Targeting etoposide to acute myelogenous leukaemia cells using nanostructured lipid carriers coated with transferrin

The aim of the present study was to evaluate the diverse properties of transferrin (Tf)-conjugated nanostructured lipid carriers (NLCs) prepared using three different fatty amines, including stearylamine (SA), dodecylamine (DA) and spermine (SP), and two different methods for Tf coupling. Etoposide-loaded NLCs were prepared by an emulsion-solvent evaporation method followed by probe sonication. Chemical coupling of NLCs with Tf was mediated by an amide linkage between the surface-exposed amino group of the fatty amine and the carboxyl group of the protein. The physical coating was performed in a Ringer-Hepes buffer medium. NLCs were characterized by their particle size, zeta potential, polydispersity index, drug entrapment percentage, drug release profiles and Tf-coupling efficiency. The cytotoxicity of NLCs on K562 acute myelogenous leukaemia cells was studied by MTT assay, and their cellular uptake was studied by a flow cytometry method. SA-containing NLCs showed the lowest particle size, the highest zeta potential and the largest coupling efficiency values. The drug entrapment percentage and the zeta potential decreased after Tf coupling, but the average particle size increased. SP-containing formulations released their drug contents comparatively slower than SA- or DA-containing NLCs. Unconjugated NLCs released moderately more drug than Tf-NLCs. Flow cytometry studies revealed enhanced cellular uptake of Tf-NLCs compared to unconjugated ones. Blocking Tf receptors resulted in a significantly higher cell survival rate for Tf-NLCs. The highest cytotoxic activity was observed in the chemically coupled SA-containing nanoparticles, with an IC(50) value of 15-fold lower than free etoposide.

Differential effects of polyamine on the cytosolic and mitochondrial NADP-isocitrate dehydrogenases

Two isozymes of NADP-dependent isocitrate dehydrogenases (EC 1.1.1.42) exist in mammalian tissues: mitochondrial (ICD1) and cytosolic (ICD2). Effects of polyamines such as spermine, spermidine, and putrescine on the cytosolic and mitochondrial NADP-isocitrate dehydrogenases were analyzed kinetically. Spermine activated ICD2, the cytosolic NADP-isocitrate dehydrogenase from rat liver with the increase in the maximal velocity and the decrease in the affinity for the substrates isocitrate and NADP. The activating action of spermine can be explained by "the uncompetitive effect," and the dissociation constant of spermine for the enzyme-substrate complex was determined to be 1.68 mM. Spermidine and putrescine showed little or no effect. ICD1, the mitochondrial form of NADP-isocitrate dehydrogenase from rat and porcine heart was inhibited by spermine effectively, and by spermidine and putrescine to a lesser extent. Spermine inhibited the enzyme competitively with respect to NADP, and noncompetitively with respect to isocitrate. K(i) value of the enzyme for spermine was 1.3 mM. These results suggest that activation by spermine of cytosolic NADP-isocitrate dehydrogenase can enhance the antioxidant activity by regeneration of GSH, and further is responsible for the stimulation of lipid biosynthesis in cytosol. Spermine may contribute to NADPH supply by enhancing transhydrogenase (EC1.6.1.2) activity through the spermine-dependent activation of Ca(2+) -incorporation to mitochondria.

Thermospermine suppresses auxin-inducible xylem differentiation in Arabidopsis thaliana

Thermospermine, a structural isomer of spermine, is synthesized by a thermospermine synthase designated ACAULIS5 (ACL5). Thermospermine-deficient acl5 mutant of Arabidopsis thaliana shows severe dwarfism and excessive xylem differentiation. By screening for compounds that affect xylem differentiation in the acl5 mutant, we identified auxin analogs that remarkably enhanced xylem vessel differentiation in the acl5 mutant but not in the wild type. The xylem-inducing effect of auxin analogs was clearly suppressed by thermospermine, indicating that auxin-inducible xylem differentiation is normally limited by thermospermine. Here, we further characterized xylem-inducing effect of auxin analogs in various organs. Auxin analogs promoted protoxylem differentiation in roots and cotyledons in the acl5 mutant. Our results indicate that the opposite action between thermospermine and auxin in xylem differentiation is common in different organs and also suggest that thermospermine might be required for the suppression of protoxylem differentiation.

Exogenous thermospermine has an activity to induce a subset of the defense genes and restrict cucumber mosaic virus multiplication in Arabidopsis thaliana

We previously proposed the defensive role of a signal pathway triggered by the polyamine spermine (Spm) in the reaction against avirulent viral pathogens in Nicotiana tabacum and Arabidopsis thaliana. In this study, we showed that thermospermine (T-Spm), an isomer of Spm, is also active in inducing the expression of the genes involved in the Spm-signal pathway at a similar dose as Spm. Furthermore, we found that T-Spm enhances the expression of a subset of pathogenesis-related genes whose expression is induced during cucumber mosaic virus (CMV)-triggered hypersensitive response. In consistent with the above observation, we further showed that exogenous T-Spm can repress CMV multiplication with same efficiency as Spm.

KEY MESSAGE

Polyamine thermospermine, an isomer of spermine, is able to induce a subset of hypersensitive response-related defense genes and can suppress cucumber mosaic virus multiplication in Arabidopsis thaliana.

[Extracellular Ca(2+) influx and NO generation are inhibited by small interference RNA targeting extracellular Ca(2+)-sensing receptor in human umbilical vein endothelial cells]

To investigate the effect of Ca(2+)-sensing receptor (CaR) on Spermine-induced extracellular Ca(2+) influx and NO generation in human umbilical vein endothelial cells (HUVEC), the small interference RNA (siRNA) specifically targeting CaR gene was designed, synthesized and transfected into HUVEC according to the cDNA sequence of human CaR gene in GenBank. The transfection efficiency and the interference efficiency of CaR protein were determined by laser scanning confocal microscopy and Western blot, respectively. Intracellular Ca(2+) concentration ([Ca(2+)](i)) was measured by Fura-2/AM loading. The production of NO and the activity of endothelial nitric oxide synthase (eNOS) were determined by the DAF-FM diacetate (DAF-FM DA). Western blot results demonstrated that siRNA targeting the CaR specifically decreased the expression of CaR protein in CaR siRNA group 48 h after transfection (P < 0.05). At the same time, the Spermine-induced [Ca(2+)](i), eNOS activity and NO generation were also significantly reduced (P < 0.05) in CaR siRNA group compared with those in the untransfected or negative siRNA transfected group. In conclusion, the present study suggests that the CaR plays an important role in the Spermine-evoked process of extracellular Ca(2+) influx and NO generation in HUVEC.

Cross-linking of serine racemase dimer by reactive oxygen species and reactive nitrogen species

Serine racemase (SR) is the only identified enzyme in mammals responsible for isomerization of L-serine to D-serine, a coagonist at N-methyl-D-aspartate (NMDA) receptors in the forebrain. Our previous data showed that an apparent SR dimer resistant to sodium dodecyl sulfate and β-mercaptoethanol was elevated in microglial cells after proinflammatory activation. Because the activation of microglia is typically associated with an oxidative burst, oxidative cross-linking between SR subunits was speculated. In this study, an siRNA technique was employed to confirm the identity of this SR dimer band. The oxidative species potentially responsible for the cross-linking was investigated with recombinant SR protein. The data indicate that nitric oxide, peroxynitrite, and hydroxyl radical were the likely candidates, whereas superoxide and hydrogen peroxide per se failed to contribute. Furthermore, the mechanism of formation of SR dimer by peroxynitrite oxidation was studied by mass spectrometry. A disulfide bond between Cys₆ and Cys₁₁₃ was identified in 3-morpholinosydnonimine hydrochloride (SIN-1)-treated SR monomer and dimer. Activity assays indicated that SIN-1 treatment decreased SR activity, confirming our previous conclusion that noncovalent dimer is the most active form of SR. These findings suggest a compensatory feedback in which the consequences of neuroinflammation might dampen D-serine production to limit excitotoxic stimulation of NMDA receptors.

Spermine, a molecular switch regulating EGFR, integrin β3, Src, and FAK scaffolding

Intracellular polyamine levels are highly regulated by the activity of ornithine decarboxylase (ODC), which catalyzes the first rate-limiting reaction in polyamine biosynthesis, producing putrescine, which is subsequently converted to spermidine and spermine. We have shown that polyamines regulate proliferation, migration, and apoptosis in intestinal epithelial cells. Polyamines regulate key signaling events at the level of the EGFR and Src. However, the precise mechanism of action of polyamines is unknown. In the present study, we demonstrate that ODC localizes in lamellipodia and in adhesion plaques during cell spreading. Spermine regulates EGF-induced migration by modulating the interaction of the EGFR with Src. The EGFR interacted with integrin β3, Src, and focal adhesion kinase (FAK). Active Src (pY418-Src) localized with FAK during spreading and migration. Spermine prevented EGF-induced binding of the EGFR with integrin β3, Src, and FAK. Activation of Src and FAK was necessary for EGF-induced migration in HEK293 cells. EGFR-mediated Src activation in live HEK293 cells using a FRET based Src reporter showed that polyamine depletion significantly increased Src kinase activity. In vitro binding studies showed that spermine directly binds Src, and preferentially interacts with the SH2 domain of Src. The physical interaction between Src and the EGFR was severely attenuated by spermine. Therefore, spermine acts as a molecular switch in regulating EGFR-Src coupling both physically and functionally. Upon activation of the EGFR, integrin β3, FAK and Src are recruited to EGFR leading to the trans-activation of both the EGFR and Src and to the Src-mediated phosphorylation of FAK. The activation of FAK induced Rho-GTPases and subsequently migration. This is the first study to define mechanistically how polyamines modulate Src function at the molecular level.

