The Anticancer Effect of Fucoidan in PC-3 Prostate Cancer Cells

Fucoidan, a sulfated polysaccharide, has a variety of biological activities, such as anti-cancer, anti-angiogenic and anti-inflammatory. However, the mechanisms of action of fucoidan as an anti-cancer agent have not been fully elucidated. The present study examined the anti-cancer effect of fucoidan obtained from Undaria pinnatifida in PC-3 cells, human prostate cancer cells. Fucoidan induced the apoptosis of PC-3 cells by activating both intrinsic and extrinsic pathways. The induction of apoptosis was accompanied by the activation of extracellular signal-regulated kinase mitogen-activated protein kinase (ERK1/2 MAPK) and the inactivation of p38 MAPK and phosphatidylinositol 3-kinase (PI3K)/Akt. In addition, fucoidan also induced the up-regulation of p21^Cip1/Waf and down-regulation of E2F-1 cell-cycle-related proteins. Furthermore, in the Wnt/β-catenin pathway, fucoidan activated GSK-3β that resulted in the decrease of β-catenin level, followed by the decrease of c-myc and cyclin D1 expressions, target genes of β-catenin in PC-3 cells. These results suggested that fucoidan treatment could induce intrinsic and extrinsic apoptosis pathways via the activation of ERK1/2 MAPK, the inactivation of p38 MAPK and PI3K/Akt signaling pathway, and the down-regulation of Wnt/β-catenin signaling pathway in PC-3 prostate cancer cells. These data support that fucoidan might have potential for the treatment of prostate cancer.     

Gliotoxin Inhibits Proliferation and Induces Apoptosis in Colorectal Cancer Cells

The discovery of new bioactive compounds from marine natural sources is very important in pharmacological research. Here we developed a Wnt responsive luciferase reporter assay to screen small molecule inhibitors of cancer associated constitutive Wnt signaling pathway. We identified that gliotoxin (GTX) and some of its analogues, the secondary metabolites from marine fungus Neosartorya pseufofischeri, acted as inhibitors of the Wnt signaling pathway. In addition, we found that GTX downregulated the β-catenin levels in colorectal cancer cells with inactivating mutations of adenomatous polyposis coli (APC) or activating mutations of β-catenin. Furthermore, we demonstrated that GTX induced growth inhibition and apoptosis in multiple colorectal cancer cell lines with mutations of the Wnt signaling pathway. Together, we illustrated a practical approach to identify small-molecule inhibitors of the Wnt signaling pathway and our study indicated that GTX has therapeutic potential for the prevention or treatment of Wnt dependent cancers and other Wnt related diseases.     

Inhibition of A549 Lung Cancer Cell Migration and Invasion by Ent-Caprolactin C via the Suppression of Transforming Growth Factor-β-Induced Epithelial—Mesenchymal Transition

The epithelial–mesenchymal transition (EMT) of cancer cells is a crucial process in cancer cell metastasis. An Aquimarina sp. MC085 extract was found to inhibit A549 human lung cancer cell invasion, and caprolactin C (1), a new natural product, α-amino-ε-caprolactam linked to 3-methyl butanoic acid, was purified through bioactivity-guided isolation of the extract. Furthermore, its enantiomeric compound, ent-caprolactin C (2), was synthesized. Both 1 and 2 inhibited the invasion and γ-irradiation-induced migration of A549 cells. In transforming growth factor-β (TGF-β)-treated A549 cells, 2 inhibited the phosphorylation of Smad2/3 and suppressed the EMT cell marker proteins (N-cadherin, β-catenin, and vimentin), as well as the related messenger ribonucleic acid expression (N-cadherin, matrix metalloproteinase-9, Snail, and vimentin), while compound 1 did not suppress Smad2/3 phosphorylation and the expression of EMT cell markers. Therefore, compound 2 could be a potential candidate for antimetastatic agent development, because it suppresses TGF-β-induced EMT.     

