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Biomedical subjects

T Kozu

Publications and source records attributed to T Kozu.

At least 19 recordsLinked to original sources
PubMed1998

Cancer inhibition by green tea.

Green tea is now an acknowledged cancer preventive in Japan. This paper discusses several important features of (-)-epigallocatechin gallate (EGCG), the main constituent of green tea and tea polyphenols. EGCG and other tea polyphenols inhibited growth of human lung cancer cell line, PC-9 cells with G2/M arrest. 3H-EGCG administered by p.o. intubation into mouse stomach revealed that small amounts of 3H-activity were found in various organs where EGCG and green tea extract had previously demonstrated their anticarcinogenic effects, such as skin, stomach, duodenum, colon, liver, lung and pancreas. Cancer onset of patients who had consumed over 10 cups of green tea per day was 8.7 years later among females and 3.0 years later among males, compared with patients who had consumed under three cups per day. The mechanisms of action of EGCG were briefly discussed with regard to inhibition of tumor necrosis factor-alpha (TNF-alpha) release.

3T3 Cells↗
PubMed1998

Tumourigenicity of MTG8, a leukaemia-related gene, in concert with v-Ha-ras gene in BALB/3T3 cells.

The MTG8 (ETO) gene has been identified as the translocation partner of AML1 (PEBP2alphaB or CBFalpha2) gene in the AML1/MTG8 (ETO) fused gene caused by t(8;21) translocation in human acute myeloid leukaemia, M2 type. Although AML1/MTG8 chimaeric protein is known to inhibit the functioning of AML1 protein, the precise function of MTG8 gene itself is not known yet. We studied the significance of MTG8 gene in the oncogenicity of AML1/MTG8 fused gene, by introducing full-length MTG8 cDNA into both BALB/3T3 cells containing v-Ha-ras gene (Bhas 42 cells) and BALB/3T3 cells without v-Ha-ras gene. Irrespective of the overexpression of MTG8 gene in both groups of cells, Bhas-MTG8 clones which contained v-Ha-ras gene and expressed the MTG8 gene at a level more than twice that of parental Bhas 42 cells induced cell transformation, whereas BALB-MTG8 clones without v-Ha-ras gene did not. Furthermore, injection of the transformed Bhas-MTG8 clones into the subcutaneous tissue of nude mice induced tumours, whereas that of BALB-MTG8 clones did not. These results suggest that MTG8 gene product, in cooperation with viral Ras protein, resulted in tumour formation. We provide the first evidence that MTG8 gene by itself has a carcinogenic property within the AML1/MTG8 (ETO) fused gene.

3T3 Cells↗
PubMed1997

Expression of the tumor necrosis factor alpha gene and early response genes by nodularin, a liver tumor promoter, in primary cultured rat hepatocytes.

Nodularin is a new liver carcinogen possessing a potent tumor-promoting activity in rat liver, mediated through inhibition of protein phosphatases 1 and 2A, and a weak initiating activity. Since we previously reported evidence that nodularin up-regulated expression of the tumor necrosis factor alpha gene (TNF alpha) and early-response genes in rat liver after its i.p. administration, and since TNF alpha had tumor-promoting activity in vitro, it is possible that TNF alpha itself is involved in liver tumor promotion. We investigated whether hepatocytes themselves induce expression of the TNF alpha gene and early-response genes in primary cultured rat hepatocytes treated with nodularin. Like nodularin, microcystin-LR, which is another liver tumor promoter belonging to the okadaic acid class, strongly induced TNF alpha gene expression in rat hepatocytes, as well as TNF alpha release from those cells into the medium. On the other hand, 12-O-tetradecanoylphorbol-13-acetate, which has been reported to induce no tumor promotion in rat liver, induced no apparent expression of the TNF alpha gene in primary cultured rat hepatocytes. As for the expression of early-response genes, 1 microM nodularin or microcystin-LR induced expression of the c-jun, jun B, jun D, c-fos, fos B and fra-1 genes in the hepatocytes, and the expression of these genes was prolonged up to 24 h, suggesting mRNA stabilization induced by inhibition of protein phosphatases 1 and 2A. This paper presents new evidence that the TNF alpha gene and early-response genes were expressed in hepatocytes treated with a liver tumor promoter.

