Biomedical subjects

E Tsuchiya

Publications and source records attributed to E Tsuchiya.

At least 37 records · Page 2Linked to original sources

PubMed1999

The expression of p73 is increased in lung cancer, independent of p53 gene alteration.

p73 gene, a new p53 homologue, has been identified: it supposedly acts as tumour suppressor gene in neuroblastoma. To clarify whether p73 might be involved in lung carcinogenesis, we examined p73 expression in resected lung cancer and paired normal lung in 60 cases using semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR). We also examined p73 gene status in three representative cases using Southern blot, and p53 gene alteration in 49 cases using PCR-single-strand conformation polymorphism (PCR-SSCP) and direct sequence. In 87% of the cases (52/60) p73 expression in tumour was more than twice as high as that in paired normal lung tissues, and the difference between p73 expression in tumour and normal lung tissue was significant (P < 0.0001). However, Southern blot analysis revealed that none of the cases showed p73 gene amplification. Compared with clinicopathological characteristics, p73 expression correlates significantly with histological differences and age of patient, independently (P < 0.05). Concerning p53 gene status, 43% (21/49) showed p53 gene alteration, but there was no correlation between p73 overexpression and p53 gene alteration. Our results suggest that need for further functional analysis of the role of p73 in lung carcinogenesis.

Adult↗

PubMed1999

Nps1/Sth1p, a component of an essential chromatin-remodeling complex of Saccharomyces cerevisiae, is required for the maximal expression of early meiotic genes.

BACKGROUND: The NPS1/STH1 gene of Saccharomyces cerevisiae is essential for mitotic growth, especially for the progression through the G2/M phase. It encodes a major component of the chromatin-remodelling complex, RSC, of unknown function. We attempted to address the function of NPS1 in meiosis. RESULTS: The homozygote of the temperature sensitive nps1 mutant, nps1-105, showed reduced and delayed levels of sporulation, accompanied with a notable decrease and delay of the expression of several early meiotic genes (IME2, SPO11 and SPO13). Deletion analysis of the IME2 promoter revealed that the defect in the gene expression occurred through the URS1 site. The sporulation defect of nps1-105 was alleviated by the over-expression of either IME1 or IME2. However, over-expression of IME1 did not permit the full expression of IME2, SPO11 and SPO13 in nps1-105. In addition, the expression of NPS1 itself increased transiently upon initiation of meiosis, before the appearance of the IME2 message but after that of IME1. The impaired increase in NPS1 transcription led to inefficient sporulation. CONCLUSION: The results suggest that Nps1p/RSC is required for the activation of gene expression at the initiation of meiosis.

Cell Cycle Proteins↗

PubMed1999

Involvement of thioredoxin peroxidase type II (Ahp1p) of Saccharomyces cerevisiae in Mn2+ homeostasis.

To identify new proteins involved in Mn2+ homeostasis, we isolated Mn(2+)-resistant mutants of Saccharomyces cerevisiae starting from a calcineurin-deficient, Mn2+ hypersensitive strain (delta cmp1 delta cmp2). The mutations were found to lie in the PMR1 gene, known to encode a "P-type" Ca(2+)-ATPase that transports Ca2+ and Mn2+ from the cytosol to the Golgi apparatus. A second gene, AHP1, was cloned as a suppressor of the Mn2+ tolerance of a delta cmp1 delta cmp2 pmr1 mutant. Ahp1p was recently described as a thioredoxin peroxidase type II, an antioxidant protein with alkyl hydroperoxide defense properties in yeast. AHP1 disruption in strain W303 decreased tolerance to Mn2+ and H2O2. We found that a GFP-Ahp1p fusion construct was in the cytosol when cells were grown in glucose, and in the mitochondria when cells were grown in oleate. Based on Mn2+ transport data, we concluded that Ahp1p is involved in cellular Mn2+ homeostasis in trafficking of Mn2+ from cytosol to mitochondria and from cytosol for export across the plasma membrane.

ATP-Binding Cassette Transporters↗

PubMed1999

Abnormal FHIT transcripts found in both lung cancer and normal lung tissue.

