The in vitro antitumor activity of Siegesbeckia glabrescens against ovarian cancer through suppression of receptor tyrosine kinase expression and the signaling pathways

Effect of Siegesbeckia glabrescens Extract on Foam Cell Formation in THP-1 Macrophages

The accumulation of cholesterol-bearing macrophage foam cells in the initial stages of atherosclerosis serves as a characteristic feature of atherosclerotic lesions. The inhibitory effect of Siegesbeckia glabrescens, a species of flowering plant in the Asteraceae family, on foam cell formation in THP-1 macrophages has not yet been elucidated. In this study, we explored the effect of S. glabrescens ethanol extract (SGEE) and hot water extract (SGWE) on foam cell formation via co-treatment with oxidized low density lipoprotein (ox-LDL) and lipopolysaccharide (LPS), mimicking the occurrence of atherosclerosis in vitro, and studied the regulation of its underlying mechanisms. THP-1 cells differentiated by PMA (1 μM) for 48 h were subsequently treated with/without SGWE and SGEE for 48 h. THP-1 macrophages were treated with ox-LDL (20 μg/mL) and LPS (500 ng/mL) for 24 h. Treatment with ox-LDL and LPS for 24 h enhanced the lipid accumulation in foam cells compared to in untreated cells, as determined by oil red O staining. In contrast, SGWE and SGEE treatment inhibited lipid accumulation in foam cells. Both extracts significantly upregulated ABCA1, LXRα, and PPARγ expression in ox-LDL- and LPS-treated cells (P<0.05). Moreover, both SGWE and SGEE decreased LOX-1, CD36, and SR-A1 expression. The co-treatment of ox-LDL and LPS increased NF-κB, COX-2, and pro-inflammatory activation and expression compared with untreated cells. However, this increase suppressed NF-κB, COX-2, and pro-inflammatory expression by SGWE and SGEE. The results indicated that both extracts can partially inhibit foam cell formation and contribute to protective effects by suppressing cholesterol accumulation during the onset of atherosclerosis.

An integrated network pharmacology approach reveals that Darutigenol reduces inflammation and cartilage degradation in a mouse collagen-induced arthritis model by inhibiting the JAK-STAT3 pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Darutigenol (DL) is a natural active product derived from the Chinese herbal medicine Sigesbeckia glabrescens (Makino) Makino. It is administered as a traditional Chinese medicine (TCM) to dispel rheumatism, benefit the joints, and detoxify. However, its potential mechanism in the treatment of rheumatoid arthritis (RA) remains unknown.

AIMS OF THE STUDY

The objectives of this research were to determine the effects and elucidate the modes of action of DL on RA-related joint inflammation.

MATERIALS AND METHODS

Network pharmacology and molecular docking were used to screen and validate candidate DL targets for RA treatment, respectively. A DBA/1 mouse rheumatoid arthritis model was induced with bovine type II collagen. Intragastric DL administration was followed by the calculation of the clinical arthritis index. A section of the ankle joint was excised and stained and the pathological changes in it were observed. Enzyme-linked immunosorbent assays (ELISA) and western blotting (WB) were used to clarify the mechanisms of DL in RA treatment.

RESULTS

DL effectively attenuated the inflammation, mitigated the articular cartilage degradation, and bone erosion, and alleviated the inflammatory joints associated with RA. Network pharmacology screened six key targets of DL while molecular docking revealed that it docked well with its protein targets. The DL treatment group presented with significantly less ankle joint redness and swelling, a lower arthritis index scores and serum and bone marrow supernatant IL-6 levels, more complete ankle joint surfaces, and less synovial inflammation, cartilage degradation, and bone erosion than the collagen-induced arthritis (CIA) group. The DL treatment also substantially downregulated the Janus kinase (JAK)1, JAK3, matrix metalloproteinase (MMP)2, MMP9, and phospho-signal transducer and activator of transcription (p-STAT)3 proteins in the joints.

CONCLUSIONS

To the best of our knowledge, the present work was the first to demonstrate that DL has significant anti-inflammatory efficacy and reduces cartilage degradation and bone erosion. It also demonstrated that the anti-RA effect of DL may be explained by its ability to inhibit joint inflammation and reduce articular cartilage degradation through the interleukin (IL)-6/JAK1,3/STAT3 axis and downregulate MMP2 and MMP9. Hence, DL might play a therapeutic role in a mouse RA model.

