Biomedical subjects

Shuji Kojima

Publications and source records attributed to Shuji Kojima.

At least 19 recordsLinked to original sources

PubMed2006

Branching mode in complex-type triantennary N-glycans as regulatory element of their ligand properties.

We address the question whether the two natural types of branching in complex-type triantennary N-glycans differ in ligand properties. Toward this end, we prepared the set of pergalactosylated undecasaccharides and derivatives with alpha2,3/6-sialylation by chemoenzymatic synthesis. Conjugation resulted in neoglycoproteins which were tested in assays with lectins/antibodies, cultured cells and animals. Solid-phase assays with galactoside-specific proteins (a plant toxin, galectins and an antibody fraction) disclosed that the branching mode did not significantly affect affinity. However, compared to previous studies under identical conditions increase in antennae number and presence of substitutions in biantennary N-glycans altered KD-values with differences between receptors. Neoglycoprotein binding to cells of eight human tumor lines was sensitive to N-glycan branching. Staining intensity revealed pronounced branch-mode-dependent differences in four cases. Biodistribution profiles in mice uncovered dramatic changes in clearance rates with prolonged serum presence associated with type II branching of sialylated N-glycans and markedly increased uptake of neoglycoproteins with type I-branched N-glycans into liver, spleen, heart and lungs. This part of the study is relevant for rational glycoengineering of pharmaproteins. In general, our study supports the concept to view details of N-glycan structure, here branching, as a means to modulate ligand properties.

Carbohydrate Conformation↗

PubMed2006

A comparative study of nitric oxide, glutathione, and glutathione peroxidase activities in cerebrospinal fluid from children with convulsive diseases/children with aseptic meningitis.

It has been reported that active oxygen and/or free radicals are produced in the central nervous system (CNS) compartment in patients with bacterial meningitis, so it is supposed that the levels of endogenous antioxidative scavengers in the cerebrospinal fluid (CSF) are elevated as an adaptive reaction to bacterial meningitis, which exerts severe stress on the human body. We assumed that they are also elevated in patients with convulsive diseases. Nitric oxide (NO) and endogenous antioxidative scavengers (glutathione (GSH), glutathione peroxidase (GPX), (total) superoxide dismutase (T-SOD), manganese superoxide dismutase (Mn-SOD), and catalase) were measured in CSF from a group of child patients with various neurological diseases and a control group. NO, GSH, and GPX activities in CSF from the patients with convulsive diseases were significantly higher than in those with aseptic meningitis or in the controls. Furthermore, all parameters in CSF from patients with bacterial meningitis were significantly higher than in any other group. The present study suggests that oxidative stress may be associated with the pathophysiology of convulsion and that its clinical attenuation will lead to improvement in the prognosis for convulsive diseases.

Brain↗

PubMed2006

Change of estrogenic activity and release of chloride ion in chlorinated bisphenol a after exposure to ultraviolet B.

Bisphenol A (BPA) and chlorinated bisphenol A (ClBPAs) were detected in wastewater from waste paper recycling plants. In previous study, we showed the acute cytotoxicity of oxidized products of BPA and ClBPAs generated by ultraviolet (UV) irradiation. However, estrogenic activities of these photoproducts have not been studied. Therefore, we investigated change of estrogenic activities of BPA and ClBPAs [3-chlorobisphenol A (3-ClBPA), 3,3'-dichlorobisphenol A (3,3'-diClBPA) and 3,3',5-trichlorobisphenol A (3,3',5-triClBPA)] after UVB irradiation using yeast two-hybrid assay. The agonist activities of ClBPAs were higher than that of BPA in the absence of S9. ClBPAs irradiated with UVB lost agonist activities. The addition of S9 also completely erased the activity. The antagonist activities of BPA and ClBPAs with or without UVB irradiation were not detected both in the absence or presence of S9. UVB irradiation (0-100 J/cm2) decreased the agonist activity of 3,3'-diClBPA in proportion to increase of released chloride ion. The agonist activity was completely lost at 50 J/cm2 of UVB, of which dose could dissociated almost all chlorine. These findings suggested that UVB irradiation could decrease the estrogenic activity of chlorinated compounds, which was due to the selective release of chloride ion.

Benzhydryl Compounds↗

PubMed2006

[Induction of glutathione and activation of immune functions by low-dose, whole-body irradiation with gamma-rays].

