Biomedical subjects

Akira Hirasawa

Publications and source records attributed to Akira Hirasawa.

At least 19 recordsLinked to original sources

PubMed2026

Updated ENIGMA recommendations for reporting germline variants in cancer susceptibility genes and their translation into twenty languages.

Genetic testing for cancer susceptibility underpins precision cancer prevention and care. Gaps in the healthcare providers' genetic literacy and an ambiguous lexicon for variant description may hinder proper delivery and clinical application of consistently trustworthy test results. The Evidence-based Network for the Interpretation of Germline Mutant Alleles (ENIGMA) international consortium supports controlled terminology and recommends a framework for reporting germline variants in cancer susceptibility genes, using breast cancer as an exemplar. Moving forward towards terminological coherence across disciplines and borders, the ENIGMA Clinical Working Group launched a multinational effort to release consortium-approved translations of the published recommendations. The herein reported Vocabulary Translation Project offered an opportunity to reappraise and align the reference text to the recent BRCA1 and BRCA2 specifications to the American College of Medical Genetics and Genomics/Association for Molecular Pathology rules by the ENIGMA Variant Curation Expert Panel and to highlight country-specific differences in breast cancer risk assessment and management. The updated recommendations and their 20 translations are now provided as easy to handle documents, covering 11 of the most widely spoken languages in the world. They will contribute to minimised erroneous inferences, more informed decision-making, improved health outcomes and equity in the use of genetic testing for cancer predisposition and in translational oncology.

Humans↗

PubMed2007

Relationship of aberrant DNA hypermethylation of CHFR with sensitivity to taxanes in endometrial cancer.

The relationship of aberrant DNA hypermethylation of cell cycle checkpoint genes with the sensitivity of cancer cells to anticancer drugs is a question of current interest. In this study, we investigated the relationship between aberrant hypermethylation of the CHFR (checkpoint with forkhead-associated and ring finger) mitotic checkpoint gene and sensitivity to taxanes in endometrial cancer. Methylation-specific PCR (MSP) indicated aberrant hypermethylation of CHFR in 12.0% (6/50) of endometrial cancer specimens, and suggested that aberrant hypermethylation is significantly more frequent in poorly differentiated adenocarcinoma (G3) (p<0.05). Of six culture cell lines, SNG-II and HEC108 cells showed aberrant hypermethylation and reduced expression of CHFR. These cells had high sensitivity to taxanes but became resistant after demethylation. Cancer specimens with aberrant hypermethylation of CHFR also exhibited high sensitivity to taxanes. To our knowledge, this study is the first to examine aberrant hypermethylation of CHFR in endometrial cancer, and our results suggest that the methylation status of CHFR may be a new molecular index that will allow design of personalized treatment in endometrial cancer. This may be particularly important in poorly differentiated adenocarcinoma (G3), which is known to have a poor prognosis.

Adult↗

PubMed2006

Glucocorticoid-induced alternative promoter usage for a novel 5' variant of granzyme A.

Glucocorticoids exert diverse physiological functions through transcriptional regulation of genes including granzyme A (GZMA). GZMA is one of the apoptotic effectors localized in cytotoxic T lymphocytes and is considered to mediate glucocorticoid-induced apoptosis of human leukemia 697 cells. In the present study, we identified a novel 5' variant transcript of GZMA in dexamethasone (DEX)-treated 697 cells. We designated this novel transcript as GZMAbeta. The transcription of GZMAbeta starts at 290 bp downstream of the first intronic glucocorticoid response element (GRE). Chromatin immunoprecipitation assay showed that glucocorticoid receptor (GR) binds to the intronic GRE in a DEX-dependent manner. Luciferase assay and RT-PCR also showed that DEX induces GZMAbeta transcription mediated by GR binding to the intronic GRE. Our results show that there exist at least two transcripts in human GZMA, whose expression is differentially regulated by glucocorticoid.

5' Untranslated Regions↗

PubMed2006

Monitoring ligand-mediated internalization of G protein-coupled receptor as a novel pharmacological approach.

