PubMed Health⌕ Search

Biomedical subjects

Seisho Takeuchi

Publications and source records attributed to Seisho Takeuchi.

At least 19 recordsLinked to original sources
PubMed2006

HIV-1 protease inhibitor ritonavir potentiates the effect of 1,25-dihydroxyvitamin D3 to induce growth arrest and differentiation of human myeloid leukemia cells via down-regulation of CYP24.

HIV-1 protease inhibitor, ritonavir (RTV) is a potent inhibitor of cytochrome p450 (CYPs) enzymes. This study explored the effects of RTV on CYP24 which converts 1,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)] to its inactive form 1,24,25,(OH)(3). Real-time RT-PCR showed that exposure of HL-60 cells to 1,25(OH)(2)D(3) induced expression of CYP24, and pre-incubation of these cells with RTV decreased this transcripts, resulting in increased intracellular levels of 1,25(OH)(2)D(3) and potentiation of the ability of 1,25(OH)(2)D(3) to induce growth arrest and differentiation of these cells. Taken together, inhibition of CYP24 might open a new paradigm for therapy using Vitamin D compounds.

Calcitriol↗
PubMed2006

SAHA, a HDAC inhibitor, has profound anti-growth activity against non-small cell lung cancer cells.

Current chemotherapy of advanced non-small cell lung cancer (NSCLC) produces only a modest increase in survival time. New approaches are needed for this disease. The development of lung cancer is associated with silencing tumor suppressor genes that can occur not only by deletion or mutation, but also by epigenetic changes including histone deacetylation of key lysines. Histone deacetylase inhibitor (HDACI) increases histone acetylation, resulting in DNA with a more open chromatin that favors transcription. We found that the HDACI, suberoylanilide hydroxamic acid (SAHA), suppressed cell growth of five non-small cell lung cancer cell lines in a dose-dependent manner (50% growth inhibition approximately 2 microM). Cell cycle assay by fluorescence-activated cell sorting (FACS) demonstrated that SAHA induced a significant G0-G1 growth arrest of NSCLC cells. Protein assay by Western blot analysis showed that SAHA induced expression of p21WAF1. These results demonstrated that administration of SAHA may be a novel approach to the treatment of non-small cell lung cancer.

Acetylation↗
PubMed2005

Aberrant methylation in promoter-associated CpG islands of multiple genes in acute lymphoblastic leukemia.

Methylation profile was analyzed in 10 childhood acute lymphoblastic leukemia (ALL) and nine adult ALL cases. Four genes (p15, p16, RARbeta, FHIT) had methylation in both diseases, four genes (p14, Rb, MLH1, DAPK) showed no methylation in both diseases, and the two genes (APC, RIZ) demonstrated methylation only in adult ALL. Methylation of the RARbeta was more frequent in adult ALL than that in childhood ALL (p=0.01). The number of patients with methylation of multiple genes was higher in adult ALL than that in childhood ALL (p=0.006). Moreover, overall frequency of methylation was higher in adult ALL than that in childhood ALL (p=0.01).

Adolescent↗
PubMed2005

Methylation analysis of the adenomatous polyposis coli (APC) gene in adult T-cell leukemia/lymphoma.

We investigated methylation status of the adenomatous polyposis coli (APC) gene in adult T-cell leukemia/lymphoma (ATL). APC methylation was found in 15 of 31 (48%) primary samples, and 2 of 4 (50%) ATL cell lines. Methylation of the APC gene occurred more frequently in acute ATL (12/21) (57%) than chronic ATL (1/8) (13%) (P = 0.03). APC was not expressed in the APC-methylated ATL cell line ST1. Demethylation with 5-azacytidine treatment restored APC expression in the ST1 cell line. Our data show that hypermethylation of the APC gene is involved in the pathogenesis of ATL.

Adenomatous Polyposis Coli Protein↗
PubMed2005

HIV-1 protease inhibitor induces growth arrest and apoptosis of human prostate cancer LNCaP cells in vitro and in vivo in conjunction with blockade of androgen receptor STAT3 and AKT signaling.

