Sustained low-dose treatment with the histone deacetylase inhibitor LBH589 induces terminal differentation of osteosarcoma cells

Histone deacetylase inhibitors (HDACi) were identified nearly four decades ago based on their ability to induce cellular differentiation. However, the clinical development of these compounds as cancer therapies has focused on their capacity to induce apoptosis in hematologic and lymphoid malignancies, often in combination with conventional cytotoxic agents. In many cases, HDACi doses necessary to induce these effects result in significant toxicity. Since osteosarcoma cells express markers of terminal osteoblast differentiation in response to DNA methyltransferase inhibitors, we reasoned that the epigenetic reprogramming capacity of HDACi might be exploited for therapeutic benefit. Here, we show that continuous exposure of osteosarcoma cells to low concentrations of HDACi LBH589 (Panobinostat) over a three-week period induces terminal osteoblast differentiation and irreversible senescence without inducing cell death. Remarkably, transcriptional profiling revealed that HDACi therapy initiated gene signatures characteristic of chondrocyte and adipocyte lineages in addition to marked upregulation of mature osteoblast markers. In a mouse xenograft model, continuous low dose treatment with LBH589 induced a sustained cytostatic response accompanied by induction of mature osteoblast gene expression. These data suggest that the remarkable capacity of osteosarcoma cells to differentiate in response to HDACi therapy could be exploited for therapeutic benefit without inducing systemic toxicity

The association between isolated oligohydramnios at term and pregnancy outcome and perinatal outcome in case of isolated oligohydramnosis: a retrospective analysis

Background: Current study was carried out to assess the impact of isolated oligohydramnios on perinatal outcomes and mode of delivery.Methods: A retrospective observational cohort study was conducted at term pregnancy with sonographic finding of isolated oligohydramnios (AFI 5-25 cm).Results: When compared to the normal AFI, women with oligohydramnios had significantly lower birth weight babies and were delivered at a significantly earlier gestational age. However there was no difference in the APGAR scores at birth and NICU admissions between the two groups. Reactive NST had more chances of good APGAR score at 1 and 5 minute and that lower the AFI more the probability of nonreactive NST and abnormal Doppler. The number of inductions and caesareans done for foetal reasons were significantly higher in the exposed group.Conclusions: Obstetric and perinatal outcome remains similar in both isolated oligohydramnios with reactive NST as well as in patients with normal amniotic fluid index. Isolated oligohydramnios is not associated with adverse perinatal outcomes. However, it increases the risk for labour induction and caesarean section

ANTAGONISM OF SOME WELL-KNOWN BIOAGENTS AGAINST CURVULARIA ERAGROSTIDIS (HENN.) J.A.MEY. - AN INCITANT OF SPIDER LILLY LEAF TIP BLIGHT

Investigation on leaf tip blight (Curvularia eragrostidis (Henn.) J. A. Mey. of spider lilly (Hymenocallis littoralis L.) under south Gujarat conditions was carried out to find out suitable management strategies. Due to hazardous effect of chemical fungicides, search for safer alternative to control the pathogen is better choice. This led to trials on the use of bioagents to control the pathogen. The eight known bioagents were evaluated by dual culture, pathogen at periphery and pathogen at the centre technique to monitor antagonistic effect. The results revealed that out of all the eight bioagents used, three bioagents viz., T. viride (73.39 %, 69.80%, and 70.73% maximum growth inhibition in dual culture, pathogen at periphery and pathogen at the centre methods respectively), T. longibrachyatum (71.76%, 64.57% and 69.93% maximum growth inhibition in dual culture, pathogen at periphery and pathogen at the centre methods respectively) and T. harzianum (67.75%, 63.55% and 67.49% maximum growth inhibition in dual culture, pathogen at periphery and pathogen at the centre methods respectively) showed strong antagonistic effect to inhibit the mycelia growth of the pathogen significantly

Rb regulates fate choice and lineage commitment in vivo

February 1, 2011Mutation of the retinoblastoma gene (RB1) tumour suppressor occurs in one-third of all human tumours and is particularly associated with retinoblastoma and osteosarcoma[superscript 1]. Numerous functions have been ascribed to the product of the human RB1 gene, the retinoblastoma protein (pRb). The best known is pRb’s ability to promote cell-cycle exit through inhibition of the E2F transcription factors and the transcriptional repression of genes encoding cell-cycle regulators[superscript 1]. In addition, pRb has been shown in vitro to regulate several transcription factors that are master differentiation inducers[superscript 2]. Depending on the differentiation factor and cellular context, pRb can either suppress or promote their transcriptional activity. For example, pRb binds to Runx2 and potentiates its ability to promote osteogenic differentiation in vitro[superscript 3]. In contrast, pRb acts with E2F to suppress peroxisome proliferator-activated receptor γ subunit (PPAR-γ), the master activator of adipogenesis[superscript 4, 5]. Because osteoblasts and adipocytes can both arise from mesenchymal stem cells, these observations suggest that pRb might play a role in the choice between these two fates. However, so far, there is no evidence for this in vivo. Here we use mouse models to address this hypothesis in mesenchymal tissue development and tumorigenesis. Our data show that Rb status plays a key role in establishing fate choice between bone and brown adipose tissue in vivo.National Cancer Institute (U.S.) (Grant)National Institutes of Health (U.S.) (Grant

The Role of Glypicans in Wnt Inhibitory Factor-1 Activity and the Structural Basis of Wif1's Effects on Wnt and Hedgehog Signaling