Effect of Spermine-NONOate on acrosome reaction and associated protein tyrosine phosphorylation in Murrah buffalo (Bubalus bubalis) spermatozoa

The present study was conducted to know the role of Nitric Oxide (NO) on the acrosome reaction (AR) in Murrah buffalo (Bubalus bubalis) spermatozoa. Ejaculated buffalo spermatozoa were washed, suspended in sp-TALP media containing 6 mg BSA/mL and cell concentration was adjusted to 50×10(6) cells/mL. The cells were incubated for 6h in the absence or presence of heparin (10 μg/mL) to induce capacitation. Fully capacitated spermatozoa were incubated in presence of 100 μg/mL Lysophosphatidyl choline (LPC, T1) or 100 μM Spermine-NONOate (T2) or 100 mM L-NAME (T3) or 100 μM Spermine-NONOate+100 mM L-NAME (T4) or 1 mM db-cAMP + 0.1 mM IBMX (T5) or 100μM H-89 (T6) or 100 μM Spermine-NONOate+100 μM H-89 (T7) in combination to induce acrosome reaction. The extent of AR was assessed by dual-staining of spermatozoa with trypan blue/Giemsa stain. AR-associated tyrosine-phosphorylated proteins were detected by SDS-PAGE followed by immunoblotting using monoclonal anti-phosphotyrosine antibody. Significant (P<0.05) number of spermatozoa were acrosome reacted in Spermine-NONOate (T2) treated cells but it was significantly (P<0.05) lower than LPC (T1) induced AR. Addition of Spermine-NONOate + L-NAME (T4) resulted in non significant (P>0.05) decrease in acrosome reaction. On addition of H-89 + Spermine-NONOate (T7) to sperm culture medium, resulted in significant (P<0.05) decrease in the percent acrosome reaction. Conversely, addition of db-cAMP+IBMX (T5, cAMP analogue) resulted in the significantly (P<0.05) higher number of acrosome reacted spermatozoa. Pattern of sperm protein tyrosine phosphorylation was also different in NO induced acrosome reaction compared to that of LPC. The present study concluded that nitric oxide is involved in acrosome reaction of buffalo spermatozoa by causing the tyrosine phosphorylation of proteins mainly p17 and p20 and through activation of cAMP/PKA pathway.

Selenium and spermine alleviate cadmium induced toxicity in the red seaweed Gracilaria dura by regulating antioxidants and DNA methylation

The protective role of exogenously supplied selenium (Se) and polyamines (PAs) such as putrescine (Put) and spermine (Spm) in detoxifying the cadmium (Cd) induced toxicity was studied in the marine red alga Gracilaria dura in laboratory conditions. The Cd exposure (0.4 mM) impede the growth of alga while triggering the reactive oxygen species (ROS viz. O(2)(•-) and H(2)O(2)) generation, inhibition of antioxidant system, and enhancing the lipoxygenase (LOX) activity, malondialdehyde (MDA) level and demethylation of DNA. Additions of Se (50 μM) and/or Spm (1 mM) to the culture medium in contrast to Put, efficiently ameliorated the Cd toxicity by decreasing the accumulation of ROS and MDA contents, while restoring or enhancing the level of enzymatic and nonenzymatic antioxidants and their redox ratio, phycobiliproteins and phytochelatins, over the controls. The isoforms of antioxidant enzymes namely superoxide dismutase (Mn-SOD, ~150 kDa; Fe-SOD ~120 kDa), glutathione peroxidase (GSH-Px, ~120 and 140 kDa), glutathione reductase (GR, ~110 kDa) regulated differentially to Se and/or Spm supplementation. Furthermore, it has also resulted in enhanced levels of endogenous PAs (specially free and bound insoluble Put and Spm) and n-6 PUFAs (C20-3, n-6 and C20-4, n-6). This is for the first time wherein Se and Spm were found to regulate the stabilization of DNA methylation by reducing the events of cytosine demethylation in a mechanism to alleviate the Cd stress in marine alga. The present findings reveal that both Se and Spm play a crucial role in controlling the Cd induced oxidative stress in G. dura.

[Acetylsalicylic acid strengthens the effects of ANISpm against hepatocellular carcinoma and its molecular mechanism]

The objective of this study is to examine the effects of ANISpm, a novel polyamine naphthalimide conjugate, with acetylsalicylic acid against hepatocellular carcinoma in vivo and in vitro and elucidate its potential molecular mechanism. The proliferation inhibition was detected by MTT assay. Cell apoptosis, intracellular fluorescence intensity and mitochondrial membrane potential (MMP) were detected by high content screening (HCS) analysis. Polyamines content was analyzed by reverse-phase high performance liquid chromatography Protein expression levels were quantified by Western blotting assay. The combination treatment strongly inhibited cell proliferation, induced cell apoptosis in HepG2 cells and H22 hepatoma cells, which was mediated by enhanced ANISpm uptake via up-regulation of spermidine/spermine N1-acetyltransferase (SSAT) and depression of intracellular polyamine. Furthermore, this synergistic apoptosis was involved in mitochondria and death-receptor signal pathway. All these findings demonstrated that the combination treatment with acetylsalicylic acid and ANISpm resulted in synergistic antitumor effects on hepatoma cells. Thus, combination therapy with these agents may be useful as a potential template for the development of better chemotherapeutic strategy against hepatoma.

Ovarian steroids modulate tumor necrosis factor-α and nitric oxide-regulated prostaglandin secretion by cultured bovine oviductal epithelial cells

Ovarian steroids assure an optimum environment for the final maturation of oocytes, gamete transport, fertilization, and early embryonic development. The aim of experiment 1 was to examine the influence of ovarian steroids on tumor necrosis factor-α (TNF-α)- or nitric oxide (NO)-regulated prostaglandin (PG), and nitrite/nitrate (NO₂/NO₃) secretion by cultured bovine oviductal epithelial cells (BOECs). BOECs were pretreated with 17β-estradiol (E₂; 10⁻⁹ M) and/or progesterone (P₄; 10⁻⁷ M) for 24 h. For the next 24 h, BOECs were treated with TNF-α (10 ng/mL) or spermine nitric oxide complex (NONOate; 10⁻⁵ M). Prostaglandin F(2α) and PGE₂ secretion was measured in medium by ELISA. The pretreatment of cells with P₄ (progesterone), E₂ (17 β-estradiol), or E₂/P₄ augmented TNF-α-induced PGF(2α) and PGE₂ secretion (P < 0.01). The pretreatment of cells with E₂ or E₂/P₄ increased NONOate-induced PGF(2α) and PGE₂ secretion (P < 0.01). TNF-α induced NO₂/NO₃ production by BOECs. The pretreatment of cells with E₂ augmented only TNF-α-induced NO₂/NO₃ production (P < 0.05). The aim of experiment 2 was to examine the influence of TNF-α, NO, and ovarian steroids on the protein content of enzymes specifically involved in PG and NO production, PG synthases, and NO synthases (NOSs). BOECs were treated with TNF-α (10 ng/mL) or NONOate (10⁻⁵ M). TNF-α increased the protein content of PGG/H synthase, PGF synthase, and PGE synthase (P < 0.05) and endothelial and inducible NOSs (P < 0.05). Nitric oxide increased the protein content of PGF synthase, PGE synthase, endothelial NOS, and inducible NOS (P < 0.05). These results show possible linkage between TNF-α and NO, modulated by ovarian steroids, in the regulation of PG synthesis by BOECs that may be important for triggering the process of oviductal contractions.

Antisense and antigene inhibition of gene expression by cell-permeable oligonucleotide-oligospermine conjugates

Oligonucleotides and their derivatives are a proven chemical strategy for modulating gene expression. However, their negative charge remains a challenge for delivery and target recognition inside cells. Here we show that oligonucleotide-oligospermine conjugates (Zip nucleic acids or ZNAs) can help overcome these shortcomings by serving as effective antisense and antigene agents. Conjugates containing DNA and locked nucleic acid (LNA) oligonucleotides are active, and oligospermine conjugation facilitates carrier-free cell uptake at nanomolar concentrations. Conjugates targeting the CAG triplet repeat within huntingtin (HTT) mRNA selectively inhibit expression of the mutant huntingtin protein. Conjugates targeting the promoter of the progesterone receptor (PR) function as antigene agents to block PR expression. These observations support further investigation of ZNA conjugates as gene silencing agents.