Agonist activation of a G protein-coupled receptor (GPCR) results in the redistribution of the receptor protein away from the cell surface into internal cellular compartments through a process of endocytosis known as internalization. Visualization of receptor internalization has become experimentally practicable by using fluorescent reagents such as green fluorescent protein (GFP). In this study, we examined whether the ligand-mediated internalization of a GPCR can be exploited for pharmacological evaluations. We acquired fluorescent images of cells expressing GFP-labeled GPCRs and evaluated the ligand-mediated internalization quantitatively by image processing. Using beta2-adrenoceptor and vasopressin V1a receptor as model GPCRs that couple to Gs and Gq, respectively, we first examined whether these GFP-tagged GPCRs exhibited appropriate pharmacology. The rank order of receptor internalization potency for a variety of agonists and antagonists specific to each receptor corresponded well with that previously observed in ligand binding studies. In addition to chemical ligand-induced internalization, this cell-based fluorescence imaging system successfully monitored the internalization of the proton-sensing GPCR TDAG8, and that of the free fatty acid-sensitive GPCR GPR120. The results show that monitoring receptor internalization can be a useful approach for pharmacological characterization of GPCRs and in fishing for ligands of orphan GPCRs.

Animals↗

PubMed2006

Developmental aberrations of liver gene expression in bovine fetuses derived from somatic cell nuclear transplantation.

Cloning by somatic cell nuclear transfer (NT) has been accomplished. However, the process itself is inefficient since most clones die before birth and survivors often display various anomalies. In an effort to determine global expression profiles of developmentally regulated liver genes in NT bovine fetuses, we employed a custom-made bovine liver complementary DNA (cDNA) microarray. The NT fetuses in early pregnancy were derived from cumulus cells as the nuclear donor cells. Normal fetuses were derived from in vitro fertilization (IVF) and artificial insemination (AI). Gene expression levels in NT, IVF, and AI fetal livers were obtained by comparing individual fetal liver samples with that of adult liver of nonpregnant cycling cows. Statistical analyses of the expression data showed widespread dysregulation of developmentally important genes in the three NT fetuses examined. It was found that the number of dysregulated genes was within a range of 3.5-7.7% of the tested genes in the NT fetal livers. The analyses revealed that one NT fetus was markedly different in liver gene expression profile from the other two NT fetal livers in which the expression profiles were highly correlated. Thus, our findings demonstrate that widespread dysregulation of liver genes occurs in the developing liver of NT bovine fetuses. It is possible that inappropriate genomic reprogramming after NT is a key factor associated with abnormal gene expressions in the livers of NT fetuses, whereas distinct expression patterns between the fellow cloned fetuses likely have resulted from variable epigenetic status of the donor nuclei.

Animals↗

PubMed2006

Relationship of the aberrant DNA hypermethylation of cancer-related genes with carcinogenesis of endometrial cancer.

Epigenetic abnormalities including the aberrant DNA hypermethylation of the promoter CpG islands play a key role in the mechanism of gene inactivation in cell carcinogenesis. To identify the genes associated with aberrant DNA hypermethylation in endometrial carcinogenesis, we studied the hypermethylation of the promoter regions of five genes: hMLH1, APC, E-cadherin, RAR-beta and p16. The frequencies of aberrant hypermethylation were 40.4% (21/52) in hMLH1, 22% (11/50) in APC, 14% (7/50) in E-cadherin, and 2.3% (1/44) in RAR-beta in endometrial cancer specimens. No aberrant DNA methylation was found in p16. In atypical endometrial hyperplasia, the frequencies of aberrant methylation were 14.3% (2/14) in hMLH1 and 7.3% (1/14) in APC, whereas normal endometrial cells showed no aberrant hypermethylation of any of the five genes. The high frequencies of the aberrant DNA hypermethylation of hMLH1, APC and E-cadherin suggest that the methylation of the DNA mismatch repair and Wnt signal-related genes may be associated with endometrial carcinogenesis.

DNA Methylation↗

PubMed2005

Free fatty acids administered into the colon promote the secretion of glucagon-like peptide-1 and insulin.

