Biomedical subjects

Y Miyoshi

Publications and source records attributed to Y Miyoshi.

At least 91 records · Page 5Linked to original sources

PubMed1999

Frequent beta-catenin abnormalities in bone and soft-tissue tumors.

We have screened mutations of the beta-catenin gene by using the polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) method in 62 malignant bone and soft-tissue tumors, including malignant fibrous histiocytomas (MFHs), osteosarcomas, synovial sarcomas, liposarcomas, malignant schwannomas, and other types of tumors, as well as 11 benign tumors. beta-Catenin-activating missense mutations were found in two malignant tumors. One found in MFH occurred at codon 45 and caused an amino acid substitution from serine (one of the GSK3 beta-targeted phosphorylation sites) to phenylalanine. The other, detected in synovial sarcoma at codon 32, resulted in an amino acid change from aspartic acid (located adjacent to the phosphorylation target, serine, encoded by codon 33) to tyrosine. Furthermore, we found accumulation of beta-catenin by western-blotting analysis in 12 of 19 malignant tumors in which we found no mutation involving exon 3. Our results suggested the possible involvement of beta-catenin activation, by beta-catenin gene mutation or alteration of other factor(s), in the formation and/or progression of various types of bone and soft-tissue tumors.

Bone Neoplasms↗

PubMed1999

Enhancement of the anti-tumor effect of 5'-deoxy-5-fluorouridine by transfection of thymidine phosphorylase gene into human colon cancer cells.

Thymidine phosphorylase (dThdPase) is an enzyme that converts 5'-deoxy-5-fluorouridine (5'DFUR) to the toxic substance 5-fluorouracil (5-FU); it is also known to be a platelet-derived endothelial cell growth factor. In order to investigate the feasibility of suicide gene therapy against colorectal cancer by means of the combination of 5'DFUR and the converting enzyme dThdPase, we transfected the dThdPase gene into the human colon cancer cell line SW480 and analyzed the growth pattern as well as the sensitivity to 5-FU or 5'DFUR of the dThdPase-transfected cells. The 50% inhibition (IC50) values of 5-FU against the SW480 parental cells, control vector-transfected cells SW480/V1, and dThdPase-transfected cells SW480/dThdPase were approximately 4.9, 6.3, and 2.9 microM, respectively. The IC50 of SW480/dThdPase was lower than that of SW480 or SW480/V1, although the differences were not statistically significant. The IC50 values of 5'DFUR for SW480, SW480/V1, and SW480/dThdPase were approximately 300, 330, and 3.2 microM, respectively. The sensitivity to 5'DFUR of SW480/dThdPase was increased by about 100-fold compared with that of SW480 or SW480/V1. With only 10% transfection efficacy, a high enough sensitivity to 5'DFUR was obtained to suppress the cell growth, indicating that a strong bystander effect was induced by this system. The in vivo growth of the s.c. transplanted SW480/dThdPase tumor in nude mice was significantly suppressed by i.p. injection of 5'DFUR compared with that in control mice that received phosphate-buffered saline (PBS) treatment. These results suggest that gene therapy using the combination of 5'DFUR and the dThdPase gene may be a useful approach for treatment of colon cancer.

Animals↗

PubMed1999

Induction of apoptosis in T98G glioblastoma cells by transfection of GML, a p53 target gene.

Expression of the glycosyl-phosphatidylinositol-anchored molecule-like protein (GML) gene, a p53 target, correlates with the sensitivity of some cancer cell lines to anticancer drugs and ionizing radiation. To investigate the function of GML further, we introduced the GML cDNA into various cancer cell lines under control of the tetracycline-regulated system. When we introduced GML into human glioblastoma cell line T98G, which lacks wild-type p53 and expresses no endogenous GML, we observed significant growth suppression accompanied by G2/M arrest in two independent, stable cell lines. We confirmed induction of apoptosis by fluorescence-activated cell sorting (FACS) analysis and nuclear staining. Our results indicated that GML could induce apoptosis of T98G without functional p53, and implied that GML plays a crucial role in the apoptotic pathway in some cancer cells.

Apoptosis↗

PubMed1999

[A case of ectopic pituitary adenoma localized in the sphenoid sinus].

