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Biomedical subjects

M Emi

Publications and source records attributed to M Emi.

At least 181 records · Page 10Linked to original sources
PubMed1995

Association of genetic alterations on chromosome 17 and loss of hormone receptors in breast cancer.

To investigate possible relationships between genetic alterations and hormonal deregulation during breast cancer development and/or progression, we examined 616 primary breast cancers for loss of heterozygosity (LOH) at chromosomal regions 16q24, 17p13.3 and 17q21, and for amplifications of the ERBB2 and c-MYC loci. A comparison of oestrogen receptor (ER) and progesterone receptor (PgR) status in tumour cells with data concerning these genetic alterations revealed that LOH at 17q21 was significantly correlated with absence of oestrogen receptors (ER) (P < 0.0003) or progesterone receptors (PgR) (P < 0.0001), and with the absence of both (P < 0.0001). Similarly, a significant association was observed between amplification of ERBB2 and the absence of either ER or PgR. LOH at 17p13.3 was associated with the absence of PgR (P < 0.01). These data suggest a possible relationship between specific genetic changes on chromosome 17 and hormonal deregulation in the progression of breast cancer.

Breast Neoplasms↗
PubMed1995

Mutation analysis of the BRCA1 gene in 76 Japanese ovarian cancer patients: four germline mutations, but no evidence of somatic mutation.

To investigate the putative role of BRCA1, a gene involved in hereditary breast and ovarian cancer, in sporadic ovarian tumors among Japanese women, we examined 76 unselected primary ovarian cancers for mutations in the coding region of BRCA1 using the single-strand conformation polymorphism technique. Although no somatic mutations were detected in any of the tumors, constitutional mutations were identified in four cases: two frameshifts, one nonsense mutation and one intronic base substitution 32 bp downstream of exon 22; RT-PCR experiments revealed that the single-base substitution in the intron seemed to increase the transcript lacking exon 22. All four cases were judged to involve truncation of the gene product. The evidence reported here supports a rather limited role of BRCA1 in ovarian carcinogenesis in the Japanese population.

BRCA1 Protein↗
PubMed1995

Human metalloprotease/disintegrin-like (MDC) gene: exon-intron organization and alternative splicing.

A recently identified gene encoding a metalloprotease-like, disintegrin-like, cysteine-rich protein (MDC) represents a candidate tumor suppressor gene for human breast cancer based on its location within a minimal region of chromosome 17q21 previously defined by tumor deletion mapping. The work reported here has shown that the MDC gene consists of 28 exons interrupted by relatively short introns, most of them 67 bp to 5 kb in length. We have identified two forms of transcripts generated by alternative splicing. The more abundant form encodes a protein of 769 amino acids; the other, a previously described cDNA, encodes 524 amino acids. Exons 1a, 1b, 1c, 1d, and 2-7 encode a proprotein domain; exons 7-13, a metalloprotease-like domain; exons 14-17, a disintegrin domain; exons 18-22, a cysteine-rich domain, including an epidermal growth factor (EGF)-like repeat domain within exons 21 and 22; exon 23, a transmembrane domain; and exons 24 and 25, a short cytoplasmic domain. These results show that human MDC contains a mosaic of exons capable of encoding several functional domains.

ADAM Proteins↗
PubMed1994

Genetic studies of 457 breast cancers. Clinicopathologic parameters compared with genetic alterations.

BACKGROUND: Human breast cancers frequently show loss of heterozygosity (LOH) and/or amplification at specific chromosomal regions. METHODS: To investigate the roles of these genetic alterations during tumor development and/or progression, 457 cases of primary breast cancer were examined for LOH at chromosomal regions 16q24, 17p13.3, and 17q21, and for amplification of the erb-B2 locus at 17q11.2 and the c-myc locus at 8q24. The genetic changes then were compared with lymph node metastasis, histologic type, and tumor stage. RESULTS: The LOH at 17q21 was observed more frequently in tumors of the solid, tubular type (41 of 75 [55%]) than in other types (48 of 187 [26%]) (P < 0.0001). The LOH at 17p13.3 was more frequent in scirrhous and solid, tubular tumors (77 of 141 [55%] and 48 of 88 [55%]) than in other types (29 of 89 [33%]) (P = 0.0004). Generally, mutations were seen more often in tumors with axillary lymph node metastases, undifferentiated tumors, and large or invasive tumors than in tumors considered less aggressive histopathologically. However, 22 tumors bearing three or more genetic alterations were found among 187 tumors histologically diagnosed as free of axillary lymph node metastasis; similarly, 12 of 122 t1 classification tumors and 4 of 89 histologically well differentiated tumors each contained three or more genetic alterations. Although these tumors would be regarded as having a relatively good prognosis on the basis of conventional clinicopathologic diagnosis, the authors suspect that, in fact, they do not. CONCLUSIONS: Patients whose tumors contain multiple genetic alterations should be treated as a new high risk group with respect to operative and/or postoperative management.

