Biomedical subjects

A Murakami

Publications and source records attributed to A Murakami.

At least 91 records · Page 5Linked to original sources

PubMed2000

A combination treatment of c-myc antisense DNA with all-trans-retinoic acid inhibits cell proliferation by downregulating c-myc expression in small cell lung cancer.

The dysregulation of both c-myc expression and retinoid signaling pathways commonly occurs in small cell lung cancers (SCLC), frequently accompanying tumor relapse, and contributing to the poor prognosis of patients with SCLC. In this study, we investigated whether c-myc antisense oligodeoxynucleoside phosphorothioate (OPT) covering the translational initiation site of c-myc mRNA used in combination with all-trans-retinoic acid (RA) would be more effective than either agent alone in inhibiting the growth of an SCLC cell line, NCI-H82, overexpressing c-myc with amplification of this gene, and whether this combination could be an experimental therapeutic tool against SCLC. c-myc antisense OPT decreased c-myc expression in Northern and Western blot analyses, thus inducing 40% and 20% cell growth inhibition compared with scrambled and sense OPT and with scrambled four guanosine-containing OPT (p < 0.01, and p < 0.01, respectively). All-trans-RA also inhibited cell proliferation at the rate of 40% by downregulating c-myc expression. Having obtained these results, we tested the hymothesis that c-myc antisense OPT in combination with all-trans-RA may further reduce c-myc expression and lead to improved cell growth control. This combination showed a greater inhibition of cell proliferation than either agent given alone (p < 0.01) (60% inhibition of cell growth compared with treatment of control scrambled or sense OPT alone, p < 0.01) through enhanced downregulation of c-myc expression. In conclusion, c-myc antisense DNA in combination with other modalities for c-myc downregulation may represent an attractive gene regulation-based therapy of SCLC in the future. Further efforts, however, using new oligodeoxynucleotide analogs, specific interventions for DNA delivery into cells, and more potent therapeutic agents are required to increase the potentiation of c-myc downregulation and cell growth inhibition.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed2000

Suppression by citrus auraptene of phorbol ester-and endotoxin-induced inflammatory responses: role of attenuation of leukocyte activation.

Auraptene (AUR), a citrus coumarin derivative, is one of the promising chemopreventive agents against skin, tongue, esophagus and colon carcinogenesis in rodents. We reported previously that AUR suppresses superoxide anion (O(2)(-)) generation from inflammatory leukocytes in in vitro experiments. In the present study, we investigated the anti-inflammatory activities of AUR using a 12-O:-tetradecanoylphorbol-13-acetate-treated mouse skin model, and compared them with those of umbelliferone (UMB), a structural analog of AUR that is virtually inactive toward O(2-) generation inhibition. Double pre-treatments of mouse skin with AUR, but not UMB, markedly suppressed edema formation, hydrogen peroxide production, leukocyte infiltration, and the rate of proliferating cell nuclear antigen-stained cells. These inhibitory effects by AUR are attributable to its selective blockade of the activation stage, as revealed by single pre-treatment experiments. In a murine macrophage line, RAW 264.7, AUR significantly attenuated the lipopolysaccharide-induced protein expression of inducible isoforms of both nitric oxide synthase and cyclooxygenase, with decreased production of nitrite anion and prostaglandin E(2), and yet suppressed the release of tumor necrosis factor-alpha. Conversely, UMB did not show any inhibitory effect. This contrasting activity profile between AUR and UMB was rationalized to be a result of their distinct differences in cellular uptake efficiencies, i.e. the geranyloxyl group in AUR was found to play an essential role in incorporation. Thus, our findings indicate that AUR is an effective agent to attenuate the biochemical responsiveness of inflammatory leukocytes, which may be essential for a greater understanding of the action mechanism that underlies its inhibition of inflammation-associated carcinogenesis.

Animals↗

PubMed2000

A simple phenolic antioxidant protocatechuic acid enhances tumor promotion and oxidative stress in female ICR mouse skin: dose-and timing-dependent enhancement and involvement of bioactivation by tyrosinase.

