Munetaka Ozeki

Redox regulation of annexin 2 and its implications for oxidative stress-induced renal carcinogenesis and metastasis

Ferric nitrilotriacetate (Fe-NTA) induces oxidative renal damage leading to a high incidence of renal cell carcinoma (RCC) in rats. Differential display analysis of such RCCs revealed elevated expression of annexin 2 (Anx2), a substrate for kinases and a receptor for tissue-type plasminogen activator and plasminogen. We conducted this study to clarify the significance of Anx2 in Fenton reaction-based carcinogenesis. Messenger RNA and protein levels of Anx2 were increased time-dependently in the rat kidney after Fe-NTA administration as well as in LLC-PK1 cells after exposure to H2O2. The latter was inhibited by pretreatment with N-acetylcysteine, pyrrolidine dithiocarbamate or catalase. Immunohistochemistry revealed negligible staining in the normal renal proximal tubules, but strong staining in regenerating proximal tubules, karyomegalic cells and RCCs. Metastasizing RCCs showed higher Anx2 protein levels. Anx2 was phosphorylated at serine and tyrosine residues in these cells and coimmunoprecipitated with phosphorylated actin. Overexpression of Anx2 induced a higher cell proliferation rate in LLC-PK1 cells. In contrast, a decrease in proliferation leading to apoptosis was observed after Anx2 antisense treatment to cell lines established from Fe-NTA-induced RCCs. These results suggest that Anx2 is regulated by redox status, and that persistent operation of this adaptive mechanism plays a role in the proliferation and metastasis of oxidative stress-induced cancer.

PCR-based identification of pathogenic Candida species using primer mixes specific to Candida DNA topoisomerase II genes

For rapid identification of Candida to the species level, degenerated primers and specific primers based on the genomic sequences of DNA topoisomerase II of C. albicans, C. dubliniensis, C. tropicalis (genotypes I and II), C. parapsilosis (genotypes I and II), C. krusei, C. kefyr, C. guilliermondii, C. glabrata, C. lusitaniae and Y. lipolytica were designed and their specificities tested in PCR‐based identifications. Each of the specific primers selectively and exclusively amplified its own DNA fragment, not only from the corresponding genomic DNA of the Candida sp. but also from DNA mixtures containing other DNAs from several fungal species. For a simpler PCR‐based identification, the specific primers were divided into three groups (PsI, PsII and PsIII), each of which contained four specific primer pairs. PCR with the primer mixes yielded four different sizes of PCR product, corresponding to each Candida sp. in the sample DNA. To obtain higher sensitivity of PCR amplification, sample DNAs were preamplified by the degenerated primer pair (CDF28/CDR148), followed by the main amplification using the primer mixes. By including this nested PCR step, 40 fg yeast genomic DNA was detected in the sample. Furthermore, we applied this nested PCR to a clinical diagnosis, using splenic tissues from experimentally infected mice and several clinical materials from patients. In all cases, the nested PCR amplifications detected proper DNA fragments of Candida spp., which were also identified by the standard identification tests. These results suggest that nested PCR, using primer mixes of the Candida DNA topoisomerase II genes, is simple and feasible for the rapid detection/identification of Candida to species level in clinical materials. Copyright

Effects of the Phenolic Contents of Mauritian Endemic Plant Extracts on Promoter Activities of Antioxidant Enzymes

Oxidative stress has been associated with a variety of pathologic conditions in humans. Increasing the transcriptional activities of antioxidant enzymes might be a strategy to prevent oxidative stress-associated diseases such as atherosclerosis and cancer. In the present paper, we studied the effects of extracts from 12 Mauritian endemic plants on the promoter activities of antioxidant enzymes; Cu, Zn-superoxide dismutase (Cu,Zn-SOD), Mn-superoxide dismutase (Mn-SOD), catalase, and glutathione dismutase (GPx). The levels of total phenolic compounds, total flavonoids, and proanthocyanidins were measured. Four luciferase expression vectors (pGL3-Basic) with promoter region of each enzyme were constructed, transfected to COS7 cells followed by an exposure to each extract (25 μg/ml, 24 h, non-toxic dose). Thereafter, luciferase activities were evaluated in comparison with a control luciferase vector with a herpes simplex virus thymidine kinase promoter. Mauritian endemic plants contained high amounts of total phenols, flavonoids and proanthocyanidins. Total phenols and flavonoids were proportionally associated with Cu,Zn-SOD promoter activity, whereas they were inversely correlated with catalase promoter activity. These results suggest that the chemopreventive potentials of the extracts might reside in their abilities to modulate the expression of the antioxidant enzyme genes.