Intrasphenoidal pituitary adenoma is relatively rare. Only 13 cases have been reported in the literature. We present a case of intrasphenoidal pituitary adenoma in a 74-year-old man. He had no endocrinological abnormalities. Skull tomograms revealed sellar floor erosion but showed no enlargement of the pituitary fossa. Computed tomographic (CT) scan revealed an isodense mass showing no contrast enhancement in the sphenoid sinus. The intrasphenoidal tumor appeared slightly hypointense compared with normal brain on T1-weighted image, and showed less contrast enhancement after intravenous injection of Gd-DTPA on magnetic resonance imaging (MRI). Transsphenoidal pituitary microsurgery was performed, and all of the intrasphenoidal tumor was removed with the mucosa. The sellar floor was thin and easily breakable in parts. After removal of the sellar floor the dura was opened, but no evidence of a pituitary tumor was shown. No connection between the pituitary gland and the sphenoidal tissue was found. Microscopic examination of sections showed tumor cell nests in the sphenoidal mucosa. We think this ectopic pituitary adenoma occurred through the migration of Rathke's pouch in the sphenoid sinus.

Adenoma↗

PubMed1999

[A case of cervical myelopathy due to dural arteriovenous fistula at the craniocervical junction].

A 70-year-old woman noted paresthesia ascending from both legs to her thighs 27 months previously. She also suffered from urinary urgency and incontinence. Thereafter, weakness in both legs developed and gradually became worse. At the time of admission, a neurological examination revealed diffuse atrophy and mild spasticity in all four extremities, bilateral mild weakness in both upper extremities, and severe weakness in both lower extremities. Her superficial sensation was moderately impaired below the Th 3 level on her right side, and below the Th 4 level on her left side along with a mildly decreased sense of vibration in her left leg. Marked hyperreflexia in all four extremities and bilateral pathological reflexes were also observed. Pollakisurea, urinary incontinence and constipation were also present. Cervical MRI showed a swelling of the spinal cord at the C3 to C7 levels. Inside the spinal cord, low signal intensity lesions were seen on the T1-weighted MRI, and high signal intensity lesions were observed on the T2-weighted MRI, and the rim of the cervical cord was also enhanced by gadolinium-DTPA. MR angiography revealed enlarged and tortuous vessels at the craniocervical junction, thus suggesting the presence of a dural arteriovenous fistula (AVF). Vertebral arteriography demonstrated abnormal vessels at the spinomedullary junction supplied by the right vertebral artery, which drained into the anterior and posterior spinal veins. After surgically treating the dural AVF, the swelling of the spinal cord, the abnormal signals on MRI, and the clinical symptoms all markedly improved. Although most of the spinal dural AVF were located at the thoracic and lumbar levels, the present case was considered to be a very rare case of dural AVF, since it was located at the craniocervical junction and thus led to the development of cervical myelopathy.

Aged↗

PubMed1999

[Detection of numerical aberrations in chromosomes by fluorescence in situ hybridization in fine needle aspirates in the preoperative diagnosis of cancer].

Fine needle aspiration (FNA) samples were obtained from 176 breast tumors suspected of malignancy, which were then subjected to conventional cytological and fluorescence in situ hybridization (FISH) analyses using the centromeric probes for chromosomes 1, 11, and 17. Histological examination revealed 157 breast cancers and 19 benign diseases (ten fibroadenomas, six intraductal papillomas, one intracystic papilloma, and two ADH). Sensitivity, specificity, and diagnostic accuracy were 85.4% 94.7%, and 86.4%, respectively, for cytology and 90.4%, 100%, and 91.5%, respectively, for FISH. These results demonstrate that FISH diagnosis of FNA samples has a diagnostic accuracy comparable to that of conventional cytology.

Biopsy, Needle↗

PubMed1999

[A case of cerebellar degeneration showing amaurosis fugax due to primary angle-closure glaucoma].

We reported a 76-year-old woman with cerebellar degeneration who had transient monocular visual loss following the acute attacks of angle-closure glaucoma. The episodes occurred only at night approximately every ten days. She denied pain or any other associated symptoms. Ophthalmological examinations including intraorbital pressure, ocular fundus, visual acuity and visual field showed no abnormalities between the attacks. Provisional diagnosis on admission was amaurosis fugax from retinal embolization. After admission, she developed a typical acute attack of glaucoma accompanied by severe pain in her left eye. Intraorbital pressures were 12 mmHg in the right eye and 58 mmHg in the left, and the diagnosis of primary angle-closure glaucoma was made gonioscopically. Following peripheral iridotomy by laser therapy, her visual acuity recovered and episodes of visual loss disappeared. In this case, the attacks of glaucoma were unusually painless, so it is very difficult to distinguish between glaucoma and amqurosis fugax from retinal embolization. The transient visual loss always occurred at night, and retrospectively, this characteristic feature might indicate that these episodes were acute attacks of angle-closure glaucoma. Glaucoma is one of the diseases that can cause painless amaurosis fugax.

Aged↗

PubMed1998

Identification of a brain-specific APC homologue, APCL, and its interaction with beta-catenin.

