MicroRNA-577 promotes the sensitivity of chronic myeloid leukemia cells to imatinib by targeting NUP160

OBJECTIVE

To explore the effect of microRNA-577 on the drug sensitivity of chronic myeloid leukemia (CML) and the underlying mechanism.

PATIENTS AND METHODS

Quantitative Real Time-Polymerase Chain Reaction (qRT-PCR) was used to detect the expression of microRNA-577 in peripheral blood of patients with chronic myeloid leukemia. Meanwhile, the expression of microRNA-577 was detected in CML cell line after imatinib treatment. Cell counting kit-8 (CCK-8) and flow cytometry assay were applied to verify the effect of microRNA-577 on cell proliferation and cycle. NUP160 was identified as a target gene of microRNA-577 by dual-luciferase reporter gene assay. Cell reverse test was performed to figure out whether microRNA-577 can enhance the sensitivity of CML to imatinib.

RESULTS

QRT-PCR results revealed that microRNA-577 level was notably decreased in peripheral blood of patients with CML, and microRNA-577 could inhibit the proliferation and cycle of CML cells. In addition, the result of dual-luciferase reporting assay indicated that microRNA-577 had a binding relationship with NUP160, and up-regulation of microRNA-577 in CML cell lines reduced the expression of NUP160, and vice versa. Lastly, cell reverse experiments confirmed that microRNA-577 can alleviate the resistance of CML to imatinib.

CONCLUSIONS

We found that microRNA-577 promotes the sensitivity of chronic myeloid leukemia cells to imatinib by down-regulating the expression of NUP160.

Genome-wide identification and comparison of mRNAs, lncRNAs and circRNAs in porcine intramuscular, subcutaneous, retroperitoneal and mesenteric adipose tissues

Many types of RNAs, including messenger RNAs (mRNAs), long noncoding RNAs (lncRNAs) and circular RNAs (circRNAs), play crucial roles in regulating fat cell differentiation and tissue development. However, the expression profiles of these RNAs in different adipose tissues are still largely unknown. To shed light on this issue, we performed a transcriptome analysis of mRNAs, lncRNAs and circRNAs obtained from intramuscular adipose tissue, subcutaneous adipose tissue, retroperitoneal adipose tissue and mesenteric adipose tissue of Chinese Erhualian pigs. A number of differentially expressed mRNAs, lncRNAs and circRNAs were identified among the four adipose tissues. Tissue-specific analysis indicated that circRNAs exhibited the highest tissue specificity among mRNAs, lncRNAs and circRNAs, whereas intramuscular adipose tissue had the most tissue-specific genes among the four adipose tissues. Gene Ontology analysis showed that differentially expressed mRNAs among groups were involved mainly in lipid metabolism and immune inflammatory response processes. Furthermore, the co-expression network construction of mRNAs-lncRNAs revealed that several important lncRNAs, such as MSTRG.426159 and MSTRG.604206, might associate with lipid metabolic process. Taken together, these data provide a genome-wide resource of mRNAs, lncRNAs and circRNAs potentially involved in porcine fat metabolism, thus improving understanding of their function in diverse adipose tissues.

MAGE-A is frequently expressed in triple negative breast cancer and associated with epithelial-mesenchymal transition

Epithelial-mesenchymal transition (EMT) is a crucial step in tumor metastasis. Triple negative (TN) breast cancer, a high metastasis phenotype, has been verified to be associated with EMT. Melanoma associated antigen-A (MAGE-A) is exclusively expressed in cancers with high aggressiveness as well as unfavorable prognosis and likely to be associated with EMT of triple negative breast cancer (TNBC). The aim of the study is to analyze the expression profile of MAGE-A in breast cancer and the correlation between MAGE-A and EMT of TNBC. Immunohistochemistry (IHC) was performed to assess the prevalence of MAGE-A, vimentin, E-cadherin and β-catenin in breast cancer tissues and correlate them with clinical pathological parameters. The association between MAGE-A and EMT markers was also evaluated. Scratch assay and transwell invasion assay were carried out to evaluate the impact of MAGE-A down-regulation on migration and invasion of the breast cancer cells. Real-time PCR was also conducted to evaluate alterations in EMT markers with decrease in MAGE-A. The results showed that MAGE-A was absent in normal tissue but expressed in tumor samples with the incidence of 49.17% (P=0.008). MAGE-A staining was higher in TNBC (76.47%, 13/17), followed by HER-2(+) (53.85%, 7/13) and Luminal set (43.33%, 39/90), and it was significantly correlated with ER (-), PR (-), HER-2 (-), lymph nodes involvement and higher histological grade (P<0.05). E-cadherin-positivity was frequent in Luminal set (94.44%, 85/90) and linked to ER (+), negative lymph nodes and lower histological grade (P<0.05). Vimentin expression was often observed in TNBC (70.56%, 12/17) and ER (-), PR (-), lymph nodes (+) groups (P<0.05). Expression of β-catenin was prevalent in Luminal set (93.33%, 84/90) and correlated with ER (+), PR (+) and lower histological grade (P<0.05). MAGE-A was inversely associated with E-cadherin (P=0.011) and β-catenin (P=0.048) but expressed in the same trend with vimentin (P=0.000). Migration and invasion of MDA-MB-231 were inhibited when MAGE-A decreased. Increase in epithelial markers and decline in mesenchymal indicators were also seen with MAGE-A reduction. Snail, Slug, ZEB1 and ZEB2 were also down-regulated. In conclusion, MAGE-A may be responsible for high aggressiveness and EMT of TNBC and can be a new choice for targeted therapy.

