Rosellichalasins A-H, cytotoxic cytochalasans from the endophytic fungus Rosellinia sp. Glinf021

Eight new cytochalasans rosellichalasins A-H (1-8), as well as two new shunt metabolites rosellinins A (9) and B (10) before intramolecular Diels-Alder cycloaddition reaction in cytochalasan biosynthesis, along with nine known cytochalsans (11-19) were isolated from the endophytic fungus Rosellinia sp. Glinf021, which was derived from the medicinal plant Glycyrrhiza inflata. Their structures were characterized by extensive analysis of 1D and 2D NMR as well as HRESIMS spectra and quantum chemical ECD calculations. The cytotoxic activities of these compounds were evaluated against four human cancer cell lines including HCT116, MDA-MB-231, BGC823, and PANC-1 with IC50 values ranging from 0.5 to 58.2 μM.

Diphenyl ethers from endophytic fungus Rhexocercosporidium sp. Dzf14 and their antibacterial activity by affecting homeostasis of cell membranes

BACKGROUND

Phytopathogenic bacteria cause severe losses to crops every year. The management of crop bacterial diseases with chemical agents has been considered as the main strategy. In order to cope with the bactericide resistance made by the pathogens, new antibacterials need to be continuously developed.

RESULTS

A chemical investigation from the endophytic fungus Rhexocercosporidium sp. Dzf14 has led to the isolation of 12 diphenyl ethers including two new ones named rhexocerin E (1) and rhexocercosporin G (2), along with two new depsides named rhexocerdepsides A (3) and B (4). The structures and absolute configurations of the new compounds were determined through comprehensive analysis of spectroscopic data and quantum chemical ECD calculations. Diphenyl ethers showed obviously antibacterial activity on Gram-positive bacteria. The structure-activity relationship of diphenyl ethers revealed that prenylation was critical to the antibacterial activity. Among them, rhexocercosporin D (12) possessed the strongest activity against Clavibacter michiganensis and Bacillus subtilis, and was selected for further mechanistic studies. It was found that rhexocercosporin D displayed bactericidal activity by affecting homeostasis of cell membranes. In addition to its rapid bactericidal effects on Gram-positive bacteria, rhexocercosporin D could restore the susceptibility against Gram-negative Agrobacterium tumefaciens by synergistic action with colistin.

CONCLUSION

Twelve diphenyl ethers and two depsides were isolated from endophytic fungus Rhexocercosporidium sp. Dzf14. Isopentenyl was critical for diphenyl ethers against Gram-positive bacteria. Rhexocercosporin D could affect homeostasis of bacterial cell membrane to exert rapid bactericidal activity. These findings highlight the antibacterial potential of the diphenyl ethers in crop bacterial disease management. © 2024 Society of Chemical Industry.

Activation of Ustilaginoidin Biosynthesis Gene uvpks1 in Villosiclava virens Albino Strain LN02 Influences Development, Stress Responses, and Inhibition of Rice Seed Germination

Villosiclava virens (anamorph: Ustilaginoidea virens) is the pathogen of rice false smut (RFS), which is a destructive rice fungal disease. The albino strain LN02 is a natural white-phenotype mutant of V. virens due to its incapability to produce toxic ustilaginoidins. In this study, three strains including the normal strain P1, albino strain LN02, and complemented strain uvpks1C-1 of the LN02 strain were employed to investigate the activation of the ustilaginoidin biosynthesis gene uvpks1 in the albino strain LN02 to influence sporulation, conidia germination, pigment production, stress responses, and the inhibition of rice seed germination. The activation of the ustilaginoidin biosynthesis gene uvpks1 increased fungal tolerances to NaCl-induced osmotic stress, Congo-red-induced cell wall stress, SDS-induced cell membrane stress, and H2O2-induced oxidative stress. The activation of uvpks1 also increased sporulation, conidia germination, pigment production, and the inhibition of rice seed germination. In addition, the activation of uvpks1 was able to increase the mycelial growth of the V. virens albino strain LN02 at 23 °C and a pH from 5.5 to 7.5. The findings help in understanding the effects of the activation of uvpks1 in albino strain LN02 on development, pigment production, stress responses, and the inhibition of rice seed germination by controlling ustilaginoidin biosynthesis.

Rosellosides A and B, two phenyloxazole glycosides from Glycyrrhiza inflata-derived fungus Rosellinia sp. Glinf021

Two new chlorinated phenyloxazole glycosides, named rosellosides A (1) and B (2), were isolated from the endophytic fungus Rosellinia sp. Glinf021, which was derived from the medicinal plant Glycyrrhiza inflata (Leguminosae). Both compounds were rare chlorinated polyketide glycosides bearing an oxazole moiety. Their structures were elucidated by analysis of the NMR and HRESIMS data, and their absolute configurations were determined by quantum chemical ECD calculations and X-ray crystallography.

A Genome-Wide Comparison of Rice False Smut Fungus Villosiclava virens Albino Strain LN02 Reveals the Genetic Diversity of Secondary Metabolites and the Cause of Albinism

Rice false smut (RFS) caused by Villosiclava virens (anamorph: Ustilaginoidea virens) has become one of the most destructive fungal diseases to decrease the yield and quality of rice grains. An albino strain LN02 was isolated from the white RFS balls collected in the Liaoning Province of China in 2019. The strain LN02 was considered as a natural albino mutant of V. virens by analyzing its phenotypes, internal transcribed spacer (ITS) conserved sequence, and biosynthesis gene clusters (BGCs) for secondary metabolites. The total assembled genome of strain LN02 was 38.81 Mb, which was comprised of seven nuclear chromosomes and one mitochondrial genome with an N50 value of 6,326,845 bp and 9339 protein-encoding genes. In addition, the genome of strain LN02 encoded 19 gene clusters for biosynthesis of secondary metabolites mainly including polyketides, terpenoids and non-ribosomal peptides (NRPs). Four sorbicillinoid metabolites were isolated from the cultures of strain LN02. It was found that the polyketide synthase (PKS)-encoding gene uspks1 for ustilaginoidin biosynthesis in strain LN02 was inactivated due to the deletion of four bases in the promoter sequence of uvpks1. The normal uvpks1 complementary mutant of strain LN02 could restore the ability to synthesize ustilaginoidins. It demonstrated that deficiency of ustilaginoidin biosynthesis is the cause of albinism for RFS albino strain LN02, and V. virens should be a non-melanin-producing fungus. This study further confirmed strain LN02 as a white phenotype mutant of V. virens. The albino strain LN02 will have a great potential in the development and application of secondary metabolites. The physiological and ecological functions of ustilaginoidins in RFS fungus are needed for further investigation.

Diphenyl Ether Derivative Rhexocerins and Rhexocercosporins from the Endophytic Fungus Rhexocercosporidium sp. Dzf14 Active against Gram-Positive Bacteria with Multidrug-Resistance

Ten new diphenyl ether polyketides, including rhexocerins A-D (1-4) and rhexocercosporins A-F (5-10), together with three known congeners (11-13), were isolated from the endophytic fungus Rhexocercosporidium sp. Dzf14 obtained from Dioscorea zingiberensis. Their structures were elucidated by analysis of NMR and HRESIMS data, and their absolute configurations were determined by quantum chemical ECD calculations and X-ray crystallography. Compounds 1-4 featured an unprecedented tetracyclic carbon skeleton (6/7/5/6). Among them, compounds 1 and 5-9 showed antibacterial activities against methicillin-resistant S. aureus T144 and vancomycin-resistant E. faecalis 10.

