Sulforaphane decreases oxidative stress and inhibits NLRP3 inflammasome activation in a mouse model of ulcerative colitis.

Excessive oxidative stress and NLRP3 inflammasome activation are considered the main drivers of inflammatory bowel disease (IBD), and inhibition of inflammasomes ameliorates clinical symptoms and morphological manifestations of IBD. Herein, we examined the roles of NLRP3 activation in IBD and modulation of NLRP3 by sulforaphane (SFN), a compound with multiple pharmacological activities that is extracted from cruciferous plants. To simulate human IBD, we established a mouse colitis model by administering dextran sodium sulfate in the drinking water. SFN (25, 50 mg·kg-1·d-1, ig) or the positive control sulfasalazine (500 mg/kg, ig) was administered to colitis-affected mice for 7 days. Model mice displayed pathological alterations in colon tissue as well as classic symptoms of colitis beyond substantial tissue inflammation. Expression of NLRP3, ASC, and caspase-1 was significantly elevated in the colonic epithelium. The expression of NLRP3 inflammasomes led to activation of downstream proteins and increases in the cytokines IL-18 and IL-1ß. SFN administration either fully or partially reversed these changes, thus restoring IL-18 and IL-1ß, substantially inhibiting NLRP3 activation, and decreasing inflammation. SFN alleviated the inflammation induced by LPS and NLRP3 agonists in RAW264.7 cells by decreasing the levels of reactive oxygen species. In summary, our results revealed the pathological roles of oxidative stress and NLRP3 in colitis, and indicated that SFN might serve as a natural NLRP3 inhibitor, thereby providing a new strategy for alternative colitis treatment.

Luteolin and its analog luteolin-7-methylether from Leonurus japonicus Houtt suppress aromatase-mediated estrogen biosynthesis to alleviate polycystic ovary syndrome by the inhibition of tumor progression locus 2.

ETHNOPHARMACOLOGICAL RELEVANCE: Leonurus japonicus Houtt (L. japonicus, Chinese motherwort), known as Yi Mu Cao which means "good for women", has long been widely used in China and other Asian countries to alleviate gynecological disorders, often characterized by estrogen dysregulation. It has been used for the treatment of polycystic ovary syndrome (PCOS), a common endocrine disorder in women but the underlying mechanism remains unknown. AIM OF THE STUDY: The present study was designed to investigate the effect and mechanism of flavonoid luteolin and its analog luteolin-7-methylether contained in L. japonicus on aromatase, a rate-limiting enzyme that catalyzes the conversion of androgens to estrogens and a drug target to induce ovulation in PCOS patients. MATERIALS AND METHODS: Estrogen biosynthesis in human ovarian granulosa cells was examined using ELISA. Western blots were used to explore the signaling pathways in the regulation of aromatase expression. Transcriptomic analysis was conducted to elucidate the potential mechanisms of action of compounds. Finally, animal models were used to assess the therapeutic potential of these compounds in PCOS. RESULTS: Luteolin potently inhibited estrogen biosynthesis in human ovarian granulosa cells stimulated by follicle-stimulating hormone. This effect was achieved by decreasing cAMP response element-binding protein (CREB)-mediated expression of aromatase. Mechanistically, luteolin and luteolin-7-methylether targeted tumor progression locus 2 (TPL2) to suppress mitogen-activated protein kinase 3/6 (MKK3/6)-p38 MAPK-CREB pathway signaling. Transcriptional analysis showed that these compounds regulated the expression of different genes, with the MAPK signaling pathway being the most significantly affected. Furthermore, luteolin and luteolin-7-methylether effectively alleviated the symptoms of PCOS in mice. CONCLUSIONS: This study demonstrates a previously unrecognized role of TPL2 in estrogen biosynthesis and suggests that luteolin and luteolin-7-methylether have potential as novel therapeutic agents for the treatment of PCOS. The results provide a foundation for further development of these compounds as effective and safe therapies for women with PCOS.

Chaetomadramines A-E, a class of siderophores with potent neuroprotective activity from the fungus Chaetomium madrasense cib-1.