A novel ent-pimarane-type diterpenoid from Sigesbeckia glabrescens with anti-inflammatory activity

A novel ent-pimarane-type diterpenoid, sigesbeckia J (1), along with two known diterpenoids, siegesbeckia acid (2) and ent-18-acetoxy-16R,17-dihydroxykauran-19-oic acid (3), were isolated from the aerial parts of Sigesbeckia glabrescens Makino. Their chemical structures were elucidated based on extensive spectroscopic interpretation. The absolute configuration of ent-pimarane-type diterpenoid (1) was determined by comparing experimental and calculated ECD spectra. Compared with the positive control minocycline (IC₅₀ 32.84 μM), compound 1 exhibited moderate cell growth anti-inflammatory activities in vitro by testing their inhibition of LPS-induced NO production in BV2 microglial cells, with IC₅₀ value of 58.74 μM.

Broussonin A- and B-mediated inhibition of angiogenesis by blockade of VEGFR-2 signalling pathways and integrin β1 expression

In the present study, we demonstrate the regulatory effects and mechanism of broussonin A and B, diphenylpropane derivatives isolated from Broussonetia kazinoki, on vascular endothelial growth factor‐A (VEGF‐A)–stimulated endothelial cell responses in vitro and microvessel sprouting ex vivo. Treatment with broussonin A or B suppressed VEGF‐A‐stimulated endothelial cell proliferation by regulating the expression of cell cycle–related proteins and the phosphorylation status of retinoblastoma protein. In addition, treatment with broussonin A or B abrogated VEGF‐A‐stimulated angiogenic responses including endothelial cell migration, invasion, tube formation and microvessel formation from rat aortic rings. These anti‐angiogenic activities of broussonin A and B were mediated through inactivation of VEGF‐A‐stimulated downstream signalling pathways, localization of vascular endothelial‐cadherin at cell‐cell contacts, and down‐regulation of integrin β1 and integrin‐liked kinase. Furthermore, treatment with broussonin A or B inhibited proliferation and invasion of non–small cell lung cancer and ovarian cancer cells. Taken together, our findings suggest the pharmacological potential of broussonin A and B in the regulation of angiogenesis, cancer cell growth and progression.

Sigesbeckia K and L, two new diterpenoids from Sigesbeckia glabrescens with anti-inflammatory activity

A chemical investigation of Sigesbeckia glabrescens Makino identified four compounds. On the basis of spectroscopic data, they were determined to be ent-pimarane-type diterpenoids and their analogues, among which were two previously undescribed compounds, Sigesbeckia K (1) and Sigesbeckia L (2). The anti-inflammatory effects of these compounds were evaluated by testing their inhibition of LPS-induced NO production in BV2 microglial cells, which revealed potential inhibitory effects with IC₅₀ value at 62.56 μM and compared with the positive control minocycline (IC₅₀ 32.84 μM).

Six novel lignanoids with complex structures from Sigesbeckia glabrescens Makino with their cytotoxic activities

Six new lignanoids, Glalignin A-E (1-5) and Glaneolignin A (6), together with four analogues, (+)-isolariciresinol (7), (+)-syringaresinol (8), dihydrodehydrodiconiferyl alcohol (9) and tribulusamide A (10), were obtained from the aerial parts of Sigesbeckia glabrescens Makino and also isolated for the first time from the Sigesbeckia genus. The structures of these compounds were elucidated by the interpretation of HRESIMS, 1D NMR, 2D NMR data and chemical evidence. The cytotoxic activities of the compounds were evaluated by testing their inhibition in several tumor cells using the MTT assay. New compound 2 and 5 displayed cytotoxicity against the human cancer cell lines human lung adenocarcinoma cells (A549) with IC₅₀ values of 32.89 ± 6.83 and 35.86 ± 6.83 μM.

Sigesbeckia glabrescens Makino extract attenuated the collagen-induced arthritis through inhibiting the synovial hyperplasia and inflammation

Background

Sigesbeckia glabrescens Makino (SG) has been traditionally used for rheumatism and joint protection. However, the anti-arthritic effects and underling mechanisms of SG have not been demonstrated. In this study, we investigated the anti-arthritic effects and mechanisms of SG extract (SGE) on collagen-induced arthritic rats and interleukin (IL)-1β-stimulated human synovial SW982 cells.