We first examined the relation between the induction of glutathione and immune functions in mice after low-dose gamma-ray irradiation. Thereafter, inhibition of tumor growth by radiation was confirmed in Ehrlich solid tumor (EST)-bearing mice. The total glutathione level of the splenocytes transiently increased soon after irradiation and reached a maximum at around 4 h postirradiation. Thereafter, the level reverted to the 0 h value by 24 h postirradiation. A significantly high splenocyte proliferative response was also recognized 4 h postirradiation. Natural killer (NK) activity was also increased significantly in a similar manner. The time at which the response reached the maximum coincided well with that of maximum total glutathione levels of the splenocytes in the gamma-ray-irradiated mice. Reduced glutathione exogenously added to splenocytes obtained from normal mice enhanced the proliferative response and NK activity in a dose-dependent manner. The inhibitory effects of radiation on tumor growth was then examined in EST-bearing mice. Repeated low-dose irradiation (0.5 Gy, four times, before and within an early time after inoculation) significantly delayed the tumor growth. Finally, the effect of single low-dose (0.5 Gy), whole-body gamma-ray irradiation on immune balance was examined to elucidate the mechanism underlying the antitumor immunity. The percentage of B cells in blood lymphocytes was selectively decreased after radiation, concomitant with an increase in that of the helper T cell population. The IFN-gamma level in splenocyte culture prepared from EST-bearing mice was significantly increased 48 h after radiation, although the level of IL-4 was unchanged. IL-12 secretion from macrophages was also enhanced by radiation. These results suggest that low-dose gamma-rays induce Th1 polarization and enhance the activities of tumoricidal effector cells, leading to an inhibition of tumor growth.

Animals↗

PubMed2006

Suppression of atopic dermatitis and tumor metastasis in mice by small amounts of radon.

We examined the effect of radon in two experimental disease models in mice by administering radon dissolved in water at 68-203 Bq/liter. Administration of radon in drinking water to NC/Nga mice significantly delayed the progression of atopic dermatitis-like skin lesions induced by picrylchloride when administered prior to the induction of disease signs. The number of pulmonary metastatic foci in C57BL/6 mice inoculated with B16 melanoma cells was also reduced significantly by administration of radon in drinking water when the number of tumor cells was small and the radon treatment was started prior to tumor inoculation. The ratio of Ifng to Il4 produced by splenocytes from BALB/c mice immunized with DNP-Ascaris was significantly increased by administration of radon in drinking water. From these results, a modulation of immunity by radon was suggested.

Animals↗

PubMed2005

Demonstration of hyperaccumulation of [18F]2-fluoro-2-deoxy-D-glucose under oxygen deprivation in living brain slices using bioradiography.

To clarify the mechanism of hyperaccumulation of glucose in acute brain ischemia by PET, changes of glucose metabolism and mitochondrial electron transfer function were examined in living brain slices in vitro during control, hypoxic, and anoxic conditions by positron autoradiography using [(18)F]2-fluoro-2-deoxy-D-glucose ([(18)F]FDG) and [(15)O]oxygen. [(15)O]Oxygen fixation reflecting mitochondrial electron transfer function was reduced and [(18)F]FDG uptake reflecting glucose metabolism was increased in proportion to the strength of oxygen deprivation during anoxia and hypoxia. Mitochondrial electron transfer function decreased with no regional differences, whereas the glucose metabolism was the most enhanced in the hippocampus and thalamus. The enhanced glucose metabolism was associated with an increased glutamate efflux after hypoxia and anoxia. Glucose metabolism was also increased by the addition of glutamate and was attenuated by the N-methyl-D-aspartate (NMDA) receptor antagonist MK-801 in the hippocampus and thalamus. The hyperaccumulation of glucose in acute brain ischemia was demonstrated in living brain slices using bioradiography with reduced mitochondrial electron transfer. The activation of NMDA receptors by glutamate during acute brain ischemia might be responsible for hyperutilization of glucose in the hippocampus and thalamus.

Animals↗

PubMed2005

Repeated 0.5-Gy gamma-ray irradiation attenuates autoimmune manifestations in MRL-lpr/lpr mice.