Five hydroxamate siderophores, chaetomadramines A-E (1-5), along with seven known compounds were isolated from the fermented rice culture of the fungus Chaetomium madrasense cib-1. Compounds 1-5 were structurally elucidated on the basis of spectroscopic data, which were a group of unusual hydroxamate siderophores, bearing a long fatty acyl on the α-NH2 of the Nδ-hydroxylated ornithine. Compounds 2-5 were new. The structural elucidation and spectroscopic data of 1 were reported for the first time. Compounds 2-4 significantly improved the survival rates of PC12 cells in the neuroprotective activity assay at the concentration of 40 µM.

Chaetonigrisins A-L, a group of 3-Indole-1,2-Propanediol derived alkaloids from Chaetomium nigricolor YT-2.

Thirteen new alkaloids (1-13) as well as ten known compounds were isolated from the solid-state fermented rice medium of the fungus Chaetomium nigricolor YT-2. Their structures were elucidated on the basis of spectroscopic data, quantum calculations, and single crystal X-ray crystallographic analysis. Chaetonigrisin A (1) represents an unprecedented carbon skeleton featuring a polycyclic 1H-pyrano[3,2:3,4-]​furo[2,​3-​b]​indole. Chaetonigrisin B (2) displays a unique carbon skeleton with a 1,3­dioxolane bridged-ring. Chaetonigrisin C (3) is a spirocyclic indole alkaloid. Chaetonigrisins D-H (4-8) are a group of asymmetric dimers, formed with two 3-indol-3yl-1,2-propanediol (4-6) or with a 3-indol-3yl-1,2-propanediol and a 3-indol-2yl-1,2-propanediol (7-8) by a pyran ring. Chaetonigrisins I-L (9-12) each contains a 3-indol-3yl-1,2-propanediol or 3-indol-2yl-1,2-propanediol substructure. Chaetonigrisin M (13) is a new quinoline alkaloid. The neuroprotective activity assay showed that at the concentration of 40 µM, compounds (4-7, 11, and 12) improved the cell viability of PC12 cells were 49.26 %, 74.69 %, 74.76 %, 86.63 %, 66.89 %, and 69.92 %, respectively induced by 6-OHDA, compound 7 showed significant neuroprotective activity via upregulation of SOD1 mRNA and Bcl-2 mRNA.

Hexachlorophene, a selective SHP2 inhibitor, suppresses proliferation and metastasis of KRAS-mutant NSCLC cells by inhibiting RAS/MEK/ERK and PI3K/AKT signaling pathways.

Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations account for 35% of the genetic alterations in non-small cell lung cancer (NSCLC). The Src-homology region 2-containing protein tyrosine phosphatase 2 (SHP2), encoded by PTPN11, is closely involved in RAS downstream pathways and development of many tumors by affecting cell proliferation, differentiation, and immunity. Targeting SHP2 with small molecules may be a promising avenue for the treatment of KRAS-mutant (mut) NSCLC. Herein, hexachlorophene (HCP) was identified as a SHP2 inhibitor with an IC50 value of 5.63 ± 0.75 µM through screening of the FDA-approved drug library. HCP specifically inhibited SHP2 rather than other phosphatases. Molecular docking showed that HCP displayed an orientation favorable for nucleophilic attack in the catalytic domain of SHP2. HCP suppressed viability of multiple KRAS-mut and KRAS-wild type cells and induced senescence and apoptosis in KRAS-mut cells. Moreover, HCP reversed epithelial-mesenchymal transition to suppress metastasis in KRAS-mut cells, and inhibited the RAS/MEK/ERK and PI3K/AKT signaling pathways by suppression of SHP2 phosphorylation and formation SHP2/Grb2/Gab1/SOS1 complex. In summary, HCP can act as a specific SHP2 inhibitor to inhibit KRAS-mut NSCLC cell proliferation and metastasis and induce senescence through suppression of the RAF/MEK/ERK and PI3K/AKT pathways. HCP warrants further investigation as a new compound skeleton for the development of selective SHP2 inhibitors for the treatment of NSCLC.

A small molecule inhibitor of caspase-1 inhibits NLRP3 inflammasome activation and pyroptosis to alleviate gouty inflammation.

