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ABSTRACT: Increased incidence of adrenal pheochromocytoma is frequently encountered in rat carcinogenicity studies. In some of the studies, the finding is judged to be due to a rat-specific mechanism of carcinogenesis caused by a disturbance of calcium homeostasis. However, direct evidence that the proliferation of chromaffin cells in the adrenal medulla is induced solely by hypercalcemia is not available. In this study, calcium gluconate was intravenously infused for 7 days to rat chromaffin cells by a tail cuff method, and cumulative labeling with bromodeoxyuridine (BrdU) was carried out to evaluate the proliferative activity. The serum calcium concentration was dose-dependently increased, and a high calcium concentration was stably sustained from day 2 to 7. In the adrenal medulla, BrdU-positive chromaffin cells increased in the calcium gluconate-treated animals, and the BrdU-labeling index increased in a dose-dependent manner. In addition, an increased BrdU-labeling index of chromaffin cells was shown to correlate with the serum calcium concentration. Our results demonstrate that hypercalcemia directly enhances the proliferative activity of chromaffin cells and that the proliferative activity is correlated with the serum calcium concentration.
Journal of Toxicologic Pathology 12/2012; 25(4):281-5. · 0.48 Impact Factor
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Shinta Kobayashi,
Hisafumi Yamada-Okabe,
Masami Suzuki,
Osamu Natori,
Atsuhiko Kato,
Koichi Matsubara,
Yu Jau Chen,
Masaki Yamazaki,
Shinichi Funahashi,
Kenji Yoshida, [......],
Hironori Mutoh,
Motooki Ashihara, Chie Kato,
Takeshi Watanabe,
Takashi Yoshikubo,
Norikazu Tamaoki,
Takahiro Ochiya,
Masahiko Kuroda,
Arnold J Levine,
Tatsumi Yamazaki
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ABSTRACT: The cancer stem cell (CSC) concept has been proposed as an attractive theory to explain cancer development, and CSCs themselves have been considered as targets for the development of diagnostics and therapeutics. However, many unanswered questions concerning the existence of slow cycling/quiescent, drug resistant CSCs remain. Here we report the establishment of colon cancer CSC lines, interconversion of the CSCs between a proliferating and a drug resistant state, and reconstitution of tumor hierarchy from the CSCs. Stable cell lines having CSC properties were established from human colon cancer after serial passages in NOD/Shi-scid, IL-2Rγ(null) (NOG) mice and subsequent adherent cell culture of these tumors. By generating specific antibodies against LGR5, we demonstrated that these cells expressed LGR5 and underwent self-renewal using symmetrical divisions. Upon exposure to irinotecan, the LGR5(+) cells transitioned into an LGR5(-) drug resistant state. The LGR5(-) cells converted to an LGR5(+) state in the absence of the drug. DNA microarray analysis and immunohistochemistry demonstrated that HLA-DMA was specifically expressed in drug resistant LGR5(-) cells and epiregulin was expressed in both LGR5(+) and drug resistant LGR5(-) cells. Both cells sustained tumor initiating activity in NOG mice, giving rise to a tumor tissue hierarchy. In addition, anti-epiregulin antibody was found to be efficacious in a metastatic model. Both LGR5(+) and LGR5(-) cells were detected in the tumor tissues of colon cancer patients. The results provide new biological insights into drug resistance of CSCs and new therapeutic options for cancer treatment.
Stem Cells 10/2012; · 7.78 Impact Factor
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ABSTRACT: Miniature swine (minipigs) are often used in non-rodent toxicity studies. However, unlike other animal species, the parathyroid glands of minipigs are often covered with thymic tissue and are similar in color, making macroscopical identification difficult. We investigated a method for sampling and tissue preparation of the parathyroid glands using 5- to 7-month-old minipigs. The glands were identified by finding the insertion site of a branch from the carotid artery into the cervical part of the thymus. Then the glands were marked and sampled. In a preliminary study, the glands were macroscopically and microscopically detected in 3/8 animals. The glands were not identified macroscopically in 5/8 animals but were detected in 3 of these animals. In total, we succeeded in detection of the glands in 6/8 animals (75%). The method was applied in the main toxicity study, and we succeeded in 100% detection through technical advancement. The method described herein enables high rate of detection and is useful in the pathological evaluation of the parathyroid glands of minipigs.
