Highly Modified Sesquiterpene Lactones with Cytotoxic Activities from Strobocalyx chunii.

Three new germacranolide sesquiterpene lactones (SLs), strochunolides A-C (1-3, respectively), and a new guaianolide SL, strochunolide D (4), were isolated from Strobocalyx chunii and structurally characterized. Compound 1 is the first example of a dihomo-germacranolide SL, characterized by an unprecedented 6/10/5 tricyclic scaffold incorporating an additional fused δ-lactone C-ring. The structure of a known germacranolide SL, spicatolide C (5), was revised as its 8-epimer. Compound 3 exhibited potent in vitro cytotoxic activity against the HL-60 cell line, with an IC50 value of 0.18 ± 0.01 µM.

Dichapetalins from the Twigs of Dichapetalum longipetalum with Cytotoxic Activities.

Continued efforts to expand the structural diversity of dichapetalins and explore further the cytotoxic structure-activity relationships have led to the isolation of 17 undescribed analogues, dichapelonins A-Q (1-17), and three known compounds (18-20) from the twigs of Dichapetalum longipetalum. Compounds 1-17 comprise five compound classes as classified by varied C6-C2 conjugates at the A ring of the 13,30-cyclodammarane skeleton, and their structures were determined by spectroscopic data analysis, experimental electronic circular dichroism measurements, and X-ray crystallography. Biological tests revealed compounds 1-7 with a phenyl-butadiene appendage to be the most potent cytotoxic compound type of those evaluated.

[Effect of Curcumin on the Proliferation, Apoptosis, and Cell Cycle of Human Acute Myeloid Leukemia Cell Line K562].

OBJECTIVE: To investigate the effects of curcumin on the proliferation, apoptosis, and cell cycle of human acute myeloid leukemia cell line K562. METHODS: MTT method was used to detect the proliferation inhibition of logarithmic growth phase human acute myeloid leukemia K562 cells, flow cytometry was used to detect the cell cycle, Annexin V-FITC was used to detect the apoptosis rate, and real-time fluorescent quantitative PCR and Western blot were used to detect the expression of Bax, BCL-2 and caspase-3 mRNA and protein, respectively. RESULTS: The inhibition rate of cell proliferation in curcumin 10, 20, and 40 µmol/L group for 24 h and 48 h were higher than that in the control group (curcumin 0 µmol/L), and the cell proliferation inhibition rate was concentration-time dependent (r=0.879, r=0.914). The proportion of G0/G1 cells and apoptosis rate of K562 cells in the curcumin 10, 20, and 40 µmol/L group were higher than those in the control group, and showed drug concentration dependent (r=0.856, r=0.782). The expression of Bax and Caspase-3 mRNA in the curcumin 10, 20, and 40 µmol/L group was higher, while BCL-2 mRNA was lower than those in the control group, and showed drug concentration dependent (r=0.861, r=0.748, r=-0.817). The gray value of Bax protein expression in the curcumin 10, 20, and 40 µmol/L group was higher than that in the control group, while the gray value of BCL-2 and Caspase-3 protein expression was lower than that in the control group, and showed drug concentration dependent (r=0.764, r=-0.723, r=-0.831). CONCLUSION: Curcumin can inhibit the proliferation of human acute myeloid leukemia cell line K562 cells, block the cell cycle at G0/G1 phase, promote cell apoptosis, and induce apoptosis by regulating Bax, BCL-2, and Caspase-3.

Phorneroids A-M, diverse types of diterpenoids from Euphorbia neriifolia.

A chemical investigation on the aerial parts of Euphorbia neriifolia led to the identification of thirteen undescribed diterpenoids, phorneroids A-M, including ent-abietane (A-D), ent-kaurane (E-G), ent-atisane (H-K), and ent-isopimarane (L and M) types, together with three known compounds. Phorneroid A represents the first example of 8-spiro-fused 9,10-seco-ent-abietane diterpenoid lactone featuring a unique 6/5/6/5 spirocyclic framework. Biological assays showed that some of the compounds displayed moderate cytotoxicity against two human tumor cell lines, A549 and HL-60.

Dolabellane Diterpenoids from the Xisha Soft Coral Clavularia viridis.