Caspase-1 is an integral regulator of innate immunity, which plays a key role in inflammasome activation and the release of pro-inflammatory cytokines. The development of novel non-peptidic small molecule caspase-1 inhibitors is an important strategy for antagonizing excessively activated caspase-1 induced by inflammatory diseases, including gouty arthritis. In the present study, we identified 63 caspase-1 inhibitors, with different structures and potencies, from bioactive compound libraries. Among them, NSC697923 potently inhibited the enzymatic activity of caspase-1, with an IC50 value of 1.737 µM. This compound adopted a favorable conformation in the active pocket of caspase-1. Furthermore, NSC697923 potently decreased mature interleukin (IL)-1ß secretion in macrophages stimulated by lipopolysaccharide plus nigericin, ATP, and monosodium urate crystal. NSC697923 also inhibited NLRP3 protein expression by suppressing the NF-κB signaling pathway and the interaction between receptor interacting protein-2 (RIP2) and pro-caspase-1, thereby blocking the priming of the NLRP3 inflammasome. In addition, NSC697923 significantly inhibited caspase-1 mediated gasdermin D cleavage and pyroptosis in macrophages. In an animal model of gouty arthritis, NSC697923 effectively inhibited joint swelling, IL-1ß release, and NLRP3 inflammasome activation. Our results indicate that NSC697923 can effectively suppress NLRP3 inflammasome activation by inhibiting caspase-1, thus warranting further investigation as a potential therapeutic for treating NLRP3 inflammasome-related diseases.

Steroidal alkaloids from the bulbs of Fritillaria pallidiflora Schrenk and their anti-inflammatory activity.

Steroidal alkaloids (1-11), including one new 24-hydroxylated cevanine-type steroidal alkaloid, named yibeinone F (1), were isolated from the bulbs of Fritillaria pallidiflora Schrenk. Their structures were elucidated by analyses of extensive spectroscopic data and comparison of the NMR data with those reported previously, and the structures of compounds 1, 7 and 11 were further confirmed by X-ray single crystal diffraction analyses. The anti-inflammatory effects of all the isolated alkaloids were evaluated in LPS-activated RAW264.7 macrophages. Among them, compounds 9 (stenanzine) and 10 (hapepunine) showed significant inhibitory effects against LPS-induced NO production with IC50 values of 8.04 µM and 20.85 µM, respectively. Furthermore, compound 9 effectively inhibited the release of cytokines such as interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and prostaglandin E2 (PGE2), and suppressed the protein expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX2) in LPS-stimulated RAW264.7 cells. Further experiments revealed the underlying mechanism that 9 blocked LPS-induced phosphorylation and degradation of inhibitor-α of nuclear transcription factor κB (IκBα) and c-Jun N-terminal kinase (JNK) in RAW264.7 cells. Taken together, compound 9 may be a valuable candidate for the treatment of inflammatory diseases.

Inhibition of Phosphodiesterase 5 Promotes the Aromatase-Mediated Estrogen Biosynthesis in Osteoblastic Cells by Activation of cGMP/PKG/SHP2 Pathway.

Mechanical stimulation induces bone growth and remodeling by the secondary messenger, cyclic guanosine 3', 5'-monophosphate (cGMP), in osteoblasts. However, the role of cGMP in the regulation of estrogen biosynthesis, whose deficiency is a major cause of osteoporosis, remains unclear. Here, we found that the prenylated flavonoids, 3-O-methoxymethyl-7-O-benzylicaritin (13), 7-O-benzylicaritin (14), and 4'-O-methyl-8-isopentylkaempferol (15), which were synthesized using icariin analogs, promoted estrogen biosynthesis in osteoblastic UMR106 cells, with calculated EC50 values of 1.53, 3.45, and 10.57 µM, respectively. 14 and 15 increased the expression level of the bone specific promoter I.4-driven aromatase, the only enzyme that catalyzes estrogen formation by using androgens as substrates, in osteoblastic cells. 14 inhibited phosphodiesterase 5 (PDE5), stimulated intracellular cGMP level and promoted osteoblast cell differentiation. Inhibition of cGMP dependent-protein kinase G (PKG) abolished the stimulatory effect of 14 on estrogen biosynthesis and osteoblast cell differentiation. Further, PKG activation by 14 stimulated the activity of SHP2 (Src homology 2 domain-containing tyrosine phosphatase 2), thereby activating Src and ERK (extracellular signal-regulated kinase) signaling and increasing ERK-dependent aromatase expression in osteoblasts. Our findings reveal a previously unknown role of cGMP in the regulation of estrogen biosynthesis in the bone. These results support the further development of 14 as a PKG-activating drug to mimic the anabolic effects of mechanical stimulation of bone in the treatment of osteoporosis.