PURPOSE: MRL-lpr/lpr mice, a model for various autoimmune diseases, were repeatedly irradiated with 0.5 Gy of gamma-rays, and changes in their autoimmune manifestations were investigated. MATERIALS AND METHODS: MRL-lpr/lpr mice at 13 weeks of age were maintained in plastic cages and exposed whole-body to 0.5 Gy gamma-ray irradiation from a 137Cs source 5 times per week for 4 weeks, from the time they were 13 weeks old until they reached 17 weeks old. Changes of autoimmune manifestations were examined 3 weeks later at the 20th week. RESULTS: Splenomegaly, lymphadenopathy, and proteinuria in MRL-lpr/lpr mice were clearly ameliorated by a total dose of 10 Gy (0.5 Gy/day x 5 days/week for 4 weeks). Histologically severe disease-specific damage to the kidney and the salivary gland, i.e., glomerulonephritis and sialoadenitis, was also improved after irradiation. CD3+ CD4- CD8- CD45R/B220+ T cell numbers, which proliferate abnormally in MRL-lpr/lpr mice, were significantly decreased by the irradiation, possibly through induction of apoptosis. The elevated NO2- and NO3- (NO(x-) production by macrophages of MRL-lpr/lpr mice was lowered by the irradiation. The irradiation also prolonged the life span of MRL-lpr/lpr mice. These phenomena may contribute to the amelioration of autoimmune manifestations in MRL-lpr/lpr mice exposed to repeated small-doses of gamma-rays. CONCLUSIONS: Repeated small-dose gamma-ray exposure ameliorates the autoimmune manifestations in MRL-lpr/lpr model mice.

Animals↗

PubMed2005

Protective effects of melatonin on gamma-ray induced intestinal damage.

PURPOSE: To examine the protective effects of melatonin on intestinal damage induced by gamma-rays. MATERIALS AND METHODS: Six-week-old Slc:ICR male mice were used. Mice were given whole-body irradiation at various exposure doses (7-21 Gy) with (137)Cs gamma-rays (0.98 Gy/min). The mice were orally administered 1 ml of either 1% carboxymethyl cellulose sodium salt (CMC) or melatonin (1, 5, 10 or 20 mg/ml) freshly prepared as a uniform suspension in CMC before or after irradiation. The concentrations of plasma melatonin were determined by the radioimmunoassay (RIA) method. The mice were killed at 3.5 days after the exposure. The jejunum was removed, fixed in formalin and then stained with hematoxylin and eosin. The numbers of crypts per transverse circumference were counted using a microscope for 10 histological sections of each mouse. RESULTS: The intestinal damage caused by gamma-ray irradiation was prevented by melatonin correlating to dosage. The D(0) (slope of the dose-survival curve) value significantly (p < 0.05) increased from 1.55 +/- 0.19 (mean +/- SD) Gy to 1.98 +/- 0.16 Gy by orally administering 20 mg melatonin 30 min before irradiation. The radioprotective effect of melatonin continued for 6 h after the administration. CONCLUSIONS: Melatonin is judged to be a potential protector against intestinal damage associated with radiotherapy. Further experimental and clinical studies on this subject are needed to allow its use for radiotherapy.

Animals↗

PubMed2005

Introduction of extended LEC14-type branching into core-fucosylated biantennary N-glycan.

A series of enzymatic substitutions modifies the basic structure of complex-type biantennary N-glycans. Among them, a beta1,2-linked N-acetylglucosamine residue is introduced to the central mannose moiety of the core-fucosylated oligosaccharide by N-acetylglucosaminyltransferase VII. This so-called LEC14 epitope can undergo galactosylation at the beta1,2-linked N-acetylglucosamine residue. Guided by the hypothesis that structural modifications in the N-glycan alter its capacity to serve as ligand for lectins, we prepared a neoglycoprotein with the extended LEC14 N-glycan and tested its properties in three different assays. In order to allow comparison to previous results on other types of biantennary N-glycans the functionalization of the glycans for coupling and assay conditions were deliberately kept constant. Compared to the core-fucosylated N-glycan no significant change in affinity was seen when testing three galactoside-specific proteins. However, cell positivity in flow cytofluorimetry was enhanced in six of eight human tumor lines. Analysis of biodistribution in tumor-bearing mice revealed an increase of blood clearance by about 40%, yielding a favorable tumor/blood ratio. Thus, the extended LEC14 motif affects binding properties to cellular lectins on cell surfaces and organs when compared to the core-fucosylated biantennary N-glycan. The results argue in favor of the concept of viewing substitutions as molecular switches for lectin-binding affinity. Moreover, they have potential relevance for glycoengineering of reagents in tumor imaging.

Agglutinins↗

PubMed2005

Involvement of mitochondrial peroxynitrite in nitric oxide-induced glutathione synthesis.