Twelve new members (1-12) of the dolabellane family, co-occurring with three related known diterpenoids (13-15), were isolated from the Xisha soft coral Clavularia viridis. Their structures were determined by extensive spectroscopic analysis, modified Mosher's method, and X-ray diffraction analysis. Clavuperoxylides A (3) and B (4) represent the first examples of dolabellanes containing peroxyl groups, especially the novel peroxide bridge in 4, whereas clavufuranolides A-C (9-11) are the first example of dolabellane diterpenoids comprising a tetrahydrofuran ring. The possible biogenetic relationship of all the isolates was proposed. In bioassay, several compounds exhibited considerable cytotoxicity against A549 and P388 cell lines. Compound 7 exhibited inhibitory activity against protein tyrosine phosphatases 1B (PTP1B), an anti-diabetic target, representing the first report of PTP1B inhibitory activity for dolabellane diterpenoids.

Sublyratins A-O, Labdane-Type Diterpenoids from Croton sublyratus.

Fifteen new labdane-type diterpenoids, sublyratins A-O (1-15), along with four known analogues (16-19) were isolated from the aerial parts of Croton sublyratus. Their structural assignments were challenging due to the stereoisomeric features evident and were achieved by analyzing comprehensively the spectroscopic data and electronic circular dichroism spectra and using X-ray crystallographic analysis. Compounds 9 and 16-18 displayed cytotoxic activity against the HL-60 cell line with IC50 values of 1.5-2.8 µM.

Discovery of four modified classes of triterpenoids delineated a metabolic cascade: compound characterization and biomimetic synthesis.

Chemical studies on Dichapetalum gelonioides have afforded 18 highly modified complex triterpenoids belonging to four compound classes as defined by the newly adapted functional motifs associated with the A ring of the molecules. Their structures were determined by solid data acquired by diverse methods. The biosynthetic pathway for the four compound classes was rationalized via cascade modifications involving diverse chemical events. The subsequent biomimetic syntheses afforded all the desired products, including compounds 16 and 19 that were not obtained in our purification, which validated the proposed biosynthetic pathway. Besides, some compounds exhibited strong cytotoxic activities, especially 2 and 4 showed nanomolar potency against the NAMALWA tumor cell line, and a gross structure-activity relationship (SAR) of these compounds against the tested tumor cell lines was delineated.

[Correlation of Blimp1 with ATF4/CHOP Signaling Pathway in Multiple Myeloma U266 Cells].

OBJECTIVE: To investigate whether Blimp1 plays an anti-apoptosis role in myeloma by interfering with ATF4/CHOP cell apoptosis pathway induced by endoplasmic reticulum stress, and to explore the anti-myeloma mechanism of aspirin. METHODS: The bone marrow fluid of 40 newly diagnosed multiple myeloma patients without treatment and 30 control people with relatively normal bone marrow was collected. Flow cytometry was used to separated the normal and abnormal plasma cells, LV-Blimp1-RNAi (40051-2) recombinant lentivirus down-regulates the expression of Blimp-1 in U266 cell line and detected the changes of the expression of ATF4 and CHOP gene. U266 cells were stimulated by aspirin at different concentrations (0, 0.5, 2.5, 5.0 mmol/L) in vitro. Then the effect of aspirin on proliferation of U266 cells was measured by CCK-8 assay, the mRNA expression levels of Blimp1, ATF4 and CHOP in four groups were detected by real-time PCR. RESULTS: The expression level of Blimp1 in phenotype abnormal plasma cells was significantly increased as compared with normal cells, while the expression of ATF4 and CHOP in phenotype abnormal plasma cells was significantly decreased as compared with normal cells (P＜0.05). In the case of MOI=100, the transfection efficiency of U266 cells was beyond 80% as detected by fluorescence microscopy. Compared with blank conrol and negatine control groups, Blimp1 mRNA expression level in positive group was significantly reduced while ATF4 and CHOP expression significantly increased. CCK-8 showed that the proliferation activity of U266 cells could be inhibited by aspirin, which showed a time-and dose-dependent manner; at the same time, the expression level of Blimp1 in U266 cells were decreased with the increasing of aspirin concentration, while the expression level of ATF4 and CHOP was increased with the increasing of aspirin concentration. CONCLUSIONS: Blimp1 may display the anti-apoptosis of myeloma cells through interfering with ATF4/CHOP signaling pathway; low dose of aspirin may play anti-myeloma effect by inhibiting the expression of Blimp1 in myeloma cells.

lncRNA PCAT18 inhibits proliferation, migration and invasion of gastric cancer cells through miR-135b suppression to promote CLDN11 expression.