Alleviation of enterotoxigenic Escherichia coli challenge by recombinant Lactobacillus plantarum expressing a FaeG- and DC-targeting peptide fusion protein

FaeG is the major subunit of K88 fimbriae. These cell surface attachments are considered to be the major virulence factor of enterotoxigenic Escherichia coli (ETEC), which causes diarrhoea in piglets. The use of dendritic cell-targeting peptide (DCpep) has been demonstrated to be an effective approach to enhance the immunity of vaccines. Lactobacillus plantarum is an attractive candidate for oral vaccination owing to its beneficial effects and safety. In this study, L. plantarum was employed to deliver a FaeG-DCpep fusion antigen, and the immune response in mice was evaluated. The synthesis of FaeG-DCpep dramatically increased the adhesion of recombinant L. plantarum (RLP) to IPEC-J2 cell surfaces, resulting in direct competition between L. plantarum and ETEC during adhesion assays. Significantly higher levels of body weight gain, sera immunoglobulin G and intestinal immunoglobulin A were observed in BALB/c mice immunised with RLP. In addition, the number of CD19+ B cells and CD11c+DC cells and the expression levels of several cytokines in the spleen and lymph nodes increased significantly compared to non-immunised mice. The oral administration of RLP also alleviated the symptoms of ETEC challenge, as shown by haematoxylin-eosin staining, indicating that RLP may be an efficient vaccine candidate.

Resting-state brain alteration after a single dose of SSRI administration predicts 8-week remission of patients with major depressive disorder

BACKGROUND

The present study investigated alteration of brain resting-state activity induced by antidepressant treatment and attempted to investigate whether treatment efficacy can be predicted at an early stage of pharmacological treatment.

METHOD

Forty-eight first-episode medication-free patients diagnosed with major depression received treatment with escitalopram. Resting-state functional magnetic resonance imaging was administered prior to treatment, 5 h after the first dose, during the course of pharmacological treatment (week 4) and at endpoint (week 8). Resting-state activity was evaluated in the course of the 8-week treatment and in relation to clinical improvement.

RESULTS

Escitalopram dynamically modified resting-state activity in depression during the treatment. After 5 h the antidepressant induced a significant decrease in the signal in the occipital cortex and an increase in the dorsolateral and dorsomedial prefrontal cortices and middle cingulate cortex. Furthermore, while remitters demonstrated more obvious changes following treatment, these were more modest in non-responders suggesting possible tonic and dynamic differences in the serotonergic system. Changes after 5 h in the caudate, occipital and temporal cortices were the best predictor of clinical remission at endpoint.

CONCLUSIONS

This study revealed the possibility of using the measurement of resting-state neural changes a few hours after acute administration of antidepressant to identify individuals likely to remit after a few weeks of treatment.

Resistance trends among clinical isolates in China reported from CHINET surveillance of bacterial resistance, 2005-2014

With the aim of gathering temporal trends on bacterial epidemiology and resistance from multiple laboratories in China, the CHINET surveillance system was organized in 2005. Antimicrobial susceptibility testing was carried out according to a unified protocol using the Kirby-Bauer method or automated systems. Results were analyzed according to Clinical and Laboratory Standards Institute (CLSI) 2014 definitions. Between 2005 and 2014, the number of bacterial isolates ranged between 22,774 and 84,572 annually. Rates of extended-spectrum β-lactamase production among Escherichia coli isolates were stable, between 51.7 and 55.8%. Resistance of E. coli and Klebsiella pneumoniae to amikacin, ciprofloxacin, piperacillin/tazobactam and cefoperazone/sulbactam decreased with time. Carbapenem resistance among K. pneumoniae isolates increased from 2.4 to 13.4%. Resistance of Pseudomonas aeruginosa strains against all of antimicrobial agents tested including imipenem and meropenem decreased with time. On the contrary, resistance of Acinetobacter baumannii strains to carbapenems increased from 31 to 66.7%. A marked decrease of methicillin resistance from 69% in 2005 to 44.6% in 2014 was observed for Staphylococcus aureus. Carbapenem resistance rates in K. pneumoniae and A. baumannii in China are high. Our results indicate the importance of bacterial surveillance studies.

Detection of circulating tumour cells may add value in endometrial cancer management

OBJECTIVE

To evaluate the role of circulating tumour cells (CTCs) in patients with endometrial cancer (EC).

