Biomedical subjects

R Kanamaru

Publications and source records attributed to R Kanamaru.

At least 37 records · Page 2Linked to original sources

PubMed1998

Cloning and functional analysis of human p51, which structurally and functionally resembles p53.

The p53 tumor suppressor gene, which is induced by DNA damage and/or stress stimuli, causes cells to undergo G1-arrest or apoptotic death; thus it plays an essential role in human carcinogenesis. We have searched for p53-related genes by using degenerate PCR, and have identified two cDNA fragments similar to but distinct from p53: one previously reported, p73, and the other new. We cloned two major splicing variants of the latter gene and named these p51A and p51B (a human homologue of rat Ket). The p51A gene encodes a 448-amino-acid protein with a molecular weight of 50.9 kDa; and p51B, a 641-amino-acid protein with a molecular weight of 71.9 kDa. In contrast with the ubiquitous expression of p53, expression of p51 mRNA was found in a limited number of tissues, including skeletal muscle, placenta, mammary gland, prostate, trachea, thymus, salivary gland, uterus, heart and lung. In p53-deficient cells, p51A induced growth-suppression and apoptosis, and upregulated p21waf-1 through p53 regulatory elements. Mutations in p51 were found in some human epidermal tumors.

Alternative Splicing↗

PubMed1998

Astrocytoma and B-cell lymphoma development in a man with a p53 germline mutation.

We report a case with a germline mutation of the p53 gene develpoing both a non-Hodgkin's lymphoma and an astrocytoma. The astrocytoma could be cured by two operations and combined chemotherapy but 33 months after the onset of the disease, he suffered from a diffuse, large cell centroblastic malignant lymphoma of B-cell lineage. In spite of clear rearranged fragments observed with IgH and c-MYC gene probes, we could not diagnose a Burkitt's lymphoma morphologically. The malignant lymphoma was chemoresistant and the patient died of multi-organ failure. He was confirmed to have a germline mutation of the p53 gene by analysis of c-DNA from peripheral lymphocytes and loss of heterozygosity (LOH) of p53 was evident in the lymphoma. The results were suggestive of the Li-Fraumeni syndrome (LFS), a rare autosomal dominantly inherited syndrome with a germline mutation of p53 gene and diverse malignancies, but this could not be confirmed in the present case. Alternatively, a de novo mutation could have been involved.

Abdominal Neoplasms↗

PubMed1998

An early phase II study of a 3-hour infusion of paclitaxel for advanced gastric cancer.

The purpose of this study was to evaluate the feasibility and efficacy of 3-hour infusional paclitaxel for the treatment of advanced gastric cancer with measurable metastatic diseases. Eligibility criteria included no more than one regimen of prior chemotherapy. Paclitaxel was administered as an intravenous infusion over 3 hours at a dose of 210 mg/m2 every 3 weeks. Premedication of dexamethazone, ranitidine, and diphenhydramine were given to all patients. Sixteen patients were registered in the study. One patient did not receive paclitaxel because of gastrointestinal bleeding before the initiation of drug's administration. Thirteen of the 15 patients had a prior history of chemotherapy. Although 10 patients (67%) developed grade 4 neutropenia, no serious infections occurred during the study. Nonhematologic toxicities were generally mild. Three (20%) patients who showed evidences of resistance to the previous intensive regimen achieved a partial response. In conclusion, a 3-hour infusion of paclitaxel is a safe and promising treatment for advanced gastric cancer. Paclitaxel appears to be non-cross resistant to other agents that are commonly used for gastric cancer. A large-scale phase II study is now underway.

Adult↗

PubMed1998

The TdT-mediated dUTP nick end labeling assay precisely assesses the DNA damage in human tumor xenografts.

