Transgenic mice with activated polyamine catabolism due to overexpression of spermidine/spermine N1-acetyltransferase show enhanced sensitivity to the polyamine analog, N1, N11-diethylnorspermine

We have recently generated transgenic mice in which polyamine catabolism has been activated by overexpressing the rate-limiting enzyme of polyamine catabolism, spermidine/spermine N1-acetyltransferase (SSAT). These animals have now been tested for their sensitivity to the polyamine analog N1,N11-diethylnorspermine (DENSPM), which is currently undergoing Phase I clinical trial. The analog is known for its ability to potently induce SSAT. Treatment for 4 days with a daily dose (125 mg/kg) of analog caused profound changes in polyamine metabolism in the transgenic animals. Liver SSAT activity was increased by approximately 800-fold while hepatic mRNA increased only 4-fold. Putrescine pools increased while spermidine and spermine pools nearly disappeared, resulting in a compensatory increase in ornithine decarboxylase activity. Similar but less profound changes were also seen in other tissues (spleen, intestine, and skin). This treatment also resulted in a 50% mortality in the transgenic animals, with no apparent histopathological changes in major organs. Nontransgenic animals exhibited no toxicity, and tissue SSAT activity was unchanged or only moderately increased. Polyamine pools were only slightly altered. Greater analog toxicity in transgenic animals may be attributable to higher tissue levels of DENSPM facilitated by SSAT-mediated decreases in spermidine and spermine. To further confirm the enhanced sensitivity of the transgenic animals to the analog, groups of nontransgenic and transgenic animals were subjected to daily injections with DENSPM. On average, transgenic mice died approximately 3 days earlier than their nontransgenic litter-mates. The findings indicate a contributing role for SSAT in whole animal toxicity by SSAT-inducing polyamine analogs.

Anti-proliferative effects of unmodified antisense oligodeoxynucleotides targeted against c-raf mRNA: use of poly (lysine/serine) copolymers or cationic lipopolyamines

1. It is now known that nuclease-resistant phosphorothioate antisense oligodeoxynucleotides (ODN) have some actions that are unrelated to antisense mechanisms. In the present study we assessed the anti-proliferative effects of phosphorothioate (PS) and phosphodiester (PO; unmodified) antisense ODN targeted against c-raf mRNA on pancreatic cancer cells in vitro, using poly (lysine/serine) copolymers conjugated with polyethylene glycol (PLSP) or cationic lipopolyamines (Transfectam) as carriers. 2. The anti-proliferative effect of the PO antisense ODN was significantly (P < 0.05) greater than that of the PS ODN, either complexed with PLSP (2 mumol/L ODN) or the Transfectam (0.5 mumol/L ODN). However, the effect of the PS or PO antisense ODN was not dependent on the antisense sequence. The c-raf mRNA levels, assessed by reverse transcription-polymerase chain reaction, were obviously reduced by both PO and PS antisense ODN compared with mismatched ODN when complexed with the Transfectam (1 mumol/L ODN). 3. Although the anti-proliferative effects were mainly unrelated to antisense mechanisms, unmodified antisense ODN complexed with some carriers could be used as anti-tumour agents considering that synthetic carriers can be modified to improve functions, such as delivery.

Brain lesions and delayed water maze learning deficits after intracerebroventricular spermine

The effects of spermine on the acquisition and retention of spatial learning in the Morris water maze were studied. Spermine 25 and 125 nmol i.c.v. did not alter the ability of rats to find a hidden platform in the water maze when administered before training over 5 days. However, the inhibitory effect of the benzodiazepine, diazepam (3 mg/kg i.p., 30 min prior to training), on path length to target was markedly potentiated by the higher dose of spermine, consistent with spermine acting as a functional antagonist at the NMDA receptor. This drug combination did not affect performance on visible platform trials. Administration of doses of 125 and 250 nmol (but not 62.5 nmol) of spermine i.c.v. in the week prior to training (daily for 5 days) dose-dependently inhibited subsequent learning of a platform position in the absence of drug. These higher doses of spermine produced neuronal loss and increased [3H]PK11195 binding indicating microglial activation predominantly in the hippocampus and to a lesser extent in the striatum, septum, thalamus and amygdala. Spermine 125 nmol i.c.v. (daily for 7 days) also abolished retention of a previously learned platform position when administered in an interval between training and retention testing. The inhibitory effects of spermine 125 nmol i.c.v. (daily for 7 days) on subsequent spatial learning were not antagonised by concomitant administration of 30 nmol dizocilpine. These results demonstrate that spermine produces a delayed neurotoxic effect in particular neuronal populations in the brain that selectively impair spatial learning and recall.

Effect of spermine administration on pancreatic maturation in unweaned rats

The effect of oral administration of spermine on pancreatic maturation was investigated in the suckling rat. The treatment consisted of 0.3-0.4 mmol spermine kg-1 body weight given orally once a day for 3 days starting at day 11 after birth. Spermine administration does not adversely affect the growth of the pancreas (wet weight, protein and DNA contents remain unchanged). The proliferating cell nuclear antigen (PCNA) index decreases significantly in spermine-treated rats, indicating that spermine slows down the proliferation rate of the organ. The enzymatic activities of trypsin, chymotrypsin and alpha-amylase are increased significantly in the pancreas of spermine-treated rats. The morphology of the organ seems affected as shown by hematoxylin-eosin staining: a cytoplasm indicative of higher synthetic activity is visible after spermine treatment. We conclude that spermine treatment of unweaned rats can induce precocious biochemical and morphological maturation of the exocrine pancreas, pushing the organ forward in the process of differentiation (closer to the adult stage).