We examined whether free fatty acids (FFAs) promote glucagon-like peptide-1 (GLP-1) secretion when administered into the intestinal tract. We found that an unsaturated long-chain FFA, alpha-linolenic acid (alpha-LA), resulted in increased plasma GLP-1 and insulin levels when administered into the colon. Such stimulatory effects were not apparent with either vehicle or a saturated middle-chain FFA, octanoic acid (OA). Concomitant with GLP-1 secretion, the administration of alpha-LA, but not vehicle or OA, also resulted in a significant increase in the population of pERK positive cells within the GLP-1 positive cells of the colonic mucosa. Moreover, colonic administration of alpha-LA into normal C3H/He mice caused a reduction in plasma glucose levels, as well as in type 2 diabetic model NSY mice. Our results indicate that the in vivo colonic administration of alpha-LA promotes secretion of incretin GLP-1 by activating the ERK pathway in L-cells and thereby enhances the secretion of insulin.

Animals↗

PubMed2005

Inhibition of protein kinase CK2 prevents the progression of glomerulonephritis.

Glomerulonephritis (GN) is a progressive inflammation that may be caused by a variety of underlying disorders. It is the primary cause of chronic renal failure and end-stage renal disease, which require dialysis and transplantation worldwide. Immunosuppressive therapy has been used to treat GN clinically, but this treatment has had insufficient therapeutic effects. Here, we show that protein kinase CK2 is a key molecule in the progression of GN. cDNA microarray analysis identified CK2alpha, the catalytic subunit of CK2, as a GN-related, differentially expressed gene. Overexpression of CK2alpha was noted in the proliferative glomerular lesions in rat GN models and in renal biopsy specimens from lupus nephritis or IgA nephropathy patients. Administration of either antisense oligodeoxynucleotide against CK2alpha or low molecular weight CK2-specific inhibitors effectively prevented the progression of renal pathology in the rat GN models. The resolution of GN by CK2 inhibition may result from its suppression of extracellular signal-regulated kinase-mediated cell proliferation, and its suppression of inflammatory and fibrotic processes that are enhanced in GN. Our results show that CK2 plays a critical role in the progression of immunogenic renal injury, and therefore, CK2 is a potential target for GN therapy.

Analysis of Variance↗

PubMed2005

Transcriptional regulation of connective tissue growth factor by sphingosine 1-phosphate in rat cultured mesangial cells.

Connective tissue growth factor (CTGF) is induced by transforming growth factor-beta (TGF-beta) via Smad activation in mesangial cells. We recently reported that sphingosine 1-phosphate (S1P) induces CTGF expression in rat cultured mesangial cells. However, the mechanism by which S1P induces CTGF expression is unknown. The present study revealed that S1P-induced CTGF expression is mediated via pertussis toxin-insensitive pathways, which are involved in the activation of small GTPases of the Rho family and protein kinase C. We also showed by luciferase reporter assays and chromatin immunoprecipitation that S1P induces CTGF expression via Smad activation as TGF-beta does.

Animals↗

PubMed2005

Bile acids promote glucagon-like peptide-1 secretion through TGR5 in a murine enteroendocrine cell line STC-1.

Bile acids play essential roles in the absorption of dietary lipids and in the regulation of bile acid biosynthesis. Recently, a G protein-coupled receptor, TGR5, was identified as a cell-surface bile acid receptor. In this study, we show that bile acids promote glucagon-like peptide-1 (GLP-1) secretion through TGR5 in a murine enteroendocrine cell line STC-1. In STC-1 cells, bile acids promoted GLP-1 secretion in a dose-dependent manner. As STC-1 cells express TGR5 mRNA, we examined whether bile acids induce GLP-1 secretion through TGR5. RNA interference experiments showed that reduced expression of TGR5 resulted in reduced secretion of GLP-1. Furthermore, transient transfection of STC-1 cells with an expression plasmid containing TGR5 significantly enhanced GLP-1 secretion, indicating that bile acids promote GLP-1 secretion through TGR5 in STC-1 cells. Bile acids induced rapid and dose-dependent elevation of intracellular cAMP levels in STC-1 cells. An adenylate cyclase inhibitor, MDL12330A, significantly suppressed bile acid-promoted GLP-1 secretion, suggesting that bile acids induce GLP-1 secretion via intracellular cAMP production in STC-1 cells.