Removal of tetracycline from water by catalytic photodegradation combined with the microalga Scenedesmus obliquus and the responses of algal photosynthesis and transcription

The antibiotic tetracycline (TC) and its degradation products (TDPs) in degradation solution present serious environmental problems, such as human health damage and ecological risk; thus further treatment is required before being released into the aquatic environment. Furthermore, their environmental impact on microalgae remains unclear. In this study, TC was degraded by photocatalysis using birnessite and UV irradiation, followed by biological purification using the microalga Scenedesmus obliquus. In addition, the photosynthetic activity and transcription of the microalgae were examined to evaluate the toxicity of TC and TDPs. The results show that photocatalytic degradation efficiency reached 92.7% after 30 min, and 11 intermediate products were detected. The microalgae achieved a high TC removal efficiency (99.7%) after 8 days. Exposure to the degraded TC solution (D) resulted in significantly lower (p < 0.05) biomass than the pure TC (T), and S. obliquus in the T treatment showed better resilience than the D treatment. Transcriptomic assays for different treatments revealed differential gene expression mainly involving the photosynthesis, ribosome, translation and peptide metabolic progresses. The up-regulation of photosynthesis-related genes and differential expression of chloroplast genes may be important for S. obliquus to acquire high photosynthetic efficiency and growth recovery when exposed to TC and TDPs. Our study provides a reference for TC removal using a combination of catalytic degradation and microalgal purification, and it is also helpful for understanding the environmental risk of TDPs in natural aquatic environments.

Metabolomics revealed the photosynthetic performance and metabolomic characteristics of Euglena gracilis under autotrophic and mixotrophic conditions

Photosynthetic and metabolomic performance of Euglena gracilis was examined and compared under autotrophic and mixotrophic conditions. Autotrophic protozoa (AP) obtained greater biomass (about 33% higher) than the mixotrophic protozoa (MP) after 12 days of growth. AP maintained steady photosynthesis, while MP showed a remarkable decrease in photosynthetic efficiency and dropped to an extremely low level at day 12. In MP, low light absorption and photosynthetic electron transport efficiency, and high energy dissipation were reflected by the chlorophyll (chl a) fluorescence (OJIP) of the protozoa. The values of Ψ_O, Φ_Eo, and ET_O/RC of MP decreased to extremely low levels, to 1/15, 1/46, and 1/9 those of AP, respectively, while DI_O/RC increased to approximately 16 times that of AP. A total of 137 metabolites were showed significant differences between AP and MP. AP accumulated more monosaccharide, lipids, and alkaloids, while MP produced more amino acids, peptides, and long-chain fatty acids including poly-unsaturated fatty acids. The top nine most important enriched pathways obtained from KEGG mapping were related to ABC transporters, biosynthesis of amino acids, purine metabolism, and carbohydrate metabolism. There were significant differences between AP and MP in photosynthetic activity, metabolites, and metabolic pathways. This work presented useful information for the production of high value bioproducts in E. gracilis cultured under different nutritional conditions.

Effects of polystyrene microplastics on copper toxicity to the protozoan Euglena gracilis: emphasis on different evaluation methods, photosynthesis, and metal accumulation

Microplastics (MPs) released into aquatic environment interact with other pollutants that already exist in water, potentially altering their toxicity, which poses a new problem for aquatic ecosystems. In the present study, we first evaluated the effects of polystyrene MPs (mPS) on copper (Cu) toxicity to the protozoan Euglena gracilis using three methods based on 96-h acute toxicity, orthogonal test and 12-d sub-acute toxicity data. Thereafter, the 12-d sub-acute exposure was employed to investigate protozoan growth, photosynthetic parameters and pigments, soluble protein, total antioxidant capacity and trace metal accumulation in E. gracilis after exposure to either 1.5 mg/L of Cu, 75-nm mPS (1 and 5 mg/L) or a combination therein, with the objective to understand the underlined mechanisms. The results show that the concentration and exposure time are key factors influencing the effects of the mPS on Cu toxicity. A mPS concentration of 5 mg/L caused significantly more dissipation energy, which is used for photosynthesis and thus decreased photosynthetic efficiency, but this effect weakened after 12 d of exposure. Exposure to Cu alone resulted in significantly high Cu accumulation in the cells and inhibited uptake of manganese and zinc. The presence of mPS did not influence the effects of Cu on trace metal accumulation. Our result suggests that application of multiple methods and indices could provide more information for a comprehensive understanding of the effects of mPS on toxicity of other pollutants. In addition, long-term exposure seems necessary for evaluating mPS toxicity.

Elucidation of ustilaginoidin biosynthesis reveals a previously unrecognised class of ene-reductases

Ustilaginoidins are a type of mycotoxin featuring a dimeric naphtho-γ-pyrone skeleton, produced by the rice false smut pathogen Ustilaginoidea virens. Here we used gene disruption, heterologous expression in Aspergillus oryzae, feeding experiments, and in vitro experiments to fully elucidate the biosynthesis of ustilaginoidins. A new route to dimeric 2,3-unsaturated naphtho-γ-pyrones via dimerization of YWA1 (and 3-methyl YWA1) followed by dehydration was discovered. Intriguingly, the reduction of the 2,3-double bond of the pyrenone ring was catalyzed by a phospholipid methyltransferase-like enzyme (UsgR). The reductase was specific for reduction of monomeric, linear naphtho-γ-pyrenones, but not for the dimers. Atroposelective coupling of various monomers by the laccase (UsgL) led to diverse ustilaginoidins. Moreover, 3-epimerism of the 3-methyl-2,3-dihydro-naphtho-γ-pyrones adds additional complexity to the biosynthesis.

The 2,3-double bond reduction of the pyrenone ring in linear naphtho-γ-pyrenones was catalyzed by a phospholipid methyltransferase-like enzyme, namely UsgR, which is a previously unrecognised class of ene-reductases.

[Expression of melanoma-associated antigen-C2 in breast cancers and mechanism]

Objective: To analyze the expression pattern, mechanism and clinical significance of melanoma-associated antigen-C2 (MAGE-C2) in tumor-free breast specimens, breast benign disease specimens and breast cancer specimens. Methods: Reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry were used to investigate the expressions of MAGE-C2 in 60 tumor-free breast specimens, 60 breast benign disease specimens and 60 breast cancer specimens. The correlation of MAGE-C2 expression with clinicopathological parameters and prognosis of breast cancer patients were analyzed. The expression of MAGE-C2 was also detected by RT-PCR in breast cancer cell MCF-7 and MDA-MB-231 treated with DNA methylase inhibitor 5-aza-2'-deoxycytidine (5-aza-CdR) and histone deacetylase inhibitor trichostatin A (TSA). Results: The positive expression rates of MAGE-C2 mRNA and protein were 61.7% (37/60) and 58.3% (35/60) in breast cancer specimens, respectively, while negative expressed in breast and begin disease specimens. MAGE-C2 protein expression was associated with tumor grade, histological type and blood vessel invasion of breast cancer patients (P<0.05). The incidence of recurrence-free survival of patients with positive MAGE-C2 expression were lower than that of patients with negative MAGE-C2 expression (P<0.05). Multivariate Cox regression analysis showed that the clinical stage (P<0.01), lymph node metastasis (P<0.05) and MAGE-C2 expression (P<0.05) were the independent prognostic factors of breast cancer patients. The MAGE-C2 mRNA was not observed in the control and TSA treated breast cancer cells while upregulated in the 5-aza-CdR treated cells. Besides, 5-aza-CdR combined with TSA further enhanced MAGE-C2 mRNA level in breast cancer cells (P<0.05). Conclusions: MAGE-C2 is one of the tumor-specific antigen and its expression is related with the poor prognosis of breast cancer patients. DNA methylation and histone acetylation may be an important regulation mechanism of MAGE-C2 gene expression.

Origin of the quasi-quantized Hall effect in ZrTe5

The quantum Hall effect (QHE) is traditionally considered to be a purely two-dimensional (2D) phenomenon. Recently, however, a three-dimensional (3D) version of the QHE was reported in the Dirac semimetal ZrTe5. It was proposed to arise from a magnetic-field-driven Fermi surface instability, transforming the original 3D electron system into a stack of 2D sheets. Here, we report thermodynamic, spectroscopic, thermoelectric and charge transport measurements on such ZrTe5 samples. The measured properties: magnetization, ultrasound propagation, scanning tunneling spectroscopy, and Raman spectroscopy, show no signatures of a Fermi surface instability, consistent with in-field single crystal X-ray diffraction. Instead, a direct comparison of the experimental data with linear response calculations based on an effective 3D Dirac Hamiltonian suggests that the quasi-quantization of the observed Hall response emerges from the interplay of the intrinsic properties of the ZrTe5 electronic structure and its Dirac-type semi-metallic character.