This study found that the HIV-1 protease inhibitor nelfinavir (NFV) induced growth arrest and apoptosis of human prostate cancer cells (LNCaP, DU145 and PC-3 cells), as measured by MTT and terminal deoxyribonucleotide transferase-mediated dUTP nick end labeling (TUNEL) assays, respectively, on the third day of culture. In addition, NFV blocked androgen receptor (AR) signaling in association with downregulation of nuclear levels of AR in LNCaP cells as measured by reporter assay and western blot analysis. As expected, NFV downregulated the level of the AR target molecule prostate specific antigen in these cells. Moreover, NFV disrupted STAT3 signaling; protease inhibitors blocked interleukin-6-induced phosphorylation of STAT3 and inhibited STAT3 DNA binding activity in LNCaP and DU145 cells, as measured by western blot analysis and enzyme-linked immunosorbent assay (ELISA), respectively. Furthermore, NFV blocked AKT signaling in prostate cancer cells as measured by kinase assay with glycogen synthase kinase-3alpha/beta as a substrate. Importantly, NFV inhibited the proliferation of LNCaP cells presented as tumor xenografts in BALB/c nude mice without side-effects. Taken together, NFV inhibited the proliferation of prostate cancer cells in conjunction with blockade of signaling by AR, STAT3, and AKT, suggesting that this family of compounds might be useful for the treatment of individuals with prostate cancer.

Animals↗
PubMed2005

Methylation of the MLH1 gene in hematological malignancies.

Hypermethylation of the MLH1 gene has been described in many kinds of human cancers with microsatellite instability (MSI). However, it is not clear whether the same mechanism occurs in hematological malignancies. Genomic DNA was extracted from 31 patients with adult T-cell leukemia/lymphoma (ATL), 9 patients with acute lymphoblastic leukemia (ALL) who had MSI, and 12 leukemia and lymphoma cell lines with MSI. Aberrant methylation of the MLH1 gene was found in 2/31 (6%) ATL patients, and in 1/12 (8%) cell lines with MSI. MLH1 promoter was not methylated in either of the twelve peripheral blood samples from normal individuals or ALL samples. The MLH1 gene was expressed in the normal peripheral blood samples, but not in the MLH1-methylated cell line KCL22. Demethylation with 5-Azacytidine treatment restored MLH1 expression in the KCL22 cell line. Methylation of the MSH2 gene was not found in any of the samples. Our data show that hypermethylation of the MLH1 gene is occasionally involved in the pathogenesis of hematological malignancies, but is not always associated with MSI.

Adaptor Proteins, Signal Transducing↗
PubMed2004

Allelic loss during progression of follicular lymphoma.

We performed loss of heterozygosity (LOH) analysis on matched lymph nodes before and after progression of follicular lymphoma (FL), and found novel LOH on chromosome arm 12p. This LOH has not been previously reported in association with FL transformation. Other sites of frequent LOH include chromosome arms 6q and 9p. LOH was observed in both transformed FL and relapse FL. These data suggest that altered tumor suppressor genes exist on 6q, 9p, and 12p that have an important role in the progression of FL. Genetic changes accumulated in relapsed FL in the absence of histological changes compared to initial diagnosis.

Chromosomes, Human, Pair 12↗
PubMed2004

Methylenetetrahydrofolate reductase genotype does not play a role in adult T-cell leukemia/lymphoma pathogenesis among human T-lymphotrophic virus type 1 carriers.

Human T-lymphotropic virus type 1 (HTLV-1) is associated with adult T-cell leukemia/lymphoma (ATL). However, the incidence of ATL is low among HTLV-1 carriers suggesting additional mechanisms are involved in the progression of the disease. A recent study found that polymorphisms in the methylenetetrahydrofolate reductase (MTHFR) gene influence the susceptibility to malignant lymphoma. We have analyzed the MTHFR genotype in 81 HTLV-1 carriers and 87 ATL patients. No statistically significant associations were found between MTHFR genotype and development of ATL. These data suggest that genetic polymorphisms in the MTHFR locus do not play a role in ATL pathogenesis among HTLV-1 carriers.