Cultured HL-60, HeLa S3 and WiDr cells grown in male BALB/c nu/nu mice were studied by conventional and field-inversion DNA gel electrophoresis (FIGE), as well as by means of cytomorphological approaches, including TdT-mediated dUTP nick end labeling (TUNEL) assay. Chemosensitivity tests revealed HL-60 to be sensitive to vindesine (VDS), and HeLa S3 and WiDr to mitomycin C (MMC). Although VDS-treated HL-60 exhibited condensation of chromatin and a DNA ladder, MMC-exposed HL-60 cells showed apoptotic figures without typical DNA ladders. With MMC-treated WiDr cells, neither DNA ladders nor apoptotic figures were observed. Cells characterized by chromatin condensation were TUNEL-positive in both treated and untreated cases with the exception of the MMC-treated WiDr case, in which many TUNEL-positive cells were observed without cytomorphological changes. On FIGE, DNA fragments of approximately 50, 300 and 400 kbp were detected in groups treated with both effective and ineffective drugs, as well as in untreated controls. Furthermore, change of the time parameters in FIGE resulted in different sizes (550 and 850 kbp) of DNA fragments. These findings indicate that i) cell death is not always detectable in terms of apoptotic figures or DNA oligonucleosomal fragmentation, ii) only the TUNEL assay is a reliable tool to detect DNA damage and, iii) FIGE does not provide accurate size profiles of macromolecular DNA fragments.

Animals↗

PubMed1998

Advanced pancreatic cancer successfully treated with continuous infusion of 5-fluorouracil and low-dose cisplatin.

Due to pyloric stenosis in a 59-year-old male with the diagnosis of unresectable pancreatic head cancer, gastro-jejunostomy and cholecysto-jejunostomy were performed. Following the operation, the patient underwent a combination chemotherapy with cisplatin 10 mg/day x 5/week and continuous infusion of 5-fluorouracil 500 mg/day for 4 weeks. After three courses, the tumor size decreased and the serum carcinoembryonic antigen (CEA) level decreased from 89.6 to 4.2 ng/ml without significant adverse effects. During the follow-up, the CEA increased and the patient is now receiving the same treatment, surviving for more than one year.

Adenocarcinoma↗

PubMed1998

[Phase I study of orally administered UFT plus l-leucovorin].

A Phase I study of UFT plus l-LV was conducted in 29 patients (pts) with G.I. cancer on a multicenter cooperative study. UFT and l-LV were given orally in two divided doses for 28 consecutive days, followed by a 14 day-rest period. UFT was fixed in three doses, 250, 313 and 375 mg/m2/day, and l-LV was increased in dose from 25 to 50 and to 100 mg/body/days. Dose-limiting toxicities were anorexia, diarrhea, and nausea/vomiting. The maximum tolerated dose of UFT was 375 mg/m2/day, and l-LV 25 mg/body/day. Severe myelotoxicity was not observed. There were three responders (PR) out of 21 pts with measurable disease at UFT doses of 313 mg/m2/day and l-LV 50 and 100 mg/body/day. Responses observed were abdominal mass (rectal ca), liver metastasis (pancreas ca) and metastasis of liver and lymph-node (gastric ca). As a result of pharmacokinetics, plasma concentrations of 5-methyl-THF were maintained > 1.0 microM for over 5 hours that was considered to have a modulating effect on the plasma concentration. In doses of 50 mg and 100 mg/body/day of l-LV. No accumulations in plasma were observed in patient treated in 28 days by l-LV/UFT therapy. It was suggested UFT and l-LV did not interfere with each other's absorption. A Phase II study is recommended, with doses of 313 mg/m2/day of UFT and 50 or 100 mg/body/day of l-LV.

Administration, Oral↗

PubMed1998

Detection of APC mutations by a yeast-based protein truncation test (YPTT).

APC gene mutations play a role in the initiation step of colorectal carcinogenesis in both familial adenomatous polyposis (FAP) and non-FAP patients. Almost all of the APC mutations are nonsense or frameshift mutations, which truncate the APC protein and are thought to inactivate normal APC function. We show a novel method for detecting nonsense and frameshift APC gene mutations by using Saccharomyces cerevisiae. Polymerase chain reaction (PCR)-amplified APC fragments are cloned directly into yeast expression vectors in vivo, and the yeast expresses a hemagglutinin epitope (HA)-tagged APC peptide. When an APC fragment contains a nonsense or frameshift mutation, HA-tagged truncating APC peptide can be detected by Western blotting using an anti-HA antibody. We identified both germ-line and somatic APC mutations in patients with FAP and non-FAP colorectal tumors, respectively. This method, called the yeast-based protein truncation test (YPTT), is simple and fairly cheap, and it can be applied to any genes that are inactivated by protein truncating mutations.

Adenomatous Polyposis Coli Protein↗

PubMed1998

[Rapid growth of glioblastoma during therapy for multiple myeloma: case report].