A light-induced phononic symmetry switch and giant dissipationless topological photocurrent in ZrTe5

Dissipationless currents from topologically protected states are promising for disorder-tolerant electronics and quantum computation. Here, we photogenerate giant anisotropic terahertz nonlinear currents with vanishing scattering, driven by laser-induced coherent phonons of broken inversion symmetry in a centrosymmetric Dirac material ZrTe₅. Our work suggests that this phononic terahertz symmetry switching leads to formation of Weyl points, whose chirality manifests in a transverse, helicity-dependent current, orthogonal to the dynamical inversion symmetry breaking axis, via circular photogalvanic effect. The temperature-dependent topological photocurrent exhibits several distinct features: Berry curvature dominance, particle-hole reversal near conical points and chirality protection that is responsible for an exceptional ballistic transport length of ~10 μm. These results, together with first-principles modelling, indicate two pairs of Weyl points dynamically created by B_1u phonons of broken inversion symmetry. Such phononic terahertz control breaks ground for coherent manipulation of Weyl nodes and robust quantum transport without application of static electric or magnetic fields.

Unconventional Hall response in the quantum limit of HfTe5

Interacting electrons confined to their lowest Landau level in a high magnetic field can form a variety of correlated states, some of which manifest themselves in a Hall effect. Although such states have been predicted to occur in three-dimensional semimetals, a corresponding Hall response has not yet been experimentally observed. Here, we report the observation of an unconventional Hall response in the quantum limit of the bulk semimetal HfTe5, adjacent to the three-dimensional quantum Hall effect of a single electron band at low magnetic fields. The additional plateau-like feature in the Hall conductivity of the lowest Landau level is accompanied by a Shubnikov-de Haas minimum in the longitudinal electrical resistivity and its magnitude relates as 3/5 to the height of the last plateau of the three-dimensional quantum Hall effect. Our findings are consistent with strong electron-electron interactions, stabilizing an unconventional variant of the Hall effect in a three-dimensional material in the quantum limit.

Eremophilane-Type Sesquiterpenoids From the Endophytic Fungus Rhizopycnis vagum and Their Antibacterial, Cytotoxic, and Phytotoxic Activities

Fourteen new eremophilane-type sesquiterpenoids, named rhizoperemophilanes A~N (1~14), together with eight known congeners, were isolated from the culture of the endophytic fungus Rhizopycnis vagum. The structures of the new compounds were elucidated by extensive spectroscopic analyses, as well as ECD calculations and the modified Mosher's method for the assignment of the absolute configurations. Rhizoperemophilane J (10) contains an uncommon C-4/C-11 epoxy ring, while rhizoperemophilane N (14) features an unprecedented 3-nor-eremophilane lactone-lactam skeleton. These metabolites were evaluated for their antibacterial, cytotoxic, and phytotoxic activities. Among them, compounds 11, 16, and 20 displayed antibacterial activities, while 14 showed selective cytotoxicity against NCI-H1650 and BGC823 tumor cells. Moreover, compounds 5, 6, 12, 13, 16, and 19 exhibited strong phytotoxic activities against the radicle elongation of rice seedlings.

Lophiostomin A–D: new 3,4-dihydroisocoumarin derivatives from the endophytic fungus Lophiostoma sp. Sigrf10

Four new 3,4-dihydroisocoumarin congeners, named lophiostomin A–D (1–4), together with two known α-pyridones (5 and 6) were isolated from cultures of the endophytic fungus Lophiostoma sp. Sigrf10 obtained from Siraitia grosvenorii. The structures of the new compounds were determined via combined analysis involving 1D and 2D NMR, high-resolution electrospray ionization mass spectrometry (HRESIMS), and electronic circular dichroism (ECD) spectra, as well as quantum chemical ECD computations for assigning the absolute configurations. All the compounds were evaluated for their antibacterial and antifungal activities. Compounds 1 and 2 displayed moderate inhibitory activities against the spore germination of Magnaporthe oryzae, whereas 5 and 6 were active against the following tested pathogenic bacteria: Bacillus subtilis, Agrobacterium tumefaciens, Ralstonia solanacearum, and Xanthomonas vesicatoria.

Four new 3,4-dihydroisocoumarin congeners, named lophiostomin A–D (1–4), together with two known α-pyridones (5 and 6) were isolated from cultures of the endophytic fungus Lophiostoma sp. Sigrf10 obtained from Siraitia grosvenorii.

Rhizovagine A, an unusual dibenzo-α-pyrone alkaloid from the endophytic fungus Rhizopycnis vagum Nitaf22

Rhizovagine A (1), a novel dibenzo-α-pyrone alkaloid with an unprecedented 5/5/6/6/6 fused pentacyclic skeleton, was isolated from the endophytic fungus Rhizopycnis vagum Nitaf22. The structure was elucidated by comprehensive spectroscopic analysis, in combination with quantum chemical ¹³C NMR and electronic circular dichroism (ECD) calculations for configurational assignment. A plausible biosynthetic pathway for 1 was proposed. Compound 1 displayed acetylcholinesterase inhibitory activity.

Rhizovagine A (1), a dibenzo-α-pyrone alkaloid with a 5/5/6/6/6 fused pentacyclic skeleton and acetylcholinesterase inhibitory activity, was isolated from the endophytic fungus Rhizopycnis vagum Nitaf22.

Hyalodendrins A and B, New Decalin-Type Tetramic Acid Larvicides from the Endophytic Fungus Hyalodendriella sp. Ponipodef12

Two new decalin/tetramic acid hybrid metabolites, hyalodendrins A (1) and B (2) were isolated from plant endophytic fungus Hyalodendriella sp. Ponipodef12. The structures of the new compounds were elucidated by analysis of the spectroscopic data, including NMR, HRMS and ECD, and by chemical conversion. Compounds 1 and 2 were phomasetin analogues, and both showed potent larvicidal activity against the fourth-instar larvae of Aedes aegypti with the median lethal dose (LC₅₀) values of 10.31 and 5.93 μg/mL, respectively.

A unified form of low-energy nodal electronic interactions in hole-doped cuprate superconductors

Using angle resolved photoemission spectroscopy measurements of Bi₂Sr₂CaCu₂O_8+δ over a wide range of doping levels, we present a universal form for the non-Fermi liquid electronic interactions in the nodal direction in the exotic normal state phase. It is described by a continuously varying power law exponent versus energy and temperature (hence named a Power Law Liquid or PLL), which with doping varies smoothly from a quadratic Fermi Liquid in the overdoped regime, to a linear Marginal Fermi Liquid at optimal doping, to a non-quasiparticle non-Fermi Liquid in the underdoped regime. The coupling strength is essentially constant across all regimes and is consistent with Planckian dissipation. Using the extracted PLL parameters we reproduce the experimental optics and resistivity over a wide range of doping and normal-state temperature values, including the T* pseudogap temperature scale observed in the resistivity curves. This breaks the direct link to the pseudogapping of antinodal spectral weight observed at similar temperature scales and gives an alternative direction for searches of the microscopic mechanism.

The normal state of hole-doped, high-temperature superconductors is a currently-unexplained "strange metal" with exotic electronic behaviour. Here, the authors show that a doping-dependent power law ansatz for the electronic scattering phenomenologically captures ARPES, transport and optics observations.

Chromone and isocoumarin derivatives from the endophytic fungus Xylomelasma sp. Samif07, and their antibacterial and antioxidant activities

Five chromone derivatives, including 2,6-dimethyl-5-methoxyl-7-hydroxylchromone (1), 6-hydroxymethyleugenin (2), 6-methoxymethyleugenin (3), chaetoquadrin D (4), and isoeugenitol (5), and three isocoumarin congeners, namely diaporthin (6), 8-hydroxy-6-methoxy-3-methylisocoumarin (7), and 6-methoxymellein (8), were isolated from the culture of the endophytic fungus Xylomelasma sp. Samif07 derived from the medicinal plant Salvia miltiorrhiza Bunge. Among them, compound 1 was a new natural product. Their structures were determined by spectroscopic methods and comparison with the literature. The isolated compounds were evaluated for their antibacterial and antioxidant activities. Compound 5 showed notable antitubercular activity against Mycobacterium tuberculosis with MIC value of 10.31 µg/mL, while compounds 1-3, and 5-7 displayed inhibitory activities against the other bacteria with MIC range of 25 ∼ 100 µg/mL. Meanwhile, compound 6 showed potent hydroxyl radical-scavenging activity with EC₅₀ value of 15.1 µg/mL, while compounds 5-7 showed certain ferric reducing ability.