Animals↗
PubMed1997

Embryological fusion between the ducts of the ventral and dorsal primordia of the pancreas occurs in two manners.

The junction between the main pancreatic duct and the accessory duct has been thought to be the site of fusion between the ducts of the ventral and the dorsal primordia of the pancreas. The aim of this study was to investigate the fusion point between the ventral and the dorsal pancreatic ducts and to determine whether there is any relationship between the configuration of the pancreatic ducts and the manner of embryological fusion. Pancreatography was performed at 22 consecutive autopsies. Immunohistochemical staining of pancreatic polypeptide (PP) was performed because PP cells were rich in the ventral pancreas but poor in the dorsal pancreas. We identified two types of fusion. In one type, the ventral and the dorsal pancreatic ducts fuse at their junction (one-point fusion). In the other type, the two ducts fuse not only at the proximal site but at a second, more distal site (two-point fusion). Analysis of the pancreatograms showed that the distance between the junction and the major papilla in two-point fusion is significantly shorter than in one-point fusion (p < 0.01). These results indicate a close correlation between the pattern seen on pancreatograms and the manner of embryological fusion.

Aged↗
PubMed1997

Significance of MTG8 in leukemogenesis.

MTG8 is a counterpart gene of AML1 in acute myeloid leukemia with t(8:21) translocation. Most of the coding region of the MTG8 is fused with AML1 runt domain. In normal tissues, the MTG8 is highly expressed in brain, but not in hematopoietic tissues. MTG8 may be important in leukemogenesis as well as in AML1 truncation. The function of MTG8 is assumed to be as a transcription factor, because it possesses several features common to transcription factors; putative zinc finger motifs, serine/threonine/proline-rich sequences and a region similar to TAF110. In this paper, we report on the protein properties of the MTG8.

Acute Disease↗
PubMed1996

Designing of chimeric DNA/RNA hammerhead ribozymes to be targeted against AML1/MTG8 mRNA.

For therapeutic purposes, two chimeric DNA/RNA hammerhead ribozymes were synthesized to cleave AML1/MTG8, the t(8;21)-associated fusion mRNA of acute myeloid leukemia. One ribozyme, A/MRZ-1, recognizes the area adjacent to the fusion point between AML1 and MTG8, and cleaves six bases downstream from this point. The other, MRZ-1, recognizes the MTG8 sequence. Both ribozymes cleaved synthetic chimeric DNA/RNA substrates at theoretical sites. Neither cleaved AML1 RNA. A/MRZ-1 cleaved only AML1/MTG8 RNA, and MRZ-1 cleaved both AML1/MTG8 and MTG8 RNAs. The two ribozymes showed growth inhibition of an acute myeloid leukemia cell line carrying t(8;21), SKNO-1 cells. The same extent of growth inhibition was attained by antisense oligonucleotides against AML1/MTG8 RNA. The results suggest that the ribozyme has the potential to be developed as a useful agent for gene therapy, in particular for leukemia with t(8;21).

Antineoplastic Agents↗
PubMed1996

In vitro catalytic activities of DNA/RNA chimeric hammerhead ribozymes against AML1-MTG8 mRNA, a fused gene transcript in acute myeloid leukemia with t(8;21).

In order to design the best construct for therapeutic hammerhead ribozymes against AML1-MTG8, the t(8;21)-associated fusion mRNA of acute myeloid leukemia, we synthesized DNA/RNA chimeric ribozymes directed to the area adjacent to the fusion point between AML1 and MTG8. Catalytic efficiency and fusion gene specificity of ribozymes were examined by kinetic studies of the cleavage reactions of AML1-MTG8, AML1, and MTG8 RNAs transcribed in vitro. Ribozyme 2 (Rz2) specifically cleaved AML1-MTG8 RNA at three nucleotides downstream of the fusion junction with high efficiency. The highest cleavage efficiency was achieved by Rz4.3, which targeted non-contiguous sequences and cleaved at 19 nucleotides downstream of the fusion junction. Rz4.3 also cleaved MTG8 RNA but the cleavage efficiency was three orders of magnitude lower than that for AML1-MTG8 RNA. Therefore, Rz4.3 and Rz2 are the proper ribozymes for in vivo application to modulate gene expression of the AML1-MTG8.