Linagliptin Protects Human SH-SY5Y Neuroblastoma Cells against Amyloid-β Cytotoxicity via the Activation of Wnt1 and Suppression of IL-6 Release

Background:Alzheimer’s disease is one of the neurodegenerative disorders typified by the aggregate of Aβ and phosphorylated tau protein. Oxidative stress and neuroinflammation, because of Aβ peptides, are strongly involved in the pathophysiology of AD. Linagliptin shows neuroprotective properties against AD pathological processes through alleviation of neural inflammation and AMPK activation. Methods:We assessed the benefits of linagliptin pretreatment (at 10, 20, and 50 nM concentrations), against Aβ1-42 toxicity (20 μM) in SH-SY5Y cells. The concentrations of secreted cytokines, such as TNF-α, IL-6, and IL-1β, and signaling proteins, including pCREB, Wnt1, and PKCε, were quantified by ELISA. Results:We observed that Aβ led to cellular inflammation, which was assessed by measuring inflammatory cytokines (TNF-α, IL-1β, and IL-6). Moreover, Aβ1-42 treatment impaired pCREB, PKCε, and Wnt1 signaling in human SH-SY5Y neuroblastoma cells. Addition of Linagliptin significantly reduced IL-6 levels in the lysates of cells, treated with Aβ1-42. Furthermore, linagliptin prevented the downregulation of Wnt1 in Aβ1-42-treated cells exposed. Conclusion: The current findings reveal that linagliptin alleviates Aβ1-42-induced inflammation in SH-SY5Y cells, probably through the suppression of IL-6 release, and some of its benefits are mediated through the activation of the Wnt1 signaling pathway. Key Words: Alzheimer disease, Interleukin-6, Linagliptin, Wnt1 protein     

The Promoting Effect of Ishige sinicola on Hair Growth

This study was conducted to evaluate the promoting effect of Ishige sinicola, an alga native to Jeju Island, Korea, on hair growth. When vibrissa follicles were cultured in the presence of I. sinicola extract for 21 days, I. sinicola extract increased hair-fiber length. After topical application of I. sinicola extract onto the back of C57BL/6 mice, anagen progression of the hair shaft was induced. The I. sinicola extract significantly inhibited the activity of 5α-reductase. Treatment of immortalized vibrissa dermal papilla cells (DPCs) with I. sinicola extract resulted in increase of cell proliferation, which was accompanied by the increase of phospho-GSK3β level, β-catenin, Cyclin E and CDK2, whereas p27^kip1 was down-regulated. In particular, octaphlorethol A, an isolated component from the I. sinicola extract, inhibited the activity of 5α-reductase and increased the proliferation of DPCs. These results suggest that I. sinicola extract and octaphlorethol A, a principal of I. sinicola, have the potential to treat alopecia via the proliferation of DPCs followed by the activation of β-catenin pathway, and the 5α-reductase inhibition.     

Structural Characteristics and Anticancer Activity of Fucoidan from the Brown Alga Sargassum mcclurei

Three different fucoidan fractions were isolated and purified from the brown alga, Sargassum mcclurei. The SmF1 and SmF2 fucoidans are sulfated heteropolysaccharides that contain fucose, galactose, mannose, xylose and glucose. The SmF3 fucoidan is highly sulfated (35%) galactofucan, and the main chain of the polysaccharide contains a →3)-α-l-Fucp(2,4SO₃⁻)-(1→3)-α-l-Fucp(2,4SO₃⁻)-(1→ motif with 1,4-linked 3-sulfated α-l-Fucp inserts and 6-linked galactose on reducing end. Possible branching points include the 1,2,6- or 1,3,6-linked galactose and/or 1,3,4-linked fucose residues that could be glycosylated with terminal β-d-Galp residues or chains of alternating sulfated 1,3-linked α-l-Fucp and 1,4-linked β-d-Galp residues, which have been identified in galactofucans for the first time. Both α-l-Fucp and β-d-Galp residues are sulfated at C-2 and/or C-4 (and some C-6 of β-d-Galp) and potentially the C-3 of terminal β-d-Galp, 1,4-linked β-d-Galp and 1,4-linked α-l-Fucp residues. All fucoidans fractions were less cytotoxic and displayed colony formation inhibition in colon cancer DLD-1 cells. Therefore, these fucoidan fractions are potential antitumor agents.     