Blotting, Southern↗
PubMed1994

Suppression of metastasis of rat prostatic cancer by introducing human chromosome 8.

In previous allelotype analyses of human prostatic cancer specimens, allelic loss on the short arm of chromosome 8 is frequently observed. However, it is still unclear whether this allelic loss is an initial event or a later one in development of prostatic cancer. Our previous studies demonstrate that introduction of human chromosome 11 into highly metastatic rat prostatic cancer cells results in suppression of metastatic ability without suppression of the in vivo growth rate or tumorigenicity of the hybrid cells (T. Ichikawa et al. Cancer Res., 52: 3486-3490, 1992). To clarify the role of human chromosome 8 in prostatic cancer, this chromosome was introduced into highly metastatic rat prostatic cancer cells using microcell-mediated chromosome transfer. Introduction of human chromosome 8 resulted in suppression of metastatic ability of the microcell hybrids, whereas no suppression of the in vivo growth rate or tumorigenicity was observed. These results demonstrate that human chromosome 8 contains metastasis suppressor gene(s) for prostatic cancer derived from a rat. These also suggest that human chromosome 8 has an important role in development of prostatic cancer.

Animals↗
PubMed1994

A 3-Mb physical map of the chromosome region 8p21.3-p22, including a 600-kb region commonly deleted in human hepatocellular carcinoma, colorectal cancer, and non-small cell lung cancer.

To isolate a putative tumor suppressor gene(s), we have constructed a physical map and a detailed deletion map of chromosome region 8p21.3-p22, where loss of heterozygosity (LOH) has been frequently seen in human hepatocellular carcinomas (HCC), colorectal cancers (CRC), and non-small cell lung cancers (NSCLC). The smallest commonly deleted region at 8p21.3-p22 in HCC and CRC was between the loci defined by C18-245 and C18-2644; in NSCLC, a region between C18-1051 and C18-2644 was commonly deleted. A contiguous physical map of 12 cosmid markers in the 8p21.3-p22 region was constructed by means of multi-color fluorescence in situ hybridization (FISH) and pulsed-field gel electrophoresis (PFGE). On the basis of this physical map, which spans roughly 3.1 Mb, the estimated sizes of the commonly deleted regions were at most 1.2 Mb in HCC and CRC and 0.6 Mb in NSCLC. As four of the 12 physically ordered markers are located within the 0.6 Mb region commonly deleted in all three tumor types, nearly one fourth to one fifth of the target region has already been covered with cosmid inserts.

Animals↗
PubMed1994

A human gene that restores the DNA-repair defect in SCID mice is located on 8p11.1-->q11.1.

In order to map the gene that is responsible for the DNA-repair defect in severe combined immune deficient (SCID) mice, a mixture of microcells independently isolated from mouse A9 cells containing pSV2neo-tagged human chromosomes 5, 7, 8, 9, 11, 15, 18 or 20 were fused with SCID fibroblast cell lines SCVA2 and SCVA4, which were originally established from lung tissue of the C.B.17-scid/scid mouse by SV40 virus transfection. After irradiation with 60Co gamma-rays and selection with antibiotic G418, 12 independent clones were obtained, of which 4 contained an intact chromosome 8, 3 clones contained a deleted chromosome 8 [del(8)q22-->qter or del(8)q23--> qter] and remaining 5 had no detectable or specific human chromosome. We further independently transferred a single human chromosome 8 or 11 into the SCVA cells via microcell fusion, and examined the radiation sensitivity of the microcell hybrids. Complementation of the radiation sensitivity was correlated with the presence of human chromosome 8 in microcell hybrids, whereas no correlation was observed in clones following the transfer of human chromosome 11. Thus, the results indicate that human chromosome 8 restored high sensitivity to ionizing radiation. A number of subclones that were radiation resistant or sensitive were isolated from the microcell hybrids. The concordance of the radiation sensitivity with the presence or absence of specific DNA fragments on chromosome 8 indicates that the human gene is located on the centromeric region of chromosome 8, i.e., 8p11.1--> q11.1.

