Biomedical subjects

Yasuto Akiyama

Publications and source records attributed to Yasuto Akiyama.

7 recordsLinked to original sources

PubMed2026

Tumor Mutational Concordance and Recurrence Timing in Hepatocellular Carcinoma.

INTRODUCTION: In hepatocellular carcinoma (HCC), intrahepatic recurrence includes true recurrence from clonal relapse and multicentric recurrence from de novo tumorigenesis. Recurrence timing is used to distinguish these types; however, its accuracy remains unclear. This study aimed to classify recurrent tumors based on somatic mutational concordance and assess the validity of recurrence timing. METHODS: Whole-exome sequencing was performed on paired primary and recurrent HCC tumors from 49 patients enrolled in a prospective institutional omics project. Tumors with ≥ 10 shared somatic mutations were classified as true recurrence. Clinicopathological features, recurrence timing, driver mutation patterns, and survival outcomes were compared between recurrence types. Mutational concordance was quantified using shared variant counts and the Jaccard similarity index. RESULTS: Of the 49 patients, 22 (44.9%) showed true recurrence and 27 (55.1%) had multicentric recurrence. Multicentric recurrence tumors harbored no shared variants or only a single shared variant with the primary tumor. True recurrence was associated with significantly higher concordance in histological differentiation and Edmondson-Steiner grading and greater retention of CTNNB1, TP53, ARID1A, and KEAP1 mutations. The number of shared variants (median: 115 vs. 0, and p < 0.001) and the Jaccard index (median: 0.44 vs. 0.00 and p < 0.001) were significantly higher in the true recurrence group. Recurrence timing was inconsistently correlated with mutational concordance, although a 3-year cutoff yielded significant separation. CONCLUSION: Recurrence timing alone insufficiently reflects clonal relationships. Genomic profiling offers a reliable framework for distinguishing between recurrence types and guiding HCC management.

clonal relapse↗

PubMed2003

Structure and characterization of hamster IL-12 p35 and p40.

Complementary DNAs coding for two subunits of hamster interleukin-12 (IL-12), p35 and p40, were cloned from a hamster dendritic cell (DC) cDNA library. The cloning demonstrated that hamster IL-12 consisted of a p35 subunit with 216 amino acid (aa) residues and a p40 subunit with 327 aa. Structural comparison of hamster p35 and p40 at the protein level showed the highest homologies with each counterpart of sigmodon (hispid cotton rat). The gene expressions of hamster IL-12 p35 and p40 in bone marrow (BM) cells cultured in the presence of mouse granulocyte macrophage-colony-stimulating factor (mGM-CSF) and IL-4 were up-regulated during culture. Immunoblot analysis of 293 cells transfected with hamster p35 and p40 expression vectors suggested the presence of a covalently linked p35/p40 heterodimer. Furthermore, supernatant from the 293 cells transfected with both expression vectors induced the up-regulation of interferon-gamma (IFN-gamma) mRNA in hamster splenocytes, indicating that the p35/p40 heterodimer IL-12 protein present in the supernatant was functional. These results suggest that the vectors containing hamster IL-12 cDNA might be suitable tools for developing an immunotherapeutic approach against experimental cancer in a hamster model.

Amino Acid Sequence↗

PubMed2002

Antitumor effects induced by dendritic cell-based immunotherapy against established pancreatic cancer in hamsters.

Because the prognosis of patients with pancreatic cancer is very poor, development of a novel approach for treatment of this disease is vital. In the present study, we investigated the effect of dendritic cell (DC)-based immunotherapy against established syngeneic hamster pancreatic cancer named HPD1NR. Hamster enriched DCs were prepared from bone marrow (BM) by a culture for 7 days in the presence of mouse GM-CSF and mouse IL-4, and characterized by the expression of specific DC markers (DEC205, DC-SIGN) mRNA using in situ hybridization (ISH). DCs pulsed with tumor lysate and N-[1-(2,3-dioleoyloxy)propyl]-N,N,N-trimethylammonium methylsulfate (DOTAP) or DCs alone were injected s.c. weekly into HPD1NR-bearing hamsters three times. Tumor growth was significantly inhibited by 82% in hamsters treated with tumor lysate and DOTAP-pulsed DCs when compared with the PBS vehicle-treated group. These findings suggest that DC-based immunotherapy may be a useful approach for the treatment of pancreatic cancers.

Animals↗

PubMed2002

Peptidomics-based approach reveals the secretion of the 29-residue COOH-terminal fragment of the putative tumor suppressor protein DMBT1 from pancreatic adenocarcinoma cell lines.

