoxib and ABL were more effective than the individual agents against xenograft tumor growth. Thus, our data suggested that the combinatorial approach of celecoxib and ABL might be helpful for breast cancer treatment.

Targeted disruption of the prostaglandin E2 E-prostanoid 2 receptor exacerbates vascular neointimal formation in mice

OBJECTIVE

Restenosis after angioplasty remains a major clinical problem. Prostaglandin E(2) (PGE(2)) plays an important role in vascular homeostasis. The PGE(2) receptor E-prostanoid 2 (EP2) is involved in the proliferation and migration of various cell types. We aimed to determine the role of EP2 in the pathogenesis of neointimal formation after vascular injury.

METHODS AND RESULTS

Wire-mediated vascular injury was induced in the femoral arteries of male wild-type (EP2+/+) and EP2 gene-deficient (EP2-/-) mice. In EP2+/+ mice, EP2 mRNA expression was increased in injured vessels for at least 4 weeks after vascular injury. Neointimal hyperplasia was markedly accelerated in EP2-/- mice, which was associated with increased proliferation and migration of vascular smooth muscle cells (VSMCs) and increased cyclin D1 expression in the neointima layer. Platelet-derived growth factor-BB (PDGF-BB) treatment resulted in more significant cell proliferation and migration in VSMCs of EP2-/- mice than in those of EP2+/+ mice. Activation and overexpression of EP2 attenuated PDGF-BB-elicited cell proliferation and migration, induced G(1)→S-phase arrest and reduced PDGF-BB-stimulated extracellular signal-regulated kinase phosphorylation in EP2+/+ VSMCs.

CONCLUSIONS

These findings reveal a novel role of the EP2 receptor in neointimal hyperplasia after arterial injury. The EP2 receptor may represent a potential therapeutic target for restenosis after angioplasty.

Krüppel-like factor 4 interacts with p300 to activate mitofusin 2 gene expression induced by all-trans retinoic acid in VSMCs

AIM

To elucidate how krüppel-like factor 4 (KLF4) activates mitofusin 2 (mfn-2) expression in all-trans retinoic acid (ATRA)-induced vascular smooth muscle cell (VSMC) differentiation.

METHODS

The mfn-2 promoter-reporter constructs and the KLF4 acetylation-deficient or phosphorylation-deficient mutants were constructed. Adenoviral vector of KLF4-mediated overexpression and Western blot analysis were used to determine the effect of KLF4 on mfn-2 expression. The luciferase assay and chromatin immunoprecipitation were used to detect the transactivation of KLF4 on mfn-2 gene expression. Co-immunoprecipitation and GST pull-down assays were used to determine the modification of KLF4 and interaction of KLF4 with p300 in VSMCs.

RESULTS

KLF4 mediated ATRA-induced mfn-2 expression in VSMCs. KLF4 bound directly to the mfn-2 promoter and activated its transcription. ATRA increased the interaction of KLF4 with p300 by inducing KLF4 phosphorylation via activation of JNK and p38 MAPK signaling. KLF4 acetylation by p300 increased its activity to transactivate the mfn-2 promoter.

CONCLUSION

ATRA induces KLF4 acetylation by p300 and increases the ability of KLF4 to transactivate the mfn-2 promoter in VSMCs.

Secondary metabolites from Inula britannica L. and their biological activities

Inula britannica L., family Asteraceae, is used in traditional Chinese and Kampo Medicines for various diseases. Flowers or the aerial parts are a rich source of secondary metabolites. These consist mainly of terpenoids (sesquiterpene lactones and dimmers, diterpenes and triterpenoids) and flavonoids. The isolated compounds have shown diverse biological activities: anticancer, antioxidant, anti-inflammatory, neuroprotective and hepatoprotective activities. This review provides information on isolated bioactive phytochemicals and pharmacological potentials of I. britannica.