Synthesis and antitumor activity in vitro of novel berbamine derivatives.

A series of new berbamine derivatives were synthesized, and their cytotoxic activity was evaluated against Human T-cell lymphoma cell line H9 and multiple myeloma cell line RPMI8226 in vitro. Compared with berbamine, the cytotoxicity of the modified derivatives was enhanced, especially simultaneously substituted at OH and 5-position. Compounds 2a and 4b exhibited high antitumor activity. The IC50 value of compound 2a was 0.30 µM for RPMI8226 cells, and the IC50 value of compound 4b was 0.36 µM for H9 cells, whereas berbamine IC50 values were 4.0 µM for H9 cells and 6.19 µM for RPMI8226 cells, respectively.[Formula: see text].

Natural Polyketides Isolated from the Endophytic Fungus Phomopsis sp. CAM212 with a Semisynthetic Derivative Downregulating the ERK/IκBα Signaling Pathways.

Three previously undescribed natural products, phomopsinin A - C (1:  - 3: ), together with three known compounds, namely, cis-hydroxymellein (4: ), phomoxanthone A (5: ) and cytochalasin L-696,474 (6: ), were isolated from the solid culture of Phomopsis sp. CAM212, an endophytic fungus obtained from Garcinia xanthochymus. Their structures were determined on the basis of spectroscopic data, including IR, NMR, and MS. The absolute configurations of 1: and 2: were assigned by comparing their experimental and calculated ECD spectra. Acetylation of compound 1: yielded 1A: , a new natural product derivative that was tested together with other isolated compounds on lipopolysaccharide-stimulated RAW 264.7 cells. Cytochalasin L-696,474 (6: ) was found to significantly inhibit nitric oxide production, but was highly cytotoxic to the treated cells, whereas compound 1: slightly inhibited nitric oxide production, which was not significantly different compared to lipopolysaccharide-treated cells. Remarkably, the acetylated derivative of 1: , compound 1A: , significantly inhibited nitric oxide production with an IC50 value of 14.8 µM and no cytotoxic effect on treated cells, thereby showing the importance of the acetyl group in the anti-inflammatory activity of 1A: . The study of the mechanism of action revealed that 1A: decreases the expression of inducible nitric oxide synthase, cyclooxygenase 2, and proinflammatory cytokine IL-6 without an effect on IL-1ß expression. Moreover, it was found that 1A: exerts its anti-inflammatory activity in lipopolysaccharide-stimulated RAW 264.7 macrophage cells by downregulating the activation of ERK1/2 and by preventing the translocation of nuclear factor κB. Thus, derivatives of phomopsinin A (1: ), such as compound 1A: , could provide new anti-inflammatory leads.

Luteolin-7-methylether from Leonurus japonicus inhibits estrogen biosynthesis in human ovarian granulosa cells by suppression of aromatase (CYP19).

Leonurus japonicus (motherwort) has been widely used to treat gynecological disorders, in which estrogen is often dysregulated, for a long time in China and other Asian countries. However, the chemical constituents and mechanisms underlying the activity of this medicinal plant are not fully understood. Seventeen of forty-six tested natural products from L. japonicus showed stimulatory or inhibitory effects on estrogen biosynthesis with different potency in human ovarian granulosa-like KGN cells. Luteolin-7-methylether (XLY29) potently inhibited 17ß-estradiol production (IC50: 5.213 µM) by decreasing the expression of aromatase, the only enzyme in vertebrates that catalyzes the biosynthesis of estrogens, but had no effect on the catalytic activity of aromatase. XLY29 decreased the expression of aromatase promoter I.3/II, and suppressed the phosphorylation of cAMP response element-binding protein. XLY29 potently inhibited phosphorylation of p38 mitogen-activated protein kinase and AKT but had no effect on phosphorylation of extracellular signal-regulated kinase and c-Jun N-terminal kinase. XLY29 also decreased the serum 17ß-estradiol level and disturbed estrous cycle in mice. These results suggest that modulation of estrogen biosynthesis is a novel effect of L. japonicus, and XLY29 warrants further investigation as a new therapeutic means for the treatment of estrogen-related diseases.