Ophiobolin O Isolated from Aspergillus ustus Induces G1 Arrest of MCF-7 Cells through Interaction with AKT/GSK3β/Cyclin D1 Signaling

Ophiobolin O is a member of ophiobolin family, which has been proved to be a potent anti-tumor drug candidate for human breast cancer. However, the anti-tumor effect and the mechanism of ophiobolin O remain unclear. In this study, we further verified ophiobolin O-induced G1 phase arrest in human breast cancer MCF-7 cells, and found that ophiobolin O reduced the phosphorylation level of AKT and GSK3β, and induced down-regulation of cyclin D1. The inverse docking (INVDOCK) analysis indicated that ophiobolin O could bind to GSK3β, and GSK3β knockdown abolished cyclin D1 degradation and G1 phase arrest. Pre-treatment with phosphatase inhibitor sodium or thovanadate halted dephosphorylation of AKT and GSK3β, and blocked ophiobolin O-induced G1 phase arrest. These data suggest that ophiobolin O may induce G1 arrest in MCF-7 cells through interaction with AKT/GSK3β/cyclin D1 signaling. In vivo, ophiobolin O suppressed tumor growth and showed little toxicity in mouse xenograft models. Overall, these findings provide theoretical basis for the therapeutic use of ophiobolin O.     

Salternamide A Suppresses Hypoxia-Induced Accumulation of HIF-1α and Induces Apoptosis in Human Colorectal Cancer Cells

Hypoxia inducible factor-1α (HIF-1α) is an essential regulator of the cellular response to low oxygen concentrations, activating a broad range of genes that provide adaptive responses to oxygen deprivation. HIF-1α is overexpressed in various cancers and therefore represents a considerable chemotherapeutic target. Salternamide A (SA), a novel small molecule that is isolated from a halophilic Streptomyces sp., is a potent cytotoxic agent against a variety of human cancer cell lines. However, the mechanisms by which SA inhibits tumor growth remain to be elucidated. In the present study, we demonstrate that SA efficiently inhibits the hypoxia-induced accumulation of HIF-1α in a time- and concentration-dependent manner in various human cancer cells. In addition, SA suppresses the upstream signaling of HIF-1α, such as PI3K/Akt/mTOR, p42/p44 MAPK, and STAT3 signaling under hypoxic conditions. Furthermore, we found that SA induces cell death by stimulating G2/M cell cycle arrest and apoptosis in human colorectal cancer cells. Taken together, SA was identified as a novel small molecule HIF-1α inhibitor from marine natural products and is potentially a leading candidate in the development of anticancer agents.     

Interactions of Globular and Ribbon [γ4E]GID with α4β2 Neuronal Nicotinic Acetylcholine Receptor

The α4β2 nAChR is implicated in a range of diseases and disorders including nicotine addiction, epilepsy and Parkinson’s and Alzheimer’s diseases. Designing α4β2 nAChR selective inhibitors could help define the role of the α4β2 nAChR in such disease states. In this study, we aimed to modify globular and ribbon α-conotoxin GID to selectively target the α4β2 nAChR through competitive inhibition of the α4(+)β2(−) or α4(+)α4(−) interfaces. The binding modes of the globular α-conotoxin [γ4E]GID with rat α3β2, α4β2 and α7 nAChRs were deduced using computational methods and were validated using published experimental data. The binding mode of globular [γ4E]GID at α4β2 nAChR can explain the experimental mutagenesis data, suggesting that it could be used to design GID variants. The predicted mutational energy results showed that globular [γ4E]GID is optimal for binding to α4β2 nAChR and its activity could not likely be further improved through amino-acid substitutions. The binding mode of ribbon GID with the (α4)₃(β2)₂ nAChR was deduced using the information from the cryo-electron structure of (α4)₃(β2)₂ nAChR and the binding mode of ribbon AuIB. The program FoldX predicted the mutational energies of ribbon [γ4E]GID at the α4(+)α4(−) interface, and several ribbon[γ4E]GID mutants were suggested to have desirable properties to inhibit (α4)₃(β2)₂ nAChR.     