We isolated a novel gene, APCL, that showed significant homology to the adenomatous polyposis coli (APC) tumor suppressor gene. This novel gene, located on chromosome 19p13.3, encodes a protein of 2303 amino acids that is expressed specifically in the brain. The predicted protein of APCL contains five copies of a 20-amino-acid motif (FXVEXTPXCFSRXSSLSSLS). Like APC, this domain of APCL was able to bind to beta-catenin and deplete the intracellular beta-catenin pool. A reporter-gene assay revealed that APCL could also regulate interaction of beta-catenin with T cell-specific transcription factor, although less actively than APC. These results suggest that the APCL protein may be involved in the Wnt/Wingless signal pathway, and the identification of a novel relative of APC may provide new insights into the function of APC.

Amino Acid Sequence↗

PubMed1998

Isolation and characterization of a novel human lung-specific gene homologous to lysosomal membrane glycoproteins 1 and 2: significantly increased expression in cancers of various tissues.

We have isolated and characterized a novel human lung-specific gene and observed its increased expression in cancers arising from various tissues. The cDNA, designated TSC403, contained an open reading frame of 1248 nucleotides encoding 416 amino acids; the deduced amino acid sequence showed significant similarities to lysosomal membrane glycoproteins (lamps) 1 and 2. We localized the gene to chromosomal band 3q27, a genomic region that is often amplified in human cancers of several tissue types. We detected a high level of the TSC403 transcript in primary cancers of the esophagus, colon, fallopian tube, ovary, breast, and liver, although expression of this gene was barely detectable in corresponding normal tissues. These findings indicated that up-regulation of the TSC403 transcript may be related to the development and/or progression of cancer in humans.

Amino Acid Sequence↗

PubMed1998

Activation of the beta-catenin gene in primary hepatocellular carcinomas by somatic alterations involving exon 3.

We screened 75 primary hepatocellular carcinomas for somatic mutations in the entire coding region of the beta-catenin gene. We detected somatic mutations in 14 tumors; 12 were considered to cause amino acid substitutions and 2 were interstitial deletions of 51 or 195 nucleotides of genomic DNA, corresponding to exon 3. Among the 12 point mutations, 6 occurred at potential serine/threonine phosphorylation residues of codons 33, 41, or 45. The remaining six tumors contained a mutation at codon 32 (aspartic acid) or 34 (glycine), flanking to the serine residue at codon 33. By Western blot analysis, we confirmed accumulation of beta-catenin in five tumors for which frozen tissues were available; the five included tumors in which amino acid alterations had occurred at codons 32, 34, or 45, and one with a 17-amino acid deletion. Our results suggested that accumulation of beta-catenin due to amino acid substitutions at potential serine/threonine phosphorylation residues or at their neighboring codons or interstitial deletions involving exon 3 could contribute to hepatocellular carcinogenesis.

Carcinoma, Hepatocellular↗

PubMed1998

Identification of a novel gene marker specific for epithelial cells by utilizing a 3'-directed cDNA library.

To achieve reliability of molecular diagnosis using reverse transcription-PCR (RT-PCR), we established a unique method to search for a novel gene marker specific for colonic epithelial cells. Of eight candidate genes selected from a 3'-directed cDNA library in colonic mucosa, two genes were expressed in normal mucosa and cancer of the colon but not in either normal lymph node or normal liver tissue. Known sequences of these genes were reported to be located in the 3' noncoding region, and an additional sequence just upstream to gs04094 (one of the candidate genes) was determined. According to the newly identified sequence, we designed a new set of primers so that we could distinguish the DNA fragment amplified in RT-PCR from that in genomic PCR. RT-PCR using these primers demonstrated that gs04094 was expressed in all of 10 primary colon cancers and 4 liver metastases from colon cancer but in none of 5 normal lymph nodes, 10 peripheral blood samples, and 2 normal liver tissues. Sensitivity of this method was so high as to detect gs04094 mRNA in 10(-6) microg of colon cancer RNA per 1 microg of normal lymph node RNA. Thus, our strategy to search for a novel gene marker using 3'-directed cDNA library proved to be highly efficient.

Animals↗

PubMed1998

Topographical distribution of [125I]-glial cell line-derived neurotrophic factor in unlesioned and MPTP-lesioned rhesus monkey brain following a bolus intraventricular injection.