The modifying effects of topical application of the phenolic antioxidant protocatechuic acid (PA) on 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced mouse skin tumor promotion were investigated. Dimethylbenz[a]anthracene-initiated female ICR mice were treated with TPA (1.6 nmol) twice weekly for 20 weeks to promote papilloma formation. Pre-treatment with 16nmol PA 30 min prior to each TPA treatment significantly inhibited the number of papillomas per mouse by 52% (P < 0.05). On the other hand, PA pre-treatment at a high dose (1600 nmol) significantly enhanced tumor numbers by 38% (P < 0.05). Interestingly, in the group treated with a quite high dose (20000 nmol) of PA 5 min prior to each TPA application, the average number of tumors per mouse was reduced by 38%, whereas the same PA dose 3 h before TPA treatment significantly enhanced tumor numbers by 84% (P < 0.01). These results suggested that topically applied PA was converted to compound(s) lacking antioxidative properties and/or rather possessing the potential to enhance tumor development. A similar tendency was also observed in the short-term experiment of TPA-induced inflammation and oxidative stress; i.e. two groups pre-treated with PA at 20000 nmol, 30min and 3h before TPA treatment, did not show suppression or even significantly enhanced TPA-induced leukocyte infiltration, H(2)O(2) generation, thiobarbituric acid-reacting substances level and proliferating cell nuclear antigen index, while PA treatment together with TPA significantly suppressed these parameters. Treatment with a high dose (20000 nmol) of PA alone for 3h enhanced oxidative stress by reducing glutathione levels in mouse skin, which was counteracted by the tyrosinase inhibitor arbutin. Oxidative stress responses such as leukocyte infiltration and H(2)O(2) generation were also counteracted by arbutin. These results suggested that tyrosinase-dependent oxidative metabolism of PA was at least partially involved in the enhanced effects of PA on TPA-induced inflammatory responses and thus tumor promotion.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed2000

Apoptosis induced by 1'-acetoxychavicol acetate in Ehrlich ascites tumor cells is associated with modulation of polyamine metabolism and caspase-3 activation.

The efficacy of the antitumor activity of 1'-acetoxychavicol acetate (ACA), reported to be a suppressor of chemically induced carcinogenesis, was evaluated in Ehrlich ascites tumor cells. ACA treatment resulted in changes in morphology and a dose-dependent suppression of cell viability. Apoptosis, characterized by nuclear condensation, membrane blebbing, cell shrinkage and a significant induction of caspase-3-like protease activity at 8 h in a time-course study were observed. Formation of apoptotic bodies was preceded by lowering of intracellular polyamines, particularly putrescine, and both dose- and time-dependent inhibitory and activation effect by ACA on ornithine decarboxylase (ODC) and spermidine/spermine N(1)-acetyltransferase (SSAT), respectively. Administration of exogenous polyamines prevented ACA-induced apoptosis represented by a reduction in the number of apoptotic bodies and also caused reduction in the induced caspase-3-like protease activity at 8 h. These findings suggest that the anticarcinogenic effects of ACA might be partly due to perturbation of the polyamine metabolic pathway and triggering of caspase-3-like activity, which result in apoptosis.

Acetyltransferases↗

PubMed2000

Characterization of RNA structure by bis-pyrene-labeled 2'-O-methyloligonucleotides.

Properties of 2'-O-methyloligoribonucleotides containing two consecutive 2'-O-(1-pyrenylmethyl)uridine were investigated as a fluorescent probe to search the single strand regions of RNA. The bis-pyrene-labeled 2'-O-methyloligoribonucleotide (OMUpy2) induced the formation of pyrene dimer upon hybridization with the complementary oligoribonucleotides and showed remarkable appearance of broad structureless fluorescence at 480 nm. Contrarily, when OMUpy2 was hybridized with the complementary oligodeoxyribonucleotides, such enhancement of fluorescence was scarcely observed. When various OMUpy2 were applied to E. coli 5S-rRNA, the fluorescence intensity at 480 nm was varied in a sequence specific manner.

Base Sequence↗

PubMed2000

Effect of serine residue on the effectiveness of cationic polypeptide-based gene delivery.