Investigation of the actions and antagonist activity of some polyamine analogues in vivo

1. The ability of three putative polyamine antagonists to antagonize behavioural changes induced by spermine was assessed. 2. Injection of an excitotoxic dose of spermine (100 microg, i.c.v.) in mice results in the development of a characteristic behavioural profile, which has two temporally distinct phases. The early events include clonic convulsions, and the later, more general excitation, includes tremor and culminates in the development of a fatal tonic convulsion. 3. Co-administration of arcaine (25 microg, i.c.v.) potentiated the early phase effects after spermine injection, but antagonized the development of spermine-induced tonic convulsions. A larger dose of arcaine (50 microg, i.c.v.) given alone resulted in the development of spermine-like body tremor and convulsions. It therefore appears that arcaine is not a pure polyamine antagonist in vivo, but may be a partial agonist. 4. Similarly, 1,10-diaminodecane appeared to act as a partial agonist in vivo, although it was less potent than arcaine. 5. In contrast, diethylenetriamine (DET) effectively inhibited the development of the early effects of spermine, but was ineffective against the spermine-induced CNS excitation and tonic convulsions. 6. It is concluded that none of the putative polyamine antagonists tested behaved as effective polyamine antagonists in vivo, although each produced some antagonism.

Effect of microencapsulation on immunogenicity of a bovine herpes virus glycoprotein and inactivated influenza virus in mice

We previously found that aqueous-based spermine-alginate or spermine-chondroitin sulfate microcapsules enhanced rotavirus-specific humoral immune responses after intramuscular inoculation of mice. To extend our observations with whole, infectious rotavirus to vaccine strategies which include inactivated virus and purified proteins, we determined the capacity of aqueous-based microcapsules to enhance virus-specific immune responses to bovine herpes virus type 1 glycoprotein D (BHV-1-gD) or ether-treated influenza virus. We found that spermine-alginate microcapsules decreased the quantity of BHV-1-gD necessary to induce protein-specific antibodies about 5000-fold. However, spermine-alginate microcapsules did not enhance influenza virus-specific antibody responses. Microcapsules composed of spermine-chondroitin sulfate did not enhance either BHV-1-gD or influenza virus-specific immune responses. Possible mechanisms of enhancement of virus-specific antibody responses by microencapsulation are discussed.

Oral administration of deuterium-labelled polyamines to sucking rat pups: luminal uptake, metabolic fate and effects on gastrointestinal maturation

Non-physiological amounts of oral polyamines have been reported to induce precocious gut maturation in rat pups. The aim of the present study was to investigate organ distribution and metabolic fate of orally administered stable-isotopically labelled polyamines in rat pups. Pups received tetradeuterium-labelled putrescine (Pu-d4; 3 mumol), spermidine (Sd-d4; 5 mumol), spermine (Sp-d4; 3 mumol), or physiological saline twice daily on postnatal days 7-10 or 12-15. They were killed on days 10 and 15. We determined activities of ileal lactase (EC 3.2.1.23), maltase (EC 3.2.1.20), sucrase (EC 3.2.1.48) and diamine oxidase (EC 1.4.3.6) and established villus and crypt lengths. Polyamines and their labelling percentages in organs were determined by GC and mass fragmentography. Treatments did not affect growth rate, but caused lower weights of liver, kidneys and heart. Maltase activity increased, lactase decreased, whereas sucrase and diamine oxidase did not change. Villus and crypt lengths increased. Organ polyamine pools were labelled to different extents. Irrespective of the orally administered polyamine, all organs contained Pu-d4, SD-d4 and Sp-d4. Administered Pu-d4 and Sd-d4 were recovered mainly as Sd-d4, whereas Sp-d4 was recovered as Sp-d4 and Sd-d4. Total polyamines in a caecum, colon and erythrocytes increased, but increases were only to a minor extent with regard to labelled polyamines. Our data confirm precocious gut maturation by exogenous polyamines. Putrescine appears to be limiting factor. The exogenous polyamines were distributed among all investigated organs. They are not only used for the synthesis of higher polyamines, but also retroconverted to their precursors. Changes in erythrocyte polyamine contents suggest precocious stimulation of erythropoiesis.

A nitric oxide donor (spermine-NONOate) prevents the formation of neointima in rabbit carotid artery

1. In the present study we investigated the effect of spermine diazeniumdiolate (spermine-NONOate), a nitric oxide donor, on the early development of atheroma-like lesions induced by a peri-arterial collar in rabbits. 2. Spermine-NONOate was given locally by incorporating the compound (1 mg/mL) into a silastic collar, which was applied on one common carotid artery of rabbit while the other carotid artery had a placebo collar (without compound) applied. 3. Fourteen days postimplantation, both carotid arteries were dissected free for histological study (n = 6). 4. After 14 days with collars, treatment with spermine-NONOate had significantly reduced (by 74%) the thickness of the neointima in comparison with the contralateral collared artery without compound. Blood pressure did not change during treatment. Nitric oxide, detected as nitrite, was still released from spermine-NONOate silastic collars after 14 days implantation. 5. These results suggest that locally administered spermine-NONOate is effective in slowing the development of neointima in this model.

The mechanism of excretion of trientine from the rat kidney: trientine is not recognized by the H+/organic cation transporter

Trientine dihydrochloride is used to treat Wilson's disease by chelating copper and increasing its urinary excretion. The mechanism of renal excretion of trientine has been investigated in-vivo and in-vitro. Trientine clearance in the rat-was significantly faster than creatinine clearance. When trientine and the same number of moles of copper ions were administered simultaneously to the rat, however, trientine clearance decreased to almost the same level as the creatinine clearance. To clarify this active excretion system for trientine, the uptake of trientine and a physiological polyamine compound, spermine, was investigated using rat renal brush-border membrane vesicles. Although, because trientine and spermine are organic cations, the H+/organic cation transporter is expected to recognize these compounds, neither an outwardly directed H+ gradient nor an inward Na+ gradient stimulated trientine uptake. [14C]Spermine uptake was, nevertheless, trans-stimulated by both unlabelled spermine and trientine and the trans-stimulating effect of spermine on trientine uptake was, furthermore, completely abolished by addition of copper ions to the incubation medium. These results suggest that there is a specific transport system for spermine and trientine on the renal brushborder membrane. This transport system contributes to the secretion of trientine in the kidney proximal tubule but does not recognize the trientine-copper complex.