Adenylyl Cyclase Inhibitors↗

PubMed2005

Free fatty acids inhibit serum deprivation-induced apoptosis through GPR120 in a murine enteroendocrine cell line STC-1.

Free fatty acids (FFAs) provide an important energy source and also act as signaling molecules. FFAs are known to exert a variety of physiological responses via their G protein-coupled receptors (GPCRs), such as the GPR40 family. Recently, we identified a novel FFA receptor, GPR120, that promotes secretion of glucagon-like peptide-1 (Hirasawa, A., Tsumaya, K., Awaji, T., Katsuma, S., Adachi, T., Yamada, M., Sugimoto, Y., Miyazaki, S., and Tsujimoto, G. (2005) Nat. Med. 11, 90-94). Here we showed that FFAs inhibit serum deprivation-induced apoptosis of murine enteroendocrine STC-1 cells, which express two types of GPCRs, GPR120 and GPR40, for unsaturated long chain FFA. We first found that linolenic acid potently activated ERK and Akt/protein kinase B (Akt) in STC-1 cells. ERK kinase inhibitors significantly reduced the anti-apoptotic effects of linolenic acid. Inhibitors for phosphatidylinositol 3-kinase (PI3K), a major target of which is Akt, significantly reduced the anti-apoptotic effects. Transfection of STC-1 cells with the dominant-negative form of Akt also inhibited the anti-apoptotic effect. These results suggested that the activation of ERK and PI3K-Akt pathways is required for FFA-induced anti-apoptotic effects on STC-1 cells. Transient transfection of STC-1 cells with GPR120 cDNA, but not GPR40 cDNA, enhanced inhibition of caspase-3 activation. RNA interference experiments showed that reduced expression of GPR120, but not GPR40, resulted in reduced ERK activation and reduced effects of FFAs on caspase-3 inhibition. Collectively, these results demonstrated that FFAs promote the activation of ERK and PI3K-Akt pathways mainly via GPR120, leading to the anti-apoptotic effect of STC-1 cells.

Animals↗

PubMed2005

Clinicopathologic manifestations of early-onset endometrial cancer in Japanese women with a familial predisposition to cancer.

AIM: The number of patients under 40 years of age with early-onset endometrial cancer is on the rise in Japan. Preservation of fertility in younger patients is a critical issue. In order to examine the clinical and pathological characteristics of these patients, cases of early-onset endometrial cancer at a single hospital were analyzed. METHODS: Seventy-four patients were diagnosed with endometrial cancer before age 40 and included in this study after obtaining informed consent. RESULTS: The clinical characteristics included a significantly higher prevalence of complications such as nulligravidity and nulliparity (P < 0.001). Pathologically, well-differentiated endometrial carcinoma was significantly more frequent (P = 0.011). The 5-year survival rate was high (98.7%). In regards to the relationship between clinicopathological features and grade of differentiation, the prevalence of G2 and G3 carcinoma was not significantly lower (P = 0.24) in patients with obesity. Although the frequency of G2 and G3 carcinoma was significantly higher in patients with a family history of cancer (P = 0.02), their 5-year survival rate was not significantly lower (100%). CONCLUSION: This study found that these two types of early-onset endometrial cancer are clinicopathologically different. In patients with a family history of cancer, their body mass index was lower, and the frequency of G2 and G3 carcinoma was significantly higher, but their 5-year disease-free survival rate was not significantly lower.

Adenocarcinoma↗

PubMed2005

[Diagnostic significance of tumor markers for gynecologic malignancies].

