Since there is a report that an inhibitor of protein kinase C (PKC) effectively suppresses the development of hepatic fibrosis, it is suggested that the PKC signaling pathway plays an important role in the pathogenesis of hepatic fibrosis. We reported that oxidized diacylglycerol (DAG), which is an activator of PKC, had a remarkably stronger PKC-activating action than un-oxidized DAG. In the present study, we explored the roles of oxidized DAG in hepatic fibrogenesis using mice, the livers of which developed fibrosis by long-term administration of carbon tetrachloride (CCl4). Liver fibrosis models were created by 4- or 8-week repetitive subcutaneous injections of CCl4 to the backs of C57BL/6J mice. The amount of oxidized DAG was significantly increased in the CCl4-treated group. Moreover, it was found that PKCα, βI, βII and δ were activated. In the CCl4-treated group, phosphorylation of ERK and JNK, which are downstream signal transmitters in the PKC pathway, was increased. It was also found in this group that there was an increase in TIMP-1, which is a fibrogenesis-promoting factor whose expression is enhanced by activated JNK, and of TNF-α, an inflammatory cytokine. Analysis by quantitative real-time RT-PCR showed that expressions of αSMA, collagen I, TNF-α and IL-10 were remarkably increased in the 8-week CCl4-treated group. The above results strongly suggested that oxidized DAG, which is increased by augmented oxidative stress, activated PKCα, βI, βII and δ molecular species and that these molecular species in turn stimulated the phosphorylation of MAP kinases including ERK and JNK, resulting in enhancement of hepatic fibrogenesis.
Alkaline conditions in the oral cavity may be caused by a variety of stimuli, including tobacco products, antacids, alkaline drinking water and bicarbonate toothpaste. However, the effects of an alkaline pH on the oral mucosa had not been elucidated. The purpose of this study was to investigate how basal keratinocytes are actively involved in re-epithelialization after alkaline chemical injury. We generated epithelial defects in the oral mucosa of mice by applying an alkaline chemical, and the localization of cytokeratin 13, cytokeratin 14, PCNA and p63 was investigated during the re-epithelialization process. PCNA- and p63-positive staining was seen in basal cells covering the wound surface at 1 day after the chemical injury. Cytokeratin 14-positive and PCNA-negative basal keratinocytes were localized in a few layers of the wound epithelium during epithelial outgrowth. Cytokeratin 14-positive and PCNA-positive basal keratinocytes, indicating proliferation, were localized over the entire layer of the epithelium at the wound margin. These results imply that basal keratinocytes at the wound margin migrate to the wound surface, provoke differentiation and keratinization during epithelial outgrowth and that epithelial cells are supplied from the wound margin to the epithelial outgrowth after alkaline chemical injury.
Nordihydroguaiaretic acid (NDGA), a lignan found in vegetables, fruits and legumin, has been shown to possess antineoplastic, antiviral and antioxidant characteristics. In this study, we examined the effect of NDGA on melanogenesis in human melanoma cells (HMVII). In vitro, NDGA does not alter mushroom tyrosinase activity. However, in NDGA-treated HMVII cells, cellular tyrosinase activity increased in both a time- and dose-dependent manner. The concomitant increases in melanin content in NDGA-treated cells indicated an elevation of melanin synthesis by tyrosinase activation. In addition, after a 7-day incubation, melanin content in 20 μM NDGA-treated cells increased 5.02 fold. Tyrosinase protein also increased by treatment with NDGA. Nevertheless, tyrosinase mRNA was not altered in NDGA-treated cells. Our results suggest that NDGA can increase tyrosinase activity and de novo synthesis of melanin in human melanoma cells. We found that NDGA is a novel potent stimulator of melanogenesis in human melanoma cells.
Hypertensive rat arteries exhibited severe medial smooth muscle cell injury and necrosis. Electron microscopic observations showed the smooth muscle cells of these arteries exhibited characteristics of focal cytoplasmic necrosis forming new cytodemarcating membrane between the healthy cytoplasm and necrotic cytoplasm. When the focal necrotic cytoplasm disappeared from the injured smooth muscle cells, it left it with a moth-eaten leaf-like appearance (moth-eaten necrosis). At an advanced stage of injury, smooth muscle cells changed to islet-like cell bodies with newly formed basement membranes around them, and further islet-like cell bodies and cell debris disappeared leaving lamellar and reticular basement membranes.In hypertensive rats injected with nitroblue tetrazolium (NBT), formazan deposits were observed in the medial cells and nitrotyrosine, a biomarker of peroxynitrite, were immunohistochemically observed in the arterial media. Nick-end positive extranuclear small granular bodies, which might have derived from focal necrotic cytoplasm and nucleus, were detected in the arterial media using DNA nick-end labeling method. Based on electron microscopical and histochemical findings, we conjectured that the focal cytoplasmic necrosis of the smooth muscle cells in the arterial media depended on injury arising from mitochondria-derived oxidants.