Animals↗
PubMed1993

Homozygous deletion and frequent allelic loss of chromosome 8p22 loci in human prostate cancer.

Allelic loss studies have been instrumental in identifying tumor suppressor gene loci in a variety of cancers. In this study we analyzed prostate cancer specimens from 52 patients for allelic loss using 8 polymorphic probes for the short arm of chromosome 8. Overall, 32 of 51 (63%) informative tumors showed loss of at least one locus on chromosome 8p. The most frequently deleted region is observed at chromosome 8p22-8p21.2. Loss of one allele is identified in 14 of 23 (61%) tumors at D8S163, in 15 of 32 (47%) tumors at lipoprotein lipase, and in 20 of 29 (69%) tumors at MSR, all on 8p22. Loss of one allele is identified in 16 of 27 (59%) tumors at D8S220 at 8p21.3-8p21.2. In addition to frequent loss of one allele at the MSR locus, one metastatic prostate cancer sample demonstrated homozygous deletion of MSR sequences. Loci telomeric and centromeric to this region are largely retained. A chromosome 8p deletion map is constructed and defines the smallest region of overlap to a 14-cM interval at 8p22 between D8S163 and lipoprotein lipase, flanking the MSR locus. Evidence of chromosome 8q multiplication at locus D8S39 was detected in 5 of 32 (16%) tumors, all of which demonstrated loss with at least one probe on chromosome 8p. This study extends the previous finding of frequent loss of chromosome 8p in prostate cancer by defining a common region of loss of heterozygosity at 8p22 and a homozygous deletion of the MSR locus contained within this region. This is the first homozygous deletion identified in the genome of a human prostate cancer and the highest rate of loss yet reported on chromosome 8p in cancer. These results strongly suggest the presence of a tumor suppressor gene in this region which is frequently inactivated in prostate cancer.

Alleles↗
PubMed1993

Binding of lipoprotein lipase to heparin. Identification of five critical residues in two distinct segments of the amino-terminal domain.

Binding to heparan sulfate governs many aspects of the physiological action and regulation of the lipolytic enzyme, lipoprotein lipase (LPL). In an attempt to identify the structural determinants which mediate this interaction, basic residues in three segments of the primary sequence of human LPL (residues 147-151, 279-282, and 292-304) were replaced with alanine, either singly or in various combinations, and variant proteins were subjected to affinity chromatography on heparin-Superose. Five basic residues in two distinct segments of the primary sequence were critical determinants of the high affinity for heparin manifested by the active enzyme (R279, K280, R282, K296, R297). By contrast, no such evidence could be detected for basic residues in the first cluster (K147, K148) or for other basic residues in the third cluster (K292, R294, K304), while the evidence for K300 was unresolved. The conformation of this heparin-binding domain can be inferred by reference to the three-dimensional structure of the homologous enzyme, pancreatic lipase (Winkler, F. K., D'Arcy, A., and Hunziker, W. (1990) Nature 343, 771-774). Affinity of the active enzyme for heparin could not be reduced below a threshold, suggesting that other heparin-binding determinants exist elsewhere in the molecule, as supported by recently published evidence (Davis, R. C., Wong, H., Nikazy, J., Wang, K., Han, Q., and Schotz, M. C. (1992) J. Biol. Chem. 267, 21499-21504).

Amino Acid Sequence↗
PubMed1993

Evidence for the presence of two tumor suppressor genes on chromosome 8p for colorectal carcinoma.