Carrier State↗
PubMed2004

Aberrant methylation in promoter-associated CpG islands of multiple genes in relapsed childhood acute lymphoblastic leukemia.

Methylation profile was analyzed in nine cases of relapsed childhood acute lymphoblastic leukemia (ALL) for p14, p15, p16, Rb, MGMT, APC, hMLH1, RARbeta, RIZ, DAPK, and FHIT genes by using methylation specific polymerase chain reaction (MSP) analysis. Frequency of methylation in each gene was: MGMT, 56%; RARbeta, 44%; and p16, 22%, respectively. None of the p14, p15, Rb, APC, hMLH1, RIZ, DAPK, and FHIT genes were hypermethylated. Five (56%) of 9 cases showed methylation of at least one gene. All of the samples with hypermethylation in p16 and MGMT gene at relapse, had already acquired the change at the time of initial diagnosis. Interestingly, three of 4 cases with RARbeta gene methylation at relapse did not have methylation of this gene at the time of initial presentation. These results suggest that hypermethylation might be involved in the relapse of childhood ALL.

Adolescent↗
PubMed2003

Allelotype analysis in relapsed childhood acute lymphoblastic leukemia.

We performed for the first time the allelotype of relapsed childhood acute lymphoblastic leukemia (ALL). A total of 38 cases were screened for loss of heterozygosity (LOH) using 71 markers. In all, 26 (68%) patients showed LOH on at least one chromosomal arm, indicating that LOH is a frequent event at relapse. The most frequent loss was found on chromosomal arm 9p at the p16/INK4a locus (39%). LOH at the TEL gene locus on chromosomal arm 12p also occurred often (25%). Frequent loss was observed on chromosome arms 4q (20%), 6q (21%), and 17q (20%). Sequential analysis (i.e. samples obtained from both initial diagnosis and relapse) shows that some patients (63%) have the identical LOH status at both phases, suggesting the presence of the same clone. Other samples (37%) showed distinct LOH alterations, indicating clonal evolution at relapse. Despite the heterogeneous and complex changes, some shared LOH loci occurred in these matched samples, suggesting that many of the same tumor-suppressor genes are aberrant at both phases. In summary, novel tumor-suppressor genes on chromosome arms 4q, 6q, and 17q, as well as the p16 and TEL genes, have an important role in the relapse of childhood ALL.

Adolescent↗
PubMed2003

Establishment of the acute myeloid leukemia cell line Kasumi-6 from a patient with a dominant-negative mutation in the DNA-binding region of the C/EBPalpha gene.

A myeloid leukemia cell line designated Kasumi-6 was established from the bone marrow cells of an individual with acute myeloid leukemia, subtype M2. Both the original leukemic cells and the Kasumi-6 cell line harbor a hemizygous point mutation in the gene encoding the CCAAT/enhancer binding protein alpha (C/EBPalpha), a critical myeloid transcriptional factor. The C to G transition at nucleotide 1063 of the C/EBPalpha gene results in amino acid transition R305P in the fork or hinge region between the DNA-binding basic region and the leucine zipper dimerization domain of the C/EBPalpha protein. The Kasumi-6 cells expressed both the p42 and p30 isoforms of the C/EBPalpha protein endogenously, but electrophoretic mobility shift assays demonstrated an absence of C/EBPalpha binding to its respective site. Exogenous expression of the mutant form of C/EBPalpha demonstrated that it was unable to bind DNA and activate transcription from a G-CSF receptor-luciferase reporter construct. Furthermore, coexpression of the wild-type and mutant forms revealed that the mutant form repressed reporter gene activation by the wild type in a dose-responsive manner. This was concomitant with a dose-responsive decrease in wild-type protein binding to the G-CSF receptor C/EBP site. The data suggest that the R305P alteration confers a dominant-negative property on the mutant C/EBPalpha protein whereby the mutant polypeptide heterodimerizes with the wild-type polypeptide and prevents it from binding to DNA, thus blocking transcriptional activation. The Kasumi-6 cell line can serve as a model to study the cellular and molecular biology of the non-t(8;21) M2 type of myeloid leukemia and can elucidate the role of mutated C/EBPalpha in leukemogenesis.