The present study determined the topographical distribution profile for [125I]-glial cell line-derived neurotrophic factor in unlesioned and MPTP-lesioned (unilateral intracarotid injection) rhesus monkeys following an intraventricular injection. Autoradiographic analysis showed that following a bolus intraventricular injection, there was widespread distribution of [125I]-glial cell line-derived neurotrophic factor throughout the ventricular system (walls of lateral, third, and fourth ventricles and aqueduct), with some accumulation at the lateral ventricle injection site, possibly associated with the ependymal cell layer. In both unlesioned and MPTP-lesioned monkeys, there was labelling of the cerebral cortex, substantia nigra/ventral tegmental area and sequestration of [125I]-glial cell line-derived neurotrophic factor adjacent to the hippocampal formation, globus pallidus, ventral to and in the substantia nigra. However, [125I]-glial cell line-derived neurotrophic factor did not appear to diffuse readily or accumulate in the caudate-putamen even though there was some penetration away from the ventricular walls. Throughout the brain, there was also substantial non-parenchymal labelling of [125I]-glial cell line-derived neurotrophic factor, possibly associated with extracellular matrix components, meninges and vasculature due to the heparin binding properties of glial cell line-derived neurotrophic factor. In addition to the extensive loss of tyrosine hydroxylase immunoreactivity within the substantia nigra, there was also decreased accumulation of [125I]-glial cell line-derived neurotrophic factor and reduced glial cell line-derived neurotrophic factor immunoreactivity ipsilateral to the lesion. Microscopic analysis showed that glial cell line-derived neurotrophic factor immunoreactivity was associated with upper cortical layers including a high density of immunoreactivity at the surface of the cortex (meningeal, pial layer, vasculature) and around the ventricular walls (with some cellular labelling and labelling of vasculature). Moderate staining was observed in nigral cells contralateral to the MPTP-lesion, whereas only minimal levels of that glial cell line-derived neurotrophic factor immunoreactivity were detected ipsilateral to the lesion. This study shows that intraventricularly injected glial cell line-derived neurotrophic factor accumulates not only around the ventricular walls, but also in specific brain regions in which sub-populations of cells are more readily accessible than others. The presence of cells labelled with [125I] and immunopositive for glial cell line-derived neurotrophic factor in the substantia nigra indicates that these cells are a target for the trophic factor following intraventricular administration. Thus, the behavioral improvement observed in MPTP-lesioned monkeys following an intraventricular injection of glial cell line-derived neurotrophic factor is likely the result of activation of nigral cells.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗

PubMed1998

Activation of the beta-catenin gene by interstitial deletions involving exon 3 in primary colorectal carcinomas without adenomatous polyposis coli mutations.

Among 222 primary colorectal cancers we examined, 58 showed no detectable APC mutations by the protein truncation test. We screened those 58 tumors for somatic mutations in the beta-catenin gene. Although amino acid substitutions in serine or threonine residues in exon 3 had been reported, we found no such mutations; however, in seven tumors, we detected somatic interstitial deletions of 234-760 bp, each of which included all or part of exon 3. Short nucleotide sequences at both ends of each deletion were either identical or complementary, indicating that repeated or inversely repeated sequences were involved in the somatic rearrangements. Reverse transcription-PCR experiments using RNAs isolated from three of these seven tumors detected transcripts that lacked exon 3, in addition to the normal transcript. In one of these cases, we confirmed accumulation of aberrant beta-catenin protein in cytoplasm and nuclei of cancer cells by Western and immunohistochemical analyses. This result suggested that, in the absence of a peptide encoded by exon 3, beta-catenin is stabilized and has a dominant oncogenic effect on colorectal tumorigenesis.

Carcinoma↗

PubMed1998

Allelic imbalance of insulin-like growth factor II gene expression in cancerous and precancerous lesions of the liver.

Allelic imbalance of the insulin-like growth factor II (IGF II) gene expression is often seen in hepatocellular carcinoma (HCC). To investigate the role of allelic imbalance in hepatocarcinogenesis, we have studied allelic expression status of the IGF II gene in dysplastic nodules, which are precancerous lesions of HCC, as well as in HCCs of different histological grade, and the influence of the allelic imbalance on IGF II gene expression has also been examined. Allelic imbalance was observed in 3 of 7 dysplastic nodules, in 7 of 9 well-differentiated HCCs, and in 8 of 9 moderately differentiated HCCs. IGF II gene expression level, which was studied by a semiquantitative reverse-transcriptase polymerase chain reaction (RT-PCR), was significantly higher (3.6-fold) in the dysplastic nodules than the control livers, but a significant increase in the IGF II gene expression was not observed in well- and moderately differentiated HCCs as compared with the control livers. These results demonstrate that the allelic imbalance of the IGF II gene expression is seen in the early stage (precancerous lesions) of hepatocarcinogenesis. Association of the allelic imbalance with an increased expression of the IGF II gene in the precancerous lesions might suggest a possible involvement of an IGF II autocrine loop in the pathogenesis of these lesions.

