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2
Second Department of Medical Biochemistry and
*
Central Research Laboratory, School of Medicine, Ehime University, Shigenobu-cho, Onsen-gun, Ehime 791-0295, Japan
2To whom correspondence should be addressed. E-mail: yokim{at}m.ehime-u.ac.jp
| ABSTRACT |
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KEY WORDS: Agaricus blazei antitumor activity antiangiogenic activity antitumor substance mice
| INTRODUCTION |
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300,000500,000 persons for the prevention of cancer and/or
as an adjuvant with cancer chemotherapy drugs after the removal of a
malignant tumor. The intake of the water extract of A.
blazei is
35 g three times daily. The hot water extract of
A. blazei has potent antitumor activity in sarcoma
180bearing mice (1| MATERIALS AND METHODS |
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Melting points, which were determined with a Yamato MO-21 capillary apparatus (Yamato Science, Tokyo, Japan), are uncorrected. Infrared and ultraviolet spectra were measured with a Shimadzu IR-400 spectrometer (Kyoto, Japan) and a JASCO ORD/UV-5 spectrometer (Tokyo, Japan), respectively. The 1H NMR (499.83 MHz) spectra were recorded in CDCl3 with a Varian Unity Inova 500 spectrometer (TOSO, Tokyo, Japan). Mass spectra were measured with an Hitachi M-4000 H spectrometer (Tokyo, Japan). Column chromatography was performed using silica gel 60 (70230 mesh; ASTM, Merck, Germany). Other chemicals were of reagent grade.
Natural materials and isolation of antitumor substances from A. blazei.
A. blazei was supplied by Bizen Chemical (Okayama, Japan). Voucher samples are stored at the Second Department of Medical Biochemistry, School of Medicine, Ehime University, Japan. The dried fungal bodies of A. blazei (1 kg) were directly extracted with chloroform/methanol (1:1, v/v) (2 L x 3) for 3 h under reflux. The chloroform/methanol extract was concentrated under reduced pressure to provide a brown extract (250 g). The chloroform/methanol extract (200 g) was divided into acetone-soluble (160 g) and -insoluble (40 g) fractions. The acetone-soluble fraction (35 g) was further divided into n-hexaneinsoluble (16 g) and soluble (14 g) fractions. The n-hexaneinsoluble fraction (15 g) was chromatographed on a silica gel column, and ergosterol (2.4 g) was isolated as an active substance. Each fraction was tested for antitumor action in sarcoma 180bearing mice.
Cells.
The highly metastatic, drug-resistant mouse Lewis lung carcinoma (LLC)3 cells were obtained from Riken Gene Bank (Tukuba, Japan) and maintained in Dulbeccos modified Eagles medium (DMEM) supplemented with 10% fetal bovine serum, penicillin (1 x 105 U/L), streptomycin (100 mg/L) and amphotericin B (0.25 mg/L). Sarcoma 180 cells were also maintained in the laboratory of the Second Department of Medical Biochemistry, School of Medicine, Ehime University.
Materials.
Mouse lymphocyte separation medium (Lympholytes-Mouse) was purchased from Dainippon Pharmacy Ltd. (Osaka, Japan), and fluorescein isothiocyanate (FITC)-labeled anti-mouse CD4 and CD8 and phycoerythrin-labeled anti-mouse NK1.1 antigen were purchased from Serotec (Oxford, U.K.). Matrigel basement membrane (reduced growth factor) was obtained from Becton Dickinson Labware (Bedford, MA). DMEM were obtained from Nissui Pharmaceutical Ltd. (Tokyo, Japan) and used as culture medium. Antibiotic and antimycotic solutions were purchased from Sigma Chemical (St. Louis, MO). Fetal bovine serum was purchased from ICN Biochemicals (Aurora, OH). Round nitrocellulose membrane chambers (pore size 0.45 µm) were purchased from Millipore (Bedford, MA). Culture plates were purchased from Corning Glass Works (Corning, NY). Other chemicals were of reagent grade. ß-Cyclodextrin was supplied by Ensui Sugar Refining Ltd. (Yokohama, Japan). Ergosterol was suspended in 9 g NaCl/L solution or distilled water containing 20 g ß-cyclodextrin/L.
Animals.
Male ICR strain mice (6 wk old) and female C57BL/6 strain mice (5 wk old) were obtained from Clea Japan (Osaka, Japan). They were housed for 1 wk in a room maintained at 25 ± 1°C with 60% humidity and had free access to standard nonpurified diet (8 g water, 51.3 g crude carbohydrate, 24.6 g crude protein, 5.6 g crude lipid, 3.1 g crude fiber, 6.4 g mineral mixture and 1 g vitamin mixture per 100 g diet; Oriental Yeast Ltd., Osaka, Japan) and water. The room was illuminated for 12 h/d starting at 0700 h. Animals were treated according to the ethical guidelines of the Animal Center, School of Medicine, Ehime University. The experimental protocol was approved by the Animal Studies Committee of Ehime University.