Somatostatin receptor (SSTR) expressions in neuroblastomas (NBs) have been confirmed employing various methods. High SSTR-2 expression was suggested to be a favorable prognostic marker, though little is known about the relationships between the expressions of SSTR subtypes, other than SSTR-2, and prognosis. We investigated the expressions of all five known SSTR subtypes in 63 neuroblastic tumors (NTs), employing immunohistochemistry, and also conducted quantitative real-time RT-PCR in 37 of these tumors. We evaluated correlations between the expressions of SSTR subtypes and prognosis, based on the International Neuroblastoma Pathology Classification and patient outcomes. More than 90% of cases expressed, at a minimum, SSTR-1 and/or 2. Ganglioneuromas and ganglioneuroblastomas expressed more than two SSTR subtypes. Among NBs, the favorable histology group showed higher SSTR subtype expressions than the unfavorable histology group. The same tendency was observed when surviving and deceased cases were compared, though SSTR-2 expression was well preserved in some of the deceased cases. In conclusion, NTs highly expressed SSTR-1 and/or 2, and expressions of SSTR generally indicate a good prognosis. However, even those in the unfavorable histology group with NBs expressing SSTR are good candidates for molecular targeting therapy using somatostatin analogues.
Cell–matrix interaction is required for tissue development. Laminin, a major constituent of the basement membrane, is important for structural support and as a ligand in tissue development. Laminin has 19 isoforms, which are determined by combinational assembly of five α, three β, and three γ chains (eg, laminin 121 is α1, β2, and γ1). However, no report has identified the laminin isoforms expressed during pituitary development. We used in situ hybridization to investigate all laminin chains expressed during rat anterior pituitary development. The α5 chain was expressed during early pituitary development (embryonic day 12.5–15.5). Expression of α1 and α4 chains was noted in vasculature cells at embryonic day 19.5, but later diminished. The α1 chain was re-expressed in parenchymal cells of anterior lobe from postnatal day 10 (P10), while the α4 chain was present in vasculature cells from P30. The α2 and α3 chains were transiently expressed in vasculature cells and anterior lobe, respectively, only at P30. Widespread distribution of β and γ chains was also observed during development. These findings suggest that numerous laminin isoforms are involved in anterior pituitary gland development and that alteration of the expression pattern is required for proper development of the gland.
The anterior pituitary gland is organized tissue comprising hormone-producing cells and folliculostellate (FS) cells. FS cells interconnect to form a meshwork, and their cytoplasmic processes are anchored by a basement membrane containing laminin. Recently, we developed a three-dimensional (3D) cell culture that reproduces this FS cell architecture. In this study of the novel function of FS cells, we used transgenic rats that express green fluorescent protein in FS cells for the 3D culture. Anterior pituitary cells were cultured with different proportions of FS cells (0%, 5%, 10%, and 20%). Anterior pituitary cells containing 5–20% FS cells formed round/oval cell aggregates, whereas amorphous cell aggregates were formed in the absence of FS cells. Interestingly, immunohistochemistry showed laminin-immunopositive cells instead of extracellular laminin deposition in FS cell-deficient cell aggregates. Double-immunostaining revealed that these laminin-immunopositive cells were gonadotrophs. Laminin mRNA expression did not differ in relation to the presence or absence of FS cells. When anterior pituitary cells with no FS cells were cultured with FS cell-conditioned medium, the proportion of laminin-immunopositive cells was lower than in control. These results suggest that a humoral factor from FS cells is required for laminin release from gonadotrophs.
Hypoxia is a characteristic feature of solid neoplasms, and insufficient oxygen supply increases cellular nicotinamide adenine dinucleotide (NADH) fluorescence, which is a main component of autofluorescence of the colorectal mucosa. We investigated whether a dual-wavelength excitation method which is optimized for sensing mucosal NADH fluorescence could be applicable to the detection of rat colorectal cancers in vivo. Rat colorectal adenocarcinomas were studied by using fluorescence stereomicroscopy. After autofluorescence images at 470 nm irradiated with dual-wavelength excitation at 365 nm (F365ex) and 405 nm (F405ex) were acquired, ratio images were produced by dividing F365ex by F405ex: The excitation-emission wavelength pairs in F365ex and F405ex were adjusted for acquisition of NADH fluorescence and reference fluorescence. Based on observations from the luminal surface in vivo, F365ex/F405ex ratio images indicated a 1.57-fold higher signal value in the cancers than in the surrounding normal mucosa. The signal values in F365ex/F405ex ratio images were less mutually related with the hemoglobin concentration index. Small adenocarcinomas (less than 4 mm) could be detected on F365ex/F405ex ratio images. The results showed that NADH fluorescence measurement with little interference from tissue hemoglobin is efficient for visualizing rat colorectal cancers in vivo, suggesting that the dual-wavelength excitation method has potential for label-free endoscopic detection of diminutive colorectal neoplasms.