ABL-N-induced apoptosis in human breast cancer cells is partially mediated by c-Jun NH2-terminal kinase activation

Introduction

The present study was designed to determine the possibility of acetylbritannilactone (ABL) derivative 5-(5-(ethylperoxy)pentan-2-yl)-6-methyl-3-methylene-2-oxo-2,3,3a,4,7,7a-hexahydrobenzofuran-4-yl 2-(6-methoxynaphthalen-2-yl)propanoate (ABL-N) as a novel therapeutic agent in human breast cancers.

Methods

We investigated the effects of ABL-N on the induction of apoptosis in human breast cancer cells and further examined the underlying mechanisms. Moreover, tumor growth inhibition of ABL-N was done in xenograft models.

Results

ABL-N induced the activation of caspase-3 in estrogen receptor (ER)-negative cell lines MDA-MB-231 and MDA-MB-468, as evidenced by the cleavage of endogenous substrate Poly (ADP-ribose) polymerase (PARP). Pretreatment of cells with pan-caspase inhibitor z-VAD-fmk or caspase-3-specific inhibitor z-DEVD-fmk inhibited ABL-N-induced apoptosis. ABL-N treatment also resulted in an increase in the expression of pro-apoptotic members (Bax and Bad) with a concomitant decrease in Bcl-2. Furthermore, c-Jun-NH₂-terminal kinase (JNK) and p38 mitogen-activated protein (MAP) kinase (p38) were activated in the apoptosis induced by ABL-N and JNK-specific inhibitor SP600125 and JNK small interfering RNA (siRNA) antagonized ABL-N-mediated apoptosis. However, the p38-specific inhibitor SB203580 had no effect upon these processes. Moreover, neither of the caspase inhibitors prevented ABL-N-induced JNK activation, indicating that JNK is upstream of caspases in ABL-N-initiated apoptosis. Additionally, in a nude mice xenograft experiment, ABL-N significantly inhibited the tumor growth of MDA-MB-231 cells.

Conclusions

ABL-N induces apoptosis in breast cancer cells through the activation of caspases and JNK signaling pathways. Moreover, ABL-N treatment causes a significant inhibition of tumor growth in vivo. Therefore, it is thought that ABL-N might be a potential drug for use in breast cancer prevention and intervention.

Flavonoids from Inula britannica L. inhibit injury-induced neointimal formation by suppressing oxidative-stress generation

AIM OF THE STUDY

We aimed to investigate whether and how the total flavonoid extracts (TFE) from Inula britannica L. block neointimal hyperplasia induced by balloon injury in rats.

MATERIALS AND METHODS

Rats were administered orally TFE doses of 12.5, 25 and 50 mg/kg/d by gastric gavage from 3 days before balloon injury to 14 days after the injury. The ratio of intima (I) to media (M) thickness (I/M) in carotid arteries was examined by morphological analyses. The MDA content and SOD activity in plasma were measured. The O(2)(-) production in vascular tissues was detected in situ. The expression of p47(phox) in carotid arteries was analyzed by Western blot analysis and immunohistochemistry.

RESULTS

The rats treated with TFE 50 mg/kg/d showed a reduction in neointimal hyperplasia, and the ratio of I/M of balloon injured-carotid arteries was significantly reduced by over 70% after TFE treatment, compared with the injured group. The inhibitory effect of TFE on neointimal hyperplasia was almost consistent with that of atorvastatin, a positive control. The plasma SOD activity was obviously increased by TFE treatment (P<0.01), while plasma MDA production was markedly decreased by TFE treatment (P<0.05). On day 14 after balloon injury, the carotid arteries showed an increase in O(2)(-) production that was most evident in the neointimal and medial layer of the vessel. Thus, TFE significantly inhibited injury-induced O(2)(-) production and p47(phox) expression in carotid arteries.

CONCLUSION

Our results suggest that TFE inhibit the neointimal hyperplasia after balloon injury, at least partly, by suppressing oxidative-stress generation.