Amelioration of salinity stress by exogenously applied spermidine or spermine in three varieties of indica rice differing in their level of salt tolerance

We present here the comparative protective potentiality of exogenously applied polyamines (PAs), namely spermidine (Spd) and spermine (Spm), in mitigating NaCl toxicity and inducing short-term salinity tolerance in three indica rice varieties, namely M-1-48 (salt-sensitive), Nonabokra (salt-tolerant) and Gobindobhog (highly sensitive). The retardation in root length or shoot length and toxic Na(+) accumulation or K(+) loss, the considerable increment in malondialdehyde/H(2)O(2) accumulation or lipoxygenase activity, all of which were particularly noteworthy in M-1-48 and Gobindobhog during salinity stress, was appreciably reduced by co-treatment with Spd or Spm. Both the PAs also inhibited the extent of salt-induced protein carbonylation in all the varieties and enhanced protease activity, especially in Gobindobhog. The prevention of chlorophyll degradation was better with Spd in Nonabokra and Gobindobhog. While the salt-induced increase in anthocyanin or reducing sugar level was further prompted by Spd or Spm in all the varieties, the proline content was elevated by Spd particularly in Gobindobhog. During salinity stress, both the PAs were effective in lowering the putrescine accumulation in M-1-48 and Gobindobhog, and strikingly increasing the Spm level in all the varieties, the highest being in Gobindobhog. In addition, they enhanced the activity of peroxidases and compensated for the decreased catalase activity in all the varieties. Thus the two PAs could recuperate all the three varieties from salt-induced damages to different degrees. The salt injuries, encountered in M-1-48 and Gobindobhog, both of which showed greater susceptibility to salinity stress, were more pronouncedly alleviated and counteracted by the PAs, than the salt-tolerant Nonabokra. The reversal of inhibitory effect of salinity stress was conferred by preventing growth inhibition or various forms of cellular damages, maintaining proper K(+)/Na(+) balance or triggering the level of osmolytes and activity of antioxidant enzymes. Our communication offers a referenced evidence for an understanding of the mechanism by which higher PAs relieve the damages particularly in salt-sensitive rice varieties.

[Extracellular Ca(2+)-sensing receptor-induced extracellular Ca2+ influx is down-regulated by caveolin-1 in human umbilical vein endothelial cells]

Although the function of extracellular Ca(2+)-sensing receptor (CaR) is known, the regulatory mechanism of the CaR function remains to be clarified. The purpose of the present study was to investigate the effect of caveolin-1 (Cav-1) on CaR-induced extracellular Ca(2+) influx by using acute caveolae disruption with Filipin or siRNA targeted to the Cav-1 in human umbilical vein endothelial cells (HUVECs). Intracellular Ca(2+) concentration ([Ca(2+)](i)) was detected by Fura-2/AM loading. The results showed that different concentrations of extracellular Ca(2+) failed to increase [Ca(2+)](i), while the CaR agonist Spermine (2 mmol/L) resulted in an increase in [Ca(2+)](i) that was diminished in buffer without Ca(2+) (P<0.05). No matter in buffer with or without 2 mmol/L Ca(2+), the [Ca(2+)](i) increase induced by Spermine in HUVECs was abolished after inhibition of CaR by a negative allosteric modulator Calhex231 (1 μmol/L) (P<0.05), conversely, the effect of Spermine on the increase in [Ca(2+)](i) in HUVECs was further augmented after acute caveolae disruption with Filipin (1.5 μg/mL) or transfection with siRNA targeted to the Cav-1 (P<0.05). This indicated that Cav-1 produced an inhibition of CaR-induced extracellular Ca(2+) influx. As to the biological mechanism of Cav-1-induced inhibition, immunofluorescence technique showed that both CaR and Cav-1 were present in HUVECs, and confocal microscopy supported the co-localization of CaR and Cav-1 on the plasma membrane. Functionally, the Cav-1 protein expression was decreased in HUVECs transfected with siRNA targeted to the Cav-1 (P<0.05); simultaneously, the CaR membrane protein expression was decreased (P<0.05), whereas CaR total protein level was unaffected (P>0.05). In conclusion, the present study suggests that CaR and Cav-1 co-localize on the plasma membrane in HUVECs and CaR-induced Ca(2+) influx is down-regulated by binding with Cav-1, and the mechanism involves the effect of Cav-1 on CaR localization on the plasma membrane and attenuating the CaR response to the agonist.

Edaravone attenuates impairment of synaptic plasticity in granule cell layer of the dentate gyrus following traumatic brain injury

Effects of edaravone, a free radical scavenger, on post-traumatic impairment of long-term potentiation (LTP) were examined in granule cell layers of the dentate gyrus (DG) in vitro. Field EPSPs (fEPSPs) evoked by stimulation of the perforant path (PP) were recorded extracellularly in the DG one week after a moderate impact applied by a fluid percussion injury (FPI) device. High frequency stimulation (HFS) of the PP caused LTP of the fEPSP-slope in slices from naïve and sham-operated rats, however, the LTP was strongly depressed in slices from FPI rats. Intraperitoneal administration of edaravone 15 min after FPI prevented the hyperactivities of DG neurons and attenuated impairment of the LTP in FPI rat dentate granular cells. In vitro application of spermine NONOate (sp-NO), a nitric oxide (NO) donor, for 30 min produced a gradual increase in the fEPSP-slope, lasting for more than 2 h. Edaravone attenuated the enhancement of the fEPSP-slope induced by sp-NO. After sp-NO treatment HFS could not produce an obvious LTP in the DG granule cell layer. Pretreatment of DG slices with edaravone prevented the sp-NO-induced impairment of LTP. These results suggest that administration of edaravone after FPI protects against post-traumatic impairment of LTP in granule cell layers of the DG, possibly by scavenging NO-related radicals.

Use of polyamine metabolites as markers for stroke and renal failure

Acrolein and H(2)O(2) are among the metabolic products of spermine and spermidine, and it was found that acrolein was more toxic than H(2)O(2). It was determined whether acrolein can serve as a biochemical marker for stroke (brain infarction) and chronic renal failure. Since acrolein rapidly reacts with lysine residues in protein, protein-conjugated acrolein (PC-Acro) was measured. PC-Acro was increased at the locus of brain infarction and in plasma in a mouse model of stroke involving photochemically induced thrombosis. An increase in PC-Acro in plasma was found to be a good biochemical marker in patients with stroke or with chronic renal failure. Using a receiver operating characteristic curve, the combined measurement of PC-Acro, IL-6 and CRP together with age indicated silent brain infarction (SBI) with 89% sensitivity and 91% specificity. The procedures to measure PC-Acro and polyamine oxidases [spermine oxidase (SMO) and acetylpolyamine oxidase (ACPAD)], and its application as markers in stroke and chronic renal failure are described in this chapter.

Osteogenic differentiation strategies for adipose-derived mesenchymal stem cells

Adipose stem cell preparations, either obtained as a freshly isolated so-called stromal vascular fraction (SVF) or as cells cultured to homogeneity and then referred to as adipose stem cells (ASCs), have found widespread use in a broad variety of studies on tissue engineering and regenerative medicine applications, including bone repair.For newcomers within the field, but also for established research laboratories having up to 10 years of expertise in this research area, it may be convenient to strive for, and use consensus protocols (1) for studying the osteogenic differentiation potential of ASC preparations in vitro, and (2) for osteogenic induction regimes for in vivo implementation. To assist in achieving this goal, this chapter describes various step-by-step osteogenic differentiation protocols for adipose-derived stem cell populations (SVF as well as ASCs) currently applied within our laboratory, with particular emphasis on protocols aimed at intra-operative use. The protocols describe the use of inducing compounds, including the bone morphogenetic proteins (BMPs), 1,25-dihydroxyvitamin-D3, and polyamines, as well as methods and parameters for evaluating the level of differentiation achieved.We would appreciate receiving feedback on the protocols described; this will facilitate the development of consensus protocols, which in turn will allow better comparison of data sets generated by different research groups. This continuing standardization, which might be reported on at international meetings like those of IFATS ( http://www.IFATS.org ), might be of benefit for the whole ASC research community.

Effects of methanolic and chloroform extracts of leaves of Alstonei boonei on rat liver mitochondrial membrane permeability transition pore

The effects of methanolic and chloroform extracts of the leaves of Alstonei boonei, a medicinal plant with anti-malarial, anti-inflammatory and analgesic properties, were assessed on liver mitochondrial membrane permeability transition (MMPT) pore were assessed in experimental animals in vitro and in vivo. The results obtained showed that calcium ions induced the opening of MMPT pore significantly (P< 0.05) in rat liver mitochondria, while spermine (0.1mM) inhibited calcium-induced opening of MMPT pore of these mitochondria thus, indicating that the mitochondria were intact, ab initio. The results further revealed the inhibitory effects of different concentrations of the various extracts of leaves of Alstonei boonei (200 microg/ml, 600 microg/ml, 1000 microg/ml, 1400 microg/ml) compared with spermine. Specifically, the data revealed that methanolic and chloroform extracts of leaves of Alstonei boonei reversed calcium-induced opening of MMPT pore in a concentration-dependent manner (26.5%, 27.4%, 56.4%, 69.3%) for methanolic extract of Alstonei boonei and (9.6%, 34.9%, 51.5% and 82.1%) for chloroform extract of Alstonei boonei, respectively. Although, the MMPT pore was not affected by low concentrations of the methanolic extract of Alstonei boonei (200 microg/ml and 600 microg/ml) in the absence of calcium, the extract at higher concentrations (1000 microg/ ml and 1400 microg/ml) induced the opening of the pore in a concentration-dependent manner. Mitochondria isolated from Wistar strain albino rats orally exposed to various doses of the methanolic extract of Alstonei boonei exhibited pore opening in the absence of calcium. In this respect, maximum (112%) induction of pore opening was obtained at 250mg/kg body weight, while minimum (31%) induction of pore opening was obtained at 200mg/kg body weight. Calcium further increased the extent of opening of the MMPT pore in animals previously exposed to methanolic extract of Alstonei boonei. These findings suggest that certain bioactive components of Alstonei boonei may be involved in inhibiting the opening of the MMPT pore in-vitro and in the induction of the opening of the pore at high doses of the extract with the eventual release of cytochrome C which is a prelude to the progression of programmed cell death.