Rapid growth of a glioblastoma during therapy for multiple myeloma is reported. A 53-year-old man was admitted to our hospital with a right costal tumor, which was resected. The diagnosis was plasmocytoma. Urine protein electrophoresis showed a monoclonal peak in the region of gamma-globulin, and examination of the bone marrow revealed 17.8% of atypical plasma cells. Brain magnetic resonance (MR) imaging detected two small lesions, but these could not be identified as brain tumor. He received chemotherapy (melphalan 10 mg/day and predonin 30 mg/day for 4 days) and was discharged. Two weeks after discharge, he was readmitted because of left hemiparesis. T1-weighted MR imaging showed two large hypointense lesions in the right frontal lobe, with ring-like enhancement following Gd-DTPA infusion. 1H-MR spectroscopy showed typical findings of tumor with increased choline and lactic acid peaks. 201Tl SPECT revealed high accumulation in both early and delayed images. Right carotid angiography showed a hypervascular tumor with venous filling and mass effect. The lesions were resected via right frontal craniotomy, followed by intraoperative radiation and placement of an Ommaya reservoir. Histological examination showed the tumors were glioblastoma. The brain between the tumors also showed the typical appearance of glioblastoma, suggesting that the lesions were continuous. Postoperatively, the patient's left hemiparesis disappeared. He received local irradiation and chemotherapy and was then discharged. Coexistence of glioblastoma and multiple myeloma is rare. The cause may be genetic abnormality, but immunodeficiency due to multiple myeloma, surgical damage, or chemotherapy may have contributed to the rapid growth of the glioblastoma.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1998

[Late phase II clinical study of RP56976 (docetaxel) in patients with advanced/recurrent gastric cancer: a Japanese Cooperative Study Group trial (group A)].

A late phase II clinical study of RP56976 (docetaxel) was conducted in patients with advanced/recurrent gastric cancer as a multicenter cooperative trial. Docetaxel was administered intravenously at a dose of 60 mg/m2 every 3-4 weeks. Of the 76 patients enrolled, 66 patients were eligible and 59 patients were evaluable for response. One patient showed complete response (CR), 13 patients partial response (PR), 1 patient minor response (MR), 19 patients no change (NC) and 25 patients had progressive disease (PD). The overall response rate in 59 evaluable patients was 23.7% (95% CI = 13.6-36.6%). The primary tumor showed a 4.3% (1/23) response, while the metastatic lesions in the abdomen, pelvic mass, lung, liver, and lymph nodes showed response rates of 62.5% (5/8), 33.3% (1/3), 33.3% (1/3), 14.8% (4/27), and 13.9% (5/26), respectively. About hematological toxicity, severe (Grade 3 or more) leukopenia was observed in 36 patients (56.3%) and neutropenia in 52 patients (81.3%). Other major toxicity (Grade 3 or more) included nausea/vomiting in 11 patients (17.2%), anorexia in 9 patients (14.1%), fatigue in 5 patients (7.8%), and alopecia in 7 patients (10.9%), all which were tolerable. The results show that docetaxel is an effective anticancer agent for advanced/recurrent gastric cancer.

Adult↗

PubMed1998

[Phase I study of raltitrexed (ZD-1694)].

A multicenter cooperative phase I study of ZD-1694 (raltitrexed), a novel, folate-based thymidylate synthase (TS) inhibitor, was conducted with single and repeated doses in 30 patients with various malignant tumors. ZD-1694 was intravenously infused over 15 minutes. In the single-dose study, the initial dose was fixed at 1.0 mg/m2 (1n), and the dose was escalated stepwise up to 3.5 mg/m2 (3.5 n). Based on the results of the single-dose study, in the repeated-dose study, doses of 2.5 n and 3 n were infused every three weeks (3 weeks/one course). In principle, patients received 2 courses or more. Of the 29 eligible patients, 16 were in the single-dose study and 13 in the repeated-dose study. Adverse reactions were evaluated in all eligible patients. In the single-dose study, neutropenia, nausea/vomiting, diarrhea, and transaminase (GOT, GPT) increases, of grade 3 or higher, occurred at high doses of 3 n and 3.5 n. These were regarded as dose-limiting toxicities (DLT). DLT of grade 3 or higher were observed in 1 of 4 patients given 3 n and 2 of 4 patients given 3.5 n. These results suggested that the maximum tolerated dose (MTD) of ZD-1694 was 3.5 n (3.5 mg/m2). In the repeated-dose study, DLT of grade 3 or higher was observed in no more than one third of each dose group, 2 of the 6 patients given 2.5 n and 2 of the 7 patients given 3 n. These results suggested that 3 n (3.0 mg/m2), a dose nearer to MTD, was the recommended dose for the phase II study. Although transaminase increases were observed in all patients, in 12 of them the increase was grade 2 or lower and reversible. A pharmacokinetic investigation showed the mean elimination half life of ZD-1694 plasma concentration was 91.5 hours in the single-dose group and 119.1 hours in the repeated dose group. It was suggested that ZD-1694 is metabolized to polyglutamates after uptake and retained in the cells for a long duration. However, no accumulation was seen in plasma concentration of ZD-1694 following repeated doses at 3-weekly intervals. One PR was observed in a patient with colorectal cancer receiving 2.5 n in the repeated-dose study. Based on these results, the recommended dosage and administration for the phase II study of ZD-1694 was 3 n (3.0 mg/m2) intravenously infused over 15 minutes every 3 weeks.