Measurements of antitumor activities and side effects of various fractions and active substances isolated from A. blazei in sarcoma 180 and LLC-bearing mice.
Solid-type sarcoma 180 was prepared through the subcutaneous transplantation of 1.0 x 106 or 2.5 x 106 cells into the right abdomen of mice on d 0. Various lipid fractions such as chloroform/methanol extract, acetone-soluble and -insoluble fractions and n-hexanesoluble and insoluble fractions were suspended in water containing 50 g gum arabic/L through sonication. These lipid fractions were administered orally for 20 consecutive d at a dose of 800 mg/kg, starting 12 h after the implantation of tumor cells. Ergosterol was administered intraperitoneally at doses of 10, 50, 100 or 200 mg/kg or orally at doses of 100, 200, 400 or 800 mg/kg for 20 consecutive d. Control mice were also fed 9 g NaCl/L or water containing 50 g gum arabic/L alone on the same schedule.
The tumor volume was determined through direct measurement with calipers and calculated by the formula [length (mm) x width (mm2)]/2 every 23 d. On d 21, blood was obtained via venipuncture in mice with diethyl ether anesthesia, and then the tumor, epididymal adipose tissue, spleen and thymus were removed and weighed for evaluation of antitumor activity and side effects. The blood samples were chilled in test-tubes containing heparin, and the number of leukocytes was measured using a Coulter Counter (Japan Scientific Instruments Ltd., Tokyo, Japan).
Solid-type LLC cells were also prepared through subcutaneous transplantation of 5 x 105 cells (1 mL) into the right abdomen of mice on day 0. Ergosterol (50, 200 or 800 mg/kg) was administered orally once daily for 24 consecutive d, starting 12 h after the implantation of tumor cells. Control mice were administered distilled water alone on the same schedule. On d 25, the mice were killed by cervical dislocation, and their spleens, thymus and lungs were quickly removed and weighed.
Measurement of lymphocyte number and T-cell population (CD4+, CD8+ and NK1.1+ T cells) in LLC-bearing C57BL/6 mice.
The spleen was gently teased to release cells through dissection in cold PBS. The cell suspension (5 mL) was layered onto 5 mL of Lympholytes-Mouse and centrifuged at 1500 x g for 30 min. The lymphocyte band at the interface was recovered, and the cells were rinsed three times with PBS (pH 7.4). The number of lymphocytes was measured using a Coulter Counter. The cell concentration was adjusted to 2 x 1010 cells/L, and then 10 µL of FITC-labeled anti-mouse CD8, FITC-labeled anti-mouse CD4 or phycoerythrin-labeled anti-mouse NK1.1 was added to 100 µL of the cell suspension. After incubation for 30 min at 4°C, lymphocytes were rinsed three times with 1 mL of PBS and centrifuged at 700 x g for 5 min. Then CD4+, CD8+ and NK1.1+ T-cell populations were analyzed by flow cytometry with an FACS Calibur (Becton Dickinson, Mountain View, CA).
Measurement of neovascularization induced by tumor cells.
In vivo tumor-induced neovascularization was assayed according to the dorsal air-sac method. Briefly, 1.5 x 106 cultured LLC cells were suspended in DMEM, packed into a round nitrocellulose membrane chamber with a diameter of 14 mm and implanted into dorsal air-sac mice on day 0. Ergosterol (5, 10 or 20 mg/kg) was administered once daily on d 15. The mice were killed on d 6, and the hair on the skin in contact with the chamber was carefully shaved off. The formation of new blood vessels in the subcutaneous region was photographed.
Measurement of Matrigel-induced neovascularization.
In vivo Matrigel-induced neovascularization was assayed according
to the methods of Passaniti et al. (6)
Briefly, female
C57BL/6 mice were each injected subcutaneously with 0.5 mL of Matrigel
containing 1 mg of acidic fibroblast growth factor (aFGF) and 64
x 103 U of heparin per L in the presence
or absence of ergosterol (400 or 800 mg/L). The mice were killed on d 5
with an overdose of pentobarbital, and the gels were removed and
weighed. Then the hemoglobin contents in the gels were determined using
Hemoglobin-Test kits (Wako Pure Chemical, Osaka, Japan).
Data and statistical analyses.
All values are expressed as means ± SEM. Data were analyzed by one-way ANOVA, and then differences in means among groups were analyzed using Dunnetts test or Fishers protected LSD multiple comparison test (significantly different at P < 0.05).