The Journal of Toxicological Sciences 01/2010; 35(2):235-8. · 1.52 Impact Factor
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ABSTRACT: The NOD/Shi-scid, IL-2Rgamma(null) (NOG) mouse is a severely immunodeficient mouse used for the engraftment of human tissues and cells. In this study, 2406 mice (8-62 weeks old, 503 males and 1903 females) were subcutaneously engrafted with human tissues. In 16 mice (12-26 weeks old, 1 male and 15 females), a mass was seen in the anteroventralis of the thorax on gross examination with an incidence of 0.7%. Histologically, the masses were composed of sheets of lymphoblastic cells. A 'starry sky' pattern was observed with numerous mitoses. Immunohistochemically the lymphoblastic cells were positive for Thy 1. The lymphoblastic cells were also seen in the spleen, lung, liver, kidney and heart. The gross and histopathological findings led to the diagnosis of spontaneous thymic lymphoma in NOG mice.
Laboratory Animals 07/2009; 43(4):402-4. · 1.21 Impact Factor
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ABSTRACT: The db/db mouse is one of the diabetes mellitus animal models and if the pathophysiological stages of diabetic changes in the mouse model could simulate the stages in human diabetes, the db/db mouse could be used to better evaluate drug candidates. Blood insulin, HbA1c levels and morphological features of pancreatic islets in db/db mice were evaluated to determine the pathophysiological stage. At 6 weeks of age, db/db mice showed the highest level of plasma insulin and lowest level of HbA1c, and histopathological examination revealed enlarged islets with a circular shape and hypertrophic islet cells. By 9 and 12 weeks of age, the plasma insulin levels had decreased to mid levels and HbA1c had increased to mid to high levels; histopathological examination at this time revealed two types of islets coexisting, enlarged circular islets and small irregular-shaped islets. By 15 and 22 weeks of age, plasma insulin had decreased further to low levels and HbA1c was at its highest level; the histopathological examination at this time revealed an increase in irregular-shaped and small islets. Based on blood insulin levels, HbA1c levels and histopathology findings in the db/db mice in this study, the clinical staging of diabetic changes were recognized. The pathophysiological stages of diabetes mellitus in this animal model were similar to the stages in humans.
Journal of Toxicologic Pathology 06/2009; 22(2):133-7. · 0.48 Impact Factor
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ABSTRACT: Glypican-3 (GPC3) is frequently upregulated in hepatocellular carcinoma (HCC). Analysis of GPC3-deficient mice implies GPC3 involvement in macrophage-lineage cells. Aim: In this study, we first assessed the association of GPC3 expression with the macrophage population in liver tissues from 30 HCC patients using immunohistochemistry.
The GPC3 expression was categorized into three patterns - one with GPC3-negative staining and two with GPC3-positive staining (one with unclear membrane staining and one with clear membrane staining, designated GPC3+/C). The number of macrophages that were stained with resident macrophage (rMvarphi) or pan-macrophage (pMvarphi) markers was counted for each GPC3 expression pattern.
GPC3 immunoreactivity was observed in 76.7% of the HCC specimens. No significant differences were observed in the number of rMvarphi marker-positive cells among the three expression patterns. In contrast, the GPC3+/C pattern showed a significantly higher number of pMvarphi-positive cells compared with the other two patterns, most of which tended to take on the morphology of migrating macrophages. A second experiment conducted to compare macrophage infiltration between the xenograft tissues of a GPC3-transfected HCC cell line and its parent GPC3-nonexpressing cell line revealed that the increase in macrophages was stimulated by membrane expression of GPC3.
The observations suggest that the increased macrophages in the GPC3+/C pattern are likely to be recruited macrophages, not resident macrophages, and that the expression of GPC3 in the membrane is involved in macrophage recruitment.
Liver international: official journal of the International Association for the Study of the Liver 02/2009; 29(7):1056-64. · 3.82 Impact Factor
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ABSTRACT: The authors previously demonstrated that high doses of recombinant human granulocyte colony-stimulating factor (rhG-CSF) induce bone changes characterized by accelerated osteoclastic bone resorption and osteogenesis due to intramembranous ossification in rats. As a basis for future analysis of the mechanisms of rhG-CSF-induced bone changes, the present study was undertaken to determine whether the bone changes observed in rats are also induced in mice. The experiment was conducted under the conditions that clearly induce bone changes in rats. Namely, 4- or 6-week-old mice received a subcutaneous injection of rhG-CSF (1,000 or 5,000 microg/kg) for 14 or 28 days, and then the femur and tibia were evaluated histopathologically. A marked increase in peripheral blood leukocyte counts, prominent splenomegaly, and a marked increase in the number of granulopoietic cells in the bone marrow, all of which are related to the major pharmacological activity of G-CSF, was observed in the rhG-CSF-treated mice. The histopathological changes observed in the rat bone, such as accelerated osteoclastic bone resorption and osteogenesis due to intramembranous ossification, were not detected in mice. These results suggest that there is a species-related difference between mice and rats in the response of the bone to rhG-CSF treatment, and that the reactivity in mice is lower than in rats.
The Journal of Toxicological Sciences 06/2008; 33(2):245-9. · 1.52 Impact Factor