STUDY DESIGN

This study included 40 patients with a pre-operative diagnosis of high-risk EC between April 2015 and May 2016. Patients were further divided into high-risk (grade 3, non-endometrioid, myometrial invasion ≥1/2 and stage III-IV) and high-intermediate-risk (grade 2-3, endometrioid, myometrial invasion <1/2 and stage I-II) groups according to postoperative pathological results. CTCs were detected using the CellSearch system, and CTC results were correlated with standard clinicopathological characteristics and serum tumour marker CA125/HE4 status using Chi-squared test, continuity correction or Fisher's exact test. The pharmacodynamic effect was detected after the first cycle of adjuvant therapy. Patients were followed up for 13 months to assess outcomes.

RESULTS

Fifteen percent of patients had one or more CTCs. The presence of CTCs was found to be significantly associated with cervical involvement (83.33% vs 11.76%, p=0.00). No significant difference in CTC-positive rates was detected between the high-risk and high-intermediate-risk groups, and no significant correlation was found between CTCs and serum CA125/HE4, either by positive rates or exact serum levels of the conventional tumour markers. No more CTCs were detected after the first cycle of standard chemotherapy in this study, and no distant metastases or recurrence were found in the CTC-positive patients during the follow-up period.

CONCLUSION

The presence of CTCs was correlated with cervical involvement. Early-stage EC patients with CTCs may benefit from additional adjuvant therapies. Assessment of CTCs may be useful in the management of high-risk EC patients.

Surface modification of LaFeO3 by Co-Pi electrochemical deposition as an efficient photoanode under visible light

The PEC performance of LaFeO₃ is promoted by Co-Pi coating due to improved surface catalytic activity and enhanced carrier separation.

Heat-shock protein 90 inhibitors synergistically enhance melanoma differentiation-associated gene-7-mediated cell killing of human pancreatic carcinoma

Pancreatic cancer is one of the intractable diseases and an effective therapeutic strategy is required to improve the prognosis. We examined possible antitumor effects of adenoviruses expressing melanoma differentiation-associated gene-7/interleukin-24 (Ad-mda-7) and a heat-shock protein 90 (Hsp90) inhibitor to human pancreatic carcinoma cells. Ad-mda-7 and an Hsp90 inhibitor, geldanamycin (GA), produced cytotoxic effects, and a combinatory use of Ad-mda-7 and GA further achieved synergistic effects. Administration of N-acetyl-L-cysteine, an inhibitor of reactive oxygen species, eliminated Ad-mda-7- and GA-mediated cytotoxicity. Ad-mda-7 augmented phosphorylated AKT levels but GA did not influence the phosphorylation. GA-treated cells showed cleavage of poly-(ADP-ribose) polymerase but not caspase-3, and upregulated Hsp70 and LC3A/B II levels, whereas Ad-mda-7-treated cells did not. GA treatments augmented ubiquitination and markedly increased melanoma differentiation-associated gene-7 (MDA-7) expression levels. These findings suggest that Ad-mda-7-mediated cytotoxicity is dependent on reactive oxygen species but independent of apoptosis or autophagy, and that GA-mediated cytotoxicity was linked with caspase-independent apoptosis and/or autophagy. A mechanism underlying the combinatory effects of Ad-mda-7 and GA remained complex and the synergism is attributable to multiple factors including increased MDA-7 protein stability by GA.

Curcumin suppresses HIF1A synthesis and VEGFA release in pituitary adenomas

Curcumin (diferuloylmethane), a polyphenolic compound derived from the spice plant Curcuma longa, displays multiple actions on solid tumours including anti-angiogenic effects. Here we have studied in rodent and human pituitary tumour cells the influence of curcumin on the production of hypoxia inducible factor 1α (HIF1A) and vascular endothelial growth factor A (VEGFA), two key components involved in tumour neovascularisation through angiogenesis. Curcumin dose-dependently inhibited basal VEGFA secretion in corticotroph AtT20 mouse and lactosomatotroph GH3 rat pituitary tumour cells as well as in all human pituitary adenoma cell cultures (n=32) studied. Under hypoxia-mimicking conditions (CoCl(2) treatment) in AtT20 and GH3 cells as well as in all human pituitary adenoma cell cultures (n=8) studied, curcumin strongly suppressed the induction of mRNA synthesis and protein production of HIF1A, the regulated subunit of the hypoxia-induced transcription factor HIF1. Curcumin also blocked hypoxia-induced mRNA synthesis and secretion of VEGFA in GH3 cells and in all human pituitary adenoma cell cultures investigated (n=18). Thus, curcumin may inhibit pituitary adenoma progression not only through previously demonstrated anti-proliferative and pro-apoptotic actions but also by its suppressive effects on pituitary tumour neovascularisation.

