Chemoprevention of azoxymethane-induced rat colon carcinogenesis by the naturally occurring flavonoids, diosmin and hesperidin

The modulating effects of dietary feeding of two flavonoids, diosmin and hesperidin, both alone and in combination, during the initiation and post-initiation phases on colon carcinogenesis initiated with azoxymethane (AOM), were investigated in male F344 rats. Animals were initiated with AOM by weekly s.c. injections of 15 mg/kg body wt for 3 weeks to induced colon neoplasms. Rats were fed the diets containing diosmin (1000 ppm), hesperidin (1000 ppm) or diosmin (900 ppm) + hesperidin (100 ppm) for 5 weeks (initiation treatment) or 28 weeks (post-initiation treatment). The others contained the groups of rats treated with diosmin, hesperidin alone or in combination, and untreated. At the end of the study (32 weeks), the incidence and multiplicity of neoplasms (adenoma and adenocarcinoma) in the large intestine of rats initiated with AOM together with, or followed by, a diet containing diosmin or hesperidin were significantly smaller than those of rats given AOM alone (P <0.001). The combination regimen during the initiation and post-initiation stages also inhibited the development of colonic neoplasms, but the tumor data did not indicate any beneficial effect of diosmin and hesperidin administered together as compared with when these agents were given individually. In addition, feeding of diosmin and hesperidin, both alone and in combination, significantly inhibited the development of aberrant crypt foci. As for cell proliferation biomarkers, dietary exposure of diosmin and hesperidin significantly decreased the 5'-bromodeoxyuridine-labeling index and argyrophilic nuclear organizer region's number in crypt cells, colonic mucosal ornithine decarboxylase activity, and polyamine levels in the blood. These results indicate that diosmin and hesperidin, both alone and in combination, act as a chemopreventive agent against colon carcinogenesis, and such effects may be partly due to suppression of cell proliferation in the colonic crypts, although precise mechanisms should be clarified.

ICRF-193, a catalytic inhibitor of DNA topoisomerase II, delays the cell cycle progression from metaphase, but not from anaphase to the G1 phase in mammalian cells

We have shown previously that ICRF-193, a catalytic inhibitor of DNA topoisomerase II (topo II), delays cell cycle progression in HeLa S3 cells. We report here that the delay of the transition in M phase is observed when HeLa S3 cells were treated with ICRF-193 during metaphase, but not thereafter. ICRF-193 also delayed the degradation of cyclin B in the transition from M to G1 phase, while in Chinese hamster ovary (CHO) cells the drug did not delay the progression in M phase. Since HeLa S3 and CHO cells are 'stringent' and 'relaxed' in mitotic control, respectively, it is suggested that under topo II inhibition, the M phase checkpoint operates through an inability for chromosome segregation.

Identification of amino acid residues responsible for differences in substrate specificity and inhibitor sensitivity between two human liver dihydrodiol dehydrogenase isoenzymes by site-directed mutagenesis

Human liver dihydrodiol dehydrogenase isoenzymes (DD1 and DD2), in which only seven amino acid residues are substituted, differ remarkably in specificity for steroidal substrates and inhibitor sensitivity: DD1 shows 20alpha-hydroxysteroid dehydrogenase activity and sensitivity to 1,10-phenanthroline, whereas DD2 oxidizes 3alpha-hydroxysteroids and is highly inhibited by bile acids. In the present study we performed site-directed mutagenesis of the seven residues (Thr-38, Arg-47, Leu-54, Cys-87, Val-151, Arg-170 and Gln-172) of DD1 to the corresponding residues (Val, His, Val, Ser, Met, His and Leu respectively) of DD2. Of the seven mutations, only the replacement of Leu-54 with Val produced an enzyme that had almost the same properties as DD2. No significant changes were observed in the other mutant enzymes. An additional site-directed mutagenesis of Tyr-55 of DD1 to Phe yielded an inactive protein, suggesting the catalytically important role of this residue. Thus a residue at a position before the catalytic Tyr residue might play a key role in determining the orientation of the substrates and inhibitors.