Spermine oxidase (SMO) activity in breast tumor tissues and biochemical analysis of the anticancer spermine analogues BENSpm and CPENSpm

BACKGROUND

Polyamine metabolism has a critical role in cell death and proliferation representing a potential target for intervention in breast cancer (BC). This study investigates the expression of spermine oxidase (SMO) and its prognostic significance in BC. Biochemical analysis of Spm analogues BENSpm and CPENSpm, utilized in anticancer therapy, was also carried out to test their property in silico and in vitro on the recombinant SMO enzyme.

METHODS

BC tissue samples were analyzed for SMO transcript level and SMO activity. Student's t test was applied to evaluate the significance of the differences in value observed in T and NT samples. The structure modeling analysis of BENSpm and CPENSpm complexes formed with the SMO enzyme and their inhibitory activity, assayed by in vitro experiments, were examined.

RESULTS

Both the expression level of SMO mRNA and SMO enzyme activity were significantly lower in BC samples compared to NT samples. The modeling of BENSpm and CPENSpm complexes formed with SMO and their inhibition properties showed that both were good inhibitors.

CONCLUSIONS

This study shows that underexpression of SMO is a negative marker in BC. The SMO induction is a remarkable chemotherapeutical target. The BENSpm and CPENSpm are efficient SMO inhibitors. The inhibition properties shown by these analogues could explain their poor positive outcomes in Phases I and II of clinical trials.

Synthesis and biological characterization of novel charge-deficient spermine analogues

Biogenic polyamines, spermidine and spermine, are positively charged at physiological pH. They are present in all cells and essential for their growth and viability. Here we synthesized three novel derivatives of the isosteric charge-deficient spermine analogue 1,12-diamino-3,6,9-triazadodecane (SpmTrien, 5a) that are N(1)-Ac-SpmTrien (5c), N(12)-Ac-SpmTrien (5b), and N(1),N(12)-diethyl-1,12-diamino-3,6,9-triazadodecane (N(1),N(12)-Et(2)-SpmTrien, 5d). 5a and 5d readily accumulated in DU145 cells at the same concentration range as natural polyamines and moderately competed for the uptake with putrescine (1) but not with spermine (4a) or spermidine (2). 5a efficiently down-regulated ornithine decarboxylase and decreased polyamine levels, while 5d proved to be inefficient, compared with N(1),N(11)-diethylnorspermine (6). None of the tested analogues were substrates for human recombinant spermine oxidase, but those having free aminoterminus, including 1,8-diamino-3,6-diazaoctane (Trien, 3a), were acetylated by mouse recombinant spermidine/spermine N(1)-acetyltransferase. 5a was acetylated to 5c and 5b, and the latter was further metabolized by acetylpolyamine oxidase to 3a, a drug used to treat Wilson's disease. Thus, 5a is a bioactive precursor of 3a with enhanced bioavailability.

Inhibition of PTP1B by trodusquemine (MSI-1436) causes fat-specific weight loss in diet-induced obese mice

Trodusquemine (MSI-1436) causes rapid and reversible weight loss in genetic models of obesity. To better predict the potential effects of trodusquemine in the clinic, we investigated the effects of trodusquemine treatment in a murine model of diet-induced obesity (DIO). Trodusquemine suppressed appetite, reduced body weight (BW) in a fat-specific manner, and improved plasma insulin and leptin levels in mice. Screening assays revealed that trodusquemine selectively inhibited protein-tyrosine phosphatase 1B (PTP1B), a key enzyme regulating insulin and leptin signaling. Trodusquemine significantly enhanced insulin-stimulated tyrosine phosphorylation of insulin receptor (IR) beta and STAT3, direct targets of PTP1B, in HepG2 cells in vitro and/or hypothalamic tissue in vivo. These data establish trodusquemine as an effective central and peripheral PTP1B inhibitor with the potential to elicit noncachectic fat-specific weight loss and improve insulin and leptin levels.

Spermine pretreatment confers dehydration tolerance of citrus in vitro plants via modulation of antioxidative capacity and stomatal response

Polyamines, small aliphatic polycations, have been suggested to play key roles in a number of biological processes. In this paper, attempts were made to investigate the possibility of improving dehydration tolerance of citrus in vitro plants by exogenous application of spermine (Spm). 'Red Tangerine' (Citrus reticulata Blanco) in vitro plants pretreated with 1 mM Spm exhibited less wilted phenotype and lower water loss and electrolyte leakage than the control under dehydration. Spm-pretreated plants contained higher endogenous polyamine content during the course of the experiment relative to the control, particularly at the end of dehydration, coupled with higher expression levels of ADC and SPMS. Histochemical staining showed that the Spm-pretreated leaves were stained to a lower extent than those without Spm pretreatment, implying generation of less reactive oxygen species (ROS). On the contrary, activities of peroxidase (POD) and superoxide dismutase (SOD) in the Spm-pretreated samples were higher than the control at a given time point or during the whole experiment, suggesting that Spm exerted a positive effect on antioxidant systems. In addition, significantly smaller stomatal aperture size was observed in Spm-pretreated epidermal peels, which showed that stomatal closure was promoted by polyamines. All of these data suggest that Spm pretreatment causes accumulation of higher endogenous polyamines and accordingly leads to more effective ROS scavenging (less tissue damage) and stimulated stomatal closure (lower water loss) upon dehydration, which may function collectively to enhance dehydration tolerance.

Nitric oxide increases cyclic GMP levels, AMP-activated protein kinase (AMPK)alpha1-specific activity and glucose transport in human skeletal muscle

AIMS/HYPOTHESIS

We investigated the direct effect of a nitric oxide donor (spermine NONOate) on glucose transport in isolated human skeletal muscle and L6 skeletal muscle cells. We hypothesised that pharmacological treatment of human skeletal muscle with N-(2-aminoethyl)-N-(2-hydroxy-2-nitrosohydrazino)-1,2-ethylenediamine (spermine NONOate) would increase intracellular cyclic GMP (cGMP) levels and promote glucose transport.

METHODS

Skeletal muscle strips were prepared from vastus lateralis muscle biopsies obtained from seven healthy men. Muscle strips were incubated in the absence or presence of 5 mmol/l spermine NONOate or 120 nmol/l insulin. The L6 muscle cells were treated with spermine NONOate (20 micromol/l) and incubated in the absence or presence of insulin (120 nmol/l). The direct effect of spermine NONOate and insulin on glucose transport, cGMP levels and signal transduction was determined.

RESULTS

In human skeletal muscle, spermine NONOate increased glucose transport 2.4-fold (p < 0.05), concomitant with increased cGMP levels (80-fold, p < 0.001). Phosphorylation of components of the canonical insulin signalling cascade was unaltered by spermine NONOate exposure, implicating an insulin-independent signalling mechanism. Consistent with this, spermine NONOate increased AMP-activated protein kinase (AMPK)-alpha1-associated activity (1.7-fold, p < 0.05). In L6 muscle cells, spermine NONOate increased glucose uptake (p < 0.01) and glycogen synthesis (p < 0.001), an effect that was in addition to that of insulin. Spermine NONOate also elicited a concomitant increase in AMPK and acetyl-CoA carboxylase phosphorylation. In the presence of the guanylate cyclase inhibitor LY-83583 (10 micromol/l), spermine NONOate had no effect on glycogen synthesis and AMPK-alpha1 phosphorylation.

CONCLUSIONS/INTERPRETATION

Pharmacological treatment of skeletal muscle with spermine NONOate increases glucose transport via insulin-independent signalling pathways involving increased intracellular cGMP levels and AMPK-alpha1-associated activity.

The role of the polyamine catabolic enzymes SSAT and SMO in the synergistic effects of standard chemotherapeutic agents with a polyamine analogue in human breast cancer cell lines

INTRODUCTION

Polyamine analogues have demonstrated significant activity against human breast cancer cell lines as single agents as well as in combination with other cytotoxic drugs. This study evaluates the ability of a polyamine analogue N (1),N (11)-bis(ethyl)norspermine (BENSpm) to synergize with six standard chemotherapeutic agents, 5-fluorouracil (FU), fluorodeoxyuridine, cis-diaminechloroplatinum(II) (C-DDP), paclitaxel, docetaxel, and vinorelbine.