Methods

Rats were induced to arthritis by collagen for 15 days and then received SGE treatment for 35 days. The body weight and arthritis severity score of the rats were monitored weekly. At the end of the experiment, the radiographic and histological changes of rats’ hind paw were obtained; the serum C-reactive protein was detected by enzyme-linked immunosorbent assay (ELISA); the expression levels of interleukin (IL)- 1β, IL6 and IL-10 in the joint muscles were determined by ELISA and immunohistochemical staining; and the level of regulatory T cells (Tregs) in the spleen was detected using flow cytometry. In addition, 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and scratch wound healing assay were used to evaluate the proliferation of SW982 synovial cells. ELISA, western blot and immunofluorescence staining were used to investigate the anti-inflammatory mechanisms of SGE on IL-1β-induced SW982 cells and joint muscles of CIA rats.

Results

SGE attenuated the collagen-induced hind paw swelling, cartilage damage and bone erosion. SGE inhibited the synovial hyperplasia to the articular cavity in the toe joint and ankle. Moreover, SGE decreased the production of C-reactive protein in serum and the expression of IL-6, IL-1β, cyclooxygenase-2 (COX-2) and phosphorylation of NF-κB p65 in the joint muscles. SGE also recovered the decreased Tregs. Results from the in vitro experiments showed that SGE not only inhibited the proliferation and migration of human synovial cell but also inhibited the IL-1β-induced expression of IL-6 and IL-8. Similarly, SGE inhibited the activation of NF-κB and the expression of COX-2.

Conclusions

SGE attenuated the collagen-induced arthritis through inhibiting the synovial hyperplasia and inflammation.

Novel functions for 2-phenylbenzimidazole-5-sulphonic acid: Inhibition of ovarian cancer cell responses and tumour angiogenesis

In this study, we investigated the effects and molecular mechanisms of 2-phenylbenzimidazole-5-sulphonic acid (PBSA), an ultraviolet B protecting agent used in sunscreen lotions and moisturizers, on ovarian cancer cell responses and tumour angiogenesis. PBSA treatment markedly blocked mitogen-induced invasion through down-regulation of matrix metalloproteinase (MMP) expression and activity in ovarian cancer SKOV-3 cells. In addition, PBSA inhibited mitogen-induced cell proliferation by suppression of cyclin-dependent kinases (Cdks), but not cyclins, leading to pRb hypophosphorylation and G1 phase cell cycle arrest. These anti-cancer activities of PBSA in ovarian cancer cell invasion and proliferation were mediated by the inhibition of mitogen-activated protein kinase kinase 3/6-p38 mitogen-activated protein kinase (MKK3/6-p38MAPK ) activity and subsequent down-regulation of MMP-2, MMP-9, Cdk4, Cdk2 and integrin β1, as evidenced by treatment with p38MAPK inhibitor SB203580. Furthermore, PBSA suppressed the expression and secretion of vascular endothelial growth factor in SKOV-3 cells, leading to inhibition of capillary-like tubular structures in vitro and angiogenic sprouting ex vivo. Taken together, our results demonstrate the pharmacological effects and molecular targets of PBSA on modulating ovarian cancer cell responses and tumour angiogenesis, and suggest further evaluation and development of PBSA as a promising chemotherapeutic agent for the treatment of ovarian cancer.

Comparison of the chemical profiles and inflammatory mediator-inhibitory effects of three Siegesbeckia herbs used as Herba Siegesbeckiae (Xixiancao)

Background

Herba Siegesbeckiae (HS, Xixiancao in Chinese) is a commonly used traditional Chinese medicinal herb for soothing joints. In ancient materia medica books, HS is recorded to be the aerial part of Siegesbeckia pubescens Makino (SP) which is also the only origin of HS in the 1963 edition of the Chinese Pharmacopeia (ChP). The aerial parts of Siegesbeckia orientalis L. (SO) and Siegesbeckia glabrescens Makino (SG) have been included as two additional origins for HS in each edition of ChP since 1977. However, chemical and pharmacological comparisons among these three species have not been conducted.

Methods

An HPLC with diode array detector (HPLC-DAD) method combined with similarity analysis, hierarchical cluster analysis (HCA) and principal component analysis (PCA) was developed for comparing the fingerprint chromatograms of the three species. The inhibitory effects of the three species on NO production and IL-6 secretion in LPS-stimulated RAW264.7 macrophages were compared.

