Shinji Naito

Stimulation of in vitro angiogenesis by hydrogen peroxide and the relation with ETS-1 in endothelial cells.

The purpose of this study was to examine the effect of hydrogen peroxide (H2O2) on angiogenesis in cultured endothelial cells. Endothelial cells obtained from bovine thoracic aorta (BAECs) were cultured between two layers of collagen type I to measure the tube formation which is a marker for angiogenesis. Addition of H2O2 (0.1-10 microM) to endothelial cells for various periods increased the rate of tube formation. The maximum stimulation of the tube formation was obtained when cells were exposed to 1 microM H2O2 for 30 min, and the enhancement of tube formation was blocked by catalase (10 U/ml). Both proliferation and migration of BAEC which are known to affect angiogenesis, were also stimulated by the addition of H2O2 (0.1 and 1 microM). Thus relatively low concentrations of H2O2 stimulated angiogenesis, proliferation and migration. Ets-1 is a member of the ets gene family of transcription factors, which binds to the ets binding motif in the cis-acting elements and regulates the expression of certain genes such as proteases including urokinase plasminogen activator (u-PA) and matrix metalloproteinase-1 (MMP-1). Interestingly, H2O2 increased the ets-1 mRNA level in BAECs compared with the basal level. The H2O2-stimulated angiogenesis was completely blocked by an ets-1 antisense oligonucleotide, but not by a mismatched oligonucleotide. These findings indicate that low concentrations of H2O2 stimulate angiogenesis in BAECs, and the stimulation mechanisms may partially involve the enhancement of proliferation and migration. Moreover, the H2O2-induced angiogenesis is likely to be mediated by the transcription factor ets-1.

TRPA1 underlies a sensing mechanism for O(2).

Oxygen (O(2)) is a prerequisite for cellular respiration in aerobic organisms but also elicits toxicity. To understand how animals cope with the ambivalent physiological nature of O(2), it is critical to elucidate the molecular mechanisms responsible for O(2) sensing. Here our systematic evaluation of transient receptor potential (TRP) cation channels using reactive disulfides with different redox potentials reveals the capability of TRPA1 to sense O(2). O(2) sensing is based upon disparate processes: whereas prolyl hydroxylases (PHDs) exert O(2)-dependent inhibition on TRPA1 activity in normoxia, direct O(2) action overrides the inhibition via the prominent sensitivity of TRPA1 to cysteine-mediated oxidation in hyperoxia. Unexpectedly, TRPA1 is activated through relief from the same PHD-mediated inhibition in hypoxia. In mice, disruption of the Trpa1 gene abolishes hyperoxia- and hypoxia-induced cationic currents in vagal and sensory neurons and thereby impedes enhancement of in vivo vagal discharges induced by hyperoxia and hypoxia. The results suggest a new O(2)-sensing mechanism mediated by TRPA1.

Carcinoma in gastric hyperplastic polyps. A phenotypic study.

One-hundred twelve hyperplastic polyps were analyzed. The aim was to study their malignant transformation. Among them, four hyperplastic polyps harbored adenocarcinoma; two were from our own institution (1.8%). The majority were pedunculated and located in the antrum with an average of 14.5 mm in diameter. The four polyps bore well-differentiated adenocarcinoma. Dysplasia and intestinal metaplasia were detected in two and three polyps, respectively. The cancer and dysplastic foci shared the same type of neutral and acid mucosubstances. p53 oncoprotein was positive in three cancer foci and in the dysplastic areas, and nucleolar organizer region counts were higher in the cancer foci. In conclusion, hyperplastic polyps have malignant potential. Such possibility increases in polyps larger than 14.5 mm. In our cases, the carcinoma foci may have arisen from dysplastic areas. Once the neoplastic changes occur, the cancer cells proliferate and behave as other adenocarcinomas of the stomach.

Expression of the ets-1 Proto-Oncogene in Human Colorectal Carcinoma

The proto-oncogene, ets-1, is a transcription factor known to control the expression of a number of genes involved in extracellular matrix remodeling and has been postulated to play a role in cell migration and tumor invasion. To elucidate the involvement of ets-1 in human colorectal carcinomas, we examined 41 cases of colorectal adenoma and 122 cases of colorectal carcinoma by immunohistochemistry and compared the degree of Ets-1 expression with the depth of carcinoma invasion. In adenomas, 12 of 41 cases (29.3%) showed immuno-positivity for Ets-1. 12 of 27 cases (44.4%) of adenoma with high grade dysplasia showed immunopositivity for Ets-1. However, there was no positive case in low or moderate dysplasia of adenoma. In contrast, 103 of 122 cases (84.4%) of colorectal adenocarcinoma showed immunoreactivity for Ets-1 in the carcinoma cells themselves. We investigated the relationship between pathological features in colorectal carcinoma and Ets-1 immunoreactivity of the tumor cells. Among the 122 cases of invasive carcinomas, Ets-1 immunoreactivity was significantly correlated with the depth grading of tumor invasion (P < .0001), the presence of lymph node metastasis (P < .05), lymphatic invasion (P < .01) and venous invasion (P < .05). However, Ets-1 expression did not correlate with histological differentiation. In situ hybridization also confirmed the presence of ets-1 mRNA in colorectal carcinomas. Expression of ets-1 mRNA was also detected in two of three human colorectal carcinoma tissues and in four of six different kinds of carcinoma cell lines by the reverse transcription polymerase chain reaction method. These findings suggest that the expression of Ets-1 is one of the important factors related to carcinogenesis and/or tumor invasion of colorectal carcinoma.