We have examined loss of heterozygosity on the short arm of chromosome 8 in 133 colorectal carcinomas, using 20 restriction fragment length polymorphism markers. Loss of heterozygosity was observed in 58 (44%) of 131 tumors that were informative with at least one locus. Among these 58, 32 revealed a partial or interstitial deletion of chromosome 8p. Detailed deletion mapping of chromosome 8p in these tumors identified two distinct, commonly deleted regions. One was located between markers C18-266 and pSVL-LPL at 8p23.2-8p22, and the other between CI8-319 and CI8-494 at 8p21.3-8p11.22. The genetic lengths of these two intervals were estimated to be 28 and 18 cM, respectively. The results suggest that at least two tumor suppressor genes associated with colorectal carcinomas are present on chromosome 8p. Correlation of loss of heterozygosity on 8p to the clinicopathological stage was also detected, suggesting that inactivation of a tumor suppressor gene(s) on 8p plays a role in progression of colorectal carcinomas.

Chromosome Deletion↗
PubMed1993

Frequent multiplication of the long arm of chromosome 8 in hepatocellular carcinoma.

Frequent allelic losses at loci on several chromosomes have been detected in human hepatocellular carcinomas, but other types of chromosomal abnormalities have not been characterized well. Using eight polymorphic DNA markers on chromosome 8, we examined 120 primary hepatocellular carcinomas for abnormalities in the copy number of these loci in tumor cells. A 2- to 6-fold increase in intensities of bands representing single alleles was observed in 32 of the 78 tumors that were informative for one or more of the markers, indicating an increase in copy number ("multiplication") of alleles on 8q. The regions that multiplied varied from almost the entire long arm to a distal segment of chromosome 8, but a terminal region distal to 8q24.11 was multiplied in all 32 cases. Similar multiplications on 8q were detected in nine of 56 colorectal carcinomas that were informative for one or more of the markers. Our study demonstrated that polymorphic DNA markers can be used to detect numerical abnormalities of chromosomal material in solid tumors in which cytogenetic analysis is technically difficult.

Alleles↗
PubMed1993

Structure, organization, and chromosomal mapping of the human macrophage scavenger receptor gene.

Macrophage scavenger receptors (MSR) mediate the binding, internalization, and processing of a wide range of negatively charged macromolecules. Functional MSR are trimers of two C-terminally different subunits that contain six functional domains. We have cloned an 80-kilobase human MSR gene and localized it to band p22 on chromosome 8 by fluorescent in situ hybridization and by genetic linkage using three common restriction fragment length polymorphisms. The human MSR gene consists of 11 exons, and two types of mRNAs are generated by alternative splicing from exon 8 to either exon 9 (type II) or to exons 10 and 11 (type I). The promoter has a 23-base pair inverted repeat with homology to the T cell element. Exon 1 encodes the 5'-untranslated region followed by a 12-kilobase intron which separates the transcription initiation and the translation initiation sites. Exon 2 encodes a cytoplasmic domain, exon 3, a transmembrane domain, exons 4 and 5, an alpha-helical coiled-coil, and exons 6-8, a collagen-like domain. The position of the gap in the coiled coil structure corresponds to the junction of exons 4 and 5. These results show that the human MSR gene consists of a mosaic of exons that encodes the functional domains. Furthermore, the specific arrangement of exons played a role in determining the structural characteristics of functional domains.

Amino Acid Sequence↗
PubMed1993

Deletion mapping of the short arm of chromosome 8 in non-small cell lung carcinoma.

Frequent losses of heterozygosity observed at several chromosomal loci in primary lung cancers have indicated the existence of several tumor suppressor genes associated with this type of cancer. We have examined loss of heterozygosity on chromosomal arm 8p in 49 cases of non-small cell lung carcinoma, using 14 restriction fragment length polymorphism markers. Of 42 cases informative with at least one marker, 21 showed allelic loss, including 15 of 32 adenocarcinomas and 5 of 9 squamous cell carcinomas. The frequency of allelic loss on 8p was similar at all clinical stages. Deletion mapping defined a single common region of deletion in these tumors within an 8 cM interval at 8p21.3-p22 flanked by the loci defined by cMSR-32 and cC18-245.