Acute Disease↗
PubMed1995

Structure and expression of the gene (HNRPA2B1) encoding the human hnRNP protein A2/B1.

Heterogeneous nuclear ribonucleoprotein (hnRNP) A2 is a major nuclear protein and one of the major components of the hnRNP core complex in mammalian cells. We first determined the complete sequence of the human gene for hnRNP protein A2 (HNRPA2B1). The human HNRPA2B1 gene exists in a single copy over 9 kb in length. The gene was split into 12 exons, including a 36-nucleotide mini-exon, which was specific to the hnRNP protein B1, providing genetic evidence that the B1 mRNA was generated from the primary HNRPA2B1 transcript by alternative splicing. The 5' region of HNRPA2B1 was GC-rich and contained several DNA motifs for the binding of several transcription factors, which included 2 CCAAT boxes and no TATA sequences. The 5' ends of the mRNA were mapped to multiple positions. These structural features are characteristic of promoter regions of housekeeping genes. Northern blot and RT-PCR analyses of the HNRPA2B1 transcripts revealed levels of B1 mRNA from 2 to 5% of total A2/B1 transcripts and showed that both A2 and B1 mRNAs were transcribed in all human cell lines and mouse tissues studied. The structural and evolutionary characteristics of the A2 and A1 proteins as they relate to each other are discussed.

Amino Acid Sequence↗
PubMed1995

Disappearance of AML1-MTG8(ETO) fusion transcript in acute myeloid leukaemia patients with t(8;21) in long-term remission.

In a study of 23 patients with t(8;21)-associated acute myeloid leukaemia the AML1-MTG8 fusion transcript was present in the majority of serial samples obtained from 17 patients followed for up to 34 months after diagnosis, but was absent in samples from all six patients who had been in continuous complete remission for 61 months after allogeneic bone marrow transplantation (BMT), or for 52, 53, 123, 182 and 198 months, respectively, after courses of intensive chemotherapy. Previous studies showed that the AML1-MTG8 fusion transcript was present in most patients with this type of translocation in long-term remission. Our results indicate that blood cells of patients with t(8;21) in remission of over 10 years may not show the AML1-MTG8 fusion transcript, and that those of patients who have undergone allogeneic BMT or intensive chemotherapy may become fusion transcript-negative much earlier. Our study suggests that leukaemic cells with the AML1-MTG8 fusion transcript may survive for some time after courses of chemotherapy or BMT, but that they may eventually be eradicated by immunologic and other antileukaemic mechanisms.

Acute Disease↗
PubMed1995

Pancreatic development and anatomical variation.

The pancreas is formed by the fusion of the ventral and dorsal anlage, and a wide spectrum of anomalies or anatomical variations may appear related to this complicated process of fusion: e.g., agenesis, aplasia of a pancreatic anlage, hypoplasia, annular pancreas, pancreas divisum or nonfusion of the ventral and dorsal duct system, pancreaticobiliary maljunction, etc. Every endoscopist who engages in pancreatography or related diagnostic and therapeutic procedures should always be aware of all sorts of anatomical variations he or she might encounter.

Aged↗
PubMed1993

Junctions of the AML1/MTG8(ETO) fusion are constant in t(8;21) acute myeloid leukemia detected by reverse transcription polymerase chain reaction.

The chromosomal translocation, t(8;21), is found frequently in acute myeloid leukemia (AML) with maturation (FAB-M2). We have previously mapped the translocation breakpoints of t(8;21) in a specific intron of the AML1 gene on chromosome 21. In this study, we cloned cDNAs synthesized from a cell line carrying t(8;21) by reverse transcription polymerase chain reaction (RT-PCR) using an AML1-specific primer. The analysis of the cDNAs structure has led to the identification of the fusion of AML1 with a gene named MTG8 on chromosome 8, which seems to be identical to ETO. Northern analysis using MTG8 (ETO) probes detected 7.8-kb and 6.2-kb RNAs and several minor RNAs in the cell line with t(8;21), but failed to detect any transcripts in a cell line without t(8;21). A set of primers were designed to detect the AML1/MTG8(ETO) fusion by PCR. The PCR amplified identical products in all 6 patients and one cell line with t(8;21), suggesting that the AML1/MTG8(ETO) fusion is a constant feature associated with t(8;21) and the junctions of the AML1/MTG8(ETO) fusion are restricted in a unique site. Because the PCR detection of the AML1/MTG8(ETO) fusion at the RNA level is highly sensitive, it can be used as a sensitive method for diagnosis and detection of minimal residual disease in t(8;21) leukemia.