BACKGROUND: Gastric cancer is a severe disease with a high occurrence rate worldwide. And lncRNAs are demonstrated to be responsible for cancer growth and metastasis. So, it is of great importance to explore the lncRNAs involved mechanism of gastric cancer occurrence and development deeply. METHODS: Transfection was conducted to build over-expression and down-expression models. Moreover, RT-qPCR and western blot were used to detect the transcriptional and translational levels. The biological functions such as proliferation, migration and invasion of AGS cells were evaluated by MTT analysis, colony formation assay, scarification detection and transwell assay, respectively. The potential binding of miR-135b and its downstream and upstream molecules was validated by dual luciferase reporter gene assay or RIP. Also, the in-vivo mice model was further used to demonstrate the role of lncRNA PCAT18 in gastric cancer. RESULTS: PCAT18 down-expression promoted proliferation, migration and invasion of gastric cancer cells. Furtherly, over-expression of miR-135b also promoted these biological characteristics of AGS cells. Importantly, we found that PCAT18 could bind miR-135b which also was bound with CLDN11. We found that miR-135b is negatively correlated with CLDN11; PCAT18 and CLDN11 are positively correlated. Moreover, miR-135b mimics could down-regulate protein level of CLDN11, whereas CLDN11 could reverse this effect. In in-vivo experiment, PCAT18 over-expression restrained tumor growth and metastasis. CONCLUSIONS: Over-expressed lncRNA PCAT18 inhibits proliferation, migration and invasion of gastric cancer cells through regulation of miR-135b/CLDN11.

Author Correction: Targeting Hsp90 with FS-108 circumvents gefitinib resistance in EGFR mutant non-small cell lung cancer cells.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

[Expression of Blimp1、ATF4 and CHOP in Multiple Myeloma Cells and Effect of Aspirin on Their Expression].

OBJECTIVE: To explore the expression of Blimp1, ATF4 and CHOP in bone marrow mononuclear cells from patients with multiple myeloma as well as the effect of aspirin on their expression. METHODS: Sixty untreated patients with multiple myeloma and 30 patients with relatively normal bone marrow were selected. Mononuclear cells from the bone marrow fluid were separated using Ficoll separation solution. CD138+ plasma cells were sorted by immunomagnetic beads method. RT-PCR was used to detect the expression levels of Blimp1, ATF4 and CHOP mRNA in U266 cells cultured in vitro. The cells were divided into blank control group, negative control group (no-loaded virus transfection) and positive experimental group [LV-Blimp1-RNAi (40051-2) transfection] by lentivirus transfection. RT-PCR was used to detect the expression of Blimp1, ATF4 and CHOP mRNA in cells of different groups. U266 cells were stimulated in vitro with different concentrations of aspirin solution (0, 0.5 mmol/L, 2.5 mmol/L, 5.0 mmol/L) for 24, 48 h and 72 h, respectively. The ability of cell proliferation in different groups was measured by CCK-8. U266 cells were stimulated with different concentrations of aspirin for 48 hours. And the mRNA expression of Blimp1, ATF4 and CHOP was detected by RT-PCR. RESULTS: Compared with plasma cells in normal group, the expression of Blimp1 mRNA in CD138+ plasma cells of MM patients significantly increased (8.040±1.878), and the mRNA expression levels of ATF4 and CHOP significantly decreased (0.735±0.089; 0.837±0.062) (P＜0.05). U266 cells were cultured in vitro. Compared with the blank control group and the negative control group, the mRNA expression level of Blimp in the positive experimental group was significantly down-regulated after infection with LV-Blimp1-RNAi (40051-2) lentiviral expression vector (0.637±0.021). ATF4 and CHOP mRNA expression levels were significantly increased (1.452 ± 0.027; 1.721 ± 0.038) (P＜0.05). The proliferation of U266 cells decreased after stimulation with aspirin. In the range of (0.5-5) mmol/L, aspirin could significantly inhibit the proliferation of U266 cells. The inhibition effect of aspirin was increased along with prolongation of time and increase of concentrations. After aspirin stimulation of different concentrations for 48 hours, the expression level of Blimp1 in U266 cells decreased with increasing of drug concentration, while the expression levels of ATF4 and CHOP increased with increasing of drug concentration. CONCLUSION: Inhibition of Blimp1 expression in multiple myeloma cells can promote the expression of ATF4 and CHOP. Aspirin can inhibit the proliferation activity of myeloma cells by down-regulating Blimp1 expression in myeloma cells and up-regulating ATF4 and CHOP expression, therefore plays an anti-tumor rote.