Occurrence of abnormal transcripts of the FHIT (fragile histidine triad) gene has been reported in various types of cancer. On the other hand, aberrant transcripts are sometimes found in non-neoplastic tissues, so the relationship between the presence of abnormal transcripts of the FHIT gene and cancer pathogenesis is controversial. We investigated alterations in the FHIT locus, detected by nested reverse transcription-polymerase chain reaction and/or allelic status, in 88 primary lung cancers and normal lung tissues, and 22 normal lung tissues with metastatic lung cancer as a control. The frequencies of abnormal transcripts were 59% in lung cancer, 35% in paired normal lung, and 64% in normal control lung; the difference in frequencies between lung cancer and paired normal lung was significant, while that between lung cancer and normal control lung was not. Sequence analysis revealed that there were no cancer-specific abnormal transcripts entirely missing two or more exons, nor were the abnormal transcripts of lung cancer identical with those of paired normal lung in the same individual. Furthermore, we found no correlation between loss of heterozygosity in the FHIT locus and occurrence of abnormal FHIT transcripts. These results suggest that the presence of abnormal FHIT transcripts, in terms of their frequency and variety, is not cancer-specific in lung carcinogenesis, and the abnormality may be mainly due to abnormal splicing and processing of the transcripts. To estimate the precise function of the FHIT gene, further study of the FHIT protein in lung carcinogenesis is needed.

Acid Anhydride Hydrolases↗

PubMed1998

A mutation in NPS1/STH1, an essential gene encoding a component of a novel chromatin-remodeling complex RSC, alters the chromatin structure of Saccharomyces cerevisiae centromeres.

The NPS1/STH1 gene encodes a nuclear protein essential for the progression of G2/M phase in Saccharomyces cerevisiae . Nps1p shares homology to Snf2/Swi2p, a subunit of a protein complex known as the SNF/SWI complex. Recently, Nps1p was found to be a component of a protein complex termed RSC (3) essential for mitotic growth, whereas its function is unknown. We isolated a temperature-sensitive mutant allele of NPS1 , nps1-105, and found that the mutation increases the sensitivity to thiabendazole (TBZ). At the restrictive temperature, nps1-105 arrested at the G2/M phase in MAD1-dependent manner and missegregated the mini-chromosome with higher frequency than the wild type cells. The nuclease digestion of the chromatin of the mutant cells revealed that the mutation causes the alteration of the chromatin structure around centromeres at the restrictive temperature. The results suggested that, in the nps1-105 mutant, impaired chromatin structure surrounding centromeres may lead to an impairment of kinetochore function and the cells arrest at G2/M phase through the spindle-assembly checkpoint system.

Cell Cycle Proteins↗

PubMed1998

Role of calcineurin and Mpk1 in regulating the onset of mitosis in budding yeast.

Signalling via calcium is probably involved in regulating eukaryotic cell proliferation, but details of its mechanism of action are unknown. In Schizosaccharomyces pombe, the onset of mitosis is determined by activation of a complex of the p34cdc2 protein kinase and a cyclin protein that is specific to the G2 phase of the cell cycle. This activation requires dephosphorylation of p34cdc2. Weel, a tyrosine kinase that inhibits p34cdc2 by phosphorylating it, is needed to determine the length of G2 phase. Here we show that calcium-activated pathways in Saccharomyces cerevisiae control the onset of mitosis by regulating Swel, a Weel homologue. Zds1 (also known as Oss1 and Hst1) is important in repressing the transcription of SWE1 in G2 phase. In the presence of high calcium levels, cells lacking Zds1 are delayed in entering mitosis. Calcineurin and Mpk1 regulate Swel activation at the transcriptional and posttranslational levels, respectively, and both are required for the calcium-induced delay in G2 phase. These cellular pathways also induce a G2-phase delay in response to hypotonic shock.

Adaptor Proteins, Signal Transducing↗

PubMed1998

Pancreatic metastasis from a lung cancer. Preoperative diagnosis and management.

A case of a surgically resectable solitary metastasis to the pancreas from a lung cancer, confirmed by immunohistochemical staining (PE-10), is reported. ERCP revealed meniscoid interruption of the main pancreatic duct, which is uncommon in patients with primary pancreatic cancers of the pancreas in our hospital. This patient lived for 29 mo after the surgical resection of the pancreatic lesion. Therefore when metastasis limited to the pancreas is evident on clinical imaging, surgical management may be more optimal than other treatment approaches.

Adenocarcinoma↗

PubMed1998

Identification of a 910-kb region of common allelic loss in chromosome bands 16q24.1-q24.2 in human lung cancer.