Sorbicillinoids From the Fungus Ustilaginoidea virens and Their Phytotoxic, Cytotoxic, and Antimicrobial Activities

Ustilaginoidea virens, the causal fungus of rice false smut, was found in previous studies to produce two types of metabolites, ustiloxins and ustilaginoidins. However, genome sequencing of U. virens revealed a plethora of secondary-metabolites-biosynthetic core genes that were capable to biosynthesize unreported metabolites. A large-scale fermentation of U. virens was thus performed, and the fungal extract was chemically re-investigated. After removing the known metabolites, we found a fraction containing unknown phytotoxic substances. Fractionation of this part has led to the isolation of six new sorbicillinoids, namely ustisorbicillinols A~F (1~6), and two new sorbicillinoid-related pyrones, named ustilopyrones A (7) and B (8), together with nine known cogeners (9~17). The structures of the new compounds were elucidated by analysis of their NMR, HRMS, and CD spectra, while ECD, ¹³C NMR and optical rotation calculations were additionally used for configurational assignments. Plausible biosynthetic pathways for the new compounds were proposed. Phytotoxicity assays revealed that the major sorbicillinoids (12~14, and 16) showed strong inhibition against the radicle and germ elongation of rice and lettuce seeds, with compound 12 displaying the strongest inhibition. The isolated compounds were also evaluated for their cytotoxic, antibacterial, and antifungal activities. Compounds 10, and 12~14 showed moderate cytotoxicities against the tested cell lines with IC₅₀s of 8.83~74.7 μM. Compounds 2, and 10~13 were active against the tested bacteria (MICs 4~128 μg/mL), while compounds 11~13 displayed moderate antifungal activities.

New nitrogen-containing metabolites from cultures of rice false smut pathogen Villosiclava virens

Two new nitrogen-containing metabolites methyl N-acetyl-O-(4-acetylphenyl)-L-homoserinate (1), dimethyl (1H-indole-3-carbonyl)-D-glutamate (2), and two new natural products, 1,2-O-isopropylidene-D-mannitol (3), N-acetyl-β-methyl-L-phenylalanine (4), along with five known compounds (5-9) were isolated from the rice false smut pathogen Villosiclava virens UV-8b cultured in the solid rice medium. The structures were elucidated by spectroscopic analysis and by comparison of their physical and spectroscopic data with the literature. These metabolites were evaluated for their antibacterial and phytotoxic activities. Compounds 5-7 showed weak inhibition against the tested bacteria, while compounds 4-6 and 9 displayed inhibitory activity against the radicle elongation of rice seeds.

Abstract PD7-11: Therapeutic strategy for ESR1 mutation driven-endocrine resistance in ER-positive breast cancers

Background: Endocrine therapy is used in estrogen receptor (ER)-positive breast cancers, however, 25% of these patients are at risk of distant relapse and the development of acquired endocrine resistance. Recently mutations in the ER gene (ESR1) have been validated to be acquired during the development of endocrine resistance. The most frequent ESR1 mutation, Y537S, promotes ligand-independent ER activity and emerges subclonally during aromatase inhibitor treatment. In this study, we examined the effects of the Y537S ESR1 mutation on cell cycle signaling and therapeutic response to a novel checkpoint inhibitor.

Material and Methods: MCF-7 cells expressing the Y537S ESR1 mutation were generated by CRISPR-Cas9 knock-in techniques. Cells were incubated in steroid deprived conditions. Cell cycle analysis and apoptosis were examined by flow cytometry annnexin-V assays. Proliferation was analyzed by BrdU incorporation. Cell cycle checkpoint kinases were examined by western blot analysis. Cell growth was analyzed using soft agar and MTT assays. Replication stress was identified by RPA32 and gamma-H2AX foci formation assay. For in vivo studies, MCF-7 ESR1 Y537S mutant cells were injected into female athymic nude mice with 17β-estradiol (E2) supplemented water. When tumors reached 350 mm3, tamoxifen (20 mg/kg; s.c.; three times a week), fulvestrant (200 mg/kg; s.c; once a week) and/or PF477736 Chk1 inhibitor (7.5 mg/kg; i.p.; twice a day and twice a week) was treated without E2.

Results: ESR1 Y537S mutant cells accumulated approximately 5 fold in S phase and 1.7 fold in G2/M phase compared to control cells in estrogen-deprived (ED) conditions. BrdU incorporation also increased about 2.5-fold, however, apoptosis was decreased about 60 % compared with wild-type ER parental cells. ESR1 Y537S mutant cells induced significant replication stress, showing increased RPA32 foci together with increased gamma H2AX foci, a marker of DNA double-stranded breaks. ChIP-seq analysis revealed binding sites on ATR and CHEK1 genomic locations. ATR/Chk1-mediated checkpoint signaling was activated in ESR1 Y537S mutant cells, and was repressed with fulvestrant, tamoxifen, or ESR1 siRNA treatment. The Chk1 inhibitor, PF477736, sensitized MCF-7 expressing the ESR1 Y537S mutation to endocrine treatments such as fulvestrant, tamoxifen, and the ER degrader AZD9496 in cell proliferation assays. In MCF-7 ESR1 Y537S mutant xenograft and patient derived mouse models, tamoxifen treatment combined with the Chk1 inhibitor PF477736 repressed primary xenograft tumor doubling times (P=0.038, Wilcoxon test). Treatment of mutant tumors with PF477736 together with fulvestrant significantly inhibited the frequency of distant lung metastases by 80% (P=0.0031, t-test), suggesting that these combinations may be useful in second line treatment of metastatic breast cancer patients resistant to endocrine therapies.

Conclusion: These preclinical results suggest that ESR1 mutant tumors have a therapeutic vulnerability to combination endocrine therapy with cell cycle checkpoint kinase inhibitors. These data demonstrate that this new therapeutic approach may be useful to restore endocrine sensitivity in metastatic breast cancer patients with ESR1 mutation driven-endocrine resistance.

Citation Format: Kim J-A, Dustin D, Gu G, Corona-Rodriguez A, Edwards D, Coarfa C, Keyomarsi K, Fuqua SA. Therapeutic strategy for ESR1 mutation driven-endocrine resistance in ER-positive breast cancers [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr PD7-11.

Cooper Pair Density of Bi2Sr2CaCu2O8+ x in Atomic scale at 4.2 K

In pursuit of the elusive mechanism of high- T _C superconductors (HTSC), spectroscopic imaging scanning tunneling microscopy (SI-STM) is an indispensable tool for surveying local properties of HTSC. Since a conventional STM utilizes metal tips, which allow the examination of only quasiparticles and not superconducting (SC) pairs, Josephson tunneling using STM has been demonstrated by many authors in the past. An atomically resolved scanning Josephson tunneling microscopy (SJTM), however, was realized only recently on Bi₂Sr₂CaCu₂O_{8+ x} (Bi-2212) below 50 mK and on the Pb(110) surface at 20 mK. Here we report the atomically resolved SJTM on Bi₂Sr₂CaCu₂O_{8+ x} at 4.2 K using Bi-2212 tips created in situ. The I- V characteristics show clear zero bias conductance peaks following Ambegaokar-Baratoff (AB) theory. A gap map was produced for the first time using an atomically resolved Josephson critical current map I _C( r) and AB theory. Surprisingly, we found that this new gap map is anticorrelated to the gap map produced by a conventional method relying on the coherence peaks. Quasiparticle resonance due to a single isolated zinc atom impurity was also observed by SJTM, indicating that atomically resolved SJTM was achieved at 4.2 K. Our result provides a starting point for realizing SJTM at even higher temperatures, rendering possible investigation of the existence of SC pairs in HTSC above the T _C.

Microbiological quality of spinach irrigated with reclaimed wastewater and roof-harvest water

AIMS

The effect of reclaimed wastewater (RCW) and roof-harvest rainwater (RHW) on the microbiological quality of irrigated spinach was investigated.