Cardioprotective effect of K-7259, a novel dilazep derivative, against ischemia-reperfusion damage in isolated, working rat hearts

Global ischemia (15 min) followed by reperfusion (10, 20 or 30 min) was performed in isolated, working rat hearts. Ischemia depressed mechanical function, which was not restored by reperfusion of 20 min. Preischemic administration of K-7259 (N,N'-bis[4-(3,4,5-trimethoxyphenyl)butyl]homopiperazine dihydrochloride) (1, 5 or 10 microM) decreased the function before ischemia, but it attenuated the ischemia-induced dysfunction during reperfusion (20 min). Postischemic administration of K-7259 (10 microM) or dilazep (20 microM) also attenuated the ischemia-induced dysfunction during reperfusion (30 min). Ischemia-reperfusion (10 min) increased the tissue malondialdehyde level, and postischemic administration of K-7259 (10 microM) or dilazep (20 microM) attenuated the malondialdehyde accumulation. K-7259 has a cardioprotective effect when given either before or after ischemia.

Modulation of N-methyl-N-amylnitrosamine-induced rat oesophageal tumourigenesis by dietary feeding of diosmin and hesperidin, both alone and in combination

The modifying effects of flavonoids diosmin and hesperidin during the initiation and post-initiation phases of oesophageal carcinogenesis initiated with N-methyl-N-amylnitrosamine (MNAN) were investigated in male Wistar rats. At 7 weeks of age, all animals except those treated each test chemical alone and control groups were given weekly intraperitoneal injections of MNAN (12.5 mg/kg body weight/injection) for 12 weeks to induce oesophageal neoplasms. For examining the modifying effects of 'initiation' treatment of test compounds, groups of animals were fed the diets containing 1000 ppm diosmin and 1000 ppm hesperidin, and the diet containing both compounds (900 ppm diosmin and 100 ppm hesperidin) for 13 weeks, starting 7 days before the MNAN dosing and then switched to the basal diet. For examining the modifying effects of 'post-initiation' treatment of these compounds, the groups given MNAN and a basal diet were switched to the experimental diets containing diosmin, hesperidin or diosmin combined with hesperidin at 1 week after the stop of MNAN injection, and maintained on these diets for 7 weeks. The other groups consisted of rats given test compounds alone or untreated rats. All animals were necropsied at the termination of the study (week 20) to determine the incidences of oesophageal neoplasms and preneoplasms, blood polyamine levels, and cell proliferation activity estimated by 5-bromodeoxyuridine (BrdU)-labelling index and by morphometric analysis of silver-stained nucleolar organizer regions' protein (AgNORs). A number of oesophageal neoplasms developed in rats treated with MNAN alone (75% and 100% incidences of carcinoma and papilloma, respectively). 'Initiation' feeding of diosmin significantly decreased the incidence of squamous cell carcinoma (P < 0.05). Also, 'initiation feeding' of both compounds singly or in combination caused a significant reduction in the multiplicities of oesophageal carcinoma and papilloma (diosmin, 78 and 58% reduction; hesperidin, 70 and 50% reduction; and the combination regimen, 70 and 30% reduction, P < 0.005). 'Post-initiation' feeding slightly decreased the multiplicities of these oesophageal neoplasms. Also, these dietary regimens reduced the multiplicities of preneoplastic lesions (hyperplasia and severe dysplasia; P < 0.05). There were no pathological alterations in rats treated with both compounds alone or the combined regimen alone or those in an untreated control group. Similarly, feeding of these compounds significantly decreased the expression of cell proliferation biomarkers (BrdU-labelling index and AgNORs number) of the non-lesional oesophageal epithelium (P < 0.05). Blood polyamine concentrations were also lowered in rats given the carcinogen and test compounds, both alone and in combination, when compared with those of rats given MNAN alone (P < 0.05). These findings suggest that diosmin and hesperidin supplementation, individually or in combination, is effective in inhibiting the development of oesophageal cancer induced by MNAN when given during the initiation phase, and such inhibition might be related to suppression of increased cell proliferation caused by MNAN in the oesophageal mucosa.