To understand the molecular pathogenesis of human lung cancer, we analyzed allelic deletions on the long arm of chromosome 16 by PCR amplification of microsatellite markers. A total of 203 lung cancer specimens (78 squamous cell carcinomas and 125 adenocarcinomas) were analyzed. In both cell types, a common region of allelic loss was identified in 16q24.1-q24.2; it is flanked by the two markers D16S534 and D16S422 that spanned at most 910 kb. These results were confirmed by fluorescence in situ hybridization. There was no correlation between allelic loss and histopathologic diagnosis or clinical stage. These results suggest the existence of a tumor-suppressor gene that plays an important role in the course of carcinogenesis in both squamous cell carcinoma and adenocarcinoma of the lungs.

Adult↗

PubMed1998

Chromosome bands 3p14.2, 9p21, and 13q14 are frequently deleted in roentgenographically occult bronchogenic squamous cell carcinoma of the lung.

Roentgenographically occult bronchogenic squamous cell carcinomas are early lung cancers that localize mainly within the bronchial wall and are thought to be a good model for elucidating chromosomal alterations during lung cancer progression. In this study, we analyzed allelic losses on chromosome regions 1p36, 3p14.2, 9p21, 10q25.3-q26.1, 13q14.12-q14.2, and 16q24.1-q24.2, in which there are putative tumor suppressor genes that may play roles in lung carcinogenesis. Forty-five cases with roentgenographically occult bronchogenic squamous cell carcinoma (ROC) and 47 cases of bronchogenic carcinoma with abnormal shadows (roentgenographically nonoccult bronchogenic squamous cell carcinoma [RNOC]) were examined. Highly frequent LOHs in both ROCs and RNOCs were observed in chromosome regions 3p14.2, 9p21, and 13q14.1-q14.2. LOHs were more frequently observed in RNOCs than in ROCs at two loci: 10q25.3-q26.1 and 16q24.1-q24.2. These results suggested that (1) putative tumor suppressor genes exist on 3p14.2, 9p21, 10q25.3-q26.1, 13q14.12-q14.2, and 16q24.1-q24.2, which may play important roles in lung carcinogenesis; (2) mutations in genes at 3p14.2, 9p21, and 13q14.12-q14.2 represent rather early events in lung carcinogenesis; and (3) mutations in genes on 10q25.3-q26.1 and 16q24.1-q24.2 represent rather late events.

Aged↗

PubMed1997

Abnormal FHIT transcripts in human breast carcinomas: a clinicopathological and epidemiological analysis of 61 Japanese cases.

Deletions in the short arm of chromosome 3 have been found in various human cancers, including breast cancer. Recently, the FHIT (fragile histidine triad) gene was identified at 3p14.2 as a candidate tumor suppressor gene. We examined the abnormal transcripts of the FHIT gene in 61 Japanese primary breast cancer specimens and found that 23 (38%) of them exhibited abnormalities, about half of which were categorized into two types of aberrant transcripts. Sequence analysis of these aberrant transcripts revealed the absence of exons 5-7 (type I) and exons 5-8 (type II). Clinicopathological and epidemiological analysis of patients showed that the abnormal FHIT transcripts were not associated with age, tumor-node-metastasis classification, tumor size, estrogen receptor and progesterone receptor status, local metastasis, family history of breast cancer, or lifestyle factors of patients, including cigarette smoking and alcohol consumption. On the other hand, we found that the abnormal transcripts of type I and type II were associated with the incidence of bilateral breast cancer and that decreased frequency of childbirth was also associated with FHIT abnormalities.

Adult↗

PubMed1997

Yeast Crv4/Ttp1, a predicted type II membrane protein, is involved in an event important for growth, functionally overlapping with the event regulated by calcineurin- and Mpk1-mediated pathways.