Cells respond to oxidative stress including nitric oxide (NO) by increasing cellular glutathione concentration, as a part of adaptive response against oxidative injury. To elucidate the mechanism by which NO induces glutathione we investigated the reactive oxygen species (ROS) generated in the cell. Treatment of RAW264.7 cells with NO donor, sodium nitroprusside (SNP), resulted in a temporary increase in glutathione in a dose-dependent manner, which peaked between 6 h and 12 h after treatment, whereas expression of gamma-glutamylcysteine synthetase (gamma-GCS) mRNA peaked around 3 h after treatment. The increase was inhibited by NO scavengers, oxyhemoglobin and carboxyl-2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO). N-Acetyl-L-cysteine (NAC) also reduced the increase in glutathione to some extent, whereas both peroxynitrite scavenger ebselen and hydroxyl radical scavenger DMSO inhibited the increase in glutathione in a dose-dependent manner and complete inhibition was observed. Hydrogen peroxide exogenously added to the cell did not increase either glutathione or gamma-GCS expression at any concentration, indicating that involvement of hydrogen peroxide is not likely. Flow cytometric analysis showed that SNP induced a marked dose-dependent increase in Rhodamine123 fluorescence, which was completely inhibited by ebselen in a dose-dependent manner, whereas, little increase in 2',7'-dichlorofluorescin (DCF) fluorescence was observed. Generation of peroxynitrite in mitochondria by SNP was confirmed by elevated level of nitrotyrosine in a mitochondria fraction isolated from SNP-treated cells, and the elevation was completely inhibited by ebselen as well. These results suggest that induction of glutathione (GSH) synthesis by SNP treatment is mediated by peroxynitrite generated in mitochondria.

Animals↗

PubMed2005

Immunomodulatory effects of gyokuheifusan on INF-gamma/IL-4 (Th1/Th2) balance in ovalbumin (OVA)-induced asthma model mice.

Asthma, a common, chronic lung disease in industrialized countries, is characterized by the production of large quantities of IgE antibody by B cells and a decrease of the IFN-gamma/IL-4 (Th1/Th2) ratio. Gyokuheifusan (GHS) is a classical formulation of traditional Chinese medicine (TCM) that is usually prescribed to prevent or treat respiratory tract diseases, such as respiratory infection and bronchial asthma. In order to evaluate the possible effectiveness of GHS on bronchial asthma, its immunomodulatory activity was examined in ovalbumin (OVA)-induced asthma model mice. All mice, except those in the normal group, were sensitized by intraperitoneal (IP) administration of OVA emulsified with Al(OH)(3), and a second immunization was given 6 d later. After a further 13, 17 and 21d, mice were challenged with inhalation of aerosolized OVA solution, except for the normal group, which received mock sensitization using saline-Al(OH)(3) emulsion and were challenged with an aerosol of saline without OVA. Allergen-specific IgE and total IgE in plasma were both significantly increased in the disease-control group. These increases were markedly blocked by GHS treatment. IFN-gamma released by splenocytes was significantly increased after co-culture with OVA for 24 h, 48 h, and 72 h. GHS treatment further elevated the IFN-gamma content compared with the disease-control group. The production of IL-4 was significantly increased when splenocytes were simulated with OVA for 72 h, but this increase was blocked by GHS treatment, so that GHS returned the decreased IFN-gamma/IL-4 (Th1/Th2) ratio of the disease-control group to the normal range. These results indicate that GHS may inhibit the development and severity of asthma.

Animals↗

PubMed2005

Glycine betaine, a beer component, protects radiation-induced injury.

Human whole-blood was exposed to 137Cs gamma-rays or 50 keV/microm carbon ions in the presence or absence of glycine betaine, a beer component in vitro. The dicentrics of chromosome aberrations in human lymphocytes were significantly (p < 0.05) reduced by glycine betaine after irradiation with 4 Gy of either gamma-rays or carbon ions. The maximum protection by glycine betaine for gamma-rays or carbon ions was 37% and 20%, respectively. C3H/He female mice, aged 14 weeks, received an i.p. injection of glycine betaine 15 min before whole-body irradiation with gamma-rays or 50 keV/microm carbon ions. Glycine betaine significantly (p < 0.05) increased the percent survival of irradiated mice with either gamma-rays or carbon ions. In conclusion, glycine betaine is a potent protector against damages caused by low- and high-LET radiation.