The structure of the isolated substance.
The isolated substance formed colorless needles with a melting point of
157°C. It was reddish violet with concentrated
H2SO4 and CH3COOH [fast atom
bombardmentmass spectrometry m/z 489 (M+
H+)]. The isolated substance was identified as ergosterol
through direct comparison of the 1H NMR spectral data of an
authentic sample. The yield was
1.5 g/kg dried body of A.
blazei.
| RESULTS |
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The chloroform/methanol extract (800 mg/kg x 20 d) strongly
inhibited tumor growth (Table 1
). Moreover, the oral administration of the acetone-soluble fraction
isolated from the chloroform/methanol extract significantly inhibited
tumor growth at a dose of 800 mg/kg during the 20-d treatment. On the
other hand, tumor growth was not affected by the oral administration of
the acetone-insoluble fraction on d 20. Therefore, the
acetone-soluble fraction, which had higher antitumor activity, was
divided into two fractions through treatment with n-hexane.
The n-hexanesoluble and insoluble fractions (800 mg/kg
x 20 d) also inhibited the tumor growth, and their
inhibitory ratios were 80.2 and 90.1%, respectively.
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Antitumor activity and side effects of ergosterol in sarcoma 180 and LLC-bearing mice.
Oral administration of ergosterol for 20 d reduced tumor volume
(Fig. 1
). The inhibition ratios for tumor growth with oral administration of
ergosterol at the doses of 100, 200, 400 and 800 mg/kg x 20 d were 0.0 ± 30.6, 62.3 ± 8.8, 70.9 ± 10.8 and 85.5
± 4.7%, respectively. Intraperitoneal injection of ergosterol
also inhibited tumor growth at doses of 10, 50, 100 and 200 mg/kg for
20 d, with inhibition ratios of 20.6 ± 20.5, 57.1 ± 6.5, 65.8 ± 4.7 and 84.7 ± 4.2%, respectively.
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Ergosterol had no effect on the numbers of splenic lymphocytes or CD4+, CD8+ or NK1.1+ T cells (data not shown). Colony numbers in the lungs of LLC-bearing mice (control) were 4.80 ± 1.24 x 106. The oral administration of ergosterol had no effect on metastasis to the lung at the doses of 50, 200 and 800 mg/kg for 23 d, with tumor colony numbers (x106) of 3.80 ± 1.62, 4.00 ± 0.58 and 5.33 ± 0.67, respectively. Ergosterol had no cytotoxicity against sarcoma 180 and LLC cells (data not shown).
Effects of ergosterol on LLC-induced neovascularization.
At 5 d after implantation of the LLC cells, which were packed into
the membrane chamber, neovascularization was evident in the region in
contact with the chamber containing LLC cells. Intraperitoneally
administered ergosterol (20 mg/kg) prevented neovascularization induced
by LLC cells (Fig. 2
).
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The gels that formed after subcutaneous implantation of Matrigel alone
were readily distinguished from surrounding tissue and produced little
or no local reaction or angiogenic response (Fig. 3A
). However, Matrigel supplemented with 1 mg aFGF and 64,000
U heparin per L produced gels that showed an
angiogenic reaction (Fig. 3B
). The Matrigel/aFGF/heparin
mixture significantly increased the weight of the gel and the
hemoglobin contents in the gels at 6 d after implantation compared
with mice treated with Matrigel alone (Table 3
). Ergosterol (400 and 800 mg/L) inhibited increases in the weight and
hemoglobin concentration of the gels (Fig. 3
, Table 3
).
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| DISCUSSION |
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300,000500,000 persons
for the prevention of cancer and/or as an adjuvant with cancer
chemotherapy drugs after the removal of a malignant tumor. There have
been a number of reports that various Basidiomycetes have antitumor
activity in sarcoma 180bearing mice. Chihara (7)
| ACKNOWLEDGMENTS |
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| FOOTNOTES |
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3 Abbreviations used: aFGF, acidic fibroblast growth factor; DMEM, Dulbeccos modified Eagles medium; FITC, fluorescein isothocyanate; LLC, Lewis lung carcinoma. ![]()
Manuscript received December 1, 2000. Initial review completed January 12, 2001. Revision accepted February 24, 2001.
| REFERENCES |
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2. Itoh H., Ito H., Amano H., Noda H. Inhibitory action of (16)-ß-glucan-protein complex (FIII 020b) isolated from Agaricus blazei Murill ("Himematsutake") on Meth A fibrosarcoma-bearing mice and its antitumor mechanism. Jpn. J. Pharmacol. 1994;66:265-271[Medline]
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