The Saccharomyces cerevisiae crv mutants (crv1, 2, 3 and 4) exhibit phenotypes, such as calcium resistance and vanadate sensitivity, which are apparently similar to those of calcineurin-deficient mutants. We have cloned and characterized the CRV4 gene that complements all the phenotypes of the crv4 mutant. DNA sequencing revealed that CRV4 is identical to the previously cloned gene TTP1, which encodes a type II membrane protein of unknown function. Deletion of CRV4/TTP1 causes no obvious phenotype except for Ca2+ resistance and vanadate sensitivity, but is synthetically lethal in combination with a deletion of MPK1, in a manner which is suppressible by the addition of an osmotic stabilizer. In medium containing sorbitol as an osmotic stabilizer, the enb1 mpk1 ttp1 triple mutant exhibits a more severe growth defect than does any of the double mutants enb1 ttp1, enb1 mpk1 or mpk1 ttp1. A high Ca2+ concentration (50 mM) or a constitutively active form of calcineurin partially suppresses the growth defect of the mpk1 ttp1 double mutant. These results indicate that Ttp1 participates in a cellular event essential for growth and morphogenesis, in parallel with the pathways involving Mpk1 MAP kinase and calcineurin.

Calcineurin↗

PubMed1997

A follow-up study of progression from dysplasia to squamous cell carcinoma with immunohistochemical examination of p53 protein overexpression in the bronchi of ex-chromate workers.

Squamous cell carcinoma (SCC) of the bronchus is considered to develop from preneoplastic 'dysplasia', but reports of sequential observation of this dysplasia-carcinoma sequence in humans are very few. We followed four dysplastic lesions found in the bronchi of three ex-chromate workers by bronchoscopy and biopsy and found that all of them progressed to SCC. Of the four lesions, three were severe dysplasias at the first biopsy which progressed to SCCs in 7-13 months. The last one was a slight dysplasia at the first biopsy and showed progression of the atypia to carcinoma in 6 years and 10 months. An immunohistochemical analysis of the chronological change in p53 protein expression in these lesions and in normal ciliated epithelium taken from the surroundings was conducted in each case. Overexpression of p53 protein was observed in two of the severe dysplasias and the one slight dysplasia, as well as their eventual SCCs. However, no such change was apparent in one case of severe dysplasia or its eventual SCC. Normal epithelium was consistently negative. Our results provide direct proof of the dysplasia-carcinoma sequence and suggest that alteration in the expression of p53 protein might be an important early event which persists. Therefore, the immunohistochemical detection of p53 overexpression in biopsy specimens of bronchial epithelium might be useful for evaluation of preneoplastic lesions in high-risk group individuals and for early diagnosis of bronchial cancer.

Aged↗

PubMed1996

The involvement of the Saccharomyces cerevisiae multidrug resistance transporters Pdr5p and Snq2p in cation resistance.

The ATP-binding cassette superfamily proteins Pdr5p and Snq2p of Saccharomyces cerevisiae are implicated in multidrug resistance. Here, we show that these transporters are also involved in cation resistance. Null mutants of PDR5 and SNQ2 genes exhibit increased sensitivity to NaCl, LiCl and MnCl2. The mutant cells grown in the presence of high concentrations of these metal salts contain higher levels of the metals than wild-type cells. The expression of PDR5 and SNQ2 is induced by the metal salts. These results provide evidence that the yeast drug transporters contribute to cation resistance by regulating cellular cation homeostasis under ionic stress conditions.

ATP-Binding Cassette Transporters↗

PubMed1996

The Saccharomyces cerevisiae SSD1 gene is involved in the tolerance to high concentration of Ca2+ with the participation of HST1/NRC1/BFR1.

The SSD1 gene of Saccharomyces (S.) cerevisiae is a polymorphic gene involved in many aspects of the yeast cell growth (Sutton et al., 1991). We found that ssd1 null mutant shows increased sensitivities of growth to trifluoperazine (TFP) and high concentration of Ca2+. A high-copy suppressor gene, HST1, for the TFP and Ca2+ sensitivities of ssd1 null mutant was cloned and sequenced. The HST1 gene encodes a polypeptide of 915 amino acids, and is identical to the NRC1/BRF1 gene in databases. The HST1 disrupted cells were viable, but they grew slowly in the presence of high levels of Ca2+, with notable morphological change. In addition, disruption of the gene in a ssd1 null mutant further increased the sensitivities of the cells to TFP and Ca2+. The results indicated the possibility that the SSD1 gene is involved in the tolerance mechanism to high concentration of Ca2+, and the HST1 gene participates with SSD1 by its functional redundancy in Ca2+ tolerance.

Alleles↗

PubMed1996

The multidrug resistance-associated protein (MRP) subfamily (Yrs1/Yor1) of Saccharomyces cerevisiae is important for the tolerance to a broad range of organic anions.