RNA interference-mediated silencing of Stat5 induces apoptosis and growth suppression of hepatocellular carcinoma cells

It has been reported that Stat5 is overexpressed in a variety of human cancer cell lines and primary tumors. Inhibition of Stat5 in tumor cell lines has been associated with growth suppression and induction of apoptosis. However, no one of published studies have investigated the expression and role of Stat5 in hepatocellular carcinoma. In this study, we used human hepatocellular carcinoma cell line SMMC7721 as a model to demonstrate that Stat5 was highly expressed in these cells. Next we showed that RNAi mediated Stat5 knockdown could inhibit the proliferation and induce the apoptosis of SMMC7721 cells in vitro. Furthermore, we demonstrated that Stat5 knockdown inhibited the growth and induced the apoptosis of SMMC7721 cells in xenografts in nude mice. Taken together, our in vitro and in vivo data suggest that Stat5 plays an important role in human hepatocellular carcinoma. Inhibition of Stat5 by RNAi holds promise to be a novel gene therapy vector for hepatocellular carcinoma.

RSUME is implicated in HIF-1-induced VEGF-A production in pituitary tumour cells

The recently cloned small RWD-domain containing protein RSUME was shown to increase protein levels of hypoxia-inducible factor-1α (HIF-1α). The latter is the oxygen-regulated subunit of HIF-1, the most important transcription factor of the cellular adaptive processes to hypoxic conditions. It is also a major regulator of vascular endothelial growth factor-A (VEGF-A), which is critically involved in the complex process of tumour neovascularisation. In this study, the expression and role of RSUME in pituitary tumours was studied. We found that RSUME mRNA was up-regulated in pituitary adenomas and significantly correlated with HIF-1α mRNA levels. Hypoxia (1% O(2)) or treatment with hypoxia-mimicking CoCl(2) enhanced RSUME and HIF-1α expression, induced translocation of HIF-1α to the nuclei and stimulated VEGF-A production both in pituitary tumour cell lines and primary human pituitary adenoma cell cultures. When RSUME expression was specifically down-regulated by siRNA, the CoCl(2)-induced increase VEGF-A secretion was strongly reduced which was shown to be a consequence of the RSUME knockdown-associated reduction of HIF-1α synthesis. Thus, RSUME plays an important role in initiating pituitary tumour neovascularisation through regulating HIF-1α levels and subsequent VEGF-A production and may therefore be critically involved in pituitary adenoma progression.

Curcumin acts as anti-tumorigenic and hormone-suppressive agent in murine and human pituitary tumour cells in vitro and in vivo

Curcumin (diferuloylmethane) is the active ingredient of the spice plant Curcuma longa and has been shown to act anti-tumorigenic in different types of tumours. Therefore, we have studied its effect in pituitary tumour cell lines and adenomas. Proliferation of lactosomatotroph GH3 and somatotroph MtT/S rat pituitary cells as well as of corticotroph AtT20 mouse pituitary cells was inhibited by curcumin in monolayer cell culture and in colony formation assay in soft agar. Fluorescence-activated cell sorting (FACS) analysis demonstrated curcumin-induced cell cycle arrest at G2/M. Analysis of cell cycle proteins by immunoblotting showed reduction in cyclin D(1), cyclin-dependent kinase 4 and no change in p27(kip). FACS analysis with Annexin V-FITC/7-aminoactinomycin D staining demonstrated curcumin-induced early apoptosis after 3, 6, 12 and 24 h treatment and nearly no necrosis. Induction of DNA fragmentation, reduction of Bcl-2 and enhancement of cleaved caspase-3 further confirmed induction of apoptosis by curcumin. Growth of GH3 tumours in athymic nude mice was suppressed by curcumin in vivo. In endocrine pituitary tumour cell lines, GH, ACTH and prolactin production were inhibited by curcumin. Studies in 25 human pituitary adenoma cell cultures have confirmed the anti-tumorigenic and hormone-suppressive effects of curcumin. Altogether, the results described in this report suggest this natural compound as a good candidate for therapeutic use on pituitary tumours.

Meat quality is associated with muscle metabolic status but not contractile myofiber type composition in premature pigs

Longissimus muscles were sampled from Erhualian (EHL) and Pietrain (PIE) pigs at 20kg of body weight. No breed differences were detected in either the proportions or the mRNA/protein expression of respective MyHC isoforms, or the mRNA expression of PGC-1α (all P>0.10). However, meat quality traits were already divergent between breeds, and were associated with distinct energy metabolic status, as reflected by dramatically lower AMPK activity yet higher CK and LDH activities (all P<0.01) in longissimus muscle of EHL pigs. Moreover, mRNA expression of glucocorticoid receptor (GR) was found to be higher (P<0.05) in longissimus muscle of EHL pigs. These results indicate that the differences in meat quality traits occur early in premature pigs, and these are attributed to skeletal muscle energy metabolism and not contractile myofiber type composition. Breed-specific GR expression in muscle may be related to the pattern of energy metabolism and meat quality, yet the mechanism awaits further investigation.