Gynecologic malignancies include ovarian cancer, uterine cervical cancer, endometrial cancer, and trophoblastic neoplasms. With ovarian tumors, due to their location within the abdominal cavity, it is difficult to make a preoperative pathological diagnosis of cancer without laparotomy. From this point of view, the use of tumor markers that consist of carbohydrate antigens, such as CA 125, in addition to diagnostic imaging are useful in the diagnosis of ovarian cancer. SCC antigen, a marker for squamous cell carcinoma, is clinically useful in the management of advanced cervical cancer. At present, there are no useful tumor markers for endometrial cancer that exhibit both high sensitivity and specificity, although CA 125 is often used in clinical practice. Finally, human chorionic gonadotropin (hCG) serves as an ideal tumor marker for trophoblastic disease; however, the incidence of trophoblastic neoplasms has decreased dramatically with the incorporation of strict clinical management of post-molar disease as well as with the overall decrease in the number of pregnancies.

Antigens, Neoplasm↗

PubMed2004

Free fatty acids regulate gut incretin glucagon-like peptide-1 secretion through GPR120.

Diabetes, a disease in which the body does not produce or use insulin properly, is a serious global health problem. Gut polypeptides secreted in response to food intake, such as glucagon-like peptide-1 (GLP-1), are potent incretin hormones that enhance the glucose-dependent secretion of insulin from pancreatic beta cells. Free fatty acids (FFAs) provide an important energy source and also act as signaling molecules in various cellular processes, including the secretion of gut incretin peptides. Here we show that a G-protein-coupled receptor, GPR120, which is abundantly expressed in intestine, functions as a receptor for unsaturated long-chain FFAs. Furthermore, we show that the stimulation of GPR120 by FFAs promotes the secretion of GLP-1 in vitro and in vivo, and increases circulating insulin. Because GLP-1 is the most potent insulinotropic incretin, our results indicate that GPR120-mediated GLP-1 secretion induced by dietary FFAs is important in the treatment of diabetes.

Animals↗

PubMed2004

cDNA microarray analysis of bovine embryo gene expression profiles during the pre-implantation period.

BACKGROUND: After fertilization, embryo development involves differentiation, as well as development of the fetal body and extra-embryonic tissues until the moment of implantation. During this period various cellular and molecular changes take place with a genetic origin, e.g. the elongation of embryonic tissues, cell-cell contact between the mother and the embryo and placentation. To identify genetic profiles and search for new candidate molecules involved during this period, embryonic gene expression was analyzed with a custom designed utero-placental complementary DNA (cDNA) microarray. METHODS: Bovine embryos on days 7, 14 and 21, extra-embryonic membranes on day 28 and fetuses on days 28 were collected to represent early embryo, elongating embryo, pre-implantation embryo, post-implantation extra-embryonic membrane and fetus, respectively. Gene expression at these different time points was analyzed using our cDNA microarray. Two clustering algorithms such as k-means and hierarchical clustering methods identified the expression patterns of differentially expressed genes across pre-implantation period. Novel candidate genes were confirmed by real-time RT-PCR. RESULTS: In total, 1,773 individual genes were analyzed by complete k-means clustering. Comparison of day 7 and day 14 revealed most genes increased during this period, and a small number of genes exhibiting altered expression decreased as gestation progressed. Clustering analysis demonstrated that trophoblast-cell-specific molecules such as placental lactogens (PLs), prolactin-related proteins (PRPs), interferon-tau, and adhesion molecules apparently all play pivotal roles in the preparation needed for implantation, since their expression was remarkably enhanced during the pre-implantation period. The hierarchical clustering analysis and RT-PCR data revealed new functional roles for certain known genes (dickkopf-1, NPM, etc) as well as novel candidate genes (AW464053, AW465434, AW462349, AW485575) related to already established trophoblast-specific genes such as PLs and PRPs. CONCLUSIONS: A large number of genes in extra-embryonic membrane increased up to implantation and these profiles provide information fundamental to an understanding of extra-embryonic membrane differentiation and development. Genes in significant expression suggest novel molecules in trophoblast differentiation.

Animals↗

PubMed2004

Involvement of overexpressed wild-type BRAF in the growth of malignant melanoma cell lines.