Aloe-emodin induces hepatotoxicity by the inhibition of multidrug resistance protein 2.

BACKGROUND: Aloe-emodin (AE) is among the primary bioactive anthraquinones present in traditional Chinese medicinal plants such as Rheum palmatum L. Multidrug resistance protein 2 (ABCC2/ MRP2) is an important efflux transporter of substances associated with cellular oxidative stress. However, the effects of traditional Chinese medicine on this protein remain unclear. PURPOSE: The aim of this research is to study the role of ABCC2 in AE-induced hepatotoxicity. METHODS: The expression of ABCC2 protein and mRNA levels were analyzed by Western-Blotting and qRT-PCR, respectively. The intracellular oxidative stress caused by AE was evaluated by quantifying the levels of intracellular reactive oxygen species, malondialdehyde, glutathione reduced and oxidized glutathione. The levels of adenosine triphosphate, mitochondrial membrane potential and mitochondrial DNA were explored to evaluate the effects of AE on mitochondrial function. The effects of AE on cell apoptosis and cell cycle were detected by flow cytometry. To further clarify the key role of ABCC2 in AE induced cytotoxicity, we used pCI-neo-ABCC2 plasmid to over express ABCC2 protein, and small interfering RNA was used to knockdown ABCC2 in HepG2 cells. Additionally, we investigated the impact of AE on ABCC2 degradation pathway and the hepatotoxic effects of AE in mice. RESULTS: AE was found to inhibit ABCC2 transport activity, downregulate ABCC2 expression and altered intracellular redox balance. Induction of oxidative stress resulted in depletion of intracellular glutathione reduced, mitochondria dysfunction and activation of apoptosis. ABCC2 overexpression significantly reduced AE-induced intracellular oxidative stress and cell death, which was enhanced by ABCC2 knockdown. Furthermore, AE was observed to promote ABCC2 degradation through induction of autophagy and hepatotoxicity was induced in mice by promoting ABCC2 degradation. CONCLUSIONS: The inhibition of ABCC2 is a novel effect of AE that triggers oxidative stress and apoptosis. These findings are helpful in understanding the toxicological effects of AE-containing medicinal plants.

Three new diterpenes from Dysoxylum lukii and their NO production inhibitory activity.

Three new diterpenes were isolated from the stems of Dysoxylum lukii Merr and characterized on the basis of spectral data. Neoclerod-13Z-ene-3α, 4ß, 15-triol (3) exhibited the inhibition of lipopolysaccharide-induced nitric oxide production in RAW264.7 macrophages with an IC50 value of 25.49 µM.[Formula: see text].

Inhibition of TPL2 by interferon-α suppresses bladder cancer through activation of PDE4D.

BACKGROUND: Drugs that inhibit the MEK/ERK pathway have therapeutic benefit in bladder cancer treatment but responses vary with patients, for reasons that are still not very clear. Interferon-α (IFN-α) is also used as a therapeutic agent for bladder cancer treatment but the response rate is low. It was found that IFN-α could enhance the cytotoxic effect of MEK inhibition. However, the potential mechanisms of that are still unclear. Understanding of the cross-talk between the IFN-α and MEK/ERK pathway will help enhance the efficacy of IFN-α or MEK inhibitors on bladder cancer. METHODS: Immunoprecipitation and pull-down assay were used to reveal the formation of signaling complex. The protein expressions were detected by western blot and immunohistochemistry. The cAMP level, Phosphodiesterase 4D (PDE4D) activity and Prostaglandin E2 (PGE2) concentration in cells, serum and tissues were detected by enzyme-linked immunosorbent assay. The role of PDE4D in bladder tumorigenesis in vivo was examined by the xenograft model. Tissue microarray chips were used to investigate the prognostic roles of PDE4D and tumor progression locus 2 (TPL2) in bladder cancer patients. RESULTS: IFN-α down-regulated the cyclooxygenase-2 (COX-2) expression in bladder cancer cells through the inhibition of TPL2/NF-κB pathway; IFN-α also inhibited COX-2 expression by suppressing cAMP signaling through TPL2-ERK mediated PDE4D activity. Reduction of the intracellular cAMP level by PDE4D potentiated the antitumor effect of IFN-α against bladder cancer in vitro and in vivo. Further analysis of clinical samples indicated that low PDE4D expression and high level of TPL2 phosphorylation were correlated to the development and poor prognosis in bladder cancer patients. CONCLUSIONS: Our data reveal that IFN-α can exert its antitumor effect through a non-canonical JAK-STAT pathway in the bladder cancer cells with low activity of IFN pathway, and the TPL2 inhibition is another function of IFN-α in the context of bladder cancer therapy. The antitumor effects of IFN-α and MEK inhibition also depend on the PDE4D-mediated cAMP level in bladder cancer cells. Suppression of the TPL2 phosphorylation and intracellular cAMP level may be possible therapeutic strategies for enhancing the effectiveness of IFN-α and MEK inhibitors in bladder cancer treatment.