Animals↗

PubMed2005

Repeated irradiations with gamma-rays at a Dose of 0.5 Gy may exacerbate asthma.

We previously showed that 0.5 Gy whole-body gamma-ray irradiation with a single or small number of repeated exposures inhibits tumor growth in mice, via elevation of the IFN-gamma/IL-4 ratio concomitantly with a decrease in the percentage of B cells. Here we examined whether repeated 0.5 Gy gamma-rays irradiation can improve asthma in an OVA-induced asthmatic mouse model. We found that repeated irradiation (10 times) with 0.5 Gy of gamma-rays significantly increased total IgE in comparison with the disease-control group. The levels of IL-4 and IL-5 were also significantly higher in the gamma-ray-irradiated group, while that of IFN-gamma was significantly lower, resulting in a further decrease of the IFN-gamma/IL-4 ratio from the normal value. These results indicate that the repeated irradiation with gamma-rays may exacerbate asthma, and may have opposite effects on different immune reactions unlike the irradiation with a single or small number of repeated exposures.

Animals↗

PubMed2005

The elevation of p53 protein level and SOD activity in the resident blood of the Misasa radon hot spring district.

To clarify the mechanism by which radon hot springs prevent cancer or not, in this study, blood was collected from residents in the Misasa hot spring district and in a control district. The level of a representative cancer-suppressive gene, p53, and the activity of a representative antioxidant enzyme, superoxide dismutase (SOD), were analyzed as indices. The level of serum p53 protein in the males in the Misasa hot spring district was found to be 2-fold higher than that in the control district, which is a significant difference. In the females in the Misasa hot spring district, SOD activity was approximately 15% higher than that in the control district, which is also statistically significant, and exceeded the reference range of SOD activity despite advanced age. These results suggested that routine exposure of the residents in the Misasa hot spring district to radon at a concentration about 3 times higher than the national mean induces trace active oxygen in vivo, potentiating products of cancer-suppressive gene and antioxidant function. As the p53 protein level was high in the residents in the Misasa hot spring district, apoptosis of cancer cells may readily occur.

Aged↗

PubMed2005

Effect of nitric oxide on gamma-ray-induced micronucleus frequency in RAW264.7 cells.

The effect of low-dose nitric oxide (NO) on gamma-ray-induced micronucleus (MN) frequency was investigated in RAW264.7 cells. Treatment of RAW264.7 cells with 0.25 mM sodium nitroprusside (SNP), a chemical NO donor, reduced the frequency of micronuclei induced by 5 Gy gamma rays by 43 to 45% between 3 and 12 h post-treatment. This effect was blocked by carboxy-PTIO, suggesting that NO may play a role in the reduction of radiation-induced MN frequency. To examine possible mechanisms underlying this effect, we first looked at changes in the antioxidant system after SNP treatment. A significant increase in intracellular glutathione (GSH) was seen in SNP-treated cells between 3 and 12 h post-treatment. Depletion of GSH with buthionine sulfoximine (BSO) increased the gamma-ray-induced increase in MN frequency. Detailed studies using various inducers of intracellular GSH suggested that GSH induction has a partial role in the reducing effect of NO on the gamma-ray-induced MN frequency. Next, the effect of NO on DNA repair and replication systems was examined. Wortmannin, an inhibitor of DNA-dependent protein kinase (DNA-PK), dose-dependently inhibited the reducing effect of NO, while caffeine, an inhibitor of ATM kinase and ATR kinase, did not. DNA-PK activity was increased by NO treatment. Etoposide, a topoisomerase II inhibitor, dose-dependently blocked the effect of NO in reducing the gamma-ray-induced MN frequency. These results suggest that the mechanisms of the effect of NO on the gamma-ray-induced MN frequency include elevation of GSH and up-regulation of DNA-PK activity for repairing double-strand breaks. NO may act as a signal for repair systems, e.g. for nonhomologous recombination and for the replication system in S phase, to reduce the MN frequency.

Animals↗

PubMed2004

Increase of intracellular glutathione by low-level NO mediated by transcription factor NF-kappaB in RAW 264.7 cells.