[A sensitive fluorometric assay for dihydrodiol dehydrogenase]

Dihydrodiol dehydrogenase (DD) oxidizes naphthalene dihydrodiol to 1,2-dihydroxynaphthalene, which is immediately autoxidized to 1,2-naphthoquinone. Here we established a fluorometric assay for the enzyme, which is based on the conversion of 1,2-naphthoquinone to fluorescent compounds by reacting with ethylenediamine. The formed fluorescent compounds were synthetically identified as 6-(2-aminoethylamino)benzo[f]quinoxaline and 2,6- or 3,6-bis(2-aminoethylamino)benzo[f]quinoxaline, which showed the same fluorescence at 550 nm at an excitation wavelength of 420 nm. This method provides a 9000-fold increase in sensitivity over a currently available assay which measures the change in the absorbance of a cofactor, NADPH. Since this simple and sensitive method allowed many samples to be assayed simultaneously, we applied it to the analysis of multiple forms of DD, separated by an anion-exchange chromatography, from six human liver specimens.

Involvement of two basic residues (Lys-270 and Arg-276) of human liver 3 alpha-hydroxysteroid dehydrogenase in NADP(H) binding and activation by sulphobromophthalein: site-directed mutagenesis and kinetic analysis

A human liver 3 alpha-hydroxysteroid dehydrogenase isoenzyme, a member of the aldo-keto reductase family, shows a marked preference for NADP(H) over NAD(H), and is activated by sulphobromophthalein, which increases the Km values for both NADP(H) and substrates. Here we report kinetic alterations in binding of the coenzymes and the activator to the enzyme caused by site-directed mutagenesis of Lys-270 and Arg-276, which are strictly conserved among the aldo-keto reductase family of enzymes. The mutated enzymes, K270M and R276M, showed increases in the Km for NADP+ of 22- and 290-fold respectively; the Km for alcohol substrate and the kca1 of the NADP(-)-linked reaction were also elevated, by 9- and 5-fold respectively. No kinetic constant of the NAD(+)-linked reaction was altered by more than 3-fold. Calculation of the free-energy changes showed that the 2'-phosphate group of NADP+ contributes 16.3 kJ/mol (3.9 kcal/mol) of binding energy to its interaction with the wildtype enzyme, and the mutagenesis to K270M and R276M destabilized the binding energy of NADP+ by 6.3 and 13.0 kJ/mol (1.5 and 3.1 kcal/mol) respectively. In addition, the mutations attenuated enzyme activation by sulphobromophthalein, which bound to the mutant enzymes as an inhibitor. The inhibition for the R276M mutant was competitive with respect to NADP+ and non-competitive with respect to the substrate, whereas that for the K270M mutant was mixed-type, showing activation at coenzyme concentrations greater than 20 x Km. These results suggest that the two basic residues in the 3 alpha-hydroxysteroid dehydrogenase isoenzyme play crucial roles in binding both the negatively charged 2'-phosphate group of NADP+ and the sulphonic groups of sulphobromophthalein.

Preparation of various lysogangliosides including lyso-fucosyl GM1 and delayed extraction matrix-assisted laser desorption ionization time-of-flight mass spectrometric analysis

Our rapid method of microwave-mediated saponification for preparing lysoglycosphingolipids from their parent glycosphingolipids was also able to prepare lysogangliosides or modified lysogangliosides, which were identified by delayed extraction matrix-assisted laser desorption ionization time-of-flight mass spectrometric (DE MALDI-TOF MS) analysis. When GM3, GM2, and GM1 isolated from adult human brain gangliosides were subjected to the saponification, GM3 was found to give rise to only lyso-GM3 containing de-N-acetylneuraminic acid (de-N-acetyl lyso-GM3), whereas the GM2 produced both lyso-GM2 and the de-N-acetyl compound, and GM1 also gave both lyso-GM1 and the de-N-acetyl compound. In the saponification of GM1 and GDla, isolated from rat brain gangliosides, GM1 similarly produced both lyso-GM1 and the de-N-acetyl compound, but GDla was found to give rise to both dehydrated de-N-monoacetyl and dehydrated de-N-diacetyl lyso-GDla. However, the saponification of the GM1 fraction isolated from porcine brain gangliosides gave rise not only to both lyso-GM1 and the de-N-acetyl compound, but also unexpectedly to both lyso-fucosyl GM1 and its de-N-acetyl compound. The untreated GM1 fraction was examined by TLC and DE MALDI-TOF mass spectrometry, and proved to contain fucosyl-GM1. The DE MALDI-TOF MS analysis of the prepared lyso-gangliosides showed that their long chain bases consisted of d18:1 and d20:1 sphingosines in various ratios reflecting those of the different mammalian brain gangliosides.