Specific Allelic Loss of p16INK4A Tumor Suppressor Gene after Weeks of Iron-Mediated Oxidative Damage during Rat Renal Carcinogenesis

Oxidative tissue damage has been shown to be associated with carcinogenesis. In human cancers p16(INK4A) is one of the most frequently mutated tumor suppressor genes. The present study used the ferric nitrilotriacetate (Fe-NTA)-induced rat renal carcinogenesis model to determine whether oxidative damage can cause specific allelic loss of p16 (INK4A). By the use of fluorescent in situ hybridization in combination with imprint cytology at single-cell resolution, we found that the number of renal tubular cells with aneuploidy (1 or 3 signals) at the p16(INK4A) locus was significantly and specifically increased (1 week, 37.2 +/- 2.3%; 3 weeks, 37.8 +/- 1.3% vs control, 22.5 +/- 1.9%; mean +/- SE, N = 8; P < 0.001 and P < 0.0001, respectively) after repeated intraperitoneal administration of 5 to10 mg of iron/kg in the form of Fe-NTA for 3 weeks. No increase in aneuploidy was observed at the loci of either the p53 or vhl tumor suppressor gene. Furthermore, the increase in the cells with 3 signals was followed by a continuous increase in those with 1 signal. Therefore, the p16 (INK4A) locus is specifically vulnerable to oxidative damage, leading to its allelic loss within weeks, presumably due to a deficiency in the replication of both the alleles.

Protective effect of colored rice over white rice on fenton reaction-based renal lipid peroxidation in rats

Rice has been one of the most important grains. While polished white rice is favored, colored strains of rice, red, or black, have been maintained for religious purposes in Japan. We studied whether feeding of unpolished colored rice instead of white rice ameliorates oxidative renal tubular damage in rats induced by ferric nitrilotriacetate. Whereas renal lipid peroxidation was exacerbated in white rice-fed group in comparison with standard chow group, this exacerbation was not observed in red or black rice-fed groups. These changes were dependent on the proportion of colored rice to standard chow in the diet. Cyanidin 3- O - g - d -glucoside was detectable neither in the serum nor kidney after one week of colored rice diet, but serum protocatechuic acid was significantly increased after black rice diet. There was a generalized decrease in the renal glutathione peroxidase activity in rice diet groups. Renal enzymatic activities of superoxide dismutase, glutathione S -transferase and NAD(P)H quinone reductase were not associated with the levels of lipid peroxidation. However, renal catalase activity was significantly increased in black rice-fed groups. These may partly explain the antioxidative effect. Furthermore, colored strains of rice are rich in proteins. Thus, our data warrants further investigation of the antioxidative effect of colored rice.

Sorbin and SH3 Domain-Containing Protein 2 Is Released From Infarcted Heart in the Very Early Phase: Proteomic Analysis of Cardiac Tissues From Patients

Background Few proteomic studies have examined human cardiac tissue following acute lethal infarction. Here, we applied a novel proteomic approach to formalin‐fixed, paraffin‐embedded human tissue and aimed to reveal the molecular changes in the very early phase of acute myocardial infarction. Methods and Results Heart tissue samples were collected from 5 patients who died within 7 hours of myocardial infarction and from 5 age‐ and sex‐matched control cases. Infarcted and control myocardia were histopathologically diagnosed and captured using laser microdissection. Proteins were extracted using an originally established method and analyzed using liquid chromatography–tandem mass spectrometry. The label‐free quantification demonstrated that the levels of 21 proteins differed significantly between patients and controls. In addition to known biomarkers, the sarcoplasmic protein sorbin and SH3 domain‐containing protein 2 (SORBS2) was greatly reduced in infarcted myocardia. Immunohistochemical analysis of cardiac tissues confirmed the decrease, and Western blot analysis showed a significant increase in serum sorbin and SH3 domain‐containing protein 2 in acute myocardial infarction patients (n=10) compared with control cases (n=11). Conclusions Our advanced comprehensive analysis using patient tissues and serums indicated that sarcoplasmic sorbin and SH3 domain‐containing protein 2 is released from damaged cardiac tissue into the bloodstream upon lethal acute myocardial infarction. The proteomic strategy presented here is based on precise microscopic findings and is quite useful for candidate biomarker discovery using human tissue samples stored in depositories.