IL-27-mediated activation of natural killer cells and inflammation produced antitumour effects for human oesophageal carcinoma cells

Interleukin IL-27, composed of p28 and EBV-induced gene 3 subunits, has diverse functions in enhancing cell-mediated immunity and silencing the immunity. We examined whether forced expression of the p28-linked EBI3 gene in human oesophageal carcinoma cells (Eca109) produced antitumour effects in a T cell-defective condition. Tumour growth of Eca109 cells expressing IL-27 (Eca109/IL-27) was retarded in nude mice compared with parental and vector DNA-transduced tumours and survival of the mice inoculated with Eca109/IL-27 cells was prolonged. Expression of the tumour necrosis factor-alpha, IL-1beta and IL-6 genes was up-regulated in Eca109/IL-27 tumour specimens while the tumours remained small in size but the increased transcription was subsequently down-regulated in enlarged tumours. Spleen cells from mice-bearing Eca109/IL-27 tumours produced interferon-gamma and showed YAC-1-targeted cytotoxic activities greater than those of mice inoculated with parental or vector DNA-transducer tumours. Numbers of DX5+CD69+ natural killer cells in spleen of mice-bearing Eca109/IL-27 tumours and those of CD31+ cells within Eca109/IL-27 tumours remained the same as found in mice-bearing parental or vector DNA-transduced tumours. These data collectively suggest that the IL-27-mediated antitumour effects produced in a mature T cell-defective condition were attributable to enhanced interferon-gamma production and natural killer activities.

Sensitive detection of PrPSc by Western blot assay based on streptomycin sulphate precipitation

Transmissible spongiform encephalopathies, also termed prion diseases, are fatal neurodegenerative disorders that affect both humans and animals, which are characterized by presences of protease-resistance disease-associated prion protein (PrP(Sc)) in brains. In the present study, we optimized the Western blot assay for PrP(Sc) with a precipitation procedure of streptomycin sulphate. After incubated with suitable amount of streptomycin sulphate, the detective sensitivity for PrP(Sc) was remarkably improved. The precipitation of PrP(Sc) was obviously influenced by pH value in the solution. Employs of PrP(Sc) stock sample into various mimic specimens, including normal hamster brain homogenate, human cerebrospinal fluid and urine, demonstrated that streptomycin precipitation markedly increased the detective sensitivity of PrP(Sc), regardless in low concentration or in large volume. In addition, the PrP(Sc) from a human brain tissue of familiar Creutzfeldt-Jakob disease (fCJD) was efficiently precipitated with streptomycin sulphate. As a sensitive, specific, rapid and flexible protocol for PrP(Sc), the protocol in this study has the potential, alone or combined with other techniques, to detect low levels of PrP(Sc) in the specimens not only from central nerve system, but also from peripheral organs or fluids.

Ab initio modeling of the interaction of electron beams and single-walled carbon nanotubes

Single-walled carbon nanotubes are readily observable in a scanning electron microscope, which traditional models fail to explain. We present an ab initio model to explain how the electron beam can interact with these structures despite the very small, nanoscale, interaction volume. In particular, we show how the electron beam can generate very strong secondary electron emission from the tip of a nanotube under external electric field. The approach may also be used in modeling the interaction of charged particles with nanostructures in other applications such as electron detection.

Lifetime of charge carriers in multiwalled nanotubes

The nature of low-energy excitations in multiwalled nanotubes (MWNTs) is investigated by means of two-color time-resolved photoemission. A careful analysis of the ballistic transport, secondary excitations, and band structure effects was employed in order to extract single electron lifetimes from the observed relaxation trend. It is demonstrated that in the vicinity of the Fermi level the energy dependence of e-e scattering times is inversely proportional to approximately the square of the excitation energy. This result provides strong evidence that electron transport in MWNTs exhibits a Fermi-liquid behavior, indicating that long-range e-e interaction along the tube vanishes due to screening.

Routes to control of H2 Coulomb explosion in few-cycle laser pulses

We have measured coincident ion pairs produced in the Coulomb explosion of H2 by 8-30 fs laser pulses at different laser intensities. We show how the Coulomb explosion of H2 can be experimentally controlled by tuning the appropriate pulse duration and laser intensity. For laser pulses less than 15 fs, we found that the rescattering-induced Coulomb explosion is dominated by first-return recollisions, while for longer pulses and at the proper laser intensity, the third return can be made to be the major one. Additionally, by choosing suitable pulse duration and laser intensity, we show H2 Coulomb explosion proceeding through three distinct processes that are simultaneously observable, each exhibiting different characteristics and revealing distinctive time information about the H2 evolution in the laser pulse.

Time-resolved photoimaging of image-potential states in carbon nanotubes

The first experimental evidence for the existence of image-potential states in carbon nanotubes is presented. The observed features constitute a new class of surface image states due to their quantized centrifugal motion. Measurements of binding energies and the temporal evolution of image state electrons were performed using femtosecond time-resolved photoemission. The associated lifetimes are found to be significantly longer than those of n=1 image state on graphite, indicating a substantial difference in electron decay dynamics between tubular and planar graphene sheets.