Significance of Angiogenic Factors in Liver Metastatic Tumors Originating from Colorectal Cancers

We examined the expression of vascularendothelial growth factor (VEGF) and microvessel countsexpressed by CD34 staining in 39 patients with primaryand 44 patients with metastatic liver tumors ofmetastatic colorectal carcinoma, and 29 patients withnonmetastatic colorectal carcinoma as control in orderto determine their value in the evaluation of prognosisand recurrence after hepatectomy. Microvessel counts in primary colorectal carcinomas of themetastatic group were significantly higher than those incontrol (P < 0.05). Neither factor correlated withany clinicopathological feature of primary or metastatic liver carcinomas. Higher microvessel counts inmetastatic liver tumors tended to be associated with ashorter disease-free interval to second recurrence inthe remaining liver (P = 0.069) and were significantly associated with poor prognosis afterhepatectomy (P < 0.05). We conclude that microvesselcount is an important marker of liver metastatasis andprognosis in patients with colorectal carcinoma treated with hepatectomy.

Stimulation of nitric oxide synthase during oxidative endothelial cell injury.

The purpose of this study was to determine changes in nitric oxide synthase (NOS) activity during the process of lethal oxidative cell injury following H2O2 treatment of endothelial cells. NOS activity was determined by measuring the conversion of [3H]arginine ([3H]Arg) to [3H]citrulline ([3H]Cit). Cell death was assessed by measuring the release of intracellular lactate dehydrogenase (LDH). Moreover, cell death and changes in cytosolic free Ca2+ (Ca(i)2+) were measured simultaneously using a confocal laser scanning system, and propidium iodide and fluo-3 as fluorescent indicators, respectively. Treatment with H2O2 (125-1000 microM) concentration dependently increased L-Cit formation from L-Arg, and a peak was obtained at 90 min after the addition of 500 or 1000 microM H2O2. The H2O2-induced increase in L-Cit formation was blocked completely by N(G)-nitro-L-arginine (L-NNA) or N(G)-methyl-L-arginine (L-NMA), both inhibitors of NOS. LDH release from endothelial cells was evoked from 120 min after the addition of H2O2 (125-1000 microM) in a concentration-dependent manner. Moreover, H2O2 increased Ca(i)2+ before cell death, and addition of Ca2+ chelator inhibited both the increase in L-Cit formation and LDH release by H2O2. The H2O2-induced LDH release was reduced by L-NNA, but not by L-NMA. These results suggest that H2O2 treatment of endothelial cells increases Ca(i)2+ before cell death, and stimulates NOS activity. The activation of NOS may be involved in oxidative endothelial cell death.

Femoral head necrosis and osteopenia in stroke-prone spontaneously hypertensive rats (SHRSPs)

Necrosis of the femoral head and osteopenia were examined histopathologically in stroke-prone spontaneously hypertensive rats (SHRSPs) aged 6 to 36 weeks and compared with that of spontaneously hypertensive rats (SHRs) and Wistar-Kyoto rats (WKYs). Avascular necrosis of the femoral head was frequently observed, mainly in the young SHRSPs and SHRs (about 8 to 15 weeks of age). SHRSPs had the highest incidence of femoral head necrosis among the three strains. This necrotic change in the femoral head was considered to be secondary ischemia induced by angiospasm or arteriosclerosis, similar to the disorders observed in the brain, kidney, and heart in SHRSPs. However, the complication occurred in spite of treatment with antihypertensive agents (ACE inhibitor: enalapril, spirapril) even though other ischemic disorders such as brain hemorrhage and renal infarction were prevented, indicating that the femoral head necrosis in SHRSPs was not due to hypertensive complications induced by angiospasm or arteriosclerosis. Bone mineral density (BMD) of the femoral bone was significantly lower in SHRSPs, and the femoral heads in this strain were the most easily deformed by loads applied during compression tests. Histopathologically, the infarctions were encountered on the lateral side of the epiphysis, but no thrombi were observed. The lateral side of the epiphysis is the anatomic site where the weight load is greatest and the site where the nutritive artery enters. Our results strongly suggest that the coexistence of vulnerable bone matrix and physical weight load to the nutritive artery plays a crucial role in the occurrence of femoral head necrosis in SHRSPs, whether based on generalized or localized osteopenia.