Poly-L-lysine(pL) was chemically modified based on two essential features which we recently reported and subjected to the gene-transfer experiment in vitro. Introduction of 25 mol% serine residue to pL slightly enhanced the gene expression level, while trimethylation of epsilon-ammonium groups of lysine did not. Only when pL was modified in both way, giving N2-trimethyl poly(lysine-co-serine), markedly enhanced gene expression was observed. The cellular uptake and localization of DNA in the cells were similar for each cationic polypeptide. DNA forming complex with the polypeptides containing serine residue was found to be well transcribed in in vitro transcription/translation system, suggesting the hydrophilic nature may allow polypeptide/DNA complexes to be recognized by the transcriptional factors and lead the subsequent effective gene expression.

Animals↗

PubMed2000

Conserved smooth muscle contractility and blood pressure increase in response to high-salt diet in mice lacking the beta3 subunit of the voltage-dependent calcium channel.

Voltage-dependent calcium channels are crucially important for calcium influx and the following smooth muscle contraction. Beta subunits of these channels are known to modify calcium currents through pore-forming alpha subunits. Among the four reported independent beta subunits, the beta3 subunit is expressed in smooth muscle cells and thought to compose L-type calcium channels in the tissue. To determine the role of the beta3 subunit in the cardiovascular system, we have analyzed beta3-null mice. Electrophysiological examinations proved the existence of dihydropyridine (DHP)-sensitive. L-type calcium channels in the smooth muscle cells. Beta3-null mice show no apparent changes in smooth muscle contraction and sensitivity to DHP, and normal blood pressure when they are raised on a normal diet, but the 13 subunit deficient mice show elevated blood pressure in response to a high-salt diet, with significant reductions in plasma catecholamine concentrations. Our finding strongly suggests a close relationship between voltage-dependent channels and high blood pressure.

Animals↗

PubMed2000

Suppression of N-nitrosomethylbenzylamine-induced rat esophageal tumorigenesis by dietary feeding of 1'-acetoxychavicol acetate.

The modifying effects of 1'-acetoxychavicol acetate (ACA) on N-nitrosomethylbenzylamine (NMBA)-induced esophageal tumorigenesis were investigated in male F344 rats. At 5 weeks of age, all test animals, except those given the test chemical alone, and the control rats received s.c. injections of NMBA (0.5 mg/kg body weight/injection, three times per week) for 5 weeks. At the termination of the study (20 weeks), 75% of rats treated with NMBA alone had esophageal neoplasms (papillomas). However, the groups given a dose of 500 ppm ACA during the initiation phase developed a significantly reduced incidence of tumors (29%; P<0.01). Exposure to ACA (500 ppm) during the post-initiation phase also decreased the frequency of the tumors (38%; P<0.05). A reduction of the incidence of preneoplastic lesions (hyperplasia or dysplasia) was obtained when ACA was administered in the initiation phase (P<0.01). Cell proliferation in the esophageal epithelium, determined by assay of proliferating cell nuclear antigen (PCNA), was lowered by ACA (P<0.05). Blood polyamine contents in rats given NMBA and the test compound were also smaller than those of rats given the carcinogen (P<0.05). These findings suggest that dietary ACA is effective in inhibiting the development of esophageal tumors by NMBA when given during the initiation or post-initiation phase, and such inhibition is related to suppression of cell proliferation in the esophageal epithelium.

Animals↗

PubMed2000

Inhibitory effects of 1'-acetoxychavicol acetate on N-Nitrosobis(2-oxopropyl)-amine-induced initiation of cholangiocarcinogenesis in Syrian hamsters.

The influence of 1'-acetoxychavicol acetate (ACA) during the initiation stage was investigated in the N-nitrosobis(2-oxopropyl)amine (BOP)-initiated hamster tumorigenesis model. Ninety male 5-week-old hamsters were divided into three groups, each consisting of 30 animals, and s.c. injected with 20 mg / kg of BOP twice with a one-week interval. Groups 1 through 3 were fed diet supplemented with ACA at concentrations of 500, 100 and 0 ppm, respectively, for 3 weeks starting one week before the first carcinogen application. At the termination of experimental week 54, the total incidence and multiplicity of cholangiocellular adenomas and carcinomas in group 1 (17.9% and 0.3 < 0.9) were significantly (P < 0.05 and P < 0.01) decreased as compared to the group 3 values (50.0% and 0.7 < 0.8). The ACA treatments also showed a tendency to reduce the development of preneoplastic lesions in the pancreas, a main target organ of BOP, although this was not statistically significant. Our results thus indicate that ACA exerts an inhibitory effect on BOP-induced cholangiocarcinogenesis in hamsters. Taken together with previous findings of inhibited colon, oral and skin carcinogenesis in rats and mice, they suggest that ACA is a candidate chemopreventive agent with a wide spectrum of activity.