Effects of molecular structure on ion disintegration patterns in ionization of O2 and N2 by short laser pulses

We demonstrate that the structure of the outermost orbitals of oxygen and nitrogen can be observed in the angular distribution of coincident ion pairs generated by the double ionization of these molecules by 8 fs laser pulses. We do this by establishing that these ions emerge from well defined excited electronic states of O2+2 and N2+2 respectively and that they are produced dominantly through a process which involves electron rescattering. The angular distributions of the ions from the two targets are very different, reflecting the different structures of the outermost orbitals of the two molecules.

Rescattering double ionization of D2 and H2 by intense laser pulses

We have measured momentum spectra and branching ratios of charged ionic fragments emitted in the double ionization of D2 (and H2) molecules by short intense laser pulses. We find high-energy coincident D+ (and H+) ion pairs with kinetic energy releases between 8 and 19 eV which appear for linearly polarized light but are absent for circularly polarized light. The dependence on the polarization, the energy distributions of the ions, and the dependence on laser intensity of yield ratios lead us to interpret these ion pairs as due to a rescattering mechanism for the double ionization. A quantitative model is presented which accounts for the major features of the data.

The hypocholesterolemic agent LY295427 reverses suppression of sterol regulatory element-binding protein processing mediated by oxysterols

The sterol LY295427 reduces plasma cholesterol levels in animals by increasing the expression of hepatic low density lipoprotein (LDL) receptors. Here we trace the hypocholesterolemic activity of LY295427 to an ability to reverse oxysterol-mediated suppression of sterol regulatory element-binding protein (SREBP) processing. Micromolar concentrations of LY295427 induced the metabolism of LDL in oxysterol-treated cultured cells and inhibited the stimulation of cholesteryl ester synthesis mediated by oxysterols. cDNA microarray and RNA blotting experiments revealed that LY295427 increased levels of the LDL receptor mRNA and those of other SREBP target genes. The compound stimulated the accumulation of SREBPs in the nuclei of cells grown in the presence of oxysterols within 4-6 h of addition to the medium. Induction required components of the normal SREBP-processing pathway, including the SREBP cleavage-activating protein and the Site 1 protease. LY295427 overcame the suppression of SREBP processing mediated by several oxysterols but not by LDL-derived cholesterol. We conclude that LY295427 achieves a therapeutically desirable end point by an unique mechanism of action.

Multipond system: a sustainable way to control diffuse phosphorus pollution

Diffuse pollution from agricultural land is one of the main causes for lake eutrophication. Multipond systems, an ancient invention in China, are composed of many tiny ponds and ditches, scattered in agricultural fields. After a long period of research in an experimental watershed in Liuchahe, it was found that multipond systems constitute diffuse pollution control. They have a large capacity for water storage and serve to control the export of water, suspended matter, and phosphorus. Multipond systems significantly reduce runoff velocity. Sediments and phosphorus retained in the Liuchahe watershed were 14.38 x 10(6) and 7016 kg yr-1, respectively (area 691.6 ha). Irrigation provides an effective way to recycle and remove phosphorus. The use of multipond systems is a sustainable way to recycle valuable nutrients and reduce their discharge and thus pollution of downstream lakes.

Transcription factor MIZ-1 is regulated via microtubule association

A synthetic drug, T113242, activates low-density lipoprotein receptor (LDLR) transcription in the presence of sterols. T113242 also covalently binds to beta-tubulin and induces microtubule depolymerization. The myc-interacting zinc finger protein (MIZ-1) associates with microtubules, can bind directly to the LDLR promoter, and can activate LDLR transcription. MIZ-1 also binds to the promoter and activates transcription of other T113242-induced genes such as alpha(2) integrin. Soft X-ray, indirect immunofluorescence, and green fluorescent protein time-lapse microscopy reveal that MIZ-1 is largely cytoplasmic but accumulates in the nuclei of HepG2 cells upon treatment with T113242. Thus, MIZ-1 appears to be regulated by association with microtubules and may activate gene transcription in response to changes in the cytoskeleton.

Unsaturated fatty acids inhibit transcription of the sterol regulatory element-binding protein-1c (SREBP-1c) gene by antagonizing ligand-dependent activation of the LXR

Sterol regulatory element-binding protein-1c (SREBP-1c) enhances transcription of genes encoding enzymes of unsaturated fatty acid biosynthesis in liver. SREBP-1c mRNA is known to increase when cells are treated with agonists of liver X receptor (LXR), a nuclear hormone receptor, and to decrease when cells are treated with unsaturated fatty acids, the end products of SREBP-1c action. Here we show that unsaturated fatty acids lower SREBP-1c mRNA levels in part by antagonizing the actions of LXR. In cultured rat hepatoma cells, arachidonic acid and other fatty acids competitively inhibited activation of the endogenous SREBP-1c gene by an LXR ligand. Arachidonate also blocked the activation of a synthetic LXR-dependent promoter in transfected human embryonic kidney-293 cells. In vitro, arachidonate and other unsaturated fatty acids competitively blocked activation of LXR, as reflected by a fluorescence polarization assay that measures ligand-dependent binding of LXR to a peptide derived from a coactivator. These data offer a potential mechanism that partially explains the long-known ability of dietary unsaturated fatty acids to decrease the synthesis and secretion of fatty acids and triglycerides in livers of humans and other animals.