Influence of membrane-active peptides on lipospermine/DNA complex mediated gene transfer

To explore whether endosomal release presents a major barrier to lipospermine-mediated gene delivery, acidic membrane-active peptides derived from influenza virus or artificial sequences were incorporated into DNA/dioctadecylamidoglycylspermine (= Transfectam) complexes. Depending on the cell line used, gene expression levels are approximately 3-30-fold higher than those obtained by applying DNA complexed to optimal amounts of Transfectam alone. In addition, gene transfer efficiency of DNA complexes with lower amounts of Transfectam (1.5-2 charge equiv) is increased by a factor of up to 1000 by peptides INF6 (influenza virus derived sequence) and INF10 (artificial sequence). The helper lipids 1,2-dioleoylphosphatidylethanolamine, egg phosphatidylethanolamine, and 1,2-dioleoyl-racglycerol also can enhance the gene transfer. Thus, endosomal escape seems to be only a moderate barrier for optimized, positively charged DNA/Transfectam complexes, but a substantial bottleneck for less positively charged complexes.

Use of nitric oxide-nucleophile adducts as biological sources of nitric oxide: effects on airway smooth muscle

Nitric oxide (NO)-nucleophile adducts are compounds of the general structure [XN(O)NO]-, where X is a nucleophile residue, and they release NO spontaneously in aqueous solution. This study determined the effects of two NO-nucleophile adducts [diethylaminodiazen-1-ium-1,2-diolate (DEA-NO) and sperminediazen-1-ium-1,2-diolate (DEA-NO) and sperminediazen-1-ium-1,2-diolate (spermine-NO)] on isometric force and the cytosolic concentrations of cyclic GMP ([cGMP]1), cyclic AMP ([cAMP]i) and calcium in canine tracheal smooth muscle. The ratio of fura-2 emission fluorescence intensities with excitation at 340- and 380-nm wavelengths (F340/ F380) was used as an index of cytosolic [Ca+2] concentration. Both DEA-NO and spermine-NO caused a concentration-dependent and reversible decrease in force (EC50 of 0.13 +/- 0.02 microM and 4.1 +/- 0.3 microM, respectively) and F340/F380, a concentration-dependent increase in [cGMP]i and no change in [cAMP]i. There were no significant differences in the relationship between [cGMP]l and the percentage decrease in force or in the relationship between the percentage decrease in F340/ F380 and the percentage decrease in force between tissues relaxed with DEA-NO or spermine-NO. Oxyhemoglobin increased the EC50 for both DEA-NO (from 0.13 +/- 0.03 microM to 8.1 +/- 0.2 microM) and spermine-NO (from 3.9 +/- 0.3 microM to 81.6 +/- 6.4 microM) and completely scavenged NO released by 0.13 (EC50) and 1 (EC100)microM DEA-NO. These results suggest that both DEA-NO and spermine-NO generate NO extracellularly and relax airway smooth muscle in association with an increase in [cGMP]i and a decrease in cytosolic Ca+2 concentration. NO-nucleophile adducts may serve as vehicles for the controlled delivery of NO into biological systems and thus provide a useful tool by which the physiology of NO can be investigated.

Analysis of structural and biochemical events occurring in the small intestine after dietary polyamine ingestion in suckling rats

In the present investigation, we analyzed the mechanism involved in spermine-induced intestinal maturation in suckling rats. Spermine was given orally to suckling pups and biochemical as well as morphological parameters were studied at different times after the beginning of the treatment. Eight hours after administration, spermine produced cell elimination at the villus tops and a decrease in intestinal DNA and protein content. In parallel, protein and DNA concentration and disaccharidase activity were enhanced in the chyme. These transitory alterations were not induced by growth inhibition, as DNA synthesis was not modified, although a brief decrease in protein synthesis was observed. Spermine was not metabolized in cytotoxic products: rat pretreatment with MDL72527 (an inhibitor of polyamine oxidase) did not avoid the decrease in disaccharidase activity and in DNA and protein content. Three days after treatment, sucrase and maltase activity was higher in rats treated with spermine and MDL72527 than that in animals receiving spermine alone. Lactulose or acetylspermine ingestion induced intestinal maturation. Our data suggest that dietary polyamines exert a direct and specific maturational effect on rat small intestine and that an early decrease in lactase activity plays an important role in this phenomenon.

Plasma pharmacokinetics and urinary excretion of the polyamine analogue 1, 19-bis(ethylamino)-5, 10, 15-triazanonadecane in CD2F1 mice

The pharmacokinetics of 1, 19-bis(ethylamino)-5, 10, 15-triazanonadecane (BE-4-4-4-4) were determined in CD2F1 female mice after administration of i.v. bolus doses of 20 mg/kg (approximately the dose lethal to 10% of the study animals, approximately LD10) as well as 15, 10, and 5 mg/kg and after s.c., i.p., or p.o. doses of 20 mg/kg. BE-4-4-4-4 in plasma and urine was derivatized with dansyl chloride and measured by gradient high-performance liquid chromatography (HPLC) with fluorescence detection. Data were modeled by noncompartmental and compartmental methods. The declines observed in plasma BE-4-4-4-4 concentrations after i.v. delivery of 20, 15, 10, and 5 mg/kg were modeled simultaneously using an interval of 2000 min between doses and were best approximated by a two-compartment, open, linear model. The time courses of plasma BE-4-4-4-4 concentrations after i.p. and s.c. delivery were fit best by a two-compartment, open, linear model with first-order absorption. Peak plasma concentrations of BE-4-4-4-4 measured following an i.v. dose of 20 mg/kg ranged between 30 and 33 microgram/ml, the terminal elimination half-life was 94 min, and the volume of distribution (Vdss) was 850 ml/kg. The plasma pharmacokinetics of BE-4-4-4-4 were linear with dose. BE-4-4-4-4 (0.5 and 2.0 microM) in mouse plasma was approximately 67% protein-bound. Bio-availabilities after i.p., s.c., and p.o. delivery were 40%, 50%, and approximately 3%, respectively. Urinary excretion of parent BE-4-4-4-4 in the first 24 h after dosing accounted for less than 30% of the delivered dose. As BE-4-4-4-4 proceeds toward and undergoes clinical evaluation, the data and analytical method presented herein should prove useful in formulating a dose-escalation strategy and, possibly, evaluating toxicities encountered.