METHODS AND RESULTS

Spinach grown in the controlled environment chamber was irrigated by RCW, RHW or creek water (CW; control water) for 4 weeks, and then six replicate spinach samples from each treatment were collected weekly at 0 h and 24 h postirrigation. Spinach samples were analysed for populations of faecal bacterial indicators and pathogens. Bacterial populations in alternative irrigation water samples were determined by the membrane filtration technique. The RCW samples contained the highest faecal bacterial indicator populations, followed by the CW and RHW throughout the entire study. Irrigation waters containing higher populations of total and faecal coliforms did not necessarily result in higher populations of these bacteria on the irrigated spinach. Higher numbers of E. coli-positive spinach samples were reported from RCW-irrigated spinach, especially with repeated irrigation. Pathogens were not detected from any water or spinach samples.

CONCLUSIONS

Spinach irrigated with RHW did not significantly affect the populations of faecal indicator bacteria when compared with CW-irrigated spinach. Repeat irrigation with RCW is not recommended due to the increased contamination of E. coli on spinach leaves.

SIGNIFICANCE AND IMPACT OF THE STUDY

RHW may potentially be used as alternative irrigation water without deleteriously affecting the microbiological safety of the spinach.

Abstract P1-02-03: The Y537S ESR1 mutation carries unique metabolomics profiling in breast cancer

Background:

Estrogen receptor (ESR1) mutations occur at a high frequency in metastatic breast tumors in patients treated with hormonal therapy in the metastatic setting. We do not know if these mutations changed metabolomics and whether these metabolomics change could affect metastasis.

Experimental design and methods:

We generated ESR1 Y537S homozygous mutations using CRISPR Casp-9 technology. Globe metabolites screening was performed using 6550 Agilent QTOF instrument. Athymic mice were used in tumor xenograft studies. Affymetrix microarrays were performed to compare gene expression changes in Y537S mutant compared with parental cells. Enriched metabolite pathways and gene expression integrated analysis was analyzed by using online analysis tool http://www.metaboanalyst.ca.

Results:

We generated CRISPR ESR1 Y537S mutation homozygous knock-in clones in MCF-7 cells. In vivo experiments revealed that mutant cells are dominant drivers of metastasis. Transcriptome profiling revealed elevated expression of Hallmark pathways, including EMT and estrogen-regulated gene expression. We performed globe metabolites screening using MCF-7 Y537S and MCF-7 parental and identified 134 metabolites. Serum starvation media was used and estrogen was used as control for both cell lines. As we expected estrogen treatment induced metabolites changes in parental cells. However, metabolites in mutant cells were not changed significantly under estrogen treatment. Interestingly, metabolites in the mutant cells at baseline were remarkably upregulated (78 out of 134 identified total metabolites) indicating mutant cells in serum starvation condition had significantly different metabolomics compared with parental cells. Top upregulated pathways include protein biosynthesis, betaine metabolism and ammonia recycling. Integration of microarray gene expression and metabolites reviewed several metabolomics pathways significantly changed in mutant compared with parental cells including for example aminoacyl-tRNA biosynthesis, arginine and proline metabolism and alanine, aspartate and glutamate metabolism.

Conclusion: The Y537S ER mutation is a driver of distant metastasis in ER-positive breast cancer cells. Y537S ER mutant had globe changes of metabolites expression which was confirmed by integrated analysis combining microarray gene expression. The roles of these metabolites need to be studied to correlate with metastasis. Enzymes responsible for converting these metabolites changes could be served as potential therapeutic targets.

Citation Format: Gu G, Piyarathna B, Coarfa C, Ellis L, Ando' S, Fuqua S. The Y537S ESR1 mutation carries unique metabolomics profiling in breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P1-02-03.

Radiation reduction of minimally invasive transforaminal lumbar interbody fusion with localisation system in overweight patients: practical technique

AIMS

Minimally invasive transforaminal lumbar interbody fusion (MITLIF) has been well validated in overweight and obese patients who are consequently subject to a higher radiation exposure. This prospective multicentre study aimed to investigate the efficacy of a novel lumbar localisation system for MITLIF in overweight patients.

PATIENTS AND METHODS

The initial study group consisted of 175 patients. After excluding 49 patients for various reasons, 126 patients were divided into two groups. Those in Group A were treated using the localisation system while those in Group B were treated by conventional means. The primary outcomes were the effective radiation dosage to the surgeon and the exposure time.

RESULTS

There were 62 patients in Group A and 64 in Group B. The mean effective dosage was 0.0217 mSv (standard deviation (sd) 0.0079) in Group A and 0.0383 mSv (sd 0.0104) in Group B (p < 0.001). The mean fluoroscopy exposure time was 26.42 seconds (sd 5.91) in Group A and 40.67 seconds (sd 8.18) in Group B (p < 0.001). The operating time was 175.56 minutes (sd 32.23) and 206.08 minutes (sd 30.15) (p < 0.001), respectively. The mean pre-operative localisation time was 4.73 minutes (sd 0.84) in Group A and 7.03 minutes (sd 1.51) in Group B (p < 0.001). The mean screw placement time was 47.37 minutes (sd 10.43) in Group A and 67.86 minutes (sd 14.15) in Group B (p < 0.001). The pedicle screw violation rate was 0.35% (one out of 283) in Group A and 2.79% (eight out of 287) in Group B (p = 0.020).

CONCLUSION

The study shows that the localisation system can effectively reduce radiation exposure, exposure time, operating time, pre-operative localisation time, and screw placement time in overweight patients undergoing MITLIF. Cite this article: Bone Joint J 2017;99-B:944-50.

Abstract S4-02: The Y537S ESR1 mutation is a dominant driver of distant ER-positive breast cancer metastasis

Background: Estrogen receptor (ESR1) mutations occur at a high frequency in metastatic breast tumors in patients treated with hormonal therapy in the metastatic setting. We do not know if these mutations are involved in metastasis.

Experimental design and methods: We generated ESR1 Y537S homozygous mutations using CRISPR Casp-9 technology. Treatment synergy was evaluated using Compusyn. Athymic mice were used in tumor xenograft studies. ChIP-Seq and transcriptome analyses were performed.

Results: We generated CRISPR ESR1 Y537S mutation homozygous knock-in clones and lentiviral stable pools in MCF-7 cells. Transcriptome profiling revealed elevated expression of Hallmark pathways, including EMT and estrogen-regulated gene expression. The EMT in mutant cells was associated with a switch from E-cadherin to vimentin, and increased expression of SNAIL and TWIST. Mutant cell growth was resistant to tamoxifen, but responsive to fulvestrant treatment. Synergistic treatment effects were observed with fulvestrant and everolimus or palbociclib. CRISPR Y537S mutant knock-in cells grown in the mammary fat-pad of athymic mice spontaneously metastasized to distant organs including the lung, intestine, and kidneys. In the presence of estrogen, there was no difference in the frequency of distant macrometastases between parental wild-type ER and CRISPR Y537S mutant ER mice. However, in the absence of estrogen, 80% of CRISPR Y537S mutant ER mice displayed overt distant macrometastases, but none were observed in parental wild-type ER mice (p=0.04). Interestingly, although CRISPR Y537S mutant ER tumors grown in the mammary fat-pad were unresponsive to tamoxifen treatment, tamoxifen significantly inhibited the growth of mutant tumors at the distant microenvironment (8-fold). Distant tumors retained ER expression and hormone sensitivity. Comparison of residual tamoxifen-treated metastatic tumors with tumors grown at the primary mammary fat-pad site using immunoblot analysis demonstrated significant reduction in estrogen-regulated gene expression, but no effect on the expression of biomarkers associated with EMT, suggesting a disconnect between EMT and distant metastasis in mutant cells. EMT genes were also identified as direct binding site targets in Y537S mutant cells compared with wide-type ER using ChIPSeq. We discovered that expression of the Y537S mutant was dominant, driving the growth of distant metastatic tumors when co-expressed with wild-type ER cells. A Y537S ER mutant-specific gene expression signature predicted poor disease-free survival of ER-positive patients using the METABRIC database, and lung-specific metastasis-free survival in a Memorial Sloan Kettering dataset.