Telomere shortening and karyotypic alterations in hepatocytes in long‐term transplanted human liver allografts

The long‐term fate of aged liver allografts in young recipients who received grafts from older donors is unknown. We evaluated graft aging by analyzing hepatocytic telomere length and karyotypic changes. Seventeen pediatric individuals who underwent living‐donor liver transplantation for congenital biliary diseases were selected. At a median of 10.4 years post‐transplant, ten had tolerated grafts with weaned off immunosuppressants, and seven had idiopathic post‐transplantation hepatitis. Fluorescence in situ hybridization was used to evaluate the telomere signal intensity (TI) and karyotypic changes. First, we measured predictive age‐dependent TI decline with regression analysis of donor livers. The mean TI at the earliest (within a year) and latest biopsies was significantly lower than the predicted TI of the studied allografts. With univariate analysis, a higher abnormal karyotype ratio in the donor liver was correlated with development of idiopathic post‐transplantation hepatitis. With multivariate analysis that included clinical parameters, a greater TI decline at the earliest biopsy was correlated with the development of idiopathic post‐transplantation hepatitis. In conclusion, graft aging as measured by TI decline and donor abnormal karyotype ratio was associated with idiopathic post‐transplantation hepatitis of long‐term transplanted liver allografts.

Peroxynitrite-mediated stress is associated with proliferation of human metastatic colorectal carcinoma in the liver.

3-Nitrotyrosine (3-NT), a product of peroxynitrite reaction, is abundantly observed in hepatocytes adjacent to human metastatic colorectal carcinoma. To elucidate its biological significance, we undertook to identify nitric oxide (NO)-producing cells and apoptosis under oxidative stress. We observed strong inducible NO-synthase (iNOS) immunoreactivity in the hepatocytes adjacent to metastatic tumor, revealing an identical pattern to 3-NT immunostaining. Furthermore, intense 3-NT immunostaining of hepatocytes was associated with apoptosis whereas carcinoma cells near those hepatocytes presented high proliferating-cell nuclear antigen. Our results suggest that contact of metastatic tumor induces apoptosis in adjacent hepatocytes through peroxynitrite, thus permitting the proliferation of cancer cells.

ZFP521 contributes to pre-B-cell lymphomagenesis through modulation of the pre-B-cell receptor signaling pathway.

ZFP521 was previously identified as a putative gene involved in induction of B-cell lymphomagenesis. However, the contribution of ZFP521 to lymphomagenesis has not been confirmed. In this study, we sought to elucidate the role of ZFP521 in B-cell lymphomagenesis. To this end, we used a retroviral insertion method to show that ZFP521 was a target of mutagenesis in pre-B-lymphoblastic lymphoma cells. The pre-B-cell receptor (pre-BCR) signaling molecules BLNK, BTK and BANK1 were positively regulated by the ZFP521 gene, leading to enhancement of the pre-BCR signaling pathway. In addition, c-myc and c-jun were upregulated following activation of ZFP521. Stimulation of pre-BCR signaling using anti-Vpreb antibodies caused aberrant upregulation of c-myc and c-jun and of Ccnd3, which encodes cyclin D3, thereby inducing the growth of pre-B cells. Stimulation with Vpreb affected the growth of pre-B cells, and addition of interleukin (IL)-7 receptor exerted competitive effects on pre-B-cell growth. Knockdown of BTK and BANK1, targets of ZFP521, suppressed the effects of Vpreb stimulation on cell growth. Furthermore, in human lymphoblastic lymphoma, analogous to pre-B-cell lymphoma in mice, the expression of ZNF521, the homolog of ZFP521 in humans, was upregulated. In conclusion, our data showed that the ZFP521 gene comprehensively induced pre-B-cell lymphomagenesis by modulating the pre-B-cell receptor signaling pathway.

An electron spin resonance study on alkylperoxyl radical in thin-sliced renal tissues from ferric nitrilotriacetate-treated rats: The effect of α-tocopherol feeding

Formation of excess free radical causes cellular oxidative stress, which has been shown to be associated with a variety of pathologic conditions. While electron spin resonance (ESR) spectroscopy has been the only method to demonstrate the presence of free radicals, its application to tissue samples has been challenging. We report here the successful ESR detection in thin-sliced fresh tissues or frozen sections in a rat model. Ferric nitrilotriacetate (Fe-NTA) induces oxidative renal tubular damage that ultimately leads to high incidence of renal carcinoma in rodents. Twenty minutes after administration of 5 mg iron/kg Fe-NTA to rats, a thin-slice of the kidney was mounted on a tissue-type cell and analyzed by ESR spin trapping with 5,5-dimethyl-1-pyrroline-N-oxide (DMPO). An ESR signal from alkylperoxyl radical adduct was obtained, and the signal was inversely proportional to renal α-tocopherol content which was modulated through diet. Furthermore, we undertook ex vivo study using frozen sections. Fe-NTA (1 mM) was added to a rat kidney frozen section for 10 min. After washing the specimen was mounted on a tissue-type cell and analyzed with ESR spin trapping using DMPO. Alkylperoxyl radical signal was dependent on thickness, incubation time and renal tissue levels of α-tocopherol, and was reduced by preincubation with catalase or dimethyl sulfoxide but not with α-tocopherol outside tissue. This versatile method facilitates identification of free radicals in pathologic conditions, and may be useful for selection of antioxidants.