Fucoidan Suppresses Hypoxia-Induced Lymphangiogenesis and Lymphatic Metastasis in Mouse Hepatocarcinoma

Metastasis, the greatest clinical challenge associated with cancer, is closely connected to multiple biological processes, including invasion and adhesion. The hypoxic environment in tumors is an important factor that causes tumor metastasis by activating HIF-1α. Fucoidan, extracted from brown algae, is a sulfated polysaccharide and, as a novel marine biological material, has been used to treat various disorders in China, Korea, Japan and other countries. In the present study, we demonstrated that fucoidan derived from Undaria pinnatifida sporophylls significantly inhibits the hypoxia-induced expression, nuclear translocation and activity of HIF-1α, the synthesis and secretion of VEGF-C and HGF, cell invasion and lymphatic metastasis in a mouse hepatocarcinoma Hca-F cell line. Fucoidan also suppressed lymphangiogenesis in vitro and in vivo. In addition, accompanied by a reduction in the HIF-1α nuclear translocation and activity, fucoidan significantly reduced the levels of p-PI3K, p-Akt, p-mTOR, p-ERK, NF-κB, MMP-2 and MMP-9, but increased TIMP-1 levels. These results indicate strongly that the anti-metastasis and anti-lymphangiogenesis activities of fucoidan are mediated by suppressing HIF-1α/VEGF-C, which attenuates the PI3K/Akt/mTOR signaling pathways.     

Two Novel Tyrosinase Inhibitory Sesquiterpenes Induced by CuCl2 from a Marine-Derived Fungus Pestalotiopsis sp. Z233

Two new sesquiterpenes, 1β,5α,6α,14-tetraacetoxy-9α-benzoyloxy-7βH-eudesman-2β,11-diol (1) and 4α,5α-diacetoxy-9α-benzoyloxy-7βH-eudesman-1β,2β,11,14-tetraol (2), were produced as stress metabolites in the cultured mycelia of Pestalotiopsis sp. Z233 isolated from the algae Sargassum horneri in response to abiotic stress elicitation by CuCl₂. Their structures were established by spectroscopic means. New compounds 1 and 2 showed tyrosinase inhibitory activities with IC₅₀ value of 14.8 µM and 22.3 µM.     

Cytotoxic and Apoptosis-Inducing Activity of Triterpene Glycosides from Holothuria scabra and Cucumaria frondosa against HepG2 Cells

The cytotoxic effects of thirteen triterpene glycosides from Holothuria scabra Jaeger and Cucumaria frondosa Gunnerus (Holothuroidea) against four human cell lines were detected and their cytotoxicity-structure relationships were established. The apoptosis-inducing activity of a more potent glycoside echinoside A (1) in HepG2 cells was further investigated by determining its effect on the morphology, mitochondrial transmembrane potential (Δψ_m) and mRNA expression levels of the apoptosis-related genes. The results showed that the number of glycosyl residues in sugar chains and the side chain of aglycone could affect their cytotoxicity towards tumor cells and selective cytotoxicity. 1 significantly inhibited cell viability and induced apoptosis in HepG2 cells. 1 also markedly decreased the Δψ_m and Bcl-2/Bax mRNA express ratio, and up-regulated the mRNA expression levels of Caspase-3, Caspase-8 and Caspase-9 in HepG2 cells. Therefore, 1 induced apoptosis in HepG2 cells through both intrinsic and extrinsic pathway. These findings could potentially promote the usage of these glycosides as leading compounds for developing new antitumor drugs.     

Dieckol Ameliorates Aβ Production via PI3K/Akt/GSK-3β Regulated APP Processing in SweAPP N2a Cell