The retinoblastoma gene regulates somatic growth during mouse development

Overexpression of the retinoblastoma gene (Rb) in mice leads to the dwarf phenotype. To explore the potential mechanism of Rb effects on the somatic growth, bitransgenic mice with tetracycline-regulated Rb expression were generated, and their phenotypes were compared with those of previously established Rb mouse models. By gestational day 12.5, embryos lacking Rb and those expressing twice the regular amount of Rb are 15% larger and 10-30% smaller, respectively, compared with their wild-type littermates. The dwarf phenotype is associated with increased plasma levels of insulin-like growth factor-I (IGF-I) but not with growth hormone and glucose concentrations. Down-regulation of the Rb transgene expression results in a reduction of the IGF-I plasma concentrations to normalcy and an increase of somatic growth prenatally and postnatally. Consistent with the in vivo results, cells overexpressing Rb require higher thresholds of IGF-I to stimulate proliferation. Thus, Rb plays an integral role for mouse somatic growth and maintenance during ontogenesis, and IGF-I pathway is likely to be a target for such regulation.

Accumulation of dietary cholesterol in sitosterolemia caused by mutations in adjacent ABC transporters

In healthy individuals, acute changes in cholesterol intake produce modest changes in plasma cholesterol levels. A striking exception occurs in sitosterolemia, an autosomal recessive disorder characterized by increased intestinal absorption and decreased biliary excretion of dietary sterols, hypercholesterolemia, and premature coronary atherosclerosis. We identified seven different mutations in two adjacent, oppositely oriented genes that encode new members of the adenosine triphosphate (ATP)-binding cassette (ABC) transporter family (six mutations in ABCG8 and one in ABCG5) in nine patients with sitosterolemia. The two genes are expressed at highest levels in liver and intestine and, in mice, cholesterol feeding up-regulates expressions of both genes. These data suggest that ABCG5 and ABCG8 normally cooperate to limit intestinal absorption and to promote biliary excretion of sterols, and that mutated forms of these transporters predispose to sterol accumulation and atherosclerosis.

Regulation of mouse sterol regulatory element-binding protein-1c gene (SREBP-1c) by oxysterol receptors, LXRalpha and LXRbeta

The liver X receptors (LXRs) are members of the nuclear hormone receptor superfamily that are bound and activated by oxysterols. These receptors serve as sterol sensors to regulate the transcription of gene products that control intracellular cholesterol homeostasis through catabolism and transport. In this report, we describe a novel LXR target, the sterol regulatory element-binding protein-1c gene (SREBP-1c), which encodes a membrane-bound transcription factor of the basic helix-loop-helix-leucine zipper family. SREBP-1c expression was markedly increased in mouse tissues in an LXR-dependent manner by dietary cholesterol and synthetic agonists for both LXR and its heterodimer partner, the retinoid X receptor (RXR). Expression of the related gene products, SREBP-1a and SREBP-2, were not increased. Analysis of the mouse SREBP-1c gene promoter revealed an RXR/LXR DNA-binding site that is essential for this regulation. The transcriptional increase in SREBP-1c mRNA by RXR/LXR was accompanied by a similar increase in the level of the nuclear, active form of the SREBP-1c protein and an increase in fatty acid synthesis. Because this active form of SREBP-1c controls the transcription of genes involved in fatty acid biosynthesis, our results reveal a unique regulatory interplay between cholesterol and fatty acid metabolism.

Role of LXRs in control of lipogenesis

The discovery of oxysterols as the endogenous liver X receptor (LXR) ligands and subsequent gene targeting studies in mice provided strong evidence that LXR plays a central role in cholesterol metabolism. The identification here of a synthetic, nonsteroidal LXR-selective agonist series represented by T0314407 and T0901317 revealed a novel physiological role of LXR. Oral administration of T0901317 to mice and hamsters showed that LXR activated the coordinate expression of major fatty acid biosynthetic genes (lipogenesis) and increased plasma triglyceride and phospholipid levels in both species. Complementary studies in cell culture and animals suggested that the increase in plasma lipids occurs via LXR-mediated induction of the sterol regulatory element-binding protein 1 (SREBP-1) lipogenic program.