Reversal of doxorubicin, etoposide, vinblastine, and taxol resistance in multidrug resistant human sarcoma cells by a polymer of spermine

We have previously described the synthesis of a cytotoxic polymeric conjugate of spermine (Poly-SPM) which is able to inhibit the transport of polyamines (spermine, spermidine, and putrescine) into normal and malignant cells. Recent studies examining the toxicity of Poly-SPM in parental and multidrug resistant (MDR) cancer cells have revealed a cross-resistance in the MDR variant Dx5 to the toxic effects of the conjugate in the MDR-positive cells. There were also differences in spermine and putrescine uptake rates between parental and MDR-positive with the MDR-positive cells having a lower Vmax and a higher Km. The ability of this Poly-SPM to reverse MDR was examined in MDR variants (Dx5 cells) of the human sarcoma cell line MES-SA. The cells express high levels of the mdr1 gene product, P-glycoprotein, and are 25-to 60-fold resistant to doxorubicin (DOX), etoposide (VP-16), vinblastine (VBL), and taxol (TAX). Cytotoxicity was measured by the MTT [3-(4,5-dimethyldiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay. Poly-SPM (50 microM) lowered the drug concentration IC50 values in the Dx5 cells by 37-fold with VBL, 42-fold with DOX, 29-fold with VP-16, and 25-fold with TAX when compared to the control IC50 values without Poly-SPM. This reversal of resistance was concentration dependent, decreasing 17-fold with DOX, 6.1-fold with VBL, 19-fold with VP-16, and 5-fold with TAX when 25 microM Poly-SPM was used. No modulation was observed in the parental cell line MES-SA, which does not express the mdr1 gene. Poly-SPM had no influence on the IC50 of non-MDR chemotherapeutic agents such as cisplatin. The modulation studies correlated with the ability of Poly-SPM to reverse the cellular accumulation defect of [3H]-VBL and [3H]-TAX in the Dx5 but not MES-SA cells. Pretreatment of the Dx5 cell with alpha-difluoromethylornithine (DFMO at 2 and 5 microM) for 24 h increased the function of the MDR transporter to further decrease the cellular accumulation of VBL and TAX when compared to untreated cells. DFMO pretreatment is known to upregulate the polyamine transporter(s). These findings show that, in addition to inhibiting polyamine transport, Poly-SPM reverses MDR in Dx5 cells, suggesting a potential relationship between the polyamine influx transporter and the MDR efflux pump. This potential functional link between the polyamine influx transporter(s) and the MDR efflux transporter (P-glycoprotein) offers a novel approach to inhibiting this form of drug resistance.

Mechanism of the nitric oxide-induced blockade of collecting duct water permeability

Nitric oxide has a diuretic effect in vivo. We have shown that nitric oxide inhibits antidiuretic hormone-stimulated osmotic water permeability in the collecting duct; however, the mechanism by which this occurs is unknown. We hypothesized that inhibition of antidiuretic hormone-stimulated water permeability by nitric oxide in the collecting duct is the result of activation of cGMP-dependent protein kinase, which in turn decreases intracellular cAMP. To test this hypothesis, we microperfused cortical collecting ducts. Antidiuretic hormone-stimulated water permeability was 317 +/- 47 microm/s (P < .001). Addition of spermine NONOate, a nitric oxide donor, to the bath decreased water permeability to 74 +/- 38 microm/s (P < .002). In the presence of LY 83583, an inhibitor of soluble guanylate cyclase, spermine NONOate did not change water permeability. Addition of spermine NONOate increased cGMP production (P < .01). In the presence of the cGMP-dependent protein kinase inhibitor, spermine NONOate did not change water permeability. Since antidiuretic hormone increases water permeability by increasing cAMP, we hypothesized that nitric oxide inhibits water permeability by decreasing cAMP. In tubules pretreated with antidiuretic hormone, intracellular cAMP was 18.9 +/- 3.9 fmol/mm. In tubules treated with antidiuretic hormone and spermine NONOate, cAMP was 9.3 +/- 1.7 fmol/mm (P < .03). We also examined the effect of spermine NONOate on dibutyryl-cAMP-stimulated water permeability. In the presence of dibutyryl-cAMP, water permeability was 388 +/- 30 microm/s. Addition of spermine NONOate had no significant effect on water permeability. Time controls and inhibitors by themselves did not change antidiuretic hormone-stimulated water permeability. We concluded that nitric oxide decreases antidiuretic hormone-stimulated water permeability by increasing cGMP via soluble guanylate cyclase, activating cGMP-dependent protein kinase and decreasing cAMP.

Synergism of the polyamine analogue, N1,N11-bisethylnorspermine with cis-diaminedichloroplatinum (II) against murine neoplastic cell lines in vitro and in vivo

The activities of naturally occurring polyamines are exploited to enhance the antitumor activity of cisplatin. The polyamine analogue, N1,N11-bis-ethylnorspermine (BE-3-3-3) is used at subtherapeutic levels in L1210 leukemia suspension cultures and plating efficiency assays of B16 F1 melanoma cells to increase the cytotoxic effect of cisplatin seven- and ten-fold, respectively. Similar experiments in mice reveal additive effects for DBA/2J mice bearing L1210 and synergistic effects in C57/B6 mice bearing B16 F1 tumor after optimizing combination ratios. In the latter model, at a BE-3-3-3/cisplatin molar ratio of 250:1, an increased lifespan (ILS) of 56% is recorded during a 9-day dosing schedule, whereas BE-3-3-3 at the same dose caused a 21% ILS, and cisplatin only exhibited a 7% ILS. Possible reasons for differences between in vitro and in vivo activity are discussed.

Synthesis and antitumor evaluation of a highly potent cytotoxic DNA cross-linking polyamine analogue, 1,12-diaziridinyl-4,9-diazadodecane

A diaziridinylspermine analogue, 1,12-diaziridinyl-4,9-diazadodecane (NSC-667005), was synthesized as a bisalkylating agent with a polyamine backbone. DNA cross-linking was detected in the reaction of linearized pBR322 DNA with 1,12-diaziridinyl-4,9-diazadodecane at concentrations comparable with that required for cross-linking by two nitrogen mustard drugs, mechlorethamine and melphalan. A significant increase in life span of female CD2F1 mice bearing L1210 murine leukemia was observed after intravenous administration of 1,12-diaziridinyl-4,9-diazadodecane in doses of less than 2.7 mg/kg, given on days 1, 5, and 9 of treatment.