Polymorphisms of the ICAM-1 exon 6 (E469K) are associated with differentiation of colorectal cancer

Background

Genetic factors are thought to play a role in development for colorectal carcinogenesis. ICAM-1 is a polymorphic gene, thus, the present study investigated the relationship between the polymorphisms of ICAM-1 and the susceptibility and phenotypical characteristics of colorectal cancer (CRC).

Methods

The polymorphisms at ICAM-1 exon 4 (G241R) and exon 6 (E469K) were detected by PCR with sequence-specific primers. The relationship between specific genotypes of ICAM-1 and differentiation of CRC was evaluated by the histological grade.

Results

We showed only GG genotype of ICAM-1 individuals in either CRC or normal controls. The KK genotype of ICAM-1 K469E was found more frequently than in the controls (P < 0.05). Patients with well-differentiated CRC displayed the KK more frequently than those of poor differentiation (P < 0.05).

Conclusion

The findings indicate that polymorphisms of G241R are rare in Chinese population and that KK genotype of ICAM-1 K469E is significantly associated with well differentiation of CRC.

Angiotensin II stimulates KLF5 phosphorylation and its interaction with c-Jun leading to suppression of p21 expression in vascular smooth muscle cells

Krüppel-like factor 5 (KLF5) and c-Jun are involved in angiotensin II (Ang II)-induced cell proliferation and play an important role in p21 expression. But the direct and functional implications of KLF5 and c-Jun in regulating p21 expression in vascular smooth muscle cells (VSMCs) are unclear. Here, we show that Ang II upregulated KLF5 and c-Jun expression and inhibited p21 expression in VSMCs, and silencing of KLF5 expression by KLF5-specific small interfering RNA (siRNA) neutralized the inhibitory effects of Ang II on p21 expression. Exposure of VSMCs to Ang II rapidly and strongly stimulated KLF5 phosphorylation, which results in an increase of the interaction of KLF5 with c-Jun. Treating VSMCs with PD98059, the ERK inhibitor, inhibited ERK activation and KLF5 phosphorylation as well as the interaction between KLF5 and c-Jun. Reporter analysis showed that both KLF5 and c-Jun cooperatively repressed the promoter of p21. Furthermore, KLF5 bound to its cis-elements in the p21 promoter, and meanwhile interacted with c-Jun in Ang II-induced VSMCs. These results suggest that Ang II induces KLF5 phosphorylation mediated by the ERK signalling in VSMCs, which in turn stimulates the interaction of KLF5 with c-Jun, subsequently leads to the suppression of p21 expression.

Krüppel-like factor 4 inhibits proliferation by platelet-derived growth factor receptor beta-mediated, not by retinoic acid receptor alpha-mediated, phosphatidylinositol 3-kinase and ERK signaling in vascular smooth muscle cells

Proliferation inhibition of vascular smooth muscle cells (VSMCs) is governed by the activity of a transcription factor network. Krüppel-like factor 4 (Klf4), retinoic acid receptor (RAR alpha), and platelet-derived growth factor receptor (PDGFR) are expressed in VSMCs and are components of such a network. However, the relationship among them in the regulation of VSMC proliferation remains unknown. Here, we investigated the mechanisms whereby Klf4 mediates the growth inhibitory effects in VSMCs through RAR alpha and PDGFR beta. We demonstrated that Klf4 directly binds to the 5' regulatory region of RAR alpha, down-regulates RAR alpha expression, and specifically inhibits RAR alpha-mediated phosphatidylinositol 3-kinase (PI3K) and ERK signaling in cultured VSMCs induced by the synthetic retinoid Am80. Of particular interest, Klf4 inhibits RAR alpha and PDGFR beta expression while blocking PI3K and ERK signaling induced by Am80 and PDGF-BB, respectively. The anti-proliferative effects of Klf4 on neointimal formation depend largely on PDGFR-mediated PI3K signaling without involvement of the RAR alpha-activated signaling pathways. These findings provide a novel mechanism for signal suppression and growth inhibitory effects of Klf4 in VSMCs. Moreover, the results of this study suggest that Klf4 is one of the key mediators of retinoid actions in VSMCs.