Conclusion: The Y537S ER mutation is a driver of distant metastasis in ER-positive breast cancer cells. Although tamoxifen treatment was ineffective at reducing the growth of mutant cells grown at the primary site, it was effective at reducing distant metastasis. A Y537S ER mutant-specific gene expression signature predicted poor disease-free, and distant lung metastasis in ER-positive patients. Mutation status is a potential new predictive factor for hormone therapy of metastatic breast cancer patients on maintenance hormonal therapy.

Citation Format: Fuqua SAW, Gu G, Rechoum Y, Gelsomino L, Dustin DJ, Corona-Rodriguez A, Beyer AR, Pejerrey SM, Gao M, Tsimelzon A, Tian L, Zhang X, Nagi C, Ando' S. The Y537S ESR1 mutation is a dominant driver of distant ER-positive breast cancer metastasis [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr S4-02.

Expression of serum miR-218 in hepatocellular carcinoma and its prognostic significance

BACKGROUND

Several recent studies have revealed that microRNAs (miRNAs) are stably detectable in the circulation and can be used as biomarkers for diagnosis and prognosis of malignancy. The aim of this manuscript is to investigate serum miR-218 expression in patients with hepatocellular carcinoma (HCC) and to analyze its potential diagnostic and prognostic value in HCC.

METHODS

Quantitative real-time quantitative PCR (qPCR) was conducted to detect serum miR-218 expression from 156 HCC and 98 benign liver diseases (BLD) as well as 64 healthy controls. The relevance of serum miR-218 expression to the clinicopathological factors was assessed. In addition, the prediction of cutoff values of the markers was performed by the receiver operating characteristic (ROC) curve. Moreover, the Kaplan-Meier method was used to plot survival curves and univariable and multivariable Cox regression analyses were used to evaluate independent prognostic factors.

RESULTS

Consequently, our findings revealed that serum miR-218 levels were remarkably underexpressed in HCC patients as compared to BLD patients and healthy controls. And its low level was obviously related to tumor size (p = 0.048), tumor number (p = 0.018), vascular invasion (p = 0.039), Edmondson grade (p = 0.042), and higher TNM stage (III-IV). ROC curve analysis showed that miR-218 had a significant diagnostic accuracy, yielded an AUC (the areas under the ROC curve) of 0.734 (95 % confidence interval (CI) 0.68-0.789, p < 0.01), thus providing a sensitivity of 66.7 % and a specificity of 69.1 % in discriminating HCC from BLD and healthy controls. Meanwhile, miR-218 can act as a useful biomarker in distinguishing the patients with large tumors (>5 cm) from patients with small tumors (<5 cm) (p < 0.01). In addition, the combination of miR-218 and AFP had greater diagnosis capacity with an AUC of 0.908 (95 % CI 0.876-0.940; p < 0.01). Both log-rank test and Cox regression analysis demonstrated that the decreased serum expression of miR-218 had a significant impact on overall survival of the patients with HCC (HR = 3.049, 95 % CI 2.028-4.585, p < 0.01).

CONCLUSION

Taken together, this study suggested that serum expression of miR-218 might be a potential noninvasive tumor biomarker in the diagnosis and assessment of prognosis of HCC.

Prognostic implications of RB1 tumour suppressor gene alterations in the clinical outcome of human osteosarcoma: a meta-analysis

Primary osteosarcoma is the most frequent malignant bone cancer in children and teenagers. Genetic alterations at the retinoblastoma 1 (RB1) gene has been implicated in the development and progression of human osteosarcoma. Here, we performed a meta-analysis to examine the impact of RB1 mutations on the survival of osteosarcoma patients, the risk of metastasis and the histological response of osteosarcoma to chemotherapy. A systemic review of the Medline, Embase, Scopus and Cochrane Library yielded 12 eligible studies with 491 patients for this study. Forest plots resulting from our meta-analyses illustrate that loss of RB1 function results in a 1.62-fold increase in the mortality rate for osteosarcoma patients (RR = 1.62, 95% CI: 1.23-2.13; Z = 3.44, P = 0.0006), a significant increase in osteosarcoma metastasis (OR = 3.95, 95% CI: 1.86-8.38; Z = 3.57; P = 0.0004), and a significant reduction in the histological response of osteosarcoma to chemotherapy (OR = 0.35; 95% CI: 0.13-0.94; Z = -2.08; P = 0.038). Additionally, the nearly symmetrical funnel plot (Egger's test, t = 1.15, P = 0.288) indicates absence of publication bias regarding the meta-analysis that examined the correlation of RB1 alterations with the survival rate for osteosarcoma patients. Our findings suggest that RB1 alterations may serve as a prognostic marker for the management of osteosarcoma patients.

Gene silencing of non-obese diabetic receptor family (NLRP3) protects against the sepsis-induced hyper-bile acidaemia in a rat model

The role of NOD-like receptor family (NLRP3) has been confirmed in various inflammatory diseases. The association between NLRP3 and hyper-bileacidaemia during the sepsis remains unclear. We aimed to investigate whether NLRP3 silencing protects against the sepsis-induced hyper-bileacidaemia. Sepsis was induced by caecum ligation and puncture (CLP). Gene silencing of NLRP3 was performed by injecting rats with NLRP3 short hairpin RNA plasmids (NLRP3 shRNA) 48 h before surgery. Rats were divided into four groups: group 1: sham; group 2: sepsis; group 3: NLRP3 shRNA + sepsis (called the 'NLRP3 shRNA' group); and group 4: scrambled shRNA + sepsis (called the 'scrambled shRNA' group). The serum levels of bile acids, hepatic expression of hepatocyte membrane transporters, hepatic cytokine levels and behaviours of immune cells were compared among the groups. Hepatic NLRP3 expression was increased dramatically during the sepsis, but was suppressed by pretreatment with NLRP3 shRNA. Compared with rats in the sepsis and the scrambled shRNA groups, rats in the NLRP3 shRNA group exhibited significantly decreased serum levels of glycine and taurine conjugated-bile acids, with rehabilitated expression of hepatocyte transporters, suppressed hepatic cytokine levels, decreased hepatic neutrophils infiltration and attenuated macrophages pyroptosis. Gene silencing of NLRP3 ameliorates sepsis-induced hyper-bileacidaemia by rehabilitating hepatocyte transporter expression, reducing hepatic cytokine levels, neutrophil infiltration and macrophages pyroptosis. NLRP3 may be a pivotal target for sepsis management.

Transplantation of NSC-derived cholinergic neuron-like cells improves cognitive function in APP/PS1 transgenic mice

The ability to selectively control the differentiation of neural stem cells (NSCs) into cholinergic neurons in vivo would be an important step toward cell replacement therapy. First, green fluorescent protein (GFP)-NSCs were induced to differentiate into cholinergic neuron-like cells (CNLs) with retinoic acid (RA) pre-induction followed by nerve growth factor (NGF) induction. Then, these CNLs were transplanted into bilateral hippocampus of APP/PS1 transgenic mice. Behavioral parameters showed by Morris water maze (MWM) tests and the percentages of GFP-labeled cholinergic neurons of CNL transplanted mice were compared with those of controls. Brain levels of choline acetyltransferase (ChAT) mRNA and proteins were analyzed by quantitative real-time PCR and Western blotting, ChAT activity and acetylcholine (ACh) concentration were also evaluated by ChAT activity and ACh concentration assay kits. Immunofluorescence analysis showed that 80.3±1.5% NSCs differentiated into CNLs after RA pre-induction followed by NGF induction in vitro. Three months after transplantation, 82.4±6.3% CNLs differentiated into cholinergic neurons in vivo. APP/PS1 mice transplanted with CNLs showed a significant improvement in learning and memory ability compared with control groups at different time points. Furthermore, CNLs transplantation dramatically increased in the expressions of ChAT mRNA and protein, as well ChAT activity and ACh concentration in APP/PS1 mice. Our findings support the prospect of using NSC-derived CNLs in developing therapies for Alzheimer's disease (AD).

On the chaotic behavior of the primal-dual affine-scaling algorithm for linear optimization

We study a one-parameter family of quadratic maps, which serves as a template for interior point methods. It is known that such methods can exhibit chaotic behavior, but this has been verified only for particular linear optimization problems. Our results indicate that this chaotic behavior is generic.