Amino Acid Sequence↗
PubMed1993

The t(8;21) translocation in acute myeloid leukemia results in production of an AML1-MTG8 fusion transcript.

The t(8;21) translocation is one of the most frequent chromosome abnormalities in acute myeloid leukemia. It has been shown that the t(8;21) breakpoints on chromosome 21 cluster within a single specific intron of the AML1 gene, which is highly homologous to the Drosophila segmentation gene runt. Here we report that this translocation juxtaposes the AML1 gene with a novel gene, named MTG8, on chromosome 8, resulting in the synthesis of an AML1-MTG8 fusion transcript. The fusion protein predicted by the AML1-MTG8 transcript consists of the runt homology region of AML1 and the most part of MTG8, which contains putative zinc finger DNA binding motifs and proline-rich regions constituting a characteristic feature of transcription factors. The MTG8 gene is not expressed in normal hematopoietic cells, whereas AML1 is expressed at high levels. Our results indicate that the production of chimeric AML1-MTG8 protein, probably a chimeric transcription factor, may contribute to myeloid leukemogenesis.

Acute Disease↗
PubMed1992

Consistent disruption of the AML1 gene occurs within a single intron in the t(8;21) chromosomal translocation.

The AML1 gene on chromosome 21 was rearranged by the t(8;21) chromosomal translocation in acute myeloid leukemia (AML). Southern blot analysis of 21 AML patients with t(8;21), including three with complex translocations, t(8;V;21), demonstrated that all the breakpoints occurred at random within a single intron between two coding exons of AML1. Clustering of the breakpoints in the restricted intron suggests the formation of a unique fusion gene between the AML1 gene and a presumable counterpart gene on chromosome 8. Nucleotide sequencing of the breakpoint region revealed that the translocation event was accompanied by deletion of a short stretch of nucleotides.

Base Sequence↗
PubMed1992

[A cases of antithrombin III (ATIII) deficiency associated with extrahepatic portal occlusion undergoing operation for esophgogastric varices].

A 23-year-old woman developed thrombosis of the superior mesenteric vein and underwent an extensive enterectomy. She was diagnosed to have ATIII deficiency with extrahepatic portal vein thrombosis and esophagogastric varices. She was admitted to our department and underwent esophageal mucosal transection and splenectomy. Her activities of ATIII were 46%, but ATIII activities of her family were over 90%. ATIII activities during perioperative period were kept more than 70% following administration of ATIII drug. After splenectomy thrombocythemia which was over 300 x 10(4)/mm3 appeared with severe headache and slight pain of hands. She was discharged on 76th postoperative day with no complications and collapse of esophageal varices.

Adult↗
PubMed1991

t(8;21) breakpoints on chromosome 21 in acute myeloid leukemia are clustered within a limited region of a single gene, AML1.

The t(8;21)(q22;q22) translocation is a non-random chromosomal abnormality frequently found in patients with acute myeloid leukemia (AML) with maturation (M2 subtype). We report here the cloning of a gene, named AML1, on chromosome 21 that was found to be rearranged in the leukemic cell DNAs from t(8;21) AML patients. The breakpoints in 16 out of 21 patients were clustered within a limited region of AML1, and detailed analysis in 3 patients revealed that the breakpoints occurred in the same intron of the gene. Sequencing of cDNA clones identified a long open reading frame encoding a 250-amino acid protein. Northern blot analysis detected four constant mRNA species in t(8;21) leukemic and normal cells; the largest species was more abundant in the leukemic cells than in normal cells. In addition, two mRNA species limited to the leukemic cells were found. These findings indicate that the AML1 gene may be involved in neoplastic transformation of AML with the t(8;21) translocation.

Acute Disease↗