Adenocarcinoma↗

PubMed2000

In vitro absorption and metabolism of a citrus chemopreventive agent, auraptene, and its modifying effects on xenobiotic enzyme activities in mouse livers.

We previously reported that auraptene (7-geranyloxycoumarin, AUR), widely occurring in citrus fruit, is a structurally novel type of effective cancer-preventive agent, as manifested in several rodent models. However, its bio-availability and metabolism in biological systems have yet to be investigated. In the present study, we examined the chemical stability of AUR at pH 1.57 and 37 degrees C (as a stomach digestion model) and observed its stoichiometric conversion to umbelliferone [7-hydroxycoumarin, UMB; half-life (t1/2) = 15 h; 7-ethoxycoumarin (ETC) was stable for 24 h]. Differentiated Caco-2 cells, a human colorectal adenocarcinoma cell line, were used as a small intestine model. ETC permeated the basolateral (portal vein) side of Caco-2 cells in a time-dependent manner; AUR slightly permeated the cells, but with an intracellular accumulation. Epoxyauraptene and UMB were detected when AUR was treated with the rat liver S-9 mixture. ETC was also converted to UMB, but its t1/2 of two hours was much shorter than that of AUR (> 24 h). This suggests that AUR, bearing a geranyloxyl side chain, is a relatively metabolism-resistant substrate for cytochrome P-450 enzymes and, thus, is stable in the liver compared with ETC. Oral administration of AUR by gavage at 50-200 mg/kg body wt dose dependently induced glutathione S-transferase (GST) activity in mouse livers without affecting cytochrome P-450 activity. Using 10 coumarin-related compounds, we found that only those coumarins having a 7-alkyloxyl group induced GST, but not cytochrome P-450, activity. The present study presumes that AUR accumulates in the epithelial cells of the small intestine and then gradually permeates into the portal vein. Stable localizability of AUR in the colon and liver may be associated with the induction of GST activity, which is important as the action mechanism for suppression of rodent chemical carcinogenesis.

Absorption↗

PubMed2000

Inhibition by (+)-persenone [corrected] A-related compounds of nitric oxide and superoxide generation from inflammatory leukocytes.

We have previously reported that persenone A, isolated from avocado fruit, is an effective inhibitor of both nitric oxide (NO) and superoxide (O2-) generation in cell culture systems. In this study, we have prepared four persenone A-related compounds and examined their inhibition of NO and O2- generation from inflammatory leukocytes. Some structural importance in persenone A to attenuate free radical generation is discussed.

Esters↗

PubMed2000

An avocado constituent, persenone A, suppresses expression of inducible forms of nitric oxide synthase and cyclooxygenase in macrophages, and hydrogen peroxide generation in mouse skin.

We investigated the suppressive effects of an avocado constituent, persenone A, on lipopolysaccharide- and interferon-y-induced inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX-2) in a mouse macrophage cell line RAW 264.7. Persenone A at concentration of 20 microM almost completely suppressed both iNOS and COX-2 protein expression. In mouse skin, double treatments with persenone A (810 nmol) significantly suppressed double 12-O-tetradecanoylphorbol-13-acetate (TPA, 8.1 nmol) application-induced hydrogen peroxide (H2O2) generation. Treatment with persenone A before the second TPA treatment was sufficient to inhibit H2O2 generation, while the first treatment was not. This study thus suggests that persenone A is a possible agent to prevent inflammation-associated diseases including cancer.

Animals↗

PubMed2000

Screening for the in vitro anti-tumor-promoting activities of edible plants from Malaysia.