Comparative genomic hybridization (CGH) using 40 cell lines derived from malignant melanomas (MMs) revealed frequent amplification at 7q33-q34 containing BRAF gene, which often is mutated in MM. We found this gene to be amplified to a remarkable degree in the MM cell lines that exhibited high-level gains at 7q33-q34 in CGH. Among 40 cell lines, the eight lines that revealed neither BRAF nor NRAS mutations showed even higher levels of BRAF mRNA expression than the 32 mutated lines, although DNA amplification at 7q33-q34 was not detected in every lines overexpressing BRAF. MM cells that carried wild-type BRAF and NRAS showed constitutive overexpression of B-Raf protein and phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2), even after serum starvation. Not only downregulation of the endogenously overexpressed wild-type B-Raf by antisense oligonucleotide but also a treatment with an inhibitor of mitogen-activated protein kinase kinase (MAPKK, MEK) reduced phosphorylated ERK1/2 and cell growth, whereas the exogenously expressed wild-type B-Raf promoted cell growth in MM cells. Our results provide the evidence that overexpression of wild-type B-Raf, in part but not always as a result of gene amplification, is one of the mechanisms underlying constitutive activation of the MAPK pathway that stimulates growth of MM cells.

Blotting, Western↗

PubMed2004

Gene expression profile in experimental mesangial proliferative glomerulonephritis.

We analyzed gene expression in rat anti-Thy1 antibody-induced glomerulonephritis by using the cDNA microarray method. Ninety-seven genes that differed by more than 1.5-fold intensity in comparison with the controls were selected. Cluster analysis showed that the expression of genes associated with inflammation reached maximum levels at 24 h, while genes involved in the development of fibrosis increased at 7 days after injection. Microarray analysis of animal disease models may be a powerful approach for understanding the gene expression programs that underlie these disorders.

Animals↗

PubMed2004

Carvedilol selectively inhibits oscillatory intracellular calcium changes evoked by human alpha1D- and alpha1B-adrenergic receptors.

BACKGROUND: Increasing evidence from clinical trials indicates that carvedilol, an antagonist of alpha1- and beta-adrenergic receptors (ARs), provides an effective treatment for chronic heart failure, whereas nonselective alpha1-AR blockade has an adverse outcome in this disease. It is, however, not clear whether carvedilol exhibits a subtype-dependent impact on three distinct alpha1-adrenergic receptors (alpha1-ARs). METHODS AND RESULTS: We determined binding properties of human ARs for carvedilol using HEK293 human embryonic kidney cells expressing a single AR subtype. Our results showed that the affinities of alpha1D-AR and alpha1B-AR for carvedilol are higher than that of the beta1-AR subtype, a major target in heart failure treatment. The affinity rank order and pKi values of ARs for carvedilol were as follows: alpha1D-AR (8.9)>alpha1B-AR (8.6)>beta1-AR (8.4)>beta2-AR (8.0)>alpha1A-AR (7.9)?alpha2C-AR (5.9)>alpha2B-AR (5.5)>alpha2A-AR (5.3). Furthermore, temporal kinetics of intracellular calcium signaling mediated via alpha1D- and alpha1B-ARs, but not via alpha1A-AR (P<0.01), showed oscillatory patterns with frequencies ranging from 0.3 to 3 per minute in human smooth muscle and HEK293 cells, which were inhibited by the therapeutic concentrations of carvedilol (10 nM) in a subtype-dependent manner. When oscillatory alpha1B-AR and non-oscillatory alpha1A-AR were co-expressed and heteromer receptors were detected with bioluminescence resonance energy transfer and co-immunoprecipitation, carvedilol suppressed only oscillatory component of global cytosolic free calcium change. CONCLUSIONS: These results indicate that in addition to beta-ARs, receptor inhibition by carvedilol is directed to alpha1-ARs, preferably to alpha1D- and alpha1B-AR-mediated signaling events, including intracellular calcium oscillations in vascular smooth muscle.

Adrenergic Antagonists↗