No evidence of drug-induced pancreatitis in rats treated with exenatide for 13 weeks

AIMS

The potential association of glucagon-like peptide receptor agonists (GLP-1RAs) with the development of pancreatitis or pancreatic malignancies in patients with diabetes has been suggested. This study evaluated the long-term effects of the GLP-1RA exenatide on pancreatic exocrine structure and function in the Zucker diabetic fatty (ZDF) rat model of type 2 diabetes.

METHODS

Rats received subcutaneous twice-daily injections of 0 (control), 6, 40 and 250 µg/kg/day exenatide for 3 months. Clinical signs, body and pancreas weight, food consumption, HbA1c, fasting serum amylase, lipase, glucose and insulin concentrations were evaluated during treatment and after a 28-day off-drug period to assess the reversibility of any observed effects. Morphometric analysis of pancreatic ductal cell proliferation and apoptosis were performed.

RESULTS

Plasma exenatide concentrations were several-fold higher than therapeutic levels observed in humans. No exenatide-related effects were observed on clinical signs, lipase concentration, pancreatic weight, pancreatic histology, ductal cell proliferation or apoptosis. Exenatide improved animal survival, physical condition, glucose concentrations and HbA1c, decreased food intake, and increased serum insulin concentration. Total amylase concentrations, although within normal ranges, were slightly higher in exenatide-treated rats; following the off-drug period, total amylase concentrations were comparable in treated and untreated rats. Exenatide-related minimal-to-moderate islet hypertrophy was observed at doses ≥6 µg/kg/day, with dose-related increases in incidence and degree. These changes were still present after the off-drug period.

CONCLUSIONS

Chronic administration of exenatide in ZDF rats resulted in the expected metabolic benefits and improved animal survival, with no adverse effects noted on pancreatic exocrine structure and function.

Abstract P4-08-09: Targeting Thyroid Receptor b in Estrogen Receptor Negative Breast Cancer

Background: The treatment of estrogen receptor (ER)-negative breast cancer (BC) is a major clinical problem due to the lack of useful therapeutic targets. Nuclear receptors (NRs) are potential targets in these patients because they regulate global transcriptional events and many already have agonists/antagonists available.

Material and Methods: We used microarray analysis of 227 ER-negative tumors to identify NR targets, and performed hierarchical clustering using 41 NRs. Expressed receptors were scored using prediction analysis of microarrays (PAM) across clustered groups. Cell lines were matched to subtypes using previously described data (Neve et al. 2006). Candidate gene expression levels were confirmed by qRT-PCR using TaqMan probes. pGIPZ lentiviral vectors encoding shRNA were used to knockdownselected candidates. MTT and soft agar assays were used to measure chemosensitivity and growth following treatment with Docetaxel (Doc), Doxorubicin (Dox), or Cisplatin (Cis). Statistical analysis was performed using Red-R.

Results: The 41 NRs clustered tumors into 5 groups. For each group we selected genes representing the highest ranked discriminators, and examined their effects in cell lines matching each groups' gene signature. Thyroid hormone receptor b (THRβ) was selected from group V. The expression levels of this receptor were confirmed by qRT-PCR and Western blot analysis.

Knockdown of THRβ in ER-negative HCC2185 cells rendered cells more resistant to all chemotherapeutics by using MTT assay. Similar results were confirmed in ER-negative MDA-MB-453 and HCC202 cells. Knockdown of THRβ enhanced colony forming potential in anchorage-independent soft agar assays in MDA-MB-453 and HCC202 cells. Statistical analysis using clinical data from Sabatier et al. (BCRT 2011) showed that patients with low THRb have a worse clinical outcome. In order to translate these findings into the clinic, we treated cells with a specific THRβ agonists, GC-1 and KB-141. GC-1 inhibited cell growth in growth assays, and synergistic effects were observed when cells were treated with GC-1 and Docetaxel in combination. Re-expression of ERα protein was observed in ER-nagative cells lines after treatment with GC-1 and KB141, suggesting that modulation of THRβ may also extend hormonal therapy to this hormonally insensitive group of patients.

Conclusion: Clinical targeting of NRs in ER-negative BCs is a novel strategy since receptors can be specifically targeted with ligands. Our data suggest that chemotherapy response in ER-negative patients overexpressing THRβ could be enhanced with a THRβ agonist. Similarly, functional re-activation of ERα by activating THRβ might extend hormonal therapies to these patients as well.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-08-09.

Prevalence of error-prone abbreviations used in medication prescribing for hospitalised patients: multi-hospital evaluation

The use of error-prone abbreviations in prescribing is a potential cause of misinterpretation that may lead to medication error. This study determined frequency and type of error-prone abbreviations in inpatient medication prescribing across three Australian hospitals. Three hundred and sixty-nine (76.9%) patients had one or more error-prone abbreviations used in prescribing, with 8.4% of orders containing at least one error-prone abbreviation and 29.6% of these considered to be high risk for causing significant harm.

The first multicenter and randomized clinical trial of herbal Fufang for treatment of postmenopausal osteoporosis

This multicenter and randomized clinical trial showed that daily oral herbal formula Xian Ling Gu Bao (XLGB) was safe in postmenopausal women over a 1-year treatment. Those patients (n ∼ 50) treated with XLGB at the conventional dose demonstrated a statistically significant increase in dual-energy X-ray absorptiometry (DXA) bone mineral density (BMD) at lumbar spine at 6 months and a numerically increased BMD at 12 months.

INTRODUCTION

The aim of this study was to examine the safety and efficacy of a herbal formula XLGB in postmenopausal women (ChiCTR-TRC-00000347).

METHODS

One hundred eighty healthy postmenopausal women (≥60 years old) with BMD T-score ≤ -2.0 (lumbar spine or femoral neck) were recruited from four clinical centers to receive low-dose (conventional dose) XLGB (L-XLGB group, 3 g/day, n = 61) or high-dose XLGB (H-XLGB group, 6 g/day, n = 58) or placebo (CON group, n = 61). Women received daily calcium (500 mg) and vitamin D (200 IU) supplementation. Primary endpoints were lumbar spine BMD and safety; secondary endpoints were femoral neck BMD and bone turnover markers measured at baseline and at 6 and 12 months.

RESULTS

Of 180 women recruited, 148 completed the study. The compliance in each group was comparable. Prominent adverse events were not observed in either group. In the L-XLGB group at 6 months, lumbar spine BMD by DXA increased significantly from baseline (+2.11% versus CON +0.58%, p < 0.05), but femoral neck BMD did not; at 12 months, BMD in the L-XLGB group decreased from 6-month levels yet remained higher than baseline, but without difference from the CON group. There was no dose-dependent response. Bone turnover marker levels declined during the first 6 months after XLGB treatment. There was no significant difference in the overall incidence of side effects among treatment and control groups.

CONCLUSION

XLGB over 1-year treatment at the conventional dose demonstrated safe and only a statistically significant increase in BMD at lumbar spine at 6 months in postmenopausal women.

Effects of electroacupuncture pretreatment on inflammatory response and acute kidney injury in endotoxaemic rats

This study investigated the effect of electroacupuncture pretreatment on the lipopolysaccharide (LPS)-induced inflammatory response and on acute kidney injury in adult male pathogen-free Wistar rats. Rats received electroacupuncture at the Zusanli (ST36) and Neiguan (PC6) acupoints, or electrical stimulation at sham points, for 30 min before stimulation with either 5 mg/kg LPS intravenously or normal saline. Plasma cytokines, plasma nitrite, renal inducible nitric oxide synthase (iNOS) and nuclear factor κB (NF-κB) activity were assessed 240 min after LPS or normal saline injection. Blood urea nitrogen (BUN), creatinine (Cr) and histopathological score for renal tubular damage were also measured. Electroacupuncture pretreatment significantly decreased LPS-induced plasma tumour necrosis factor-α and interleukin (IL)-1β, increased plasma IL-10, and decreased plasma nitrite, renal iNOS and NF-κB activity. It also significantly decreased LPS-induced BUN, Cr and the renal histopathological score. These findings suggest that electroacupuncture pretreatment at the ST36 and PC6 acupoints attenuated the LPS-induced inflammatory response and mitigated acute kidney injury.