Induction of mucosal anti-HIV antibodies by facilitated transfection of airway epithelium with lipospermine/DNA complexes

BACKGROUND

Expression of microbial protein sequences in eukaryotic cells transfected by transcriptional/translational permissive cDNA constructs can induce systemic humoral and cellular responses in vivo. Two methods of in vivo transfection have been described to date. One method uses large quantities of naked DNA injected into skeletal muscle. The second method uses relatively small quantities of DNA complexed to gold particles for bollistic penetration of the plasma membrane of keratinocytes. The major disadvantage of the bolistic method is that instrumentation is required which is not generally available.

OBJECTIVES

The objectives of this study were to determine whether the use of DNA complexed with a cationic lipopolyamine could reduce the quantity of DNA required to induce systemic humoral responses following muscle transfection and whether similar DNA/lipopolyamine complexes could induce mucosal humoral responses following airway exposure.

STUDY DESIGN

Balb/c mice were exposed by nasal aerosol or intramuscular inoculation to a mammalian transcriptional/translational permissive DNA construct containing the entire sequence for the HIV-1 envelope polyprotein. Experimental animals were further segregated by the number of exposures at 3-week intervals and whether the DNA was complexed to dioctadecylamidoglycylspermine (DOGS) at a 5:1 molar charge ratio of DOGS/DNA.

RESULTS

DOGS facilitated in vivo transfection of mouse muscle reduced the quantity of DNA required for a systemic humoral response to surface expressed HIV-envelope proteins by one order of magnitude. Exposure of airway mucosa to both 10 micrograms and 1 microgram quantities of DNA complexed to DOGS produced systemic humoral responses to HIV-envelope as well as mucosal antibodies in pulmonary and colonic epithelia. Molecular modeling of DOGS/DNA complexes at the 5:1 charge ratio used in this study indicates that the DNA component is not exposed to aqueous solvents and may be relatively resistant to degradation under common biological environments.

CONCLUSION

Facilitated transfer of DNA by DOGS to transcriptional/translational competent cells offers several distinct advantages to the use of DNA alone. Since significantly smaller amounts of DNA are required, the potential for the induction of antibodies against DNA itself lessens the likelihood for the development of a lupus-like syndrome. More importantly, however, is the apparent ability to transfect mucosal cells which results in the development of specific mucosal immune responses. This procedure may allow the development of general methods for the induction of mucosal immunity at the level of entry for mucosal pathogens without the disadvantages inherent in live attenuated vectors.

Preclinical antitumor efficacy of the polyamine analogue N1, N11-diethylnorspermine administered by multiple injection or continuous infusion

Certain N-alkylated analogues of the natural polyamine spermine have been found to disrupt polyamine pool homeostasis and inhibit tumor cell growth. The most effective of these analogues, N1, N11-diethylnorspermine (DENSPM), apparently depletes intracellular polyamine pools primarily by inducing the polyamine acetylating enzyme spermidine/spermine N1-acetyltransferase, which contributes to polyamine depletion via increased polyamine excretion and catabolism. In this report, the experimental therapeutic efficacy of DENSPM was further examined with the use of other human solid tumor xenografts, including A121 ovarian carcinoma, A549 lung adenocarcinoma, HT29 colon carcinoma, and SH-1 melanoma, and compared with previously obtained findings with MALME-3M and PANUT-3 human melanomas. In vitro studies indicated that the growth sensitivity of most tumor cell lines to DENSPM was similar, with characteristically flat dose-response curves and IC50s ranging between 0.1 and 1 micrometer the only exception was the HT29 colon carcinoma cell line, which had an IC50 of >100 micrometer. For in vivo studies, DENSPM was administered by i.p. injection to female nude athymic mice at 40 and/or 80 mg/kg 3 times a day (every 8 h) for 6 days or by continuous s.c. infusion with the use of Alzet pumps at 120, 240, or 360 mg/kg/day for 4 days. Treatment began after s.c. tumor xenografts had reached 100-200 mm3. The SH-1 melanoma, A549 lung adenocarcinoma, and A121 ovarian carcinoma xenografts responded well to the i.p. administration of analogue with obvious tumor regressions, long-term tumor growth suppressions, and a significant proportion (up to 40%) of apparent cures (i.e., lack of tumor regrowth). However, in similarity to in vitro findings, HT29 colon carcinoma xenografts responded poorly to DENSPM treatment. Massive induction of N1-acetyltransferase activity and extensive depletion of polyamine pools were consistent findings in most tumor types after in vivo or in vitro treatment with DENSPM. The rapidly growing human LOX melanoma xenograft, however, demonstrated poor induction of N1-acetyltransferase activity and the poorest response to DENSPM treatment. In nude athymic mice with MALME-3M melanoma xenografts, constant infusion delivery of DENSPM resulted in prolonged inhibition of tumor growth and long-term tumor regressions comparable to those produced by multiple i.p. injections. On the basis of the unique structure of DENSPM, novel target and mode of intervention, mild host toxicity, and activity against different human solid tumor xenografts, DENSPM is currently being developed as an antitumor agent in humans.

The importance of dietary polyamines in cell regeneration and growth

The polyamines putrescine, spermidine and spermine are essential for cell renewal and, therefore, are needed to keep the body healthy. It was previously believed that polyamines are synthesized by every cell in the body when required. However, in the present paper evidence is provided to show that, as in the case of the essential amino acids, the diet can supply sufficient amounts of polyamines to support cell renewal and growth. Systematic analysis of different foods was carried out and from the data obtained, the average daily polyamine consumption of British adults was calculated to be in the range 350-500 mumol/person per d. The major sources of putrescine were fruit, cheese and non-green vegetables. All foods contributed similar amounts of spermidine to the diet, although levels were generally higher in green vegetables. Meat was the richest source of spermine. However, only a part of the polyamines supplied by the diet is available for use by the body. Based on experiments with rats it was established that polyamines were readily taken up from the gut lumen, probably by passive diffusion, and were partly metabolized during the process of absorption. More than 80% of the putrescine was converted to other polyamines and non-polyamine metabolites, mostly to amino acids. The enzyme responsible for controlling the bioavailability of putrescine was diamine oxidase (EC 1.4.3.6). For spermidine and spermine, however, about 70-80% of the intragastrically intubated dose remained in the original form. Considering the limitations on bioavailability (metabolism and conversion), the amounts of polyamines supplied by the average daily diet in Britain should satisfy metabolic requirements.