The proteolytic processing of amyloid precursor protein (APP) by β-secretase (BACE1) and γ-secretase releases amyloid-β peptide (Aβ), which deposits in amyloid plaques and contributes to the initial causative events of Alzheimer’s disease (AD). In the present study, the regulatory mechanism of APP processing of three phlorotannins was elucidated in Swedish mutant APP overexpressed N2a (SweAPP N2a) cells. Among the tested compounds, dieckol exhibited the highest inhibitory effect on both intra- and extracellular Aβ accumulation. In addition, dieckol regulated the APP processing enzymes, such as α-secretase (ADAM10), β-secretase, and γ-secretase, presenilin-1 (PS1), and their proteolytic products, sAPPα and sAPPβ, implying that the compound acts on both the amyloidogenic and non-amyloidogenic pathways. In addition, dieckol increased the phosphorylation of protein kinase B (Akt) at Ser473 and GSK-3β at Ser9, suggesting dieckol induced the activation of Akt, which phosphorylated GSK-3β. The specific phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 triggered GSK-3β activation and Aβ expression. In addition, co-treatment with LY294002 noticeably blocked the effect of dieckol on Aβ production, demonstrating that dieckol promoted the PI3K/Akt signaling pathway, which in turn inactivated GSK-3β, resulting in the reduction in Aβ levels.     

Chitosan Oligosaccharides Alleviate Colitis by Regulating Intestinal Microbiota and PPARγ/SIRT1-Mediated NF-κB Pathway

Chitosan oligosaccharides (COS) have been shown to have potential protective effects against colitis, but the mechanism underlying this effect has not been fully elucidated. In this study, COS were found to significantly attenuate dextran sodium sulfate-induced colitis in mice by decreasing disease activity index scores, downregulating pro-inflammatory cytokines, and upregulating Mucin-2 levels. COS also significantly inhibited the levels of nitric oxide (NO) and IL-6 in lipopolysaccharide-stimulated RAW 264.7 cells. Importantly, COS inhibited the activation of the NF-κB signaling pathway via activating PPARγ and SIRT1, thus reducing the production of NO and IL-6. The antagonist of PPARγ could abolish the anti-inflammatory effects of COS in LPS-treated cells. COS also activated SIRT1 to reduce the acetylation of p65 protein at lysine 310, which was reversed by silencing SIRT1 by siRNA. Moreover, COS treatment increased the diversity of intestinal microbiota and partly restored the Firmicutes/Bacteroidetes ratio. COS administration could optimize intestinal microbiota composition by increasing the abundance of norank_f_Muribaculaceae, Lactobacillus and Alistipes, while decreasing the abundance of Turicibacte. Furthermore, COS could also increase the levels of propionate and butyrate. Overall, COS can improve colitis by regulating intestinal microbiota and the PPARγ/SIRT1-mediated NF-κB pathway.     

Fucoidan Isolated from Sargassum confusum Suppresses Inflammatory Responses and Oxidative Stress in TNF-α/IFN-γ- Stimulated HaCaT Keratinocytes by Activating Nrf2/HO-1 Signaling Pathway

Recent studies have revealed that marine brown seaweeds contain numerous bioactive compounds which exhibit various bioactivities. The present study investigated the effect of low molecular weight fucoidan (SCF) isolated from Sargassum confusum, a brown alga, on inflammatory responses and oxidative stress in HaCaT keratinocytes stimulated by tumor necrosis factor (TNF)-α/interferon (IFN)-γ. SCF significantly increased the cell viability while decreasing the intracellular reactive oxygen species (ROS) production in TNF-α/IFN-γ-stimulated HaCaT keratinocytes. In addition, SCF effectively reduced inflammatory cytokines (interleukin (IL)-1β, IL-6, IL-8, IL-13, TNF-α, and IFN-γ) and chemokines (Eotaxin, macrophage-derived chemokine (MDC), regulated on activation, normal T cell expressed and secreted (RANTES), and thymus and activation-regulated chemokine (TARC)) expression, by down-regulating the expression of epithelial and epidermal innate cytokines (IL-25, IL-33, and thymic stromal lymphopoietin (TSLP)). Furthermore, SCF suppressed the activation of TNF-α/IFN-γ-stimulated mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) signaling pathways, while activating the nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) signaling pathway. The cytoprotective effect of SCF against TNF-α/IFN-γ stimulation was considerably reduced upon inhibition of HO-1 activity by ZnPP. Overall, these results suggest that SCF effectively suppressed inflammatory responses and oxidative stress in TNF-α/IFN-γ-stimulated HaCaT keratinocytes via activating the Nrf2/HO-1 signaling pathway.