Regulation of absorption and ABC1-mediated efflux of cholesterol by RXR heterodimers

Several nuclear hormone receptors involved in lipid metabolism form obligate heterodimers with retinoid X receptors (RXRs) and are activated by RXR agonists such as rexinoids. Animals treated with rexinoids exhibited marked changes in cholesterol balance, including inhibition of cholesterol absorption and repressed bile acid synthesis. Studies with receptor-selective agonists revealed that oxysterol receptors (LXRs) and the bile acid receptor (FXR) are the RXR heterodimeric partners that mediate these effects by regulating expression of the reverse cholesterol transporter, ABC1, and the rate-limiting enzyme of bile acid synthesis, CYP7A1, respectively. Thus, these RXR heterodimers serve as key regulators of cholesterol homeostasis by governing reverse cholesterol transport from peripheral tissues, bile acid synthesis in liver, and cholesterol absorption in intestine.

Glutathione S-transferase metabolism of the antineoplastic pentafluorophenylsulfonamide in tissue culture and mice

The microtubule disrupting agent 2-fluoro-1-methoxy-4-pentafluorophenylsu lfonamidobenzene (T138067) binds covalently and selectively to beta-tubulin and has been shown to evade drug-efflux pumps that confer multidrug resistance to other antimitotic drugs that are used in cancer chemotherapy (Shan et al., 1999). In addition to these resistance mechanisms, eukaryotic cells have developed other protection mechanisms that involve enzymes that modify electrophilic xenobiotics. To determine whether T138067 is a substrate for such enzymatic detoxification pathways, a metabolism study was initiated. GSH conjugation was shown to play a major role in T138067 metabolism. T138067-GSH conjugates were isolated from the culture media of T138067-treated cells and the bile of mice treated i.v. with T138067. The major T138067-GSH degradation products were also isolated from these sources. 19F NMR studies of the metabolites showed that metabolic conversions occurred through substitution of the para fluorine atom in the pentafluorophenyl ring of T138067. The T138067-GSH conjugate was also isolated from T138067 incubation buffer that had been exposed to mouse, rat, dog, or human liver slices, suggesting that this mechanism is not species-specific. All three human glutathione S-transferases (alpha, mu, and pi), which are expressed in a wide variety of tissues including human tumors, were shown to metabolize T138067 effectively in vitro. The combined data show that T138067 is being metabolized, in vitro and in vivo, predominantly via a glutathione S-transferase-mediated metabolic pathway.

Prevention of intima hyperplasia by mitogen-activated protein kinase antisense oligodeoxynucleotide

AIM

To investigate the preventive effect of Ca(2+)-calmodulin dependent kinase (CCDPK) (formerly: mitogen-activated protein kinase or MAPK) antisense phosphorothioate oligodeoxynucleotide (ODN) on vascular smooth muscle cell (VSMC) proliferation in vitro and on intima hyperplasia after injury in vivo.

METHODS

Liposomal transfection was used to introduce phosphorothioate-protected 17-mer antisense CCDPK ODN directed against the initiation of translation sites of the p42 and p44 CCDPK isoforms into cultured rat VSMC to deplete CCDPK and DNA synthesis induced by endothelin-1 (ET) or platelet derived growth factor (PDGF). A 17-mer sense and a random sequence CCDPK ODN were used as controls. CCDPK protein p44 and p42 levels were measured by Western blot. DNA synthesis was measured by [3H]thymidine incorporation. In in vivo study, rat balloon angioplasty was performed by a 2F Fogarty catheter. The antisense CCDPK ODN 200 micrograms was administered to the adventitial surface of the injured carotid artery by pluronic gel 30% (w/v) solution. Two weeks after vascular injury, carotid arteries were removed and cross sections were made and stained with hematoxylin/eosin for patho-histological examination. Fluorecein isothiocynate (FITC)-labeled and phosphorothioate-protected ODN was used to detect the uptake of ODN in vitro and in vivo.

RESULTS

CCDPK antisense ODN (0.4 mumol.L-1) reduced p42/p44 protein expression and inhibited VSMC [3H]thymidine incorporation stimulated by ET and PDGF. Antisense CCDPK ODN treatment at 2 wk after injury resulted in a significant inhibition of intima hyperplasia, compared with untreated vessels.

CONCLUSION

The p42/p44-CCDPK antisense ODN inhibits in vitro stimulated rat VSMC proliferation and in vivo injured arterial intima hyperplasia.

FXR, a bile acid receptor and biological sensor

Bile acid synthesis is a major pathway for cholesterol disposal and thus represents a potential therapeutic target pathway for the treatment of hypercholesterolemia. Recently, the nuclear farnesoid X receptor (FXR) was identified as a bile acid receptor and biological sensor for the regulation of bile acid biosynthesis. FXR was shown to regulate cholesterol metabolism in two ways: (1) chenodeoxycholic acid (CDCA), a primary bile acid, binds directly to and activates FXR, which then mediates the feedback suppression by bile acids of cholesterol 7 alpha-hydroxylase (CYP7A1), the rate-limiting enzyme in bile acid biosynthesis from cholesterol; and (2) FXR participates in the activation of intestinal bile acid binding protein (IBABP), which is involved in the enterohepatic circulation of bile acids. Thus FXR constitutes a potential therapeutic target that can be modulated to enhance the removal of cholesterol from the body.