A total of 114 methanol extracts from 42 plant families of edible Malaysian plants were screened for their inhibitory activities toward tumor promoter 12-O-hexadecanoylphorbol-13-acetate (HPA)-induced Epstein-Barr virus (EBV) activation in Raji cells. By testing at a concentration of 200 micrograms/ml, 74% of the 114 extracts inhibited EBV activation by 30% or more. This rate is comparable to those observed in the previous tests on edible Thai (60%) and Indonesian (71%) plants, and, importantly, much higher than that (26%) observed for Japanese edible plants. Approximately half of the Malaysian plants did not taxonomically overlap those from the other three countries, suggesting that Malaysian plants, as well as Thai and Indonesian plants, are an exclusive source of effective chemopreventive agents. Further dilution experiments indicated an extract from the leaves of Piper betle L. (Piperaceae) to be one of the most promising species. The high potential of edible Southeast Asian plants for cancer chemoprevention is collectively discussed.

Antineoplastic Agents↗

PubMed2000

[Recent donation and clinical results of homograft tissue].

Between August 1995 and July 1999, we have experienced 14 donors for allografts (mean age: 39.8 +/- 15.8, M/F = 10/4, mean warm ischemic time: 359 minutes). Donated tissues were included 12 aortic valves and 12 pulmonary valves, respectively. Since February 1994, clinical diagnoses of 14 patients included 7 congenital heart disease, 5 infective heart disease, 1 artificial graft infection, and 1 thrombosed valve. There was no graft-transmitted disease. In congenital heart disease, 3 patients (HLHS: 1, Truncus: 1, TOF + PA: 1) died (early mortality, 42%) and 1 with TGA had residual conduit stenosis. However, in infective heart disease, all patients survived without recurrent infection and did not need reoperation (early mortality, 0%). Our clinical results of homograft implantation for infective heart disease were excellent, but more careful consideration will be needed for congenital heart disease in neonates and/or patients with poor preoperative condition.

Adolescent↗

PubMed2000

Prevention of colonic aberrant crypt foci by dietary feeding of garcinol in male F344 rats.

The modifying effects of dietary feeding of a polyisoprenylated benzophenone, garcinol, isolated from Garcinia indica fruit rind on the development of azoxymethane (AOM)-induced colonic aberrant crypt foci (ACF) were investigated in male F344 rats. We also assessed the effects of garcinol on proliferating cell nuclear antigen (PCNA) index in ACF and activities of detoxifying enzymes of glutathione S-transferase (GST) and quinone reductase (QR) in liver. In addition, we examined the effects of garcinol on 12-O-tetradecanoylphorbol-13-acetate-induced O(2)(-) generation in differentiated human promyelocytic HL-60 cells and lipopolysaccharide (LPS)- and interferon (IFN)-gamma-induced nitric oxide (NO) generation in mouse macrophage RAW 264.7 cells. Western blotting analysis of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression was done in LPS- and IFN-gamma-treated mouse macrophage RAW 264.7 cells. Rats were given subcutaneous injections of AOM (15 mg/kg body wt) once a week for 3 weeks to induce ACF. They also received the experimental diet containing 0.01 or 0.05% garcinol for 5 weeks, starting 1 week before the first dosing of AOM. AOM exposure produced 97 +/- 15 ACF/rat at the end of the study (week 5). Dietary administration of garcinol caused significant reduction in the frequency of ACF: 72 +/- 15 (26% reduction, P < 0.01) at a dose of 0.01% and 58 +/- 8 (40% reduction, P < 0.001) at a dose of 0.05%. Garcinol administration significantly lowered PCNA index in ACF. Feeding of garcinol significantly elevated liver GST and QR activities. In addition, garcinol could suppress O(2)(-) and NO generation and expression of iNOS and COX-2 proteins. These findings might suggest possible chemopreventive ability of garcinol, through induction of liver GST and QR, inhibition of O(2)(-) and NO generation and/or suppression of iNOS and COX-2 expression, on colon tumorigenesis.

Animals↗

PubMed2000

Suppression of N-nitrosomethylbenzylamine-induced rat esophageal tumorigenesis by dietary feeding of auraptene.