[Photosynthetic mechanism of tea yield and quality affected by different habitats]. / ç”Ÿå¢ƒå¯¹èŒ¶å¶å“è´¨å’Œäº§é‡å½±å“çš„å ‰åˆç”Ÿç†æœºåˆ¶.

To understand photosynthetic mechanism of tea yield and quality, an experiment was conducted with four different typical habitats, including three intercropping patterns (S1:Osmanthus-Tea, S2:Michelia-Tea, S3:Osmanthus-Michelia-Tea) and a control (CK) at Changsha Agricutural Observation Station of Chinese Academy of Sciences. The photosynthetic physiological and ecological characteristics of tea yield and quality were examined. The results showed that the habitats S1, S2, S3 reduced the leaf temperature (TL), photosynthesis active radiation flux (PAR), net photosynthetic rate (Pn), transpiration rate (Tr), and stomatal conductance (gs), as well as the tea polyphenol content. Habitats S1, S2, S3 significantly increased leaf relative humidity (RHS), total amino-acid content of tea, and the yield and quality of tea, with a pattern of S3>S1>S2>CK. The leaves in habitats S1 and S3 could be made into high-grade green tea and famous green tea respectively. Comprehensive indicators showed that habitat S3 is an ideal intercropping pattern for high quality and high yield of tea garden.

Bioactive steroidal alkaloids from the fruits of Solanum nigrum.

The investigation of the fruits of Solanum nigrum led to the isolation of four previously undescribed steroidal alkaloids, named solanine A, 7α-OH khasianine, 7α-OH solamargine and 7α-OH solasonine, together with six known ones. The structures of the isolated compounds were elucidated unambiguously by spectroscopic data analyses and chemical methods. Solanine A represents an unusual steroidal alkaloid with an unprecedented 6/5/6/5/5/6 hexacyclic ring system, and its structure was confirmed by X-ray single crystal diffraction analysis. Compounds 2-4 were rare naturally occurring steroidal alkaloid glycosides bearing a hydroxyl group at C-7 position. Solanine A showed the most potent inhibitory activity against the LPS-induced NO production in murine RAW264.7 macrophages with an IC50 value of 3.85 ± 0.71 µM and significant cytotoxicity against MGC803, HepG2 and SW480 cancer cell lines with IC50 values of 6.00 ± 0.52 µM, 9.25 ± 0.49 µM and 6.23 ± 0.26 µM, respectively.

Flavonoid glycosides and alkaloids from the embryos of Nelumbo nucifera seeds and their antioxidant activity.

Chemical investigation of the embryos of Nelumbo nucifera afforded four new flavone C-glycosides, named nelumbosides A-D (1-4), together with nine known ones, comprising five flavonoids (5-9) and four alkaloids (10-13). The chemical structures of the new compounds were elucidated by 1D, 2D-NMR and HR-ESI-MS techniques, together with chemical methods. Nelumbosides A-D (1-4) are rarely present in naturally occurring flavone C-glycosides featuring a 4-hydroxystyrene unit connected to the flavonoid skeleton. Compounds 2-13 were evaluated for their antioxidant activity by ABTS and DPPH radical-scavenging assay. Among them, compounds 2, 6, 7 and 11 exhibited strong scavenging activity with SC50 values ranging from 12.07 to 25.68µM compared with the positive control l-ascorbic acid.