Results

Fingerprint chromatograms of the three species showed different profiles, but had 13 common peaks. Results from HCA and PCA of the common peaks demonstrated that all 14 herbal samples of the three species tended to be grouped and separated species dependently. The extents of inhibition on NO production and IL-6 secretion of the three species were different, with SG being the most and SP the least potent.

Conclusions

Both chemical profiles and inflammatory mediator-inhibitory effects of the three species were different. These findings provide a chemical and pharmacological basis for determining whether the three species can all serve as the origins of HS.

The role of the Hedgehog signaling pathway in cancer: A comprehensive review

The Hedgehog (Hh) signaling pathway was first identified in the common fruit fly. It is a highly conserved evolutionary pathway of signal transmission from the cell membrane to the nucleus. The Hh signaling pathway plays an important role in the embryonic development. It exerts its biological effects through a signaling cascade that culminates in a change of balance between activator and repressor forms of glioma-associated oncogene (Gli) transcription factors. The components of the Hh signaling pathway involved in the signaling transfer to the Gli transcription factors include Hedgehog ligands (Sonic Hh [SHh], Indian Hh [IHh], and Desert Hh [DHh]), Patched receptor (Ptch1, Ptch2), Smoothened receptor (Smo), Suppressor of fused homolog (Sufu), kinesin protein Kif7, protein kinase A (PKA), and cyclic adenosine monophosphate (cAMP). The activator form of Gli travels to the nucleus and stimulates the transcription of the target genes by binding to their promoters. The main target genes of the Hh signaling pathway are PTCH1, PTCH2, and GLI1. Deregulation of the Hh signaling pathway is associated with developmental anomalies and cancer, including Gorlin syndrome, and sporadic cancers, such as basal cell carcinoma, medulloblastoma, pancreatic, breast, colon, ovarian, and small-cell lung carcinomas. The aberrant activation of the Hh signaling pathway is caused by mutations in the related genes (ligand-independent signaling) or by the excessive expression of the Hh signaling molecules (ligand-dependent signaling - autocrine or paracrine). Several Hh signaling pathway inhibitors, such as vismodegib and sonidegib, have been developed for cancer treatment. These drugs are regarded as promising cancer therapies, especially for patients with refractory/advanced cancers.

Effects of Tribulus terrestris on monosodium iodoacetate‑induced osteoarthritis pain in rats

Tribulus terrestris L. (T. terrestris) has been used as a traditional medicine for the treatment of diuretic, lithontriptic, edema and urinary infections. Previous studies have indicated that it is effective in improving inflammation by regulating tumor necrosis factor‑α (TNF)‑α, interleukin (IL)‑6, IL‑10, nitric oxide (NO) and cyclooxygenase (COX)‑2. However, the effects and mechanism of action of T. terrestris on osteoarthritis (OA) remain unknown. Therefore, the present study aimed to evaluate the effects of the ethanolic extract of T. terrestris (ETT) in a monosodium iodoacetate (MIA)‑induced OA animal model. OA was induced in LEW/SSNHSD rats by intra‑articular injection of MIA. Morphometric changes and parameters of the tibial trabecular bone were determined using micro‑computed tomography. The molecular mechanisms of ETT in OA were investigated using reverse transcription‑polymerase chain reaction, western blotting and gelatin zymogram analysis. Treatment with ETT attenuated MIA‑induced OA, and this effect was mediated by the downregulation of NO synthase 2, COX‑2, TNF‑α and IL‑6. Furthermore, the ETT‑mediated attenuation of OA was also dependent on the expression of matrix metalloproteinases‑2 and ‑9. The results of the current study indicate that further evaluation of the mechanisms underlying the attenuation of MIA‑induced OA by ETT are required, and may support the development of ETT as a potential therapeutic agent for the treatment of inflammatory diseases such as OA.

Trigonostemon reidioides modulates endothelial cell proliferation, migration and tube formation via downregulation of the Akt signaling pathway

Trigonostemon reidi`oides (TR) is used as a Thai traditional medicine for the treatment of drug addiction, asthma, food poisoning, constipation and snake bites. The present study investigated the effects and molecular mechanisms of the ethanolic extract of TR (ETR) on mitogen-induced human umbilical vein endothelial cells (HUVECs) responses, proliferation, adhesion, migration and tube formation. ETR treatment inhibited mitogen-induced HUVEC proliferation by downregulation of cell cycle-associated proteins, including cyclins and cyclin-dependent kinases, which induced retinoblastoma protein hypophosphorylation. The present study also demonstrated that ETR treatment suppressed mitogen-induced HUVEC adhesion, migration, invasion and tube formation, and that these anti-angiogenic activities were mediated by inactivation of mitogen-induced Akt and matrix metalloproteinase (MMP)-2, but not of extracellular signal-regulated kinase, p70 ribosomal S6 kinase or MMP-9. Collectively, the results of the present study suggested pharmacological functions and molecular mechanisms of ETR in regulating endothelial cell fates, and supported further evaluation and development of ETR as a potential therapeutic agent for the treatment and prevention of angiogenesis-associated diseases, including cancer.