Deleted in malignant brain tumors 1 is a putative tumor suppressor protein in brain, lung, esophageal,gastric, and colorectal cancer. Here we report the mass spectrometric identification of a 3335 Da peptide, which was found in serum-free conditioned medium from 5 of 15 pancreatic adenocarcinoma cell lines but not from 35 carcinoma cell lines and 2 nonmalignant pancreatic duct cell lines. The peptide was the 29 COOH-terminal amino acids from deleted in malignant brain tumors 1. It is suggested that the peptide is generated inside the cells by limited proteolysis and extracellularly secreted. Our peptidomics-based approach will help screen candidate marker peptides for a particular type of cancer.

Adenocarcinoma↗

PubMed2002

Identification of HLA-A24-restricted CTL epitope encoded by the matrix protein pp65 of human cytomegalovirus.

The activation of a specific cellular immune response against human cytomegalovirus (CMV) is an important key factor to solving CMV infection after bone marrow transplantation (BMT). In the present study, our purpose was to identify the HLA-A24-restricted cytotoxic T cell (CTL) epitope from the CMV immunogenic matrix protein pp65. We selected five CMV pp65 peptides with HLA-A24 binding motif from the HLA peptide binding predictions web site. Peptide binding assay was performed using biotinylated HLA-A24-restricted MAGE-1 peptide as a reference peptide and transporter associated with antigen processing (TAP)-deficient T2-A24 cells expressing high level of HLA-A24 protein as target cells. After co-incubation of biotinylated MAGE-1 and titrated amounts of competitor peptides with T2-A24 cells, the binding of each peptide was analyzed on a flow cytometer. Peptide binding assay showed that three out of five peptides derived from CMV pp65 bound to T2-A24 cells with various affinity levels. CTL induction assay using peptide-pulsed DC derived from eight HLA-A24(+) donors revealed that the peptide (QYDPVAALF) with the highest affinity was able to elicit potent CTLs which killed peptide-pulsed TISI cells. These CTLs were found to show the killing activity against human fibroblast cells transduced with both HLA-A*2402 and CMV pp65 cDNAs, and CMV-infected HLA-A24(+) fibroblast cells. These results suggested that the peptide (QYDPVAALF) is one of HLA-A24-restricted CTL epitope derived from CMV pp65 protein and may be of therapeutic value in peptide-based vaccines against CMV infection in BMT patients.

Antibodies, Monoclonal↗

PubMed2002

Hamster DEC-205, its primary structure, tissue and cellular distribution.

DEC-205, a putative antigen uptake receptor, belongs to a family of transmembrane C-type lectins. This molecule is known to be one of the most authentic markers for the lineage of dendritic cells. In the present study, we determined the primary structure, tissue distribution and cellular localization of hamster DEC-205. The multi-domain structure of mouse and human DEC-205 was completely conserved in hamster with the overall identity of approximately 80%. DEC-205 transcripts were detected in the thymus and bone marrow cells cultured in the presence of mouse granulocyte macrophage colony-stimulating factor and interleukin-4 in which the DEC-205 expression was up-regulated in the course of cultures. Hamster DEC-205 was mainly detected on cell membrane and shown to mediate the uptake of flourescein isothiocyanate-conjugated ovalbumin. DEC-205 is a highly conserved molecule across the species suggesting its fundamental role in the immune system.

Amino Acid Sequence↗

PubMed2002

Retroviral-mediated IL-12 gene transduction into human CD34+ cell-derived dendritic cells.

Genetically modified dendritic cells (DCs) with Th1 type cytokine genes are useful for activating anti-tumor immune response. We made human interleukin (IL)-12 p70 gene-transduced DCs generated from CD34+ progenitor cells using a retrovirus system and investigated the function of IL-12-producing DCs. We used the pMX retroviral vector and made cytokine gene-containing viral vectors referred to as GFP pMX and hIL-12 pMX. Supernatants from BOSC23 cells transfected with GFP pMX and hIL-12 pMX were harvested and used for transfection of DC. Cord blood CD34+ cells were incubated with supernatants containing retrovirus for 48 h with cytokines such as IL-3, IL-6, SCF, Flt3 ligand (FL), bFGF and IGF-I. The cells were cultured for 12 days in the presence of GM-CSF, SCF, FL, IL-4 and TNF-alpha to get mature DC-enriched population. Analysis of surface marker on DCs and allogeneic MLR assay were also performed. After a 14-day culture, 60-70% of cultured CD34+ cells were DC marker (CD1a, DEC205) positive. The IL-12 p70 protein levels in supernatant of DC-GFP and DC-hIL-12 were 0.2 ng/ml and 53 ng/ml/5 x 10(5) DCs for 72 h, respectively. The addition of CH296 fibronectin fragment (FN) increased 3-fold IL-12 gene transduction efficiency into DCs. MLR assay showed that IL-12-producing DC exhibited more potent T cell growth-stimulating activity compared with GFP-DC. These results suggested that genetically modified CD34+ cell-derived DCs with human IL-12 gene are fully efficient in T cell priming, and could be a good tool for effective cancer immunotherapy.

Antigens, CD1↗