Proper assignment of cellular fates relies on correct interpretation of Wnt and Hedgehog (Hh) signals. Members of the Wnt Inhibitory Factor-1 (WIF1) family are secreted modulators of these extracellular signaling pathways. Vertebrate WIF1 binds Wnts and inhibits their signaling, but its Drosophila melanogaster ortholog Shifted (Shf) binds Hh and extends the range of Hh activity in the developing D. melanogaster wing. Shf activity is thought to depend on reinforcing interactions between Hh and glypican HSPGs. Using zebrafish embryos and the heterologous system provided by D. melanogaster wing, we report on the contribution of glypican HSPGs to the Wnt-inhibiting activity of zebrafish Wif1 and on the protein domains responsible for the differences in Wif1 and Shf specificity. We show that Wif1 strengthens interactions between Wnt and glypicans, modulating the biphasic action of glypicans towards Wnt inhibition; conversely, glypicans and the glypican-binding “EGF-like” domains of Wif1 are required for Wif1's full Wnt-inhibiting activity. Chimeric constructs between Wif1 and Shf were used to investigate their specificities for Wnt and Hh signaling. Full Wnt inhibition required the “WIF” domain of Wif1, and the HSPG-binding EGF-like domains of either Wif1 or Shf. Full promotion of Hh signaling requires both the EGF-like domains of Shf and the WIF domains of either Wif1 or Shf. That the Wif1 WIF domain can increase the Hh promoting activity of Shf's EGF domains suggests it is capable of interacting with Hh. In fact, full-length Wif1 affected distribution and signaling of Hh in D. melanogaster, albeit weakly, suggesting a possible role for Wif1 as a modulator of vertebrate Hh signaling

Charge transport mechanisms in monovalent doped mixed valent manganites

Abstract In this communication, we report the results of the studies on structural and transport properties of monovalent Na + doped La 1-x Na x MnO 3 (LNMO; x = 0.00, 0.05, 0.10, 0.15, 0.20, 0.25 and 0.30) manganites synthesized by conventional ceramic method. X-ray diffraction (XRD) and Rietveld refinements reveal the single phasic nature of LNMO manganites without any detectable impurity within the measurement range. Temperature dependent resistivity, under different applied magnetic fields, has been performed on LNMO samples. Samples understudy exhibit metal to insulator (semiconductor) transition at temperature T P which is strongly influenced by the substitution of Na + at La 3+ site. -T plots also exhibit resistivity upturn behavior at low temperature well below 40K under all the applied fields. Variation in T P and resistivity has been discussed in the context of the competition between the transport favoring tolerance factor and zener double exchange (ZDE) mechanism and transport degrading Jahn-Teller (JT) and size variance effects. In order to understand the mechanisms responsible for the charge transport in metallic and semiconducting regions and to explore the possible electronic processes responsible for the observed low temperature resistivity minima in all the presently studied LNMO manganites, various models have been employed. It has been found that VRH mechanism gets successfully fitted to the resistivity data in the semiconducting region while ZDE polynomial law is responsible for the charge conduction in metallic region for all the presently studied LNMO samples. A strong dependence of activation energy on the Na + -content as well as applied magnetic field has been discussed in the context of variation and interrelations between the structural parameters. Charge conduction in metallic region has been discussed in the light of electron-phonon interactions which is influenced by the Na + -content and applied magnetic field. Electrostatic blockade model has been employed to understand the low temperature resistivity minima behavior. Blocking energy for the charge carriers shows a dependence on the magnetic energy provided to the charge carriers. Present study can be useful to understand and to control the charge conduction in the manganites and hence to design the manganite based thin film devices for various spintronic applications

Oligomerization of the E. coli Core RNA Polymerase: Formation of (α2ββ'ω)2–DNA Complexes and Regulation of the Oligomerization by Auxiliary Subunits

In this work, using multiple, dissimilar physico-chemical techniques, we demonstrate that the Escherichia coli RNA polymerase core enzyme obtained through a classic purification procedure forms stable (α2ββ'ω)2 complexes in the presence or absence of short DNA probes. Multiple control experiments indicate that this self-association is unlikely to be mediated by RNA polymerase-associated non-protein molecules. We show that the formation of (α2ββ'ω)2 complexes is subject to regulation by known RNA polymerase interactors, such as the auxiliary SWI/SNF subunit of RNA polymerase RapA, as well as NusA and σ70. We also demonstrate that the separation of the core RNA polymerase and RNA polymerase holoenzyme species during Mono Q chromatography is likely due to oligomerization of the core enzyme. We have analyzed the oligomeric state of the polymerase in the presence or absence of DNA, an aspect that was missing from previous studies. Importantly, our work demonstrates that RNA polymerase oligomerization is compatible with DNA binding. Through in vitro transcription and in vivo experiments (utilizing a RapAR599/Q602 mutant lacking transcription-stimulatory function), we demonstrate that the formation of tandem (α2ββ'ω)2–DNA complexes is likely functionally significant and beneficial for the transcriptional activity of the polymerase. Taken together, our findings suggest a novel structural aspect of the E. coli elongation complex. We hypothesize that transcription by tandem RNA polymerase complexes initiated at hypothetical bidirectional “origins of transcription” may explain recurring switches of the direction of transcription in bacterial genomes

Molecular alterations as target for therapy in metastatic osteosarcoma: a review of literature

Treating metastatic osteosarcoma (OS) remains a challenge in oncology. Current treatment strategies target the primary tumour rather than metastases and have a limited efficacy in the treatment of metastatic disease. Metastatic cells have specific features that render them less sensitive to therapy and targeting these features might enhance the efficacy of current treatment. A detailed study of the biological characteristics and behaviour of metastatic OS cells may provide a rational basis for innovative treatment strategies. The aim of this review is to give an overview of the biological changes in metastatic OS cells and the preclinical and clinical efforts targeting the different steps in OS metastases and how these contribute to designing a metastasis directed treatment for OS