A sesquiterpene lactone from Siegesbeckia glabrescens suppresses Hedgehog/Gli-mediated transcription in pancreatic cancer cells

Pancreatic cancer is aggressive and therefore difficult to treat; however, continued efforts have been made with the aim of developing an effective therapy against the disease. The Hedgehog (Hh) signaling pathway is reportedly involved in the proliferation and survival of pancreatic cancer cells. The transcription factor glioma-associated oncogene (Gli) is a key component of the Hh signaling pathway and the primary effector of pancreatic cancer development. Inhibiting Gli is a proven therapeutic strategy for this disease. The present study examined the regulation of Gli and the expression of its target genes to identify an inhibitor of the Sonic Hh (Shh) pathway. A germacranolide sesquiterpene lactone (GSL) was isolated from Siegesbeckia glabrescens as an inhibitor of Gli-mediated transcription. The results demonstrated that GSL inhibited Shh-induced osteoblast differentiation and Gli homolog 1 (Gli1)-mediated transcriptional activity in mesenchymal C3H10T1/2 stem cells. Furthermore, GSL suppressed Gli-mediated transcriptional activity in human pancreatic cancer PANC-1 and AsPC-1 cells, which resulted in reduced cancer cell proliferation and downregulated expression of the Gli-target genes, Gli1 and cyclin D1. A sesquiterpene lactone from S. glabrescens may therefore serve as a candidate for the treatment of Hh/Gli-dependent pancreatic cancer.

A human IgG-like bispecific antibody co-targeting epidermal growth factor receptor and the vascular endothelial growth factor receptor 2 for enhanced antitumor activity

Both Epidermal Growth Factor Receptor (EGFR) and the Vascular Endothelial Growth Factor Receptor 2 (VEGFR2) play critical roles in tumorigenesis. We hypothesized co-targeting EGFR and VEGFR2 using a bispecific antibody might have significant therapeutic potential. Here,we designed and produced a human IgG-like bispecific antibody (Bi-Ab) based on the variable regions of cetuximab (an anti-EGFR antibody) and mAb-04 (an anti-VEGFR2 antibody developed in our lab) . The Bi-Ab was found to inhibit the proliferation, survival and invasion of cancer cells via ablating phosphorylation of receptor and downstream signaling. In vivo efficacy was demonstrated against established HT-29 and SKOV-3 xenografts grown in nude mice. Studies revealed our Bi-Ab was able to restrain xenografted tumor growth and prolong survival of mice through inhibiting cell proliferation,promoting apoptosis and anti-angiogenesis. In contrast to cetuximab or mAb-04 alone, our Bi-Ab exhibits enhanced antitumor activity and has equal or slightly superior activity to their combination (Combi). It shows promise as a therapeutic agent, especially for use against tumors EGFR and/or VEGFR2 over-expressing malignancies.

Ligularia fischeri inhibits endothelial cell proliferation, invasion and tube formation through the inactivation of mitogenic signaling pathways and regulation of vascular endothelial cadherin distribution and matrix metalloproteinase expression

Ligularia fischeri (LF) has been used as an edible herb and traditional medicine for the treatment of inflammatory and infectious diseases. In the present study, we report the effects and molecular mechanism of the ethanolic extract of LF on cell proliferation, invasion and tube formation in human umbilical vein endothelial cells (HUVECs). LF-mediated inhibition of cell proliferation was accompanied by reduced expression of cell cycle-related proteins such as cyclin-dependent kinases (Cdks) and cyclins, leading to pRb hypophosphorylation and G1 phase cell cycle arrest. We also show that LF treatment inhibited cell invasion and tube formation in HUVECs. These anti-angiogenic activities of LF were associated with the inactivation of mitogenic signaling pathways, induction of vascular endothelial (VE)-cadherin distribution at cell-cell contacts and inhibition of matrix metalloproteinase (MMP) expression. Collectively, our findings demonstrate the pharmacological functions and molecular mechanisms of LF in regulating endothelial cell fates, and support further development as a potential therapeutic agent for the treatment and prevention of angiogenesis-related disorders including cancer.