Switch of coenzyme specificity of mouse lung carbonyl reductase by substitution of threonine 38 with aspartic acid

Mouse lung carbonyl reductase, a member of the short-chain dehydrogenase/reductase (SDR) family, exhibits coenzyme specificity for NADP(H) over NAD(H). Crystal structure of the enzyme-NADPH complex shows that Thr-38 interacts with the 2'-phosphate of NADPH and occupies the position spatially similar to an Asp residue of the NAD(H)-dependent SDRs that hydrogen-bonds to the hydroxyl groups of the adenine ribose of the coenzymes. Using site-directed mutagenesis, we constructed a mutant mouse lung carbonyl reductase in which Thr-38 was replaced by Asp (T38D), and we compared kinetic properties of the mutant and wild-type enzymes in both forward and reverse reactions. The mutation resulted in increases of more than 200-fold in the Km values for NADP(H) and decreases of more than 7-fold in those for NAD(H), but few changes in the Km values for substrates or in the kcat values of the reactions. NAD(H) provided maximal protection against thermal and urea denaturation of T38D, in contrast to the effective protection by NADP(H) for the wild-type enzyme. Thus, the single mutation converted the coenzyme specificity from NADP(H) to NAD(H). Calculation of free energy changes showed that the 2'-phosphate of NADP(H) contributes to its interaction with the wild-type enzyme. Changing Thr-38 to Asp destabilized the binding energies of NADP(H) by 3.9-4.5 kcal/mol and stabilized those of NAD(H) by 1.2-1.4 kcal/mol. These results indicate a significant role of Thr-38 in NADP(H) binding for the mouse lung enzyme and provide further evidence for the key role of Asp at this position in NAD(H) specificity of the SDR family proteins.

Chemoprevention of 4-nitroquinoline 1-oxide-induced oral carcinogenesis in rats by flavonoids diosmin and hesperidin, each alone and in combination

The modifying effects of the two flavonoids diosmin and hesperidin given during the initiation and postinitiation phases of oral carcinogenesis initiated with 4-nitroquinoline 1-oxide (4-NQO) were investigated in male F344 rats. The compounds were tested alone and in combination. At 6 weeks of age, animals were divided into experimental and control groups and fed diets containing 1000 ppm diosmin and 1000 ppm hesperidin and a diet containing both compounds (900 ppm diosmin and 100 ppm hesperidin). At 7 weeks of age, all animals except those treated with each test chemical alone and control groups were given 4-NQO (20 ppm) in the drinking water for 8 weeks to induce oral cancer. Starting 7 days before the 4-NQO exposure, groups of animals were fed the diets containing test chemicals for 10 weeks and then switched to the basal diet. Starting 1 week after the cessation of 4-NQO exposure, the groups given 4-NQO and a basal diet were switched to the diets containing diosmin, hesperidin, or diosmin combined with hesperidin and maintained on these diets for 22 weeks. The other groups consisted of rats given diosmin (1000 ppm), hesperidin (1000 ppm), and the combination regimen of these two compounds (900 ppm diosmin with 100 ppm hesperidin) alone, and untreated rats. All animals were necropsied at the termination of the study (week 32). The incidences of tongue lesions (neoplasms and preneoplasms), polyamine levels in the tongue tissue, and cell proliferation activity estimated by a 5-bromodeoxyuridine-labeling index and by morphometric analysis of silver-stained nucleolar organizer regions protein were compared among the groups. Feeding of both compounds singly or in combination during the initiation phase caused a significant reduction in the frequency of tongue carcinoma [diosmin, 68% reduction (P < 0.01); hesperidin, 75% reduction (P < 0.005); and the combination regimen, 69% (P < 0.05)]. When fed the test compounds singly or the combination regimen after 4-NQO exposure, the frequency of tongue cancer was also decreased [diosmin, 77% reduction (P < 0.005); hesperidin, 62% reduction (P < 0.05); and the combination regimen, 77% (P < 0.005)]. The incidences of oral preneoplasia (hyperplasia and dysplasia) in these groups were also decreased when compared with carcinogen controls (P < 0.05-P < 0.001). There were no pathological alterations in rats treated with test compounds or the combined regimen alone or those in an untreated control group. Dietary administration of these compounds significantly decreased the expression of cell proliferation biomarkers (5-bromodeoxyuridine-labeling index and silver-stained nucleolar organizer regions protein number) of the nonlesional tongue squamous epithelium (P < 0.05). Also, polyamine concentrations in the oral mucosa were lowered in rats given the carcinogen and test compounds, alone and in combination, compared with those of rats given 4-NQO alone (P < 0.05). These findings suggest that supplementation with the flavonoids diosmin and hesperidin, individually and in combination, is effective in inhibiting the development of oral neoplasms induced by 4-NQO, and such inhibition might be related to suppression of increased cell proliferation caused by 4-NQO in the oral mucosa.