6-Hydroxy-3-O-methyl-kaempferol 6-O-glucopyranoside potentiates the anti-proliferative effect of interferon α/ß by promoting activation of the JAK/STAT signaling by inhibiting SOCS3 in hepatocellular carcinoma cells.

Suppressor of cytokine signaling 3 (SOCS3) is a key negative regulator of type I interferon (IFN α/ß) signaling. Inhibition of SOCS3 by small molecules may be a new strategy to enhance the efficacy of type I IFN and reduce its side effects. We established a cell-based screening assay using human hepatoma HepG2 cells stably transfected with a plasmid wherein the luciferase reporter activity was propelled by interferon α-stimulated response element (ISRE), which is a motif specifically recognized by type I IFN-induced activation of Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway. After screening our chemical library, 6-hydroxy-3-O-methyl-kaempferol 6-O-glucopyranoside (K6G) was identified to be a potent activator of type I IFN with EC50 value of 3.33±0.04µM. K6G enhanced the phosphorylation of JAK1, Tyk2, and STAT1/2 but decreased the phosphorylation of STAT3. K6G also promoted endogenous IFN-α-regulated genes expression. More interestingly, K6G significantly decreased the expression of SOCS3 without affecting the expression of SOCS1. Furthermore, K6G enhanced the anti-proliferative effect of IFN-α on hepatocellular carcinoma (HCC) cells. These results suggested that K6G potentiated the inhibitory effect of IFN-α on HCC cell proliferation through activation of the JAK/STAT signaling pathway by inhibiting SOCS3 expression. K6G warrants further investigation as a novel therapeutic method to enhance the efficacy of IFN-α/ß.

Dietary quercetin potentiates the antiproliferative effect of interferon-α in hepatocellular carcinoma cells through activation of JAK/STAT pathway signaling by inhibition of SHP2 phosphatase.

Type I interferons (IFN-α/ß) have broad and potent immunoregulatory and antiproliferative activities, which are negatively regulated by Src homology domain 2 containing tyrosine phosphatase-2 (SHP-2). Inhibition of SHP2 by small molecules may be a new strategy to enhance the effcacy of type I IFNs. Using an in vitro screening assay for new inhibitors of SHP2 phosphatase, we found that quercetin was a potent inhibitor of SHP2. Computational modeling showed that quercetin exhibited an orientation favorable to nucleophilic attack in the phosphatase domain of SHP2. Quercetin enhanced the phosphorylation of signal transducer and activator of transcription proteins 1 (STAT1) and promoted endogenous IFN-α-regulated gene expression. Furthermore, quercetin also sensitized the antiproliferative effect of IFN-α on hepatocellular carcinoma HepG2 and Huh7 cells. The overexpression of SHP2 attenuated the effect of quercetin on IFN-α-stimulated STAT1 phosphorylation and antiproliferative effect, whereas the inhibition of SHP2 promoted the effect of quercetin on IFN-α-induced STAT1 phosphorylation and antiproliferative effect. The results suggested that quercetin potentiated the inhibitory effect of IFN-α on cancer cell proliferation through activation of JAK/STAT pathway signaling by inhibiting SHP2. Quercetin warrants further investigation as a novel therapeutic method to enhance the efficacy of IFN-α/ß.

Nitric oxide production inhibition and mechanism of phenanthrene analogs in lipopolysaccharide-stimulated RAW264.7 macrophages.

Natural phenanthrene derivatives are considered to be important resource for the anti-inflammatory therapeutics, but their structure-activity relationship and mechanisms are still unknown. In this study we evaluated 20 synthesized phenanthrene analogs in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. Compounds 10, 11 and 17 were found to inhibit the production of nitric oxide (NO) with IC50 values of 37.26µM, 5.05µM and 20.31µM, respectively. Compound 11 decreased LPS-induced expression of inducible NO synthase (iNOS), inhibited phosphorylation of p38 mitogen-activated protein kinase (MAPK) and serine/threonine kinase Akt. It also suppressed the phosphorylation and degradation of inhibitory kappa B-α (IκBα). Data obtained suggest that compound 11 exerts anti-inflammatory effects by inhibiting p38 MAPK and nuclear factor κB (NF-κB) pathways, which warrants further investigation as a new anti-inflammatory pharmaceutical tool.