MATERIALS AND METHODS

Four human breast cancer cell lines (MDA-MB-231, MCF-7, Hs578t, and T47D) and one immortalized, non-tumorigenic mammary epithelial cell line (MCF-10A) were used for in vitro combination studies with BENSpm and cytotoxic drugs. Xenograft mice models generated with MDA-MB-231 cells were used for in vivo studies with BENSpm and paclitaxel.

RESULTS AND CONCLUSION

BENSpm exhibited synergistic inhibitory effect on cell proliferation in combination with 5-FU or paclitaxel in human breast cancer cell lines (MDA-MB-231 and MCF-7) and was either antagonistic or less effective in the non-tumorigenic MCF-10A cell line. Synergism was highest with 120 h concomitant treatment or pre-treatment with BENSpm for 24 h followed by concomitant treatment for 96 additional hours. Since the cytotoxic effects of many polyamine analogues and cytotoxic agents are believed to act, in part, through induction of the polyamine catabolic enzymes SSAT and SMO, the role of these enzymes on synergistic response was evaluated in MDA-MB-231 and MCF-7 treated with BENSpm and 5-FU or paclitaxel. Combination treatments of BENSpm with 5-FU or paclitaxel resulted in induction of SSAT mRNA and activity in both cell lines compared to either drug alone, while SMO mRNA and activity were increased only in MDA-MB-231 cells. Induction was greater with BENSpm/paclitaxel combination than BENSpm/5-FU. Further, RNAi studies demonstrated that both SSAT and SMO play a significant role in the response of MDA-MB-231 cells to treatment with BENSpm and 5-FU or paclitaxel. In MCF-7 cells, only SSAT appears to be involved in the response to these treatments. In an effort to translate combination studies from in vitro to in vivo, and to form a basis for clinical setting, the in vivo therapeutic efficacy of BENSpm alone and in combination with paclitaxel on tumor regression was evaluated in xenograft mice models generated with MDA-MB-231 cells. Intraperitoneal exposure to BENSpm or taxol singly and in combination for 4 weeks resulted in significant inhibition in tumor growth. These findings help elucidate the mechanisms involved in synergistic drug response and support combinations of polyamine analogues with chemotherapeutic agents which could potentially be used in the treatment of breast cancer.

AMPA receptor subunit GluR1 downstream of D-1 dopamine receptor stimulation in nucleus accumbens shell mediates increased drug reward magnitude in food-restricted rats

Previous findings suggest that neuroadaptations downstream of D-1 dopamine (DA) receptor stimulation in nucleus accumbens (NAc) are involved in the enhancement of drug reward by chronic food restriction (FR). Given the high co-expression of D-1 and GluR1 AMPA receptors in NAc, and the regulation of GluR1 channel conductance and trafficking by D-1-linked intracellular signaling cascades, the present study examined effects of the D-1 agonist, SKF-82958, on NAc GluR1 phosphorylation, intracranial electrical self-stimulation reward (ICSS), and reversibility of reward effects by a polyamine GluR1 antagonist, 1-NA-spermine, in ad libitum fed (AL) and FR rats. Systemically administered SKF-82958, or brief ingestion of a 10% sucrose solution, increased NAc GluR1 phosphorylation on Ser845, but not Ser831, with a greater effect in FR than AL rats. Microinjection of SKF-82958 in NAc shell produced a reward-potentiating effect that was greater in FR than AL rats, and was reversed by co-injection of 1-NA-spermine. GluR1 abundance in whole cell and synaptosomal fractions of NAc did not differ between feeding groups, and microinjection of AMPA, while affecting ICSS, did not exert greater effects in FR than AL rats. These results suggest a role of NAc GluR1 in the reward-potentiating effect of D-1 DA receptor stimulation and its enhancement by FR. Moreover, GluR1 involvement appears to occur downstream of D-1 DA receptor stimulation rather than reflecting a basal increase in GluR1 expression or function. Based on evidence that phosphorylation of GluR1 on Ser845 primes synaptic strengthening, the present results may reflect a mechanism via which FR normally facilitates reward-related learning to re-align instrumental behavior with environmental contingencies under the pressure of negative energy balance.

Waterlogging tolerance of Welsh onion (Allium fistulosum L.) enhanced by exogenous spermidine and spermine

Soil flooding is a seasonal factor that negatively affects plant performance and crop yields. In order to investigate the effects of spermidine (Spd) and spermine (Spm) on the waterlogging stress, it was checked that the content of relative water content (RWC), proline, chlorophyll and malondialdehyde (MDA), net photosynthesis, the rate of hydrogen peroxide (H(2)O(2)) and superoxide radicals (O(2)(-)) generation and the antioxidant enzyme activities of superoxide dismutase (SOD) (EC 1.15.1.1), catalase (CAT) (EC 1.11.1.6), ascorbate peroxidase (APX) (EC 1.11.1.11) and glutathione reductase (GR) (EC 1.6.4.2) in Welsh onion (Allium fistulosum L) plants. Pretreatment with 2 mM of Spd and Spm effectively maintained the balance of water content in plant leaves and roots under flooding stress. In addition, the data indicate that the protective role of proline should be considered minimal, as its accumulation was found to be inversely correlated with tolerance to stress; it also significantly retarded the loss of chlorophyll, enhanced photosynthesis, decreased the rate of O(2)(-) generation and H(2)O(2) content, and prevented flooding-induced lipid peroxidation. Spd and Spm helped to maintain antioxidant enzyme activities under flooding; however, APX activity was found to increase slightly in response to Spm. The antioxidant system, an important component of the water-stress-protective mechanism, can be changed by PAs, which are able to moderate the radical scavenging system and to lessen in this way the oxidative stress. The results suggest that pretreatment with Spd and Spm prevents oxidative damage, and the protective effect of Spd was found to be greater than that of Spm.

Effects of the polyamine spermine on arterial chemoreception

Polyamines modulate many biological functions. Here we report a novel inhibitory modulation by spermine of catecholamine release by the rat carotid body and have identified the molecular mechanism underpinning it. We used molecular (RT-PCR and confocal microscopy) and functional (i.e., neurotransmitter release, patch clamp recording and calcium imaging) approaches to test the involvement of: (i) voltage-dependent calcium channels, and; (ii) the extracellular calcium-sensing receptor, CaR, a G protein-coupled receptor which is also activated by polyamines. RT-PCR and immunohistochemistry of isolated carotid bodies revealed that only Ca(v)1.2 and Ca(v)2.2 were expressed in type 1 cells while Ca(v)1.3, Ca(v)1.4, Ca(v)2.1, Ca(v)2.3 and Ca(v)3.1, Ca(v)3.2 and Ca(v)3.3, could not be detected. CaR expression was detected exclusively in the nerve endings. In isolated carotid bodies, the hypoxia-dependent (7% O(2) for 10 minutes) and depolarization-evoked catecholamine release were partially suppressed by pre- (and co)-incubation with 500microM spermine. In dissociated type 1 glomus cells intracellular calcium concentration did not change following spermine treatment, but this polyamine did inhibit the depolarisation-evoked calcium influx. Whole-cell patch clamp recordings of HEK293 cells stably transfected with Ca(v)1.2 demonstrated that spermine inhibits this calcium channel. Interestingly, this inhibition was not apparent if the extracellular solution contained a concentration of Ba(2) above 2 mM as the charge carrier. In conclusion, spermine attenuates catecholamine release by the carotid body principally via inhibition of Ca(v)1.2. This mechanism may represent a negative feedback, which limits transmitter release during hypoxia.

Differential elicitation of proteases and protease inhibitors in two different genotypes of chickpea (Cicer arietinum) by salicylic acid and spermine

Elicitation of proteases and protease inhibitors (PIs) by salicylic acid (SA) and spermine (Spm) was investigated in roots and shoots of two different genotypes of chickpea cultivars ICCV10 and L550, which were resistant and susceptible to wilt disease, respectively. SA and Spm were found to suppress the elicitation of proteases in the resistant cv, whereas they induce it in susceptible cv. Elicitation of new trypsin and chymotrypsin inhibitors was observed in the roots and shoots of resistant cv treated with SA and Spm. However, no such elicitation was observed in susceptible cv. These results show for the first time that SA and Spm could elicit synthesis of new PIs capable of inhibiting the proteases of insect Helicoverpa armigera and Fusarium oxysporum, wilt causing pathogen. Antifungal property of root extract of resistant cv increased following treatment of seedling with SA and Spm compared with susceptible cv.