3T3 Cells↗
PubMed2003

Analysis of K-ras codon 12 mutation in flat and nodular variants of serrated adenoma in the colon.

PURPOSE: The developmental process of serrated adenomas is obscure, and the importance of genetic alterations has not been elucidated clearly. The possibility that the developmental process and genetic alterations of serrated adenomas could differ from those of ordinary tubular adenomas was explored in this work. METHODS: Serrated adenomas were obtained by endoscopic resection (n = 57) and divided into two groups: flat (n = 10) and nodular (n = 47). Mutation of the K-ras gene was analyzed by enriched polymerase chain reaction-enzyme-linked mini-sequence assay, which can detect not only the presence of a mutation but also the mutation type of K-ras codon 12 with high sensitivity. Methylation-specific polymerase chain reaction was performed with specific primers for the DNA repair gene O6-methylguanine-DNA methyltransferase. RESULTS: Serrated adenomas located in the rectum were more likely to have a K-ras mutation (9/12, 75 percent), whereas serrated adenomas of the flat type were less likely to have one (1/10, 10 percent). Furthermore, nodular serrated adenomas that occurred in the rectum possessed a high frequency of K-ras gene codon 12 point mutation (8/10, 80 percent) despite an overall frequency of 46.8 percent (22/47). A mutation of the K-ras codon 12 gene was detected in 23 (40.4 percent) of 57 serrated adenomas. Three types of point mutations of codon 12 were detected, with the mutation of GAT being observed most frequently. CONCLUSIONS: This study shows that development of nodular serrated adenomas may depend on the mutation of the K-ras codon 12 gene, whereas development of flat serrated adenomas may not. Additionally, serrated adenomas that occur in the rectum are closely related to the mutation of the K-ras codon 12 gene. K-ras mutations in serrated adenomas may be unaffected by the epigenetic silencing of O6-methylguanine-DNA methyltransferase by promoter hypermethylation.

Adenoma↗
PubMed2003

Frameshift mutations in caspase-5 and other target genes in leukemia and lymphoma cell lines having microsatellite instability.

Microsatellite instability (MSI) was examined in 49 lymphoid leukemia/lymphoma cell lines. Frameshift mutations within eight MSI target genes were analyzed in the 12 cell lines and nine childhood acute lymphoblastic leukemia (ALL) samples with MSI. Six cell lines (50%) showed mutations within the coding repeats of the BLM, caspase-5, TCF-4, and PTEN genes. No mutations were identified in the nine childhood ALL samples with MSI. This is the first report that describes mutations of these genes in hematological malignancies. Mutations, presumably caused by an abnormality of the DNA repair genes, may be selected for during the establishment of cell lines.

Adenosine Triphosphatases↗
PubMed2003

Mutations in the retinoblastoma-related gene RB2/p130 in adult T-cell leukaemia/lymphoma.

The retinoblastoma (Rb) family consists of the tumor suppressor Rb/p105 and related proteins p107 and Rb2/p130. Although the involvement of the RB/p105 gene in Adult T-cell leukaemia/lymphoma (ATL) has been studied, no mutational data is reported regarding the RB2/p130 gene in ATL. We screened for mutations of the RB2/p130 gene. Mutation was detected in 1 of 41 primary ATL sample. This is the first report describing mutation of the RB2/p130 gene in ATL, suggesting that RB2/p130 may be involved in the development of ATL, and may behave as a tumor suppressor gene in T lymphocytes.

Cell Cycle↗