Crokonoids A-C, A Highly Rearranged and Dual-Bridged Spiro Diterpenoid and Two Other Diterpenoids from Croton kongensis.

Crokonoid A (1), a highly rearranged diterpenoid featuring a dual-bridged tricyclo[4.4.1.11,4]dodecane-2,11-dione ring system and its two possible ent-kaurene diterpenoid precursors (2 and 3), was isolated and structurally characterized by solid data from Croton kongensis. Compound 1 exhibited significant cytotoxicity against HL-60 and A-549 cell lines with IC50 values of 1.24 ± 0.56 and 1.92 ± 0.60 µM, respectively.

Tetramerized Sesquiterpenoid Ainsliatetramers A and B from Ainsliaea fragrans and Their Cytotoxic Activities.

Two guaianolide sesquiterpenoid tetramers named ainsliatetramers A and B were separated from Ainsliaea fragrans. Through spectroscopic analyses, especially the band-selective CT-HSQC and CT-HMBC techniques, the complex skeleton was constructed from four sesquiterpene units via three different linkages. A biosynthetic pathway was proposed featuring a Michael addition and a regular and a hetero-Diels-Alder cycloaddition. Both exhibited potent cytotoxicity against human cancer cell lines with IC50 values ranging from 2 to 15 µM.

Matrine protects oligodendrocytes by inhibiting their apoptosis and enhancing mitochondrial autophagy.

Stressed oligodendrocytes (OLGs) activate microglia to produce an inflammatory response, and the impairment of mitochondria further aggravates OLG damage, which is the earliest pathological change in multiple sclerosis (MS), an inflammatory demyelinating disease of the central nervous system. Matrine (MAT), a tetracyclic quinolizine alkaloid derived from the herb radix sophorae flavescentis, has been shown to effectively ameliorate clinical signs of experimental autoimmune encephalomyelitis (EAE), an animal model of MS. However, the mechanisms underlying the effect of MAT treatment need to be further studied. In the present study, we show that MAT effectively suppressed ongoing EAE, and significantly reduced the expression of caspase-3 and alpha B-crystallin in OLGs, therefore lessen OLG apoptosis, microglial activation and inflammatory factors secretion. MAT treatment also reduced the content of cytochrome c and malondialdehyde, an oxidative stress marker, in the central nervous system. In contrast, the levels of autophagy-related proteins Beclin1, microtubule-associated protein l light chain 3 and glutathione peroxidase was upregulated, hence enhancing mitochondrial autophagy and alleviating the imbalance of the oxidation/antioxidation system caused by mitochondrial damage. Our research indicates that MAT is effective in treating EAE, at least in part, by protecting OLGs through inhibiting their apoptosis and enhancing mitochondrial autophagy.

17- nor-Cephalotane-Type Diterpenoids from Cephalotaxus fortunei.

Seventeen new 17- nor-cephalotane-type diterpenoids, fortalpinoids A-Q (1-17), were isolated from the seeds of Cephalotaxus fortunei var. alpine. Compound 12 represents the first 17- nor-cephalotane-type diterpenoid featuring an 8-oxabicyclo[3.2.1]oct-2-ene moiety. The absolute configuration of fortunolide A (18) was determined for the first time, and the structure of cephinoid Q was revised to 14- epi-cephafortoid A (24) by X-ray crystallographic data analysis. Some of the compounds showed significant cytotoxicity against A549 and HL-60 cells, and the structure-activity relationship of this compound class is discussed.

Cytotoxic Tigliane Diterpenoids from Croton damayeshu.