New cytotoxic sesquiterpenoids from Siegesbeckia glabrescens

Two new sesquiterpenoids, siegenolides A (1) and B (2), and two known sesquiterpenes 3 and 4 were isolated from Siegesbeckia glabrescens. Their structures were elucidated by spectroscopic analyses, and they were further evaluated for their cytotoxic activities against human cancer cells (MCF-7, AsPC-1, SW480, HCT 116, HepG2, HeLa). Compounds 1–4 showed differential cytotoxic effects on the target cancer cells with IC₅₀ values in the range of 0.9–33.3 μM.

Anti-angiogenic effects of Siegesbeckia glabrescens are mediated by suppression of the Akt and p70S6K-dependent signaling pathways

Siegesbeckia glabrescens (SG) Makino (Compositae) has been used as a traditional medicine for the treatment of allergic and inflammatory diseases. In the present study, we report the effects and molecular mechanism of an ethanolic extract of SG on cell proliferation, migration and tube formation in vascular endothelial growth factor-A (VEGF-A)-treated human umbilical vein endothelial cells. SG treatment inhibited VEGF-A-stimulated endothelial cell proliferation through downregulation of cyclin D and upregulation of cyclin-dependent kinase inhibitors such as p27Kip1 and p21WAF1/Cip1. In addition, SG inhibited VEGF‑A-stimulated endothelial cell migration and tube formation. These anti-angiogenic activities of SG were mediated by inactivation of the Akt- and p70S6K-dependent signaling pathways. Collectively, our findings demonstrate the pharmacological roles and molecular mechanism of SG in regulating angiogenic responses and support further evaluation and development of SG as a potential therapeutic agent for the treatment and prevention of angiogenesis-related diseases including cancer.

Regulatory effects of Siegesbeckia glabrescens on non-small cell lung cancer cell proliferation and invasion

Siegesbeckia glabrescens (SG) Makino (Compositae) has been used as a traditional medicine for the treatment of allergic and inflammatory diseases. In the present study, we examined the effects and molecular mechanism of the ethanol extract of SG on cell proliferation and invasion in p53 wild-type A549 and p53-deficient H1299 non-small cell lung cancer (NSCLC) cells. SG treatment markedly inhibited the proliferation and invasion in both cell lines, independently of p53 expression. The anti-proliferative effect of SG on A549 cells was mediated by the inactivation of Akt and p70(S6K) as evidenced by treatment with LY294002 and rapamycin, respectively. In addition, anti-invasive activity of SG in A549 cells was found to be associated with the inhibition of p70(S6K). In contrast, in H1299 cells the inactivation of p38(MAPK) appeared to be involved in SG-mediated inhibition of cell proliferation and invasion. Collectively, these findings suggest that SG modulates cellular fates such as proliferation and invasion by differential regulation of signaling pathways, depending on the status of p53 expression in NSCLC, and support the development of SG as a potent therapeutic agent for the treatment of NSCLC.

Broussonetia kazinoki modulates the expression of VEGFR-2 and MMP-2 through the inhibition of ERK, Akt and p70S6K‑dependent signaling pathways: Its implication in endothelial cell proliferation, migration and tubular formation

Broussonetia kazinoki (BK) has been used as a traditional medicine to improve vision, as well as for inflammatory and infectious diseases. In the present study, we investigated the effects and molecular mechanism of the ethanolic extract of BK on cell proliferation, migration and tubular formation in vascular endothelial growth factor-A (VEGF-A)-treated human umbilical vein endothelial cells. BK treatment inhibited VEGF-A-stimulated endothelial cell proliferation through the downregulation of cell cycle-related proteins including cyclin-dependent kinases and cyclins. Moreover, BK treatment suppressed cell migration and tubular formation in response to VEGF-A. These anti-angiogenic activities of BK were associated with the inactivation of mitogenic signaling pathways including extracellular signal-regulated kinase, Akt and p70S6K, and the subsequent downregulation of VEGFR-2 and matrix metalloproteinase-2. Taken together, these findings suggest further evaluation and development of BK as a potential therapeutic agent for the treatment and prevention of angiogenesis-related diseases including cancer.