Activation of hepatic glutaminase by spermine

Glutaminase activity in intact mitochondria from rat liver is activated by spermine, as indicated both by increased glutamate production from glutamine and by increased respiration with glutamine as sole substrate. Glutaminase activity assayed in membranes from frozen-thawed mitochondria, is activated by spermine about 6-fold at physiological concentrations of its other effectors (NH4+ at 0.7 mM, Pi 5 mM) and at pH 7.4. Spermine decreased the apparent Km for glutamine from 38 to 15 mM at 5 mM Pi, and increased the sensitivity of the enzyme for phosphate activation so that the concentration required for 50% stimulation decreased from 15 to 4 mM. Half-maximal spermine effects occurred at 0.15 mM, which is in the physiological range. Spermine was effective in the presence of physiological concentrations of Mg2+. We suggest that spermine may be a physiological activator of hepatic glutaminase.

Pretreatment with the polyamine analog 1,19-bis-(ethylamino)-5,10,15-triazanonadecane (BE-4-4-4-4) inhibits etoposide cytotoxicity in U-251 MG (NCI) human brain tumor cells

We studied whether pretreatment of U-251 MG human brain tumor cells with the polyamine analog 1,19-bis-(ethylamino)-5,10,15-triazanonadecane (BE-4-4-4-4) affected the cytotoxicity of the topoisomerase II inhibitor etoposide. We found that BE-4-4-4-4 protected cells from the cytotoxic effects of etoposide. Possible mechanisms for this protection may be related to enhanced DNA-nuclear matrix association in analog-treated cells.

Temporal and spatial expression of lipospermine-compacted genes transferred into chick embryos in vivo

We have optimized a lipospermine-based transfection method for introducing genes into intact vertebrate embryos in vivo. The method employs small amounts of the cationic lipid Transfectam (DOGS), in a concentrated (40 mM) ethanolic solution, to compact and to transfer exogenous genes into chick embryos during the early stages of development (< 36 h of incubation). Plasmid vectors containing the reporter gene luciferase were used to follow the time course of expression. Luciferase activity was detected as early as 12 h post-transfection and was highest at this time. Enzyme activity then decreased over the next two days and was usually undetectable by 72-h post-transfection. To follow the spatial expression of the exogenous genes, a Rous sarcoma virus (RSV)-beta-galactosidase vector was used. When the transfection complex was applied externally around the developing embryo, the main site of expression was the cardiac tissue. Expression could be targeted to the nervous system by micro-injecting the DNA/DOGS (DNA/dioctadecylamidoglycylspermine) complex into the developing brain. The results show that reporter genes can be efficiently expressed in both the developing central nervous system and heart. This raises the possibility that lipospermines can be used to transfer functional genes into embryos during defined periods of development and also to deliver genes in other species and in other in vivo contexts.

Intestinal development in suckling rats: direct or indirect spermine action?

The present investigation addresses the question of whether spermine orally given to unweaned rats directly or indirectly exerts its effects on the intestinal brush border disaccharidases and if the adrenal gland secretions play a role in this phenomenon. The results showed that spermine, surgically placed in the lower part of the distal small intestine, induced sucrase, stimulated maltase-specific activity and decreased lactase-specific activity in both proximal and distal segments of the small intestine. Introduction of spermine into the lumen of the large intestine stimulated the specific activities of disaccharidases in the whole small intestine. Intraperitoneal injection had no effect except a slight reduction of lactase-specific activity in the distal intestine. Adrenalectomy prevented the oral effect of spermine on sucrase- and maltase-specific activity but not on lactase-specific activity. Addition of spermine to intestinal explants in organ cultures fails to reproduce any of these effects. It even reduced maltase-specific activity. These findings suggest that dietary polyamines have either direct and indirect effects on properties of rat immature intestine.

Evolution of biochemical parameters characterizing the proximal small intestine after orally administered spermine in unweaned rats

Important variations in intestinal biochemical characteristics were recorded after ingestion of a single dose of spermine (8 mumol 50 microliters-1 water) by rats which were 11 days old. Two phases of events were observed. During the first hours which follow spermine administration, we mainly noted: -a decrease in the weight of DNA and of intestine per cm, -a decrease in the specific activity of lactase and of maltase, -an increase in the spermine content. The second phase of events started about 30 h after spermine ingestion. We observed: 1. An increase in the weight of DNA and of intestine per cm; 2. The appearance of sucrase activity; 3. An increase in maltase specific activity; 4. An increase in spermidine content; 5. tendency to normalization of the spermine content. The epithelial cells of the proximal intestine were isolated in fractions from the top of the villi to the bottom of the crypts. Two hours after spermine administration, we noted: 1. An increase in the lactase specific activity of the epithelial cells located at the top of the vili; 2. A decrease in the activity of the cells situated at the lower part of the crypts; 3. An increase in the specific activity of maltase contained in the different categories of enterocytes, except in those from the bottom of the crypts; 4. An increase in the content of putrescine present in the epithelial cells of the whole axis excepted in the bottom of the crypts; 5. An increase in the spermidine and spermine content of all the cell fractions.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunization of rabbits with spermine induces antibodies to self antigens

Rabbits were immunized under different schedules with spermine in the free form or with random noncovalent complexes of spermine or spermidine with ovalbumin. The specificity of the induced antibodies was determined by ELISA and by dot-immunobinding assay. Our results show that in vitro conjugation of spermine and spermidine to a carrier is not an obligatory prerequisite for obtaining corresponding antibodies. Anti-spermine antibodies were found in 9 of 19 animals injected with spermine. Furthermore, all 19 rabbits produced distinct populations of IgM and IgG antibodies which reacted with histones, various synthetic peptides of histones, as well with ubiquitin, a peptide of ubiquitin, dsDNA and two 29-base 5' synthetic oligodeoxynucleotides. Even in antisera with no detectable reactivity with spermine, antibodies to some of the unrelated antigens were found. The pattern of reactivity of the antisera with the various antigens was different for each immunized animal. These findings lend support to the view that polyamines may play a role in the appearance of autoantibodies.