Adenocarcinoma↗
PubMed1993

Allelic loss at chromosome band 8p21.3-p22 is associated with progression of hepatocellular carcinoma.

Human hepatocellular carcinomas (HCC) frequently show loss of heterozygosity at loci on the short arm of chromosome 8. To define a region on 8p commonly deleted in HCC, we used 20 restriction fragment length polymorphism markers to carry out detailed deletion mapping in 142 HCC. Of the 124 informative cases, 56 (45%) showed allelic losses in tumors. While more than half of them had lost alleles at every locus on the short arm, others lost them partially or interstitially. Common deletion of an 8-cM region flanked by cMSR-32 and cC18-245, at 8p21.3-p22, suggested the presence of a tumor suppressor gene(s) in this interval. Correlation between allelic losses on 8p and clinicopathological parameters were examined in the 51 cases for which detailed clinical data were available; allelic losses on 8p were observed in none of five tumors at stage T1 (0%), nine of 20 tumors at stage T2 (45%), and 17 of 26 tumors at stage T3/T4 (65%). A higher frequency of allelic losses on 8p was observed in poorly differentiated tumors (10/14, 71%) than in well differentiated tumors (3/13, 23%). The association of allelic losses on 8p with advanced clinical stage and poor differentiation implies that loss or inactivation of a tumor suppressor gene(s) on 8p may play a role in the progression of HCC.

Carcinoma, Hepatocellular↗
PubMed1993

A primary genetic linkage map of 14 polymorphic loci for the short arm of human chromosome 8.

A genetic linkage map of markers for the short arm of human chromosome 8 has been constructed with 14 polymorphic DNA markers on the basis of genotypes obtained in 40 CEPH reference families. This unbroken map spans 45 cM in males and 79 cM in females. The 14 markers include three genes, MSR, LPL, and NEFL, and one anonymous DNA segment that were previously assigned to chromosome 8. The other 10 marker had been isolated from a chromosome 8-specific cosmid library and physically localized to chromosomal bands by fluorescence in situ hybridization. The order of loci determined by genetic linkage was consistent with their physical locations. This map will facilitate efficient linkage studies of human genetic diseases that may be segregating on chromosome 8p and will provide anchor points for development of high-resolution maps for this chromosomal region.

Chromosome Mapping↗
PubMed1993

The cell adhesion regulator (CAR) gene, TaqI and insertion/deletion polymorphisms, and regional assignment to the peritelomeric region of 16q by linkage analysis.

We have identified two types of polymorphism at the CAR (cell adhesion regulator) locus. One is a conventional TaqI polymorphism and the other is an insertion/deletion polymorphism in the coding region. One has the nucleotide sequence AGTGAGGCA (Ser-Gln-Ala) at nt 271-279, whereas the variant has ACAC-AGTGAGGCCCA (Thr-Gln-Ser-Gly-Pro). Although it is not clear whether this variation of amino acids affects the biological function of the gene product, this variant was detected in nine chromosomes among 30 unrelated Japanese individuals. Genetic linkage analysis based on the genotypes of TaqI polymorphism in CEPH families revealed close linkage of CAR to D16S7 and D16S154, which are located in the peritelomeric region of the long arm of chromosome 16.

Amino Acid Sequence↗
PubMed1993

Human tissue factor pathway inhibitor (TFPI) gene: complete genomic structure and localization on the genetic map of chromosome 2q.

Tissue factor pathway inhibitor (TFPI), a protease inhibitor that circulates in association with plasma lipoproteins (VLDL, LDL and HDL), helps to regulate the extrinsic blood coagulation cascade. We have cloned a 125-kb genomic region containing the entire human TFPI gene on six overlapping cosmids and prepared a restriction map of this contig to clarify gene structure. More than half (45 kb) of the 85-kb gene is occupied with 5' noncoding elements: coding begins at exon 3. A HindIII RFLP identified with one cosmid was genotyped in the CEPH panel of 59 reference families. Linkage analysis using markers on human chromosome 2 located the TFPI gene on 2q, 36 cM proximal to D2S43(pYNZ15) and 13 cM distal to the crystalline gamma-polypeptide locus CRYGP1(p5G1).

Base Sequence↗