The mechanism underlying the elevation of intracellular glutathione (GSH) in RAW 264.7 cells exposed to low concentrations of sodium nitroprusside (SNP), a well-known nitric oxide (NO) donor, was investigated. The peak of intracellular GSH was reached at 6 h after exposure of the cells to SNP (0.1-0.5 mM), and this was preceded by the induction of mRNA for gamma-glutamylcysteine synthetase (gamma-GCS; the rate-limiting enzyme of de novo GSH synthesis), which peaked at 3 h. N-alpha-Tosyl-L-phenylalanine chloromethyl ketone (TPCK) and caffeic acid phenethyl ester (CAPE), specific inhibitors of NF-kappaB, significantly suppressed the SNP-induced elevation of GSH protein and gamma-GCS mRNA, while curcumin, an inhibitor of AP-1, was less effective. Electrophoretic mobility shift assay (EMSA) showed that SNP exposure markedly increased the DNA binding of NF-kappaB, but not that of AP-1. Deletion or mutagenesis of the NF-kappaB site in the gamma-GCS gene promoter abolished the SNP-induced up-regulation of GSH protein and gamma-GCS mRNA. These results suggest that the elevation of intracellular GSH in RAW 264.7 cells exposed to low concentrations of SNP occurs through the operation of the de novo GSH pathway, and is mediated by transcriptional up-regulation of the gamma-GCS gene, predominantly at the NF-kappaB binding site in its promoter.

Animals↗

PubMed2004

Determination of modulation of ligand properties of synthetic complex-type biantennary N-glycans by introduction of bisecting GlcNAc in silico, in vitro and in vivo.

We have investigated the consequences of introducing a bisecting GlcNAc moiety into biantennary N-glycans. Computational analysis of glycan conformation with prolonged simulation periods in vacuo and in a solvent box revealed two main effects: backfolding of the alpha1-6 arm and stacking of the bisecting GlcNAc and the neighboring Man/GlcNAc residues of both antennae. Chemoenzymatic synthesis produced the bisecting biantennary decasaccharide N-glycan and its alpha2-3(6)-sialylated variants. They were conjugated to BSA to probe the ligand properties of N-glycans with bisecting GlcNAc. To assess affinity alterations in glycan binding to receptors, testing was performed with purified lectins, cultured cells, tissue sections and animals. The panel of lectins, including an adhesion/growth-regulatory galectin, revealed up to a sixfold difference in affinity constants for these neoglycoproteins relative to data on the unsubstituted glycans reported previously [André, S., Unverzagt, C., Kojima, S., Dong, X., Fink, C., Kayser, K. & Gabius, H.-J. (1997) Bioconjugate Chem. 8, 845-855]. The enhanced affinity for galectin-1 is in accord with the increased percentage of cell positivity in cytofluorimetric and histochemical analysis of carbohydrate-dependent binding of labeled neoglycoproteins to cultured tumor cells and routinely processed lung cancer sections. Intravenous injection of iodinated neoglycoproteins carrying galactose-terminated N-glycans into mice revealed the highest uptake in liver and spleen for the bisecting compound compared with the unsubstituted or core-fucosylated N-glycans. Thus, this substitution modulates ligand properties in interactions with lectins, a key finding of this report. Synthetic glycan tailoring provides a versatile approach to the preparation of newly substituted glycans with favorable ligand properties for medical applications.

Acetylglucosamine↗

PubMed2004

Chemoprevention of colorectal cancer by grape seed proanthocyanidin is accompanied by a decrease in proliferation and increase in apoptosis.

Effects of proanthocyanidin (PA), procyanidin B-2 (B-2), and epigallocatechin gallate (EGCG) on azoxymethane (AOM)-induced colonic preneoplastic aberrant crypt foci (ACF) formation were investigated using F344 rats. The numbers of total ACF in rats treated with 0.002% PA and 0.05% B-2 were significantly decreased compared with the AOM alone group (control). Cell proliferation in the colon, as shown by proliferating cells nuclear antigen (PCNA), was also reduced in those treatments. The single-stranded DNA (ssDNA) labeling index, a marker for apoptosis, was significantly increased in 0.002% PA and 0.05% B-2 groups compared with control. Moreover, the numbers of CD11b/c+ cells (macrophages) and NKR-P1A+ cells (NK cells) in the all groups were significantly increased compared with control. In an in vitro study using rat colon cancer cell line RCN-9, PA, especially 5-10mer of PA (PA5/10), strong growth inhibition was shown. PA5/10 caused the most remarkable apoptosis as cleared by FACS analysis. These cells showed significantly increased caspase-3 activity. The results would suggest that the PA, especially PA5/10, might strongly enhance caspase-3 activity and cause apoptosis in cancer cells. PA at fairly low doses in the long term might serve as an effective means for preventing colon carcinogenesis.

Animals↗