Spermine facilitates the generation of long-term potentiation of evoked potential in the dentate gyrus of anesthetized rats

The effects of the polyamines, spermine, spermidine and putrescine, on long-term potentiation (LTP) of evoked potential were investigated in the dentate gyrus of anesthetized rats. Injection of 5 nmol spermine into the lateral ventricle did not influence the basal amplitude of the population spike, but significantly enhanced the potentiation induced by subthreshold tetanic stimulation (20 pulses at 60 Hz). The effect of spermine resulted in facilitation of LTP generation. Injection of the same dose of spermidine or putrescine affected neither the basal response nor the potentiation induced by subthreshold tetanus at all, indicating that the LTP-facilitating effect is specific to spermine. Furthermore, the LTP-facilitating effect of spermine was dose-dependent in the range of 0.5-50 nmol. When 5 nmol ifenprodil, an antagonist at the polyamine site of the NMDA receptor channel complex, was concomitantly injected, spermine could not facilitate the generation of LTP. Since injection of ifenprodil alone did not influence the generation of LTP, it is probable that ifenprodil specifically blocks the effect of spermine. These results suggest that spermine facilitates the generation of hippocampal LTP, probably through an ifenprodil-sensitive polyamine site associated with the NMDA receptor.

Effect of spermine on sperm capacitation of guinea pig in vitro

Spermine (Sp) 10(-5) mM had vigorous activity of guinea pig spermatozoa, while it completely abolished sperm forward motility (SFM) at a concentration of 10(-3) mM. There appeared to be a dose relationship to inhibition to motility. 2-Difluoromethylornithine 10 mM antagonized the Sp-induced inhibition of SFM after 3 h of incubation. Capacitation of a guinea pig sperm was inhibited by Sp in a concentration-dependent manner. The majority of acrosome-reacted sperm did not display hyperactivated motility. Precapacitated sperm were able to undergo the acrosome reaction (AR) in the presence of Sp. Moreover, Sp-mediated inhibition of capacitation was a reversible process. Once sperm capacitation was completed, Sp no longer inhibited AR. Before capacitation, the content of Sp in spermatozoa was 4.5 +/- 0.5 micrograms/5 x 10(7) cells, whereas in case of capacitated spermatozoa it was significantly decreased (2.1 +/- 0.4 micrograms/5 x 10(7) cells). The penetration of spermatozoa into the zona-free hamster eggs in the presence of Sp was markedly decreased, but it did not affect the fertilizability of ova as compared to the control. These results suggest that Sp may be an inhibitory agent of sperm capacitation in guinea pig in vitro, and it may also be involved in the modulation of capacitation.

Changes in ingestive behavior induced by intracranial injection of spermine

Effect of intracranial injection of spermine on feeding and drinking behavior was studied in rats. A significant and long-term suppression of feeding and drinking behavior appeared when 30 nmol/hemisphere of spermine was bilaterally injected into the lateral hypothalamic area, substantia nigra or ventral noradrenergic bundle. Micro-injected spermine into the medial amygdaloid nucleus produced a weak and short-time but significant suppression of ingestive behavior. On the other hand, a significant increase in feeding and drinking behavior was observed when spermine was injected into the ventromedial hypothalamic nucleus. These results suggest that spermine inhibits neuronal activity of all the brain regions studied here.

Polyamines stimulate the phosphorylation of phosphatidylinositol in rat mast cell granules

Rat mast cell granules were obtained by homogenization of highly purified rat mast cells and isolated in a Percoll gradient. Diphosphoinositide (DPI) synthesis in rat mast cell granules was assayed by measuring the incorporation of 32P from [gamma 32P] ATP into DPI in the absence of exogenous phosphatidylinositol (PI). Lipids were isolated with methanol/chloroform/HCl and were separated by thin-layer chromatography on oxalic acid impregnated silica gel plates. DPI areas were identified by staining with iodine, scraped and measured for 32P radioactivity. The addition of polyamines, spermine and spermidine, to the granules caused an increase of DPI synthesis, which can be catalyzed by PI kinase. This effect of polyamines in the DPI synthesis was in a dose-dependent manner and maximal effects were observed at 1 mM spermine and 10 mM spermidine, respectively.

Cochleotoxic effects of spermine and kanamycin

Aminoglycosides are organic bases that contain multiple amino groups. The ototoxic potential of these amine groups was studied using spermine, which is a polyamine with four amine groups (two amino and two imino). Twenty-four pigmented guinea pigs were studied. One-tenth milliliter of different concentrations of kanamycin A sulfate or spermine were given intratympanically. The temporal bones were removed 4 days after the injections, and the cochleas were examined using the scanning electron microscope. The damage to the hair cells was recorded in cytocochleograms. The results show that spermine is cochleotoxic when given intratympanically. Dosage of 50 mumol for kanamycin A sulfate and 5 mumol for spermine caused total damage of the outer hair cells in all ears. Lower dosage of kanamycin A sulfate (20 mumol) and spermine (1 mumol) did not cause any histologically discernible changes.

A possible mechanism of protection by polyamines against gastric damage induced by acidified ethanol in rats: polyamine protection may depend on its antiperoxidative properties

The protective mechanism of polyamines against acidified ethanol-induced gastric damage was studied. Their oral administration prevented the formation of gastric mucosal lesions induced by 90% ethanol in 150 mM HCl in a dose-dependent manner, with the order of the protective potency being spermine greater than spermidine greater than putrescine. The acidified ethanol-induced lesions were accompanied by a concomitant increase in gastric mucosal lipid peroxide levels, but spermine in a protective dose could prevent the increment of lipid peroxides. Polyamines, in a concentration-dependent fashion, inhibited the reduction of nitroblue tetrazolium by superoxide anion radicals generated in vitro in the xanthine-xanthine oxidase system and the lipid peroxidation in vitro induced by ferrous ion in the porcine gastric mucosal homogenate. The order of the superoxide scavenging potency and the inhibitory potency of iron-induced lipid peroxidation by polyamines corresponded to the order to the protective potency against acidified ethanol-induced gastric lesions. The present results suggest that cytoprotection by polyamines may be responsible for their antiperoxidative activities.