Overexpression of Ets-1 transcription factor in angiosarcoma of the skin.

Angiosarcoma of the skin is a rare malignant tumor which is slow-growing but highly aggressive and often recurs following surgery and/or radiation therapy, finally metastasizing to the regional lymph nodes. The ets-1 protooncogene is shown to be transcribed in endothelial cells during angiogenesis in granulation tissue and in malignant cells during tumor invasion. Furthermore, it can regulate the expression of metalloproteinase genes such as collagenase-1 (MMP-1), stromelysin (MMP-3) and urokinase-type plasminogen activator (uPA). In this study we investigated the ets-1 and MMP-1 expression in 7 angiosarcomas of the skin, compared with 7 hemangiomas and 7 granuloma pyogenicums of the skin, which are well known as benign vascular diseases. The ets-1 and MMP-1 mRNAs and their proteins were overexpressed in all angiosarcomas tested, and the localization of MMP-1 expression corresponded to that of ets-1. On the other hand, they were weakly or not at all expressed in hemangiomas and granuloma pyogenicums. These results suggest that the constitutive overexpression of ets-1 might be closely related with the malignant progression of angiosarcoma, possibly through the up-regulation of the transcription of MMP-1.

Leukemia inhibitory factor enhances bone formation in calvarial bone defect.

For bone defect reconstruction, locally administered cytokine plasmid was examined. Leukemia inhibitory factor (LIF) can bind to the osteoblast cell surface and induce bone formation both in vitro and in vivo. The authors investigated the local mouse LIF complementary deoxyribonucleic acid (cDNA) plasmid in the pcDNA 3 expression vector, which is promoted by cytomegalovirus and is stabilized by bovine growth hormone polyadenylation, with a gelatin sponge carrier. A total of 150 male Wistar rats were used. They were divided into three groups. Group 1 (N = 30) was treated with the gelatin carrier of the pcDNA 3 vector, group 2 (N = 90) was treated with three different doses of LIF cDNA (0.1, 1, and 10 micrograms) in the pcDNA 3-vector plasmid along with the gelatin carrier, and group 3 (N = 30) was treated with recombinant human bone morphogenetic protein -2. Ten animals in each group were euthanized at 1, 3, and 5 weeks postoperatively. Animals treated with LIF cDNA showed significantly enhanced bone mineral density (p < 0.05), as confirmed by dual-energy X-ray absorptiometry (DEXA), in 3 weeks compared with the control vehicle. By 3 weeks, the number of fibroblast-like cells and collagen fibers decreased, whereas the osteoblast-like cells increased inversely, as revealed during histological examination. LIF messenger ribonucleic acid demonstrated by in situ hybridization was observed most markedly in osteocytes of the LIF cDNA-treated group. Also, LIF peptide was detected in the same cell type by immunohistochemistry. Locally administered LIF cDNA plasmid in a gelatin carrier can increase bone density significantly, with subsequent bone formation, probably via osteocyte activation.

Detailed clinicopathological characteristics and possible lymphomagenesis of type II intestinal enteropathy-associated T-cell lymphoma in Japan

Twenty-six Japanese cases of type II enteropathy-associated T-cell lymphoma (EATL) were examined. Multiple tumors throughout the small intestine were found in 15 patients (58%) and duodenal and colonic mucosal lesions in 8 and 6 cases, respectively. Histologically, intramucosal tumor spread and a zone of neoplastic intraepithelial lymphocytes (IELs) neighboring the main transmural tumors were detected in 20 (91%) and 17 (77%) of the 22 cases examined, respectively. Inside and outside the IEL zone, some degree of enteropathy with many reactive small IELs and villous atrophy was detected in 11 cases (50%). Immunohistologically, many CD56/CD8-positive small IELs were found in the enteropathic lesions of 4 (36%) and 7 (64%) of these 11 cases. Lymphoma cells expressed tyrosine kinase receptor c-Met, serial phosphorylated (p)-mitogen-activated protein kinase/extracellular signal-regulated kinase, c-Myc, and Bcl2 in 18 (78%), 21 (91%), 11 (42%), and 19 (73%) of the total cases, respectively. By fluorescence in situ hybridization, chromosomal loci 7q31 (c-Met) and 8q24 (c-Myc) were amplified in 11 (65%) and 12 (71%) of the 17 cases analyzed. Gain of 7q31 and c-Met expression were significantly (P < .01) higher than in peripheral CD8-positive T-cell or CD56-positive natural killer-cell lymphomas. Enteropathy was seen near the IEL zone in type II EATL, and activation of the c-Met, mitogen-activated protein kinase/extracellular signal-regulated kinase-mitogen-activated protein kinase pathway, and c-Myc-Bcl2-mediated cell survival may play important roles in lymphomagenesis, converting enteropathy to type II EATL. Seven cases in the early clinical stages I and II-1 showed significantly (P < .01) better prognoses than did those in the advanced stages. Early detection of the mucosal lesions and tumors may improve patient prognosis.