Alleles↗

PubMed1998

Localization of the gene responsible for Peutz-Jeghers syndrome within a 6-cM region of chromosome 19p13.3.

Patients with Peutz-Jeghers syndrome (PJS), an autosomal dominant disease characterized by hamartomatous polyposis of the gastrointestinal tract, are thought to be predisposed to malignancies of the digestive tract, genital tract, and other organs. Using microsatellite markers on chromosome 19p, we have closely defined the region containing the gene responsible for this disorder through linkage analysis in seven affected families. The lack of obligate recombinants at two of these loci, D19S883 and D19S878, with maximum LOD scores of 2.88 and 3.75, confirmed the localization of the PJS locus to chromosome 19. Furthermore, haplotype analysis placed the PJS locus within a 6-cM telomeric region of chromosome 19p, between D19S886 and D19S565.

Centromere↗

PubMed1998

Nine novel germline mutations of STK11 in ten families with Peutz-Jeghers syndrome.

Peutz-Jeghers Syndrome (PJS) is an autosomal dominant hereditary disease characterized by hamartomatous polyposis involving the entire bowel. Recently STK11, a gene bearing a mutation responsible for PJS, was isolated. We investigated the entire coding region of STK11 in 15 unrelated PJS families by the PCR-SSCP (polymerase chain reaction-single strand conformation polymorphism) method and PCR-direct sequence analysis, and found nine different, novel mutations among ten of those families. One nonsense mutation and five different frameshift mutations (two families carried the same mutation), all of which would cause truncation of the gene product, were found in seven families; mutations found in five families were clustered within exon 6. Among these five mutations, three occurred at the mononucleotide-repeat region (CCCCCC) of codons 279-281, suggesting that this region is likely to be a mutational hotspot of this gene. One of the remaining three families carried a 3-bp in-frame deletion that would eliminate an asparagine residue within a kinase domain of the product; the other two carried intronic mutations at or adjacent to the consensus dinucleotide sequences of splice-acceptor or -donor sites, which were likely to lead to aberrant splicing.

AMP-Activated Protein Kinase Kinases↗

PubMed1998

Identification of brain-specific splicing variants of the hDLG1 gene and altered splicing in neuroblastoma cell lines.

The human homologue of Drosophila tumor suppressor dlg, hDLG1, is one of the proteins known to interact with APC, a tumor suppressor for colorectal cancer. Alternative splicing of this gene generates transcripts either with [insertion 1 (I1)] or without 99 nucleotides in the 5' part of the dlg homology repeats (DHR) domain. We found almost equivalent expression of these two splicing variants in most human tissues; however, in skeletal muscle the transcript with the 99-bp insertion was predominant, and in the brain, that without the 99-bp insertion was expressed predominantly. We also examined alternative splicing in the region between the SH3 and GUK domains where two different sizes of insertions, 34 nucleotides (I2) or 100 nucleotides (I3), had been reported, and found various splicing patterns among the tissues examined. In brain we detected six different, alternatively spliced transcripts, two of which included a novel, 36-bp, brain-specific exon encoding a peptide bearing significant homology to a portion of rat synapse-associated protein, SAP97/PSD95. Subsequently, we investigated the splicing patterns of the hDLG1 gene in 24 neuroblastoma cell lines. In two-thirds of these lines, the splicing patterns were altered from those observed in normal brain tissue. As one-third retained the normal brain-splicing pattern, the loss of normal splicing of hDLG1 may not in itself cause formation of tumors, but it might reflect the biological character of individual neuroblastomas.

Adaptor Proteins, Signal Transducing↗

PubMed1998

Novel germline mutations of hMSH2 in a patient with hereditary nonpolyposis colorectal cancer (HNPCC) and in a patient with six primary cancers.

We screened for germline mutations of mismatch repair genes, hMLH1 and hMSH2, in five Japanese families carrying hereditary nonpolyposis colorectal cancer (HNPCC) and in a patient with multiple primary cancers. Screening the entire coding regions of both genes using polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis, we found two novel germline mutations in hMSH2. One was a 1-bp insertion in exon 12, detected in a patient who had undergone surgery six times for independent tumors (four primary colorectal carcinomas, a small intestinal carcinoma, and an endometrial cancer). The other, in a second patient, was a missense mutation from CTT to TTT at codon 390 in exon 7 that resulted in substitution of phenylalanine for leucine. This conservative alteration was not found in any of 50 normal controls, but we cannot exclude the possibility that it may represent a rare polymorphism rather than a factor in the disease.

Adult↗