Antimicrobial, antiparasitic and cytotoxic spermine alkaloids from Albizia schimperiana

Albizia schimperiana Oliv. (Leguminosae) is a tree distributed in the highland of Kenya, where it is used as a traditional medicine for the treatment of bacterial and parasitic infections, notably pneumonia and malaria, respectively. Bioassay guided isolation of the CH2Cl2-MeOH 1:1/ MeOH-H20 9:1 (mixed) extract of A. schimperiana afforded the new bioactive macrocyclic spermine alkaloid, namely 5,14-dimethylbudmunchiamine L1 (1) and three known budmunchiamine analogs 2-4. The structures of the compounds 1-4 were determined by 1D and 2D NMR data, including COSY, HMQC, and HMBC experiments, and ESI-HRMS. Compounds 1 and 3 exhibited significant in vitro antimicrobial activity against a panel of microorganisms, including C neoformans, methicillin-resistant S. aureus, E. coli, M. intracellulare, and A. fumigatus. In Saddition, they demonstrated strong in vitro antimalarial activities against chloroquine-susceptible (D6) and -resistant (W2) strains of Plasmodium falciparum with IC50s ranging from 120-270 ng/mL. Compounds 1-4 were also evaluated for cytotoxic activity against selected human cancer cell lines and mammalian kidney fibroblasts (VERO cells). It was observed that hydroxyl substitution of the side chain of the budmunchiamines dramatically reduced the cytotoxicity and antimicrobial activity of the alkaloids 2 and 4 without decreasing antimalarial activity.

Gene expression analysis of HCT116 colon tumor-derived cells treated with the polyamine analog PG-11047

BACKGROUND

The conformationally restricted polyamine analog PG-11047 has significant growth inhibitory activity against prostate and lung cancer cell lines and is currently under evaluation in several clinical trials, both alone and in combination with other drugs, for the treatment of relapsed or refractory cancer. The objective of this study was to identify the molecular signature of genes responsive to PG-11047 treatment and the biochemical effects of this drug in the HCT116 colon cancer cell line.

MATERIALS AND METHODS

Gene expression analysis was performed using Affymetrix GeneChip human genome U133 Plus 2.0 arrays. Changes in protein expression were evaluated using 2D polyacrylamide gels followed by LCMS/MS.

RESULTS

Treatment of cells with PG-11047 at concentrations ranging from 0.1 to 10 microM caused inhibition of cell growth. The activity of PG-11047 was found to correlate with its transcriptional effects on cell cycle control, focal adhesion, adherent and gap junction genes, MAPK-, Wnt- and, TGF-beta signaling pathways, transport and DNA/RNA transcription factor genes. PG-11047 caused depletion of polyamine pools. Proteomics analysis showed that PG-11047 restricts the modification of eukaryotic translation initiation factor 5A (eIF5A), resulting in suppression of general protein synthesis in PG-11047-treated cells.

CONCLUSION

These data show that PG-11047 has a broad spectrum of anticancer activity in colon cancer cells.

Spermine signaling plays a significant role in the defense response of Arabidopsis thaliana to cucumber mosaic virus

We have proposed that the polyamine spermine (Spm) functions as a signaling molecule to evoke defense reactions/cell death in avirulent pathogen-attacked tobacco plants. To understand its molecular basis in depth, Spm-responsive genes in Arabidopsis thaliana were identified by SuperSAGE analysis. Close to 90% of the Spm-responsive genes also responded during cucumber mosaic virus (CMV)-elicited hypersensitive response. Spm modulated the expression of genes of redox components, and genes involved in protein folding and secretion, protein degradation and defense. Two other prominent changes, the coordinately enhanced expression of members of the photorespiration pathway and a diversion in electron flow from the primary electron transfer chain of respiration to an alternative oxidase pathway, occurred in response to Spm. Spm activated the expression of 6 transcription factor genes including ZAT7, ZAT12, AtWRKY40 and AtbZIP60, of which the former three genes' products are currently assigned as components of H(2)O(2) signaling pathway, suggesting the involvement of H(2)O(2) in Spm-triggered responses. Since AtbZIP60 plays a proven master role in the unfolded protein response in Arabidopsis thaliana, it may function to control the expression of genes participating in protein folding and secretion, which were mentioned above. Spm induction and CMV-triggered up-regulation of the genes described mainly coincided and their induction was suppressed by inhibitors of Spm oxidation. Furthermore, treatment with those inhibitors prior to CMV inoculation allowed higher viral multiplication in Arabidopsis thaliana plants. These results support the existence of a Spm-signaling pathway in Arabidopsis thaliana and its significant role in defense against CMV.

Elevated polyamines induce c-MYC overexpression by perturbing quadruplex-WC duplex equilibrium

The biological role of quadruplexes and polyamines has been independently associated with cancer. However, quadruplex-polyamine mediated transcriptional regulation remain unaddressed. Herein, using c-MYC quadruplex model, we have attempted to understand quadruplex–polyamine interaction and its role in transcriptional regulation. We initially employed biophysical approach involving CD, UV and FRET to understand the role of polyamines (spermidine and spermine) on conformation, stability, molecular recognition of quadruplex and to investigate the effect of polyamines on quadruplex–Watson Crick duplex transition. Our study demonstrates that polyamines affect the c-MYC quadruplex conformation, perturb its recognition properties and delays duplex formation. The relative free energy difference (ΔΔG°) between the duplex and quadruplex structure indicate that polyamines stabilize and favor c-MYC quadruplex over duplex. Further, we investigated the influence of polyamine mediated perturbation of this equilibrium on c-MYC expression. Our results suggest that polyamines induce structural transition of c-MYC quadruplex to a transcriptionally active motif with distinctive molecular recognition property, which drives c-MYC expression. These findings may allow exploiting quadruplex–polyamines interaction for developing antiproliferative strategies to combat aberrant gene expression.

[Effects of exogenous spermidine and spermine on Celastrus orbiculatus antioxidant system under soil NaHCO3 stress]

This paper studied the effects of foliar spraying spermidine and spermine on the leaf antioxidant system of Celastrus orbiculatus under soil NaHCO3 stress. The results showed that under the stress, spraying spermidine and spermine could significantly decrease the leaf O2-* production rate, H2O2 and MDA contents, and electrolyte leakage of C. orbiculatus (P < 0.05). Spraying spermidine increased the leaf SOD, CAT, POD and APX activities and GSH, CAR and Pro contents obviously, but had no effect on leaf AsA content. Spraying spermine also increased leaf POD and APX activities and GSH, CAR and Pro contents obviously, but had lesser effect on leaf SOD activity and AsA content, and even, caused a significant decrease in leaf CAT activity. In the meantime, spermidine and spermine effectively improved the growth of C. orbiculatus seedlings. It was suggested that under soil NaHCO3 stress, exogenous spermidine and spermine could improve the functions of membrane protective system and decrease the O2-* accumulation in C. orbiculatus leaves, and consequently, increase the C. orbiculatus tolerance to NaHCO3 exposure.

Reward-potentiating effects of D-1 dopamine receptor agonist and AMPAR GluR1 antagonist in nucleus accumbens shell and their modulation by food restriction

RATIONALE

Previous studies have suggested that chronic food restriction (FR) increases sensitivity of a neural substrate for drug reward. The neuroanatomical site(s) of key neuroadaptations may include nucleus accumbens (NAc) where changes in D-1 dopamine (DA) receptor-mediated cell signaling and gene expression have been documented.

OBJECTIVES

The purpose of the present study was to begin bridging the behavioral and tissue studies by microinjecting drugs directly into NAc medial shell and assessing behavioral effects in free-feeding and FR subjects.

MATERIALS AND METHODS

Rats were implanted with microinjection cannulae in NAc medial shell and a subset were implanted with a stimulating electrode in lateral hypothalamus. Reward-potentiating effects of the D-1 DA receptor agonist, SKF-82958, AMPAR antagonist, DNXQ, and polyamine GluR1 antagonist, 1-na spermine, were assessed using the curve-shift method of self-stimulation testing. Motor-activating effects of SKF-82958 were also assessed.

RESULTS

SKF-82958 (2.0 and 5.0 microg) produced greater reward-potentiating and motor-activating effects in FR than ad libitum fed (AL) rats. DNQX (1.0 microg) and 1-na spermine (1.0 and 2.5 microg) selectively decreased the x-axis intercept of rate-frequency curves in FR subjects, reflecting increased responding for previously subthreshold stimulation.

CONCLUSIONS

Results suggest that FR may facilitate reward-directed behavior via multiple neuroadaptations in NAc medial shell including upregulation of D-1 DA receptor function involved in the selection and expression of goal-directed behavior, and increased GluR1-mediated activation of cells that inhibit nonreinforced responses.

Glucose-induced inhibition of seed germination in Lotus japonicus is alleviated by nitric oxide and spermine

Seed germination is sensitive to glucose (Glc), nitric oxide (NO) and polyamine (PA). To elucidate whether cross-talk among Glc, NO and PAs occurs in mediation of seed germination, effects of Glc, NO and spermine on seed germination of Lotus japonicus were studied. Glc retarded seed germination in a concentration-dependent manner. NO donor sodium nitroprusside (SNP) alleviated Glc-induced inhibition of seed germination, whereas the NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide (cPTIO) diminished the SNP-dependent alleviation of seed germination. These observations indicate that Glc may inhibit seed germination by interacting with NO signaling pathways. Exogenous spermine enhanced and the inhibitor of the spermine synthase, methylglyoxal-bis-guanyl hydrazone (MGBG), inhibited seed germination, respectively. Like SNP, spermine alleviated the Glc-induced inhibition of seed germination, whereas MGBG exaggerated the Glc-induced inhibition of seed germination. These results suggest that Glc may inhibit the spermine synthesis, leading to reductions in seed germination. NO scavenger and spermine synthase inhibitor diminished the SNP-induced alleviation of Glc-induced inhibition of seed germination. These findings reveal that both NO and spermine participate in the Glc-induced inhibition of seed germination in L. japonicus.