P1-12-04: EBP50 – A Novel Biomarker for Resistance to Endocrine and HER2−Targeted Therapies in Breast Cancer

Background: Therapeutic strategies directed at inhibiting the action of ERa using antiestrogens, such as tamoxifen (Tam), or inhibiting HER2 signalling using a monoclonal antibody-Trastuzumab (Tras) are the standard therapies offered to women with ERa or ERa/HER2−positive cancer. However, not all patients respond to these targeted therapies, and a large number of patients who do respond will eventually develop disease progression or recurrence while on therapy. EBP50 functions as a molecular scaffold to coordinate a diverse range of regulatory processes and a number of studies suggest a role for EBP50 in cancer progression.

Material and Methods: Microarray profiling was used to identify genes associated with response to tamoxifen in primary as compared to metastatic breast tumor recurrences. Stable transfection of EBP50 shRNA was performed in ZR75B and BT-474 cells. Cell response to Tam and/or Tras was evaluated using soft agar and MTT growth assays. The molecular signaling pathways affected by EBP50 knockdown were explored using immunoblot, and immunoprecipitation. Cellular localization was determined using confocal microscopy. Mammosphere potential was used to evaluate the stem cell renewal capacity in BT-474 cells.

Results: The mean levels of EBP50 were reduced in the tamoxifen-resistant, metastatic breast tumors compared to tamoxifen-sensitive tumors. Knockdown of EBP50 levels decreased Tam sensitivity in ZR75B cells. Thus reduction in EBP50 levels analygous to that discovered in resistant patients, conferred resistance to the growth inhibitory effects of Tam. Cells with knockdown of EBP50 (shEBP50 cells) showed higher levels of phosphorylated HER2, EGFR and HER3, as well as their downstream signalling pathways. PI3K and AKT inhibitors were able to restore Tam sensitivity in shEBP50 cells. After long term treatment of ZR75-B cells with Tam resulted in decreased endogenous levels of EBP50, suggesting that only cells evolving with lower EBP50 levels were able to survive Tam treatment. Similarly, knockdown EBP50 in ERa/HER2 positive BT-474 cells significantly increased phosphorylated HER2 and these cells were resistant not only to Tam, but also to Tras treatment. BT-474 cells acquired Tras resistance concomittant with decreased EBP50 levels in a dose-dependent manner respective to parental cells. Interestingly, shEBP50 cells demonstrated an enhanced capacity to form mammospheres compared to vector control cells. We demonstrate that EBP50 is able to bind HER2 using immunoprecipitation, suggesting that EBP50 interacts directly with HER2. Confocal microscope analysis demonstrated the colocalization of these two proteins. Inhibitors to c-Src, PI3K, AKT and EGFR were used in combination with Tras; shEBP50 cells were sensitive to both PI3K and AKT inhibitors, and EGFR inhibitors were able to restore Tras sensitivity.

Discussion: Our data suggest that EBP50 is a novel negative regulator of HER2 signaling, and its loss conferred resistance to both Tam and Tras. EBP50 loss might function to stabilize HER2, and enhance dimerization with EGFR and HER3. We hypothesize that EBP50 levels might be a new predictive biomarker for targeted therapy; patients with low EBP50 levels might best be treated with a combination of therapies including PI3K/AKT inhibitors.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P1-12-04.

Abstract P5-06-02: Loss of Rho GDIa Function and Tamoxifen Resistance in ERa-Positive Breast Cancer Cells

Background: We have previously shown that increased phosphorylation of the S305 site in ERa via mutation of ERa can lead to tamoxifen (Tam) resistance. We have also discovered that shRNA knockdown of the Rho disassociation inhibitor (Rho GDIa) can render estrogen receptor (ERa)- positive breast cancer cells more aggressive via an increase in their metastatic ability. Rho GDIa is a negative regulator of the Rho family of proteins, which play an important role in the regulation of the actin cytoskeleton. While the Rho pathway is known to influence metastasis in breast and other types of cancers, it is unclear how this pathway impacts on Tam sensitivity. Since loss of Rho GDIa causes an increase in the activity of the downstream Rho proteins (Rho, Rac, and Cdc42), it is possible that increased activity of downstream Rho effectors may lead to Tam resistance through crosstalk with the ERa signaling pathway. Materials and Methods: Rho GDIa was stably silenced in MCF-7 cells using shRNA and its levels validated using Western blot analysis. Kinase assays were perfomed using GST-tagged ERa fragments to assess the effect of various kinases on ERa. ERE-luciferase reporter assays were used to look at ERa transactivation with estrogen and Tam treatment. In vitro-derived Tam-resistant cells were generated by culturing MCF-7 cells in Tam for &gt;6 months.

Results: Knockdown of Rho GDIa in ER-positive breast cancer cells resulted in Tam-resistant growth in vivo. Tam stimulated primary tumor growth in athymic nude mice. Mice injected with Rho GDIa knockdown cells exhibited metastatic lesions to the lung when treated with either estrogen or Tam. No lung tumors were detected in vector control transfected MCF-7 cells. Rhotekin pulldown assays revealed that Rho (A, B, and C), Rac1, and Cdc42 had higher activity in the Rho GDIa knockdown cells as compared to vector control cells. Immunecomplex kinase assays revealed that PAK1, a known downstream effector of the Rho pathway, exhibited increased activation in the Rho GDIa knockdown cells, and that this increased activity led to increased phosphorylation of ERa on the S305 residue. As expected, the acetylation of ERa was decreased when S305 was phosphorylated and this decrease in acetylation was dependent on phosphorylation of S305 since transfection of a plasmid containing a S305A mutation did not display decreased acetylation. ERE-luciferase assays showed that Rho GDIa knockdown cells had higher levels of estrogen and tamoxifen-induced activity in Rho GDIa knockdown cells as compared to vector control cells. Further possible effectors of Rho GDIa are being investigated as possible candidates playing roles in the crosstalk between these two pathways. Interestingly, cells which became Tam-resistant due to long term culture in the presence of Tam, also exhibited a decrease in endogenous Rho GDIa levels.

Discussion: Loss of Rho GDIa in ERa-positive breast cancer cells conferred a Tam-resistant and metastatic phenotype. Cells with decreased Rho GDIa levels displayed increased phosphorylation of ERa, suggesting that there is a level of crosstalk between the Rho family of signaling entwork and the ERa signaling pathway. We hypothesize that disruption of this crosstalk may be an approach to prevent or reverse Tam resistance in patients.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P5-06-02.

Abstract P5-06-14: Ezrin Binding Protein Ebp50 Negatively Regulates HER2 and Alters Tamoxifen Sensitivity

Background: Targeted therapy with antiestrogens and aromatase inhibitors are the mainstay of treatment for estrogen receptor (ER) a-positive breast cancer; however, resistance to these therapies ultimately occurs and patients recur with resistant disease.

Materials and Methods: Stable overexpression of a shRNA to Ebp50 or full-length Ebp50 was performed in MCF-7 breast cancer cells. Cell responsiveness to tamoxifen (Tam) was evaluated using soft agar and MTT growth assays. The molecular signaling pathways affected by Ebp50 knockdown were explored using immunoblot analysis, and immunoprecipitation assays. Cellular localization was determined using confocal microscopy.

Results: Modulation of Ebp50 levels altered cellular response to Tam treatment. Overexpression enhanced Tam sensitivity, whereas knockdown decreased Tam sensitivity. Thus reduction in Ebp50 levels analygous to that discovered in resistant patients, conferred resistance to the growth inhibitory effects of Tam. Since it is known that Ebp50 can bind to a number of cell surface receptors, we performed binding assays, and found that Ebp50 was able to bind to HER-2 in MCF-7 cells. In addition, this interaction was enhanced with Tam treatment. Enhanced activation of phospho-HER2 and total-HER2 levels, as well as pAKT were seen in the Ebp50 knockdown cells. We expressed deletion mutants of Ebp50 we saw increased levels of cytoplasmic ERa when the ERM domain was deleted. The ERM domain, which is know to be important for the binding cytoplasmic proteins, may thus be a determinant of ERa localization. Ebp50 was also shown to affect ERa transcriptional activity. Discussion: Our data suggest that Ebp50 may be a negative regulator of HER2 signaling, and its loss confered homrone resistance. Ebp50 loss might function to stabilize HER2 levels.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P5-06-14.