The modifying effects of auraptene on N-nitrosomethylbenzylamine (NMBA)-induced esophageal tumorigenesis were investigated in male F344 rats. At 5 weeks of age, all animals, except those with the test chemical alone and control rats, received s.c. injections of NMBA (0.5 mg/kg body weight/injection, three times per week) for 5 weeks. At the end of the study (20 weeks), 75% of the rats treated with NMBA alone had esophageal neoplasms (papillomas). However, the groups who received a dose of 500 ppm auraptene during the initiation phase developed significantly reduced incidence of tumors (39%; P<0.05). Exposure to auraptene (500 ppm) during the post-initiation phase also decreased the frequency of the tumors (29%; P<0.01). The reduction of the incidence of severe dysplasia was obtained when auraptene was administered in the post-initiation phase (P<0.05). Cell proliferation in the esophageal epithelium determined by proliferating cell nuclear antigen (PCNA) was lowered by auraptene (P<0.01). Blood polyamine contents in rats who received NMBA and the test compound were also smaller than those of rats that received the carcinogen (P<0.05). These findings suggest that dietary auraptene is effective in inhibiting the development of esophageal tumors by NMBA when given during the initiation as well as post-initiation phases, and such inhibition is related to suppression of cell proliferation in the esophageal epithelium.

Animals↗

PubMed1999

Retinoic acid-regulated expression of fibroblast growth factor 3 requires the interaction between a novel transcription factor and GATA-4.

fgf-3 shows a complex spatial-temporal pattern of transcription during mouse development, and the gene product appears to be an important intercellular signaling molecule. Here we show that the major enhancer, which is obligatory for transcription, is composed of three elements with different properties. Both functional analyses in undifferentiated and differentiated F9 cells and characterization of DNA-protein complexes in vitro have identified the sequence motifs GTGACT(C), ATTGT, and GATA as the key transcription factor binding sites. The GTGACT(C) motif, while not essential, is required for full enhancer activity. However, binding at ATTGT is crucial for transcriptional activity and is required for cooperative binding at the proximal GATA site. The GATA binding site mediates the retinoic acid/dibutyryl cyclic AMP stimulation of transcription and correlates with the binding of Gata-4 which is induced by retinoic acid in differentiating F9 cells. The ATTGT and GATA motifs are inactive when placed separately on a minimal thymidine kinase (TK) promoter, but together they act as a strong retinoic acid-regulated enhancer. In undifferentiated F9 cells, gata-4 expression stimulates the fgf-3 promoter, whereas in differentiated F9 cells already expressing gata-4, no further increase in promoter activity was observed.

Animals↗

PubMed1999

A diacetylenic spiroketal enol ether epoxide, AL-1, from Artemisia lactiflora inhibits 12-O-tetradecanoylphorbol-13-acetate-induced tumor promotion possibly by suppression of oxidative stress.

The inhibitory effects of the diacetylenic spiroketal enol ether epoxide AL-1 from Artemisia lactiflora on a variety of tumor promoter-induced biological responses such as oxidative stress as well as tumor promotion in ICR mouse skin were investigated. AL-1 inhibited TPA-induced intracellular peroxide formation in differentiated HL-60 cells, suggesting that this suppression might be attributable to the inhibition of O2- generation. In a double TPA application system in mouse skin, double pretreatments of AL-1 (810 nmol) significantly suppressed double TPA application-induced H2O2 generation. Pretreatment of AL-1 only before the second TPA treatment was sufficient to inhibit, while only with first treatment was not. From these results we concluded that AL-1 is a specific inhibitor of the activation phase in H2O2 production induced by double TPA treatments. In addition, AL-1 strongly inhibited tumor promoter-induced Epstein-Barr virus (EBV) activation in Raji cells (IC50 = 0.5 microM), which was comparable to or even stronger than that of curcumin, a well-known antioxidative chemopreventer from turmeric. In a two-stage carcinogenesis experiment with TPA (topical application at 1.6 nmol) and 7,12-dimethylbenz[a]anthracene (DMBA, at 0.19 micromol) in ICR mouse skin, topical application of AL-1 (at 160 nmol) significantly reduced tumor incidence, the numbers of tumors per mouse, and edema formation by 58% (P < 0.01 in t-test), 20% (P < 0.005 in chi2-test) and 42% (P < 0.01), respectively. These results together indicate that an inhibitor of O2 generation is an effective chemopreventer of mouse skin carcinogenesis by their antioxidative property.

9,10-Dimethyl-1,2-benzanthracene↗