RNA as a new target for toxic and protective agents

In contrast to damage of genomic DNA and despite its potential to affect cell physiology, RNA damage is a poorly examined field in biomedical research. Potential triggers of RNA damage as well as its pathophysiological implications remain largely unknown. While less lethal than mutations in genome, such non-acutely lethal insults to cells have been recently associated with underlying mechanisms of several human chronic diseases. We investigated whether RNA damage could be related to the exposure of particular xenobiotics by testing the RNA-damaging activity of a series of chemicals with different mechanisms of action. Cultured human T-lymphoblastoid cells were treated with ethyl methanesulfonate (EMS), H(2)O(2), doxorubicin, spermine, or S-nitroso-N-acetylpenicillamine (SNAP). Furthermore, we studied the potential protective activity of a pomegranate extract against RNA damage induced by different chemicals. Special attention has been paid to the protective mechanisms of the extract. The protective effect of pomegranate can be mediated by alterations of the rates of toxic agent absorption and uptake, by trapping of electrophiles as well as free radicals, and protection of nucleophilic sites in RNA. We used two different treatment protocols (pre- and co-treatment) for understanding the mechanism of the inhibitory activity of pomegranate. We demonstrated that total RNA is susceptible to chemical attack. A degradation of total RNA could be accomplished with doxorubicin, H(2)O(2), spermine and SNAP. However, EMS, a well-known DNA-damaging agent, was devoid of RNA-damaging properties, while spermine and SNAP, although lacking of DNA-damaging properties, were able to damage RNA. Pomegranate reduced the RNA-damaging effect of doxorubicin, H(2)O(2), and spermine. Its inhibitory activity could be related with its ability to forms complexes with doxorubicin and H(2)O(2), or interacts with the intracellular formation of reactive species mediating their toxicity. For spermine, an alteration of the rates of spermine absorption and uptake can also be involved.

Endogenous polyamines regulate cortical neuronal excitability by blocking voltage-gated Na+ channels

Because the excitable properties of neurons in the neocortex depend on the characteristics of voltage-gated Na(+) channels, factors which regulate those characteristics can fundamentally modify the dynamics of cortical circuits. Here, we report on a novel neuromodulatory mechanism that links the availability of Na(+) channels to metabolism of polyamines (PAs) in the cerebral cortex. Using single channel and whole-cell recordings, we found that products of PA metabolism, the ubiquitous aliphatic polycations spermine and spermidine, are endogenous blockers of Na(+) channels in layer 5 pyramidal cells. Because the blockade is activity-dependent, it is particularly effective against Na(+) channels which fail to inactivate rapidly and thus underlie the persistent Na(+) current. At the level of the local cortical circuit, pharmacological depletion of PAs led to increased spontaneous spiking and periods of hypersynchronous discharge. Our data suggest that changes in PA levels, whether associated with normal brain states or pathological conditions, profoundly modify Na(+) channel availability and thereby shape the integrative behavior of single neurons and neocortical circuits.

[YC-1-like potentiation of nitric oxide-dependent activation of soluble guanylyl cyclase by adrenochrome]

The influence of adrenochrome and YC-1 on spermine NONO-induced activation of human soluble guanylyl cyclase was investigated. Adrenochrome (0.1-10 microM) had no effect on the basal activity, but it potentiated in concentration-dependent manner the spermine NONO-induced activation of this enzyme. Adrenochrome, like YC-1, sensitized guanylyl cyclase towards nitric oxide (NO) and produced the leftward shift of spermine NONO concentration responce curve. Addition of adrenochrome decreased the YC-1-induced leftward shift of spermine NONO concentration response curve. Adrenochrome also inhibited (by 63%) the enzyme activation by YC-1. These data demonstrates the possible competition between adrenochrome and YC-1. Thus, synergistic activation of NO-stimulated guanylyl cyclase activity by adrenochrome represents a new biochemical effect of this compound and indicates that adrenochrome may act as an endogenous regulator of NO-dependent stimulation of soluble guanylyl cyclase. This new property of adrenochrome, similar to YC-1, is necessary taking into account, especially under conditions of overproduction of adrenochrome in organism.

Novel oral absorption system containing polyamines and bile salts enhances drug transport via both transcellular and paracellular pathways across Caco-2 cell monolayers

The combinatorial use of spermine (SPM), a typical polyamine, and sodium taurocholate (STC), a typical bile salt, was found to be a promising safe preparation for improving the oral absorption of poorly water-soluble and/or poorly absorbable drug in our previous studies utilizing rats and dogs. To clarify the mechanisms behind the synergistic enhancement effect of the polyamine and bile salt, the transport of rebamipide, which is classified into Biopharmaceutics Classification System Class IV, was investigated in Caco-2 cell monolayers. The synergistic enhancement of rebamipide transport by SPM and STC was certainly observed in Caco-2 cells as well, while the separate use of either SPM or STC did not significantly improve the transport of rebamipide. The combinatorial use of SPM and STC significantly decreased the transepithelial electrical resistance (TEER) in Caco-2 cell monolayers, suggesting that the opening of paracellular pathway. On the other hand, it was also confirmed that the decrease in TEER was transient and reversible after removal of SPM and STC and that cell viability was maintained. Voltage-clamp study clearly showed that their combinatorial use improved rebamipide transport via both paracellular and transcellular pathways, and that the contribution of transcellular route could be larger than paracellular route.

Thermospermine is required for stem elongation in Arabidopsis thaliana

Loss-of-function mutants of the ACAULIS5 (ACL5) gene in Arabidopsis thaliana have severe defects in stem elongation. ACL5 was previously reported as encoding a spermine synthase. A more recent study, however, showed that the bacterial expressed recombinant ACL5 protein catalyzes the conversion of spermidine to thermospermine, a structural isomer of spermine, rather than to spermine. In the present study, we found that thermospermine was detected in wild-type seedlings but was not detectable in the acl5-1 mutant. We further examined the effect of exogenous application of these isomers on the growth of acl5-1. Daily application of 0.1 mM thermospermine onto the shoot apex partially rescued the dwarf phenotype of acl5-1, while that of spermine had no effects on the morphology of the mutant. The acl5-1 transcript level in acl5-1 seedlings, which is much higher than the ACL5 transcript level in wild-type seedlings, was reduced by exogenous thermospermine. Thus we conclude that thermospermine is indeed produced through the action of ACL5 and required for stem elongation in Arabidopsis.

Mepacrine antagonises tumour cell growth induced by natural polyamines

BACKGROUND

Mepacrine is an antiproliferative agent, characterised by an aliphatic chain similar to that of natural polyamines whose activation is closely associated with cell proliferation and may lead to malignant transformation and neurodegenerative diseases. This study aims to investigate a possible antagonism between mepacrine and polyamines in tumour proliferation.

MATERIALS AND METHODS

MCF-7 and Vero cells were cultured in Eagle's minimum essential medium and then subjected to graded concentrations of putrescine, spermine and spermidine alone and in combination with mepacrine. Methyl thiazole tetrazolium test and Western-blotting were performed.

RESULTS

Putrescine and spermidine at 0.5 mg/l significantly stimulated cell growth, whereas mepacrine treatment confirmed the enhanced p21 expression previously reported by a recent study and growth inhibition. When used in combination, mepacrine antagonized MCF-7 growth induced by polyamines.

CONCLUSION

Our results suggest that mepacrine may represent a choice in the treatment of tumours induced by the modified concentration of polyamines.

Effect of polyamine deficiency on proteins involved in Okazaki fragment maturation

Polyamine depletion causes S phase prolongation, and earlier studies indicate that the elongation step of DNA replication is affected. This led us to investigate the effects of polyamine depletion on enzymes crucial for Okazaki fragment maturation in the two breast cancer cell lines MCF-7 and L56Br-C1. In MCF-7 cells, treatment with N(1),N(11)-diethylnorspermine (DENSPM) causes S phase prolongation. In L56Br-C1 cells the prolongation is followed by massive apoptosis. In the present study we show that L56Br-C1 cells have substantially lower basal expressions of two Okazaki fragment maturation key proteins, DNA ligase I and FEN1, than MCF-7 cells. Thus, these two proteins might be promising markers for prediction of polyamine depletion sensitivity, something that can be useful for cancer treatment with polyamine analogues. DENSPM treatment affects the cellular distribution of FEN1 in L56Br-C1 cells, but not in MCF-7 cells, implying that FEN1 is affected by or involved in DENSPM-induced apoptosis.

Polyamine catabolism in colorectal cancer cells following treatment with oxaliplatin, 5-fluorouracil and N1, N11 diethylnorspermine

PURPOSE

Our previous studies showed that combined treatment of oxaliplatin and N(1), N(11) diethyl-norspermine (DENSPM) results in massive induction of spermidine/spermine N(1)-acetyltransferase (SSAT) mRNA and activity. Since oxaliplatin and 5-fluorouracil (5FU) are used clinically in treatment of colorectal cancers, this study examines the effect of adding DENSPM to oxaliplatin/5FU combination on SSAT and spermine oxidase (SMO) in HCT-116 cells.