Oral administration of spermine inhibits gastric acid secretion in rats

Administration of spermine by oral route inhibits the histamine-stimulated gastric acid secretion in pylorous ligated rats. The extent of both the acid and volume of secretion is dependent on the dose of spermine. The polyamine is completely ineffective when injected by the intravenous route. A single oral dose of spermine suppresses acid secretion for at least 6 hr. An inverse relationship between the efficacy of oral spermine and age of the animals was observed. These data suggest a therapeutic potential for the naturally occurring polyamine compounds.

[Effects of intraperitoneally administered spermine on ingestive behavior, serum glucose and free fatty acids concentrations in rats (author's transl)]

The intraperitoneal administration of spermine (SPM) produced a dual-phasic feeding suppression. The first suppression appeared immediately after the administration and disappeared on the 2nd day. The next suppression was observed on the 3rd day and continued for 2-4 days. The 50% dose which induced suppression on the 3rd day was 64.9 (60.9-69.2) mumol/kg. Drinking behavior was also suppressed on the 1st day, but was facilitated on the 2nd day and lasted for 4-5 days. Serum glucose and free fatty acids concentrations increased after the administration of SPM (80 mumol/kg). Their maximal values obtained at 3 hours after the dosing were 116% and 156% of the control values, respectively. These increases in both substances were not observed in the adrenal-demedullated rats. The same dose of SPM enhanced serum glutamic oxaloacetic transaminase and glutamic pyruvic transaminase activities. The maximal values obtained at 2 hours after the dosing were 264% and 142% of the control values, respectively. On the contrary, serum cholinesterase activity decreased to 44% of the control value at the same hour. These variations of the enzyme activities disappeared at 3 hour, but were again observed between the 1st and 4th days. The results suggest that SPM releases catecholamines from the adrenal medulla, and exerts a toxic action on the liver. The anorexia induced by SPM may be due to these actions on the viscera.

Spermine stimulation of CCl4 depressed protein synthesis in rabbits

CCl4, 2.5 ml/kg body weight, was administered via a gastric tube to fed rabbits 2 hr before the livers were removed and perfused. Electron microscope studies of the liver showed that CCl4 caused a decrease in the rough endoplasmic reticulum and an increase in the smooth reticulum. The reticulum was dilated and vesiculated with few attached ribosomes. Sucrose gradient analysis of the endoplasmic reticulum bound polysomes showed them to be considerably disaggreated, and albumin synthesis and 14C-incorporation into proteins secreted into the perfusate were decreased. These effects were partially reversed when these livers were perfused with either 1 mM spermine of 10 mM arginine. Perfusion with both arginine and spermine increased endoplasmic reticulum bound polysome aggregation to about 92% of control and albumin synthesis increased from a low of 3.3 mg/100 g wet liver weight to 8.2 mg/hr or 37% of control. 14C-Incorporation into total hepatic protein and secretory proteins increased as well. The combination of spermine and arginine was more effective in stimulating albumin synthesis than either agent alone. The ability of spermine to partially reverse a specific toxic effect of carbon tetracholoride, namely polysome disaggregation, and to stimulate protein production is noted.

Effects of intraventricularly administered polyamines spermidine and spermine on sleep-wakefulness cycles in rats

Freely moving rats with chronically implanted electrodes were used and the electroencephalogram (EEG) from the occipital cortex and the dorsal hippocampus, the electromyogram (EMG) and the electrooculogram (EOG) were simultaneously recorded. The REM (rapid eye movement) sleep stage was significantly shortened without a marked change of the Non-REM sleep from the 24th to the 32nd hr following injection of 40 microgram of SPD. The waking stage significantly increased, and the Non-REM sleep and REM sleep markedly decreased immediately after the injection of 40 microgram of SPM to the 8th, and from the 24th to the 32nd hr. The amount of total sleep significantly shortened from the 72nd to the 80th hr following injection of 40 microgram of SPD. The administration of 40 microgram of SPM significantly reduced the amount of total sleep in every period measured for 8 hr. Marked change was observed from the 24th to the 32nd hr following injection of 100 microgram of PUT, and Non-REM sleep and total sleep produced a significant decrease. These results show that the intraventricular administration of polyamines including PUT inhibits the amount of normal sleep.

Pharmacological actions of intracerebrally administered polyamines in mice

Pharmacological actions of spermidine (SPD) and spermine (SPM) in mice given these polyamines by intracerebral injection (i.c.) were investigated. The spontaneous motor activity (SMA) assessed by the photocell counter method did not change immediately following injection of 80 mug SPD, but was enhanced 24 hours after the injection of 40 or 80 mug. A significant decrease of SMA was not immediately evident after the administration of 40 mug SPM but was demonstrated 24 hours later. Mice given single doses of 20 mug SPD exhibited increase in weight gain and those given 40 mug showed no significant difference, whereas a conspicuous decrease in weight occurred in mice given 80 mug of SPD. The body weights of mice given single doses of 10 mug SPM remained much the same, while significant weight losses occurred in both the SPM 20 mug and 40 mug dosed groups. There was a significant prolongation of pentobarbital induced sleep 6 days after the injection of high doses of SPD or SPM. Similar prolongation of sleeping time was also evident 30 minutes after the injection of SPM. A maximal hypothermic response with a fall by about 1 degree C was observed immediately following injection of 80 mug of SPD and 24 hours after the injection of 40 mug SPM, respectively.

Hyperglycaemia produced by the polyamines spermine and spermidine

1 Intravenous injection of rabbits with the polyamines spermine (10-30 mg/kg) and spermidine (50-90 mg/kg) produced hyperglycaemia.2 Given by intraventricular injection, spermine and spermidine gave rise to hyperglycaemia in doses 250-500 times smaller than those effective intravenously.3 Intraventricular injections of the polyamines also produced hyperglycaemia in rats. Adrenal demedullation abolished the response.4 In the rabbit, the hyperglycaemia resulting from intraventricular injection of polyamines was abolished in reserpine-treated animals. Anaesthesia had no effect on the response unless accompanied by anoxia, when the response was potentiated.5 Intracisternal injections of the polyamines in rabbits were less effective than intraventricular injections in that doses about four times larger were required to elicit an equivalent response.