Comparison of susceptibility to apoptosis induced by rhTNF-alpha and cycloheximide between human circulating and exudated neutrophils

To determine whether exudated neutrophils differ from circulating ones in their apoptosis, rhTNF-alpha plus cycloheximide-induced apoptosis in human salivary neutrophils was compared to that in human neutrophils in peripheral blood. Concomitant treatment of peripheral blood neutrophils with rhTNF-alpha and cycloheximide-induced apoptosis in blood neutrophils within 3 hr, as evaluated both by light microscopic changes characteristic to apoptosis and by DNA fragmentation, whereas the same treatment failed to induce any apoptosis in salivary neutrophils. These results indicate that the exudation of neutrophils from blood into tissue is associated with marked changes in their functions such as alteration in their sensitivity to apoptosis-inducing stimuli.

Effect of isosorbide on distortion-product otoacoustic emissions and endocochlear DC potential in experimentally induced hydropic ears

The effects of isosorbide on distortion-product otoacoustic emissions (DPOAEs) and endocochlear DC potential (EP) were examined in experimentally induced endolymphatic hydropic ears and untreated control ears using 20 albino guinea pigs. DPOAEs and EP in the hydropic ears decreased after obliteration of the endolymphatic duct and sac. The administration of isosorbide restored DPOAEs to the normal level, whereas EP was further reduced. In control ears there was no significant change in DPOAEs and EP after the administration of isosorbide. The results obtained in the present study indicate that the effect of isosorbide on DPOAEs is different from that on EP, and the recovery of DPOAEs in hydropic ears is not a secondary phenomenon due to the recovery of EP.

Effect of MET-88, a gamma-butyrobetaine hydroxylase inhibitor, on myocardial derangements induced by hydrogen peroxide in the isolated perfused rat heart

The effect of MET-88 (3-(2,2,2-trimethylhydrazinium) propionate dihydrate), a gamma-butyrobetaine (gamma-BB) hydroxylase inhibitor, on the hydrogen peroxide (H2O2)-induced mechanical and metabolic derangements was studied in the isolated rat heart, which was perfused aerobically by the Langendorff's technique at a constant flow rate and driven electrically. In the first series of experiments, MET-88 (100 mg/kg/d) was orally administered to rats for 10 days prior to isolation of the heart. In the second series of experiments, MET-88 or gamma-BB was directly infused to the isolated perfused heart. In both series of experiments, H2O2 (600 microM) decreased the left ventricular developed pressure (mechanical dysfunction) and the tissue levels of high-energy phosphates (metabolic derangement). In the first series of experiments, oral pretreatment with MET-88 attenuated the H2O2-induced metabolic derangement with a marked increase in the myocardial level of gamma-BB, while it did not attenuate the H2O2-induced mechanical dysfunction. In the second series of experiments, MET-88 (1 mM) did not attenuate the H2O2-induced metabolic derangement, whereas gamma-BB (500 microM or 1 mM) attenuated it. Nevertheless, gamma-BB did not modify the energy metabolism of H2O2-untreated heart (normal heart). These results suggest that oral pretreatment with MET-88 protects the energy metabolism against the H2O2-induced derangement and that the beneficial effect of the oral pretreatment with MET-88 may be mediated by gamma-BB that has accumulated in the myocardium because of inhibition of gamma-BB hydroxylase.