Additive beneficial effects of amlodipine and atorvastatin in reversing advanced cardiac hypertrophy in elderly spontaneously hypertensive rats

1. Additive beneficial effects on cardiovascular disease have been reported for amlodipine and atorvastatin. However, it is still unclear whether the combination of amlodipine and atorvastatin has additive beneficial effects on the regression of advanced cardiac hypertrophy in hypertension. In the present study, the effects of the drug combination on advanced cardiac hypertrophy were investigated in elderly spontaneously hypertensive rats (SHR). 2. Elderly SHR (36 weeks old) were randomly allocated into four groups of 12: (i) a vehicle-treated control group; (ii) an amlodipine (10 mg/kg per day)-treated group; (iii) an atorvastatin (10 mg/kg per day)-treated group; and (iv) a group treated with a combination of amlodipine and atorvastatin (both at 10 mg/kg per day). Drugs were administered by oral gavage every morning for a period of 12 weeks before hearts were harvested for analysis. 3. Combined administration of amlodipine and atorvastatin significantly suppressed cardiomyocyte hypertrophy, interstitial fibrosis and upregulation of hypertrophic and profibrotic genes, and also improved left ventricular diastolic dysfunction to a greater extent than did amlodipine monotherapy. Further beneficial effects of combination therapy on advanced cardiac hypertrophy were associated with a greater reduction of NADPH oxidase-mediated increases in cardiac reactive oxygen species (ROS), rather than decreased blood pressure and serum cholesterol levels. 4. To elucidate the underlying molecular mechanisms, we examined cardiovascular NADPH oxidase subunits and found that amlodipine clearly attenuated the expression of p47(phox) and p40(phox) and slightly but significantly reduced p22(phox) and Rac-1 levels in heart tissue. Combination treatment with amlodipine plus atorvastatin led to a further reduction in p22(phox), p47(phox) and Rac-1 protein levels compared with amlodipine alone. 5. In conclusion, combined amlodipine and atorvastatin treatment has a greater beneficial effect on advanced cardiac hypertrophy compared with amlodipine monotherapy. The benefits are likely to be related to the additive effects of the drugs on the suppression of NADPH oxidase-mediated ROS generation.

1,6-O,O-diacetylbritannilactones inhibits IkappaB kinase beta-dependent NF-kappaB activation

To determine the chemical constituents responsible for pharmacological effects of Inula britannica-F., three specific sesquiterpene lactones in Inula britannica were isolated from chloroform extract and identified, including britannilactone (BL), 1-O-acetylbritannilactone (ABLO), and 1,6-O,O-diacetylbritannilactone (ABLOO). Electrophoretic mobility shift assay (EMSA) was performed to detect the nuclear translocation of nuclear factor-kappaB (NF-kappaB) p65. The expressions of IkappaBalpha, pIkappaBalpha, inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), IkappaB kinase alpha/beta (IKKalpha/beta) and NF-kappaB kinase (NIK) were detected by Western blot and RT-PCR. We found that acetyl side groups enhanced the inhibitory action of the agents on LPS/IFN-gamma-induced iNOS and COX-2 expression. Their inhibiting activity was positive correlation with the acetyl side group number. The effects of LPS/IFN-gamma were reversed by ABLOO, and BL without acetyl side groups showed only a weak inhibitory action. Further study indicated that ABLOO markedly inhibited the phosphorylation of IKKbeta down to based level, but not IKKalpha, corresponding with decreased in IkappaBalpha degradation and phosphorylation induced by LPS/IFN-gamma, resulting in the suppression of NF-kappaB nuclear translocation and activity. These results suggest that the acetyl moieties add to the lipophilicity, and consequently enhance cellular penetration, so that ABLOO possess the most anti-inflammatory effect and may be a potent lead structure for the development of therapeutic and cytokine-suppressing remedies valuable for the treatment of various inflammatory diseases.