METHODS

HCT-116 cells were treated with clinically relevant concentrations of drugs for 20 h followed by 24 h in drug free medium. SSAT and SMO mRNA and protein were assayed by QRT-PCR and Westerns respectively; polyamine pools were measured by HPLC. SSAT and SMO mRNA in tumor biopsies from patients with rectal cancer receiving oxaliplatin, capecitabine and radiation were measured by QRT-PCR.

RESULTS

Oxaliplatin + 5FU + DENSPM produced significantly higher levels of SSAT and SMO mRNA, protein and activity than those seen with oxaliplatin+5FU with a significant depletion of cellular spermine and spermidine pools. Oxaliplatin/DENSPM was superior to 5FU/DENSPM in SSAT induction but similar for SMO. Oxaliplatin + DENSPM revealed synergistic growth inhibition at >IC(50) concentrations and antagonism at

CONCLUSIONS

These studies demonstrated that combining DENSPM with oxaliplatin + 5FU provides an added benefit by aiming at the clinically relevant therapeutic target, the polyamine catabolism. Further, we show for the first time, that SMO and SSAT induction could be measured in tumor biopsies in patients receiving chemo-radiation. Optimization of treatment conditions in vivo should facilitate a clinical evaluation of the three drug combination.

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MESH Headings

• Acetyltransferases/genetics
• Acetyltransferases/metabolism
• Antineoplastic Combined Chemotherapy Protocols/pharmacology
• Antineoplastic Combined Chemotherapy Protocols/therapeutic use
• Blotting, Western
• Cell Line, Tumor
• Colonic Neoplasms/drug therapy
• Colonic Neoplasms/metabolism
• Colonic Neoplasms/pathology
• Drug Synergism
• Fluorouracil/pharmacology
• Fluorouracil/therapeutic use
• Gene Expression/drug effects
• Humans
• Organoplatinum Compounds/pharmacology
• Organoplatinum Compounds/therapeutic use
• Oxaliplatin
• Oxidoreductases Acting on CH-NH Group Donors/genetics
• Oxidoreductases Acting on CH-NH Group Donors/metabolism
• Polyamines/metabolism
• Rectal Neoplasms/drug therapy
• Rectal Neoplasms/metabolism
• Rectal Neoplasms/pathology
• Spermine/analogs & derivatives
• Spermine/pharmacology
• Spermine/therapeutic use
• Polyamine Oxidase

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Grants

• CA 10656 NCI NIH HHS
• CA 109619 NCI NIH HHS

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Affiliation(s)

Suzanne Hector Department of Medicine, Roswell Park Cancer Institute, Elm and Carlton Streets, Buffalo, NY 14263, USA
Ramakumar Tummala
Nicholas D Kisiel
Paula Diegelman
Slavoljub Vujcic
Kimberly Clark
Marwan Fakih
Debora L Kramer
Carl W Porter
Lakshmi Pendyala

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Effects of Microdesmis keayana roots on sexual behavior of male rats

In the present study, the aphrodisiac properties of Microdesmis keayana J. Léonard root extract and major isolated alkaloids were evaluated by observing the sexual behavior of male rats. Aqueous extract (150mg/kg body weight) and pure alkaloids (3mg/kg body weight) were administered orally by gavage to male rats. Latent times of observation, intromission and ejaculation, mounting behavior, number of intromissions and mating performances were evaluated and compared to those obtained with untreated rats in the presence of receptive and non-receptive females. The results have shown that aqueous extract and alkaloids of M. keayana stimulate sexual parameters in rats' sexual behavior. A short-term toxicity study undertaken to establish the therapeutic index of aqueous extract, showed that a high dose of the extract (2g/kg body weight) caused no mortality or changes in rats' behavior.

[Effect of spermine on kinetic characteristics of ATP-hydrolase systems of the uterus myocyte plasma membranes]

The paper deals with the activation effect of aliphatic polyamine spermine (1 mM) on the enzymatic activity of ouabain-sensitive Na+,K(+)-ATPase and the ouabain-resistant basal Mg(2+)-ATPase in the suspension of the myometrium cell plasma membranes treated with 0.1% digitonin solution. It was found that spermine increased the enzymatic Na+,K(+)-ATPase activity without disrupting of its dome-shaped dependence on the ratio of [Na+]/ [K+] in isotonic condition. The constants of the enzyme activation by Na+ and K+ ions did not vary. Spermine also did not change the character of dependence of Na+,K(+)-ATPase and Mg(2+)-ATPase activity on the concentration of MgCl2 (0.1-2 mM) and on the concentration of ATP (0.05-1 mM). In this case the affinity for the corresponding compounds did not also vary. Thus, the activation by spermine occurred mainly due to enlargment of enzyme "turnover number" according to V(max) increase. It is expected that the obtained experimental data can be important for further investigations of regulation mechanisms of Na+,K(+)-ATPase and Mg(2+)-ATPase activity and also mechanisms of cations exchange control in the smooth muscles.

Exogenous spermidine differentially alters activities of some scavenging system enzymes, H(2)O(2) and superoxide radical levels in water-stressed cucumber leaves

In order to examine whether polyamines (PAs) modify the functioning of the scavenging system and oxidative stress levels in water-stressed plants, cucumber (Cucumis sativus L.) seedlings were treated with spermidine (Spd) prior to dehydration, and stress-evoked changes in superoxide dismutase (SOD) (EC 1.15.1.1), catalase (EC 1.11.1.6), guaiacol peroxidase (EC 1.11.1.7) activities, H(2)O(2) and superoxide radical levels were determined. Free PA content during Spd treatment and during the stress period were also determined. Exogenous application of Spd differentially influenced enzymes of the antioxidative system under stress conditions; we observed an increase of guaiacol peroxidase activity, and, to a lesser degree, a reduction of SOD and catalase activities in Spd-treated plants in comparison to untreated stressed plants. Hydrogen peroxide and superoxide radical contents were also reduced in stressed plants after Spd pretreatment. These positive effects were observed in the case of 1mM Spd concentration. A higher concentration (3mM) influenced negative, more significant stress-induced changes, but a lower concentration (0.1mM) had a very limited effect. In summary, PAs are able to moderate the activities of scavenging system enzymes and to influence oxidative stress intensity.

Participation of hippocampal ionotropic glutamate receptors in histamine H(1) antagonist-induced memory deficit in rats

RATIONALE

Pyrilamine, a selective histamine H(1) antagonist, impaired spatial memory, and decreased hippocampal theta activity during a radial maze task.

OBJECTIVE

We investigated the ameliorative effects of glutamatergic drugs on pyrilamine-induced spatial memory deficit and the decrease in hippocampal theta activity in rats.

MATERIALS AND METHODS

Drug effects were measured using an eight-arm radial maze with four arms baited. Hippocampal theta rhythm during the radial maze task was also recorded with a polygraph system using a telemetric technique.

RESULTS

Intraperitoneal injection of pyrilamine (35 mg/kg) resulted in impaired reference and working memory in the radial maze task and a decrease in the amplitude and power of hippocampal theta waves. The working memory deficit and the decrease in hippocampal theta power were antagonized by intrahippocampal injection of D: -cycloserine (1 microg/side), spermidine (10 microg/side), spermine (10 microg/side), aniracetam (1 microg/side), and 1-(1,3-benzodioxol-5-ylcarbonyl) piperidine (1-BCP) (1 microg/side), but not concanavalin A.

CONCLUSION

These results clearly indicate that H(1) antagonist-induced working memory deficit, and the decrease in hippocampal theta activity was closely associated with hippocampal glutamatergic neurotransmission mediated by N-methyl-D: -aspartate (NMDA) and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors.

New stereoselective titanium reductive amination synthesis of 3-amino and polyaminosterol derivatives possessing antimicrobial activities

A series of 3-amino and polyaminosterol analogues of squalamine and trodusquemine were synthesized involving a new stereoselective titanium reductive amination reaction in high chemical yields of up to 95% in numerous cases. These derivatives were evaluated for their in vitro antimicrobial properties against human pathogens. Activity was highly dependent on the different compounds' structures involved and best results have been obtained with aminosterol derivatives 4b, 4e and 6i exhibiting activities against yeasts, Gram positive and Gram negative bacteria at average concentrations of 6.25-12.5 microg/mL.

Effects of polyamines and polyamine biosynthetic inhibitors on mitotic activity of Allium cepa root tips

The genotoxic and cytotoxic effects of exogenous polyamines (PAs), putrescine (Put), spermidine (Spd), spermine (Spm) and PA biosynthetic inhibitors, alpha-difluoromethylornithine (DFMO), cyclohexilamine (CHA), methylglioxal bis-(guanylhydrazone) (MGBG) were investigated in the root meristems of Allium cepa L. The reduction of mitotic index and the induction of chromosomal aberrations such as bridges, stickiness, c-mitotic anaphases, micronuclei, endoredupliction by PAs and PA biosynthetic inhibitors were observed and these were used as evidence of genotoxicity and cytotoxicity.