Chemical investigation of an EtOH extract of the twigs and leaves of Croton damayeshu afforded 10 new tigliane diterpenoids, crodamoids A-J (1-10), along with five known compounds. Their structures were elucidated by physical data analysis. Compounds 8, 9, and 15 displayed cytotoxic effects against two human tumor cell lines, A549 and HL-60 (IC50: 0.9-2.4 µM).

Ainsliatriolides A and B, Two Guaianolide Trimers from Ainsliaea fragrans and Their Cytotoxic Activities.

Ainsliatriolides A (1) and B (2), two guaianolide sesquiterpenoid trimers possessing an unprecedented skeleton, were isolated from Ainsliaea fragrans. Their structures were elucidated through extensive analysis of spectroscopic data and confirmed by single-crystal X-ray diffraction experiment. Ainsliatriolides A and B are first examples of compound trimerized from guaianolide sesquiterpenoids through two different C-C linkages (type A, 4-2'/15-14'; type B, 15'-15″). Ainsliatriolide A displayed potent cytotoxicity with an averaged IC50 value of 1.17 µM against four cancer cells.

Cephanolides A-J, Cephalotane-Type Diterpenoids from Cephalotaxus sinensis.

Ten new cephalotane-type diterpenoids, cephanolides A-J (1-10), and two known analogues were isolated and characterized from Cephalotaxus sinensis. Compounds 1-3 represent the first examples of A-ring-contracted cephalotane-type dinorditerpenoids, and compound 4 is an A-ring-contracted norditerpenoid. The biosynthetic pathways for compounds 1-4 are postulated with the coexisting cephalotane-type troponoids as the precursors. Compounds 11 and 12 showed significant cytotoxicities against a panel of tumor cell lines (A549, KB, HL-60, and HT-29) with IC50 values ranging from 0.464 to 6.093 µM.

Phainanolide A, Highly Modified and Oxygenated Triterpenoid from Phyllanthus hainanensis.

Phainanolide A (1), a highly modified triterpenoid incorporating an unprecedented 6/9/6 heterotricyclic system and a highly oxygenated 5,5-spirocyclic ketal lactone, along with three new triterpenoids 2-4 were isolated from Phyllanthus hainanensis. Their structures were completely elucidated by a combination of diverse methods including 2D NMR, quantum chemical NMR and ECD calculations, and NMR data analogy with model compounds. Compounds 1-4 exhibited both remarkable cytotoxic and immunosuppressive activities.

Placental growth factor silencing ameliorates liver fibrosis and angiogenesis and inhibits activation of hepatic stellate cells in a murine model of chronic liver disease.

Placental growth factor (PlGF) is a member of the vascular endothelial growth factor (VEGF) family and is involved in pathological angiogenesis associated with chronic liver diseases. However, the precise mechanisms underlying PlGF signalling contributing to liver fibrosis and angiogenesis remain largely unexplored. This study aimed to assess the effect of reducing PlGF expression using small interfering RNA (siRNA) on experimental liver fibrosis and angiogenesis, and to elucidate the underlying molecular mechanisms. Fibrosis was induced in mice by carbon tetrachloride (CCl4 ) for 8 weeks, and mice were treated with PlGF siRNA or non-targeting control siRNA starting two weeks after initiating CCl4 injections. The results showed that PlGF was highly expressed in cirrhotic human and mice livers; which mainly distributed in activated hepatic stellate cells (HSCs). PlGF silencing robustly reduced liver inflammation, fibrosis, intrahepatic macrophage recruitment, and inhibited the activation of HSCs in vivo. Moreover, PlGF siRNA-treated fibrotic mice showed diminished hepatic microvessel density and angiogenic factors, such as hypoxia-inducible factor-1α (HIF-1α), VEGF and VEGF receptor-1. Moreover, down-regulation of PlGF with siRNA in HSCs inhibited the activation and proliferation of HSCs. Mechanistically, overexpression of PlGF in activated HSCs was induced by hypoxia dependent on HIF-1α, and PlGF induces HSC activation and proliferation via activation the phosphatidylinositol 3-kinase (PI3K)/Akt signalling pathways. These findings indicate that PlGF plays an important role in liver fibrosis-associated angiogenesis and that blockage of PlGF could be an effective strategy for chronic liver disease.