A new approach to the development of anti-ischemic drugs. Substances that counteract the deleterious effect of lysophosphatidylcholine on the heart

Lysophosphatidylcholine (LPC) is an amphiphilic metabolite that can be produced from membrane-phospholipids by activation of phospholipase A2 (PLA2), and it accumulates in the heart during ischemia and reperfusion. It is known that LPC is an arrhythmogenic substance. Recent studies have revealed that LPC produces mechanical and metabolic derangements in perfused working rat hearts, and Ca(2+)-overload in isolated cardiac myocytes. Thus, LPC possesses an ischemia-like effect on the heart. LPC accumulated in the myocardium activates phospholipase A2, establishing a vicious circle; i.e. LPC itself has an ability to produce another LPC. Therefore, a drug that has an anti-LPC effect would protect or improve ischemia/reperfusion damage. This article will review the effect of LPC in relation to ischemia, and consider a possibility of developing new anti-ischemic drugs on the basis of the anti-LPC action.

Stac, a novel neuron-specific protein with cysteine-rich and SH3 domains

In RLGS-M (restriction landmark genomic scanning using methylation-sensitive endonuclease) displays of mouse brains, spot #91 is one of tissue-specific gel spots whose intensity changes developmentally. We have now cloned the corresponding cDNA from this spot and analyzed its structure and expression. The deduced amino acid sequence revealed that the #91 cDNA encodes a novel protein of 403 amino acids which consists of a cysteine-rich domain and a SH3 domain. We designated this gene as Stac. Northern blotting and in situ hybridization analyses demonstrated that 2.7 kb of Stac mRNA is expressed predominantly in brain and neurons, especially in hippocampus, cerebellum and inferior olive. Further, the gene product of 47 kDa was found by western blotting analysis in the soluble fractions of brain as well as Stac-expression vector-transfected NIH3T3 cells. Although the function of Stac is unknown so far, it is likely involved in a neuron-specific signal transduction.

Lysophosphatidylcholine induces Ca2+-independent cellular injury attenuated by d-propranolol in rat cardiomyocytes

In isolated rat cardiomyocytes, exogenous lysophosphatidylcholine (LPC) (15 microM) increased the intracellular Ca2+ concentration (Ca2+]i) from 72 +/- 5 to 3042 +/- 431 nM accompanied by cell injury as indicated by the hypercontracture of the cells and the increase in creatine phosphokinase (CPK) release. In order to understand whether the cell injury induced by LPC was a consequence of the elevation of [Ca2+]i, the effect of LPC was examined in the Ca2+-free solution containing EGTA. Under the Ca2+ -free conditions, LPC did not increase [Ca2+]i, whereas it still inflicted injury on the cells in terms of cell-shape change and CPK release to the same degree as that under the Ca2+-present condition. Addition of ryanodine (10 microM) failed to prevent the changes in cell-shape and CPK release induced by LPC under both Ca2+-free and Ca2+-present conditions. Preincubation of the myocytes with d-propranolol (50 microM) inhibited the LPC-induced changes in cell-shape and CPK release under both Ca2+ -free and Ca2+ -present conditions (p < 0.05). Our study provides clear evidence that the cellular injury induced by LPC could be independent of the increase in [Ca2+]i, and the Ca2+-independent cellular injury induced by LPC could be attenuated by d-propranolol, although the mechanism remains unknown.

Threonine 1342 in human topoisomerase IIalpha is phosphorylated throughout the cell cycle

To investigate the relationship between the modulation of topoisomerase II activity and its phosphorylation state during the cell cycle, a monoclonal antibody against C-terminal peptide (residues 1335-1350) of topoisomerase IIalpha containing a consensus sequence of casein kinase II, TDDE and its phosphorylated threonine were prepared. In an enzyme-linked immunosorbent assay, the antibody, named PT1342, recognized the immunogenic phosphopeptide but not the non-phosphorylated form of the peptide. The PT1342 antibody reacted only with a 170-kDa protein from HeLa cells and recognized anti-topoisomerase IIalpha immunoprecipitants. Furthermore, the antibody did not react with the human topoisomerase IIalpha mutated at codon 1342 from threonine to alanine, showing that PT1342 was directed against the phosphorylated threonine 1342. To examine the level of phosphorylation of threonine 1342 of topoisomerase IIalpha through the cell cycle, HeLa cells were stained simultaneously for phosphorylated topoisomerase IIalpha and DNA and analyzed by flow cytometry. Cells in the G2-M phase contained about double the PT1341-reacted topoisomerase IIalpha than did cells in G1 or S phases. The antibody stained the nuclei in interphase and mitotic chromosomes and its periphery, as seen with anti-topoisomerase IIalpha antibody. Thus, threonine 1342 in topoisomerase IIalpha is phosphorylated throughout the cell cycle.

