Biomedical subjects

Kazuhiko Ochiai

Publications and source records attributed to Kazuhiko Ochiai.

7 recordsLinked to original sources

PubMed2005

Analysis of genetic variations in the exon 27 region of the canine BRCA2 locus.

Mammary tumors are the most common tumor type in women as well as in female dogs. The BRCA2 gene encodes a large nuclear protein that is involved in DNA repair, and mutations in the human BRCA2 confer an increased risk of female mammary tumors. The BRCA2 protein acts as a tumor suppressor, and inactivation of BRCA2 by loss of heterozygosity is implicated in mammary carcinogenesis. In this study, to establish an appropriate polymorphic marker for loss of heterozygosity analysis of the canine BRCA2, we analyzed the genomic sequences of the exon 27 regions of 30 mammary-tumor-bearing and 21 tumor-free dogs. In addition to 10204ins/delAAA, which is the only polymorphism previously identified for the canine BRCA2 locus, we discovered four novel single nucleotide polymorphisms. The analysis of these five polymorphisms revealed the presence of four allele types. Since 10204ins/delAAA was the most common of the five polymorphisms identified, we developed a PCR-based assay method to assay for this polymorphism. We believe that this method is valuable for loss of heterozygosity analysis of the canine BRCA2 gene in tumor pathogenesis.

Animals↗

PubMed2005

Insertion/deletion polymorphism in the BRCA2 nuclear localization signal.

Mutations in human BRCA2 confer an increased risk of female breast cancer. In this study, we found a novel insertion/deletion polymorphism (10204insAAA causing amino acid change M3332IK) in canine BRCA2, which is located in the putative second nuclear localization signal (NLS2) and C-terminal Rad51-binding region. The nuclear localization of the insAAA C-terminus was more efficient than localization of the delAAA sequence when NLS1 was mutated. Strong, comparable Rad51 binding was observed for both the insAAA and delAAA C-termini. Dogs with the insertion/deletion polymorphism will provide a new model for studying the function of BRCA2.

Alleles↗

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

Overexpression of HER-2/neu is not a risk factor in ovarian clear cell adenocarcinoma.

OBJECTIVE: To evaluate the significance of the expression of HER-2/neu as a prognostic factor, we retrospectively examined its overexpression rates chiefly in ovarian clear cell adenocarcinoma (CCA) and their relationships with FIGO stage, lymph node metastasis, and prognosis. METHODS: In addition to 90 specimens of CCA (stage I, 52; stage II, 7; stage III, 28; stage IV, 3) obtained between 1987 and 2002, 19 specimens of serous adenocarcinoma (S), 19 specimens of mucinous adenocarcinoma (M), and 19 specimens of endometrioid adenocarcinoma (E) collected at initial surgery were studied. The expression of HER-2/neu was immunohistologically scored on a scale of 0 to 3+ according to the HercepTest scoring system, and 2+ and 3+ were regarded as overexpression. The relationship between HER-2/neu overexpression and outcome was evaluated by the Kaplan-Meier method and the log-rank test. The relationship with advanced-stage cancer was analyzed by Fisher's exact test. The relationships with lymph node metastasis and histologic types were compared by the t test. RESULTS: The rate of HER-2/neu overexpression in CCA was 45.6% (0, 1+, 2+, and 3+ in 14, 35, 36, and 5 cases, respectively), and no differences in the overexpression rate were noted among histologic types: 52.7% in S, 42.1% in M, and 26.4% in E. In CCA, no association was observed between HER-2/neu overexpression and cumulative survival rate (P = 0.5708), FIGO stage (P = 0.5147), or lymph node metastasis (P = 0.3624). CONCLUSION: The absence in CCA of an association between HER-2/neu overexpression and outcome, stage, or lymph node metastasis indicates that HER-2/neu overexpression is not a prognostic risk factor.

Adenocarcinoma, Clear Cell↗

PubMed2003

Association of the nucleocapsid protein of the Seoul and Hantaan hantaviruses with small ubiquitin-like modifier-1-related molecules.

We performed yeast two-hybrid screening of a human kidney cell cDNA library to study the biological role of the hantavirus nucleocapsid protein (NP). We found that Seoul virus (SEOV) and Hantaan virus (HTNV) NPs were associated with small ubiquitin-like modifier (SUMO)-1-interacting proteins PIAS1, PIASxbeta, HIPK2, CHD3, and TTRAP, which interacted with the SUMO-1 conjugating enzyme (Ubc-9) and SUMO-1 in the yeast two-hybrid assay. Interactions between the HIPK2, CHD3, and TTRAP proteins and SEOV NP were also shown in a mammalian two-hybrid assay. However, there was no interaction between PIAS proteins and NP, which was probably due to the inhibitory effect of PIAS on transcription in the mammalian two-hybrid assay. Nevertheless, a co-expression experiment suggested the existence of a PIAS-NP interaction in the cytoplasm. The region spanning amino acids 100-125 of SEOV NP, which represents a critical region for NP-NP polymerization, was found to be responsible for the interaction with SUMO-1-related molecules in both the yeast and mammalian two-hybrid assays. These results add to the information on interactions of hantavirus NP and host cellular proteins.

Animals↗

PubMed2003

Preoperative diagnosis of malignant transformation arising from mature cystic teratoma of the ovary.

OBJECTIVE: Mature cystic teratoma of the ovary (MCT) is the most common ovarian cystic disease in young women. Although it is a rare occurrence, some cases develop malignant transformation (MT), which results in serious consequences. However, MT is currently diagnosed only by postoperative pathology in most cases. We have conducted a retrospective study in an attempt to seek the factor to diagnose MT from MCT prior to surgery. STUDY DESIGN: Eighty-one patients with MCT and 39 patients with MT were entered in this study. Patient's age, tumor size, serum CEA levels, and serum SCC levels were tested by the Mann-Whiteney U test. Sensitivity and specificity were calculated, and the most suitable point was searched from the receiver operating characteristic (ROC) curve. RESULTS: A significant difference was recognized in both patient's age and serum SCC level (P < 0.0001). For a patient less than 40 years old, the sensitivity to MT was 95%, and then the specificity to MT was 63%. When the standard value of the SCC level of the serum was established as 2.5 ng/ml, the sensitivity to MT was 80% and the specificity to MT was 94%. We apply two criteria at the same time (serum SCC levels less than 2.5 ng/ml and patient's age less than 40 years old). The sensitivity for MT was 77% and specificity was 96%. CONCLUSION: The combination of the two criteria which are patient's age (under 40 years old) and serum SCC level (under 2.5 ng/ml) was considered a suitable marker for differential diagnosis between MCT and MT. Further the possibility for MT is quite low when the patient is 39 years old or younger and the serum SCC level is under 2.5 ng/ml. When any patient satisfies this condition, laparoscopic surgery will be able to be planned safely.

Adult↗

PubMed2003

Properties of the tumor suppressor gene brca2 in the cat.

Mammary tumors are common in cats. As mutations in human Brca2 confer an increased risk of breast cancer, the full-length cDNA of the feline homologue of Brca2 was sequenced to obtain a basis for studying the relationship between its function and susceptibility to mammary tumors. The feline Brca2 cDNA is 10 kb long, and encodes 3,371 amino acids. The amino acid sequence of feline Brca2 shares low homology with the Brca2 of other mammals, e.g., 53% homology with the murine protein. Analysis of the expression pattern of the feline Brca2 gene revealed that, as previously reported for other mammals, it is transcribed in various tissues, including the mammary gland.

Animals↗