We have cloned and characterized a Saccharomyces cerevisiae gene YRS1 that complements the phenotype of the mutant sensitive to the anionic drug reveromycin A. The YRS1 gene, which is identical to the recently identified YOR1 gene, encodes a protein with extensive homology to the human multidrug resistance-associated protein (MRP) and the yeast cadmium factor (Ycf1). A chromosomal deletion of YRS1 lead to viable Deltayrs1 cells, which exhibited hypersensitivity to reveromycin A. Elevation of the YRS1 gene dosage in wild type cells conferred increased resistance to reveromycin A. By analyzing the effect of YRS1 disruption and overexpression it was demonstrated that Yrs1 is involved in the detoxification of a wide range of the organic anions that contain carboxyl group(s) but none of the other type of toxic compounds examined. Fluorescence-activated cell sorter analysis indicated the increased accumulation of the anionic fluorescent compound rhodamine B in Deltayrs1 cells. The expression of YRS1 was induced strikingly by reveromycin A. These results suggest that Yrs1 is a multispecific organic anion transporter important for tolerance against toxic environmental organic anions. Yrs1 had an overlapping specificity with Ycf1 in the resistance to cadmium.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1996

Genetic evidence for the functional redundancy of the calcineurin- and Mpk1-mediated pathways in the regulation of cellular events important for growth in Saccharomyces cerevisiae.

Saccharomyces cerevisiae mutants which exhibit phenotypes (calcium resistance and vanadate sensitivity) similar to those of calcineurin-deficient mutants were isolated. The mutants were classified into four complementation groups (crv1,2,3 and 4). Crv1 was allelic to cnb1, a mutation in the regulatory subunit of calcineurin. The nucleotide sequences of CRV2 and CRV3 genes which complemented the crv2 and crv3 mutations, respectively, are identical to those of BCK1/SLK1/SKC1/SSP31 and MPK1/SLT2, respectively, which are both involved in the MAP kinase cascade. A calcineurin-deletion mutation (delta cnb1), which by itself has no detectable effect on growth and morphology, enhanced some phenotypes (slow growth and morphological abnormality) of crv2 and crv3 mutants. These phenotypes of crv2 and crv3 mutants were partially suppressed by Ca2+ or by overproduction of the calcineurin subunits (Cmp2 and Cnb1). Like the calcineurin-deficient mutant, crv2 and crv3 mutants were defective in recovery from alpha-factor-induced growth arrest. The defect in recovery of the delta cnb1 mutant was suppressed by overexpression of MPK1. These results indicated that the calcineurin-mediated and the Mpk1- (Bck1-) mediated signaling pathways act in parallel to regulate functionally redundant cellular events important for growth.

Calcineurin↗

PubMed1996

[Early cancer--the concept, and its relationship with carcinoma in situ, superficial carcinoma and micro-carcinoma].

The concept, "early cancer", is a carcinoma at the stage which can be cured by treatment. This idea was first proposed in the field of stomach cancer in 1962. After that, the concept was gradually accepted for cancers of other organs. Carcinoma in situ (or non-invasive carcinoma) is the name for a carcinoma whose invasion is not yet beyond the basement membrane. Superficial carcinoma is a carcinoma whose invasion is limited to mucosa or submucosa with or without lymph node metastasis. The name micro-carcinoma is generally used for a cancer visible only through a microscope or an incidental cancer or a latent cancer. All carcinomas in situ and most superficial carcinomas and micro-carcinomas are included in the term "early cancer".

Carcinoma in Situ↗

PubMed1995

Protein phosphatase 2B of Saccharomyces cerevisiae is required for tolerance to manganese, in blocking the entry of ions into the cells.

The role of protein phosphatase 2B (PP2B/calcineurin) of Saccharomyces cerevisiae in the tolerance to divalent cations was investigated. PP2B-deficient mutants were found to be sensitive to MnCl2, but not to ZnCl2, CuCl2, NiCl2 and CoCl2. By measuring both manganese uptake and its efflux, it was found that the sensitivity of the mutant cells was due to an increase in manganese uptake and that the wild-type cells were able to prevent manganese entry into the cells, rather than export it in a more efficient manner. In the presence of the immunosuppressant FK506, the behavior of wild-type cells became similar to that of PP2B mutants. Out of various divalent cations tested, externally added magnesium ions were able to block manganese uptake in both wild-type and PP2B mutant strains.

Biological Transport↗