In vivo implantation of human osteosarcoma cells in nude mice induces bones with human-derived osteoblasts and mouse-derived osteocytes

Two human osteosarcoma cell lines, Hu09 and OST, were suspended in Matrigel (Becton Dickinson Labware, Bedford, Massachusetts) and implanted subcutaneously in the backs of nude mice. To study phenotypic changes of tumor cells and host cells, expression of mRNA for osteopontin (OPN), osteocalcin (OC), and osteonectin (ON) was analyzed by in situ hybridization. Bone tissue was formed in the tumors derived from Hu09 cells. OPN mRNA was transcribed predominantly in osteocyte-like cells within the bone, whereas OC mRNA was transcribed in osteoblast-like cells that surrounded the bone. ON mRNA was detected in both types of cells. The similarity of the expression pattern of OPN, OC, and ON during osteogenesis of Hu09 cells to that of normal skeletal development suggests that the bone formed in Hu09-implanted mice is the same as normal bone tissue. By DNA-DNA in situ hybridization using a human-specific Alu probe and a mouse-specific m-L1 probe, osteoblast-like cells in Hu09 tumorous bone were, however, of human origin, whereas osteocyte-like cells were of mouse origin. In the tumors derived from OST cells, no osteogenesis was observed during the experimental period, and the expression of OPN, OC, and ON was not detected in tumor cells. An endochondral bone formation was not evident when these cells were simply implanted into muscle tissue. An endochondral bone was, however, reactively induced in the host mUscle tissue either when 1 alpha-hydroxyvitamin D3 and all-transretinoic acid were administered to OST-implanted mice or when Hu09 cells were pretreated with dexamethasone before implantation. Hu09 implantation seems to be a useful tool not only for the study of the differentiation of osteosarcoma cells but also for the investigation of the mechanism of bone formation. This system, using Hu09 and OST, may provide us with a new tool for the isolation of the unidentified factors that induce or inhibit osteogenesis in vivo.

Chemoprevention of 4-nitroquinoline 1-oxide-induced rat oral carcinogenesis by the dietary flavonoids chalcone, 2-hydroxychalcone, and quercetin

The modifying effects of dietary exposure of three flavonoids, chalcone, 2-hydroxychalcone, and quercetin, during the initiation and postinitiation phases of oral tumorigenesis initiated with 4-nitroquinoline-1-oxide (4-NQO) were investigated in male F344 rats. At 6 weeks of age, animals were divided into experimental and control groups. At 7 weeks of age, all animals except those treated with test chemicals alone and the untreated control group were given 4-NQO [20 parts/million (ppm)] in the drinking water for 8 weeks to induce oral neoplasms. For chemopreventive study by feeding of test compounds during the initiation phase, groups of animals were given diets containing 500 ppm chalcone, 500 ppm 2-hydroxychalcone, or 500 ppm quercetin for 10 weeks, starting 1 week before 4-NQO exposure. Seven days after stopping 4-NQO exposure, these groups were switched to the basal diet and kept on this diet until the end of the experiment. For chemopreventive study by treatment with test chemicals during the postinitiation phase, starting 1 week after the cessation of 4-NQO administration, the groups given 4-NQO and the basal diet were switched to the diets mixed with test chemicals and maintained on these diets for 22 weeks. The other groups consisted of rats fed diets containing 500 ppm test chemicals alone or of untreated rats. Thirty-two weeks after the start of the study, the incidence of tongue neoplasms and preneoplastic lesions, polyamine levels in the tongue epithelium, and cell proliferation activity estimated by bromodeoxyuridine labeling index were compared among the different dietary groups. Feeding of all test chemicals during either initiation or postinitiation phases caused a significant reduction in the frequency of tongue carcinoma (68-88% reduction; P < 0.05). Dietary administration of these test chemicals also significantly decreased the bromodeoxyuridine labeling index of the tongue squamous epithelium (P < 0.05). In addition, polyamine levels in the oral mucosa were lowered in rats treated with 4-NQO and test chemicals when compared to those given 4-NQO alone. These results indicate that the flavonoids chalcone, 2-hydroxychalcone, and quercetin present in our daily foods have an inhibitory effect on oral carcinogenesis initiated with 4-NQO, and such a modifying effect may be related partly to the suppression of cell proliferation.

Relationship between vitellogenin and its related egg yolk proteins in Sakhalin taimen (Hucho perryi)

Vitellogenin (Vg) and its three egg yolk protein products, lipovitellin (Lv), phosvitin (Pv) and beta'-component, were isolated from mature female Sakhalin taimen (Hucho perryi). Vg had an apparent molecular weight of 540 kDa and appeared as a major 240 kDa band in SDS-PAGE, which resolved into two major bands (165 and 125 kDa) after reduction. The estimated molecular weights of purified Lv, Pv, and beta'-component were 330, 23, and 30 kDa, respectively. Lv appeared as a main band of 150 kDa in SDS-PAGE which resolved into two smaller bands (92 and 29 kDa) after reduction. beta'-component appeared as a 34 kDa band before and as a 17kDa band after reduction. Except for Pv, the purified proteins all reacted with an antiserum to Vg. In SDS-PAGE, Pv appeared as a 23 kDa band and a second < 6.5 kDa diffuse band. An antiserum to Pv dephosphorylated by alkaline phosphatase (Ap) was prepared. In Western blots, the antiserum reacted with dephosphorylated Pv and Vg, but not with Lv and beta'-component. This is the first immunological proof that three egg yolk proteins (Lv, Pv, and beta'-component) are derived from Vg in fish.

Localization of Bax and Bcl-2 proteins, regulators of programmed cell death, in the human central nervous system

Bax and Bcl-2 proteins are identified as regulating molecules for programmed cell death. In the central nervous system, programmed cell death or apoptosis is considered to be an important phenomenon that is related to neuron vulnerability to a variety of toxic effects, including ischaemic insult. In this study, localization of Bax and Bcl-2 proteins was investigated in the human central nervous system using autopsy cases without any neurological disorder. Results were compared with findings in the rat. Most neurons in human cerebral cortex, basal ganglia and brain stem were positive for both Bax and Bcl-2 proteins, whereas Purkinje cells in cerebellum and neurons in hippocampal CA1, CA2 and CA3 regions were positive for Bax but negative or weakly positive for Bcl-2. Glial cells examined in all sections were negative for both proteins. Choroid plexus, ependymal cells and arachnoid villi showed positive reactivity for both proteins. A possible relationship between the localization of Bax or Bcl-2 proteins and the cell vulnerability in central nervous system is discussed.

Dilazep and its derivative, K-7259, attenuate mechanical derangement induced by palmitoyl-L-carnitine in the isolated, perfused rat heart

The effect of dilazep, a potentiator of the adenosine-mediated effects, on the palmitoyl-L-carnitine (PALCAR)-induced mechanical derangement was studied in the isolated rat heart and compared with that of K-7259, a dilazep derivative having less potentiating action on the adenosine-mediated effects. The heart was perfused aerobically by the Langendorff's technique at a constant flow and driven electrically. PALCAR (5 microM) decreased the left ventricular developed pressure and increased the left ventricular end diastolic pressure in the heart (i.e., mechanical dysfunction). These mechanical alterations induced by PALCAR were attenuated by dilazep (1 microM) and K-7259 (1 microM). In contrast, adenosine (10 or 100 microM) did not attenuate the PALCAR-induced mechanical derangement. On the other hand, neither dilazep nor K-7259 modified the mechanical function of the normal (PALCAR-untreated) heart. These results suggest that dilazep and K-7259 attenuate the PALCAR-induced mechanical derangement and that the protective action of both drugs is not due to potentiation of adenosine-mediated effects.