Adult↗

PubMed1997

Rapid colorectal adenoma formation initiated by conditional targeting of the Apc gene.

Familial adenomatous polyposis coli (FAP) is a disease characterized by the development of multiple colorectal adenomas, and affected individuals carry germline mutations in the APC gene. With the use of a conditional gene targeting system, a mouse model of FAP was created that circumvents the embryonic lethality of Apc deficiency and directs Apc inactivation specifically to the colorectal epithelium. loxP sites were inserted into the introns around Apc exon 14, and the resultant mutant allele (Apc580S) was introduced into the mouse germline. Mice homozygous for Apc580S were normal; however, upon infection of the colorectal region with an adenovirus encoding the Cre recombinase, the mice developed adenomas within 4 weeks. The adenomas showed deletion of Apc exon 14, indicating that the loss of Apc function was caused by Cre-loxP-mediated recombination.

Adenomatous Polyposis Coli↗

PubMed1997

Cellular distribution of mammalian DNA topoisomerase II is determined by its catalytically dispensable C-terminal domain.

Mammalian cells express two genetically distinct isoforms of DNA topoisomerase II, designated topoisomerase IIalphaand topoisomerase IIbeta. We have recently shown that mouse topoisomerase IIalpha can substitute for the yeast topoisomerase II enzyme and complement yeast top2 mutations. This functional complementation allowed functional analysis of the C-terminal domain (CTD) of mammalian topoisomerase II, where the amino acid sequences are divergent and species-specific, in contrast to the highly conserved N-terminal and central domains. Several C-terminal deletion mutants of mouse topoisomerase IIalpha were constructed and expressed in yeast top2 cells. We found that the CTD of topoisomerase IIalphais dispensable for enzymatic activity in vitro but is required for nuclear localization in vivo. Interestingly, the CTD of topoisomerase IIbetawas also able to function as a signal for nuclear targeting. We therefore examined whether the CTD alone is sufficient for nuclear localization in vivo . The C-terminal region was fused to GFP (green fluorescent protein) and expressed under the GAL1 promoter in yeast cells. As expected, GFP signal was exclusively detected in the nucleus, irrespective of the CTD derived from either topoisomerase IIalphaor IIbeta. Surprisingly, when the upstream sequence of each CTD was added nuclear localization of the GFP signal was found to be cell cycle dependent: topoisomerase IIalpha-GFP was seen in the mitotic nucleus but was absent from the interphase nucleus, while topoisomerase IIbeta-GFP was detected predominantly in the interphase nucleus and less in the mitotic nucleus. Our results suggest that the catalytically dispensable CTD of topoisomerase II is sufficient as a signal for nuclear localization and that yeast cells can distinguish between the two isoforms of mammalian topoisomerase II, localizing each protein properly.

Amino Acid Sequence↗

PubMed1997

Differentiation dependent expression and distinct subcellular localization of the protooncogene product, PEBP2beta/CBFbeta, in muscle development.

The Pebpb2/Cbfb gene encodes the non-DNA binding subunit of the heterodimeric transcription factor, PEBP2/CBF. To examine the expression of the PEBP2beta/CBFbeta protein in vivo, we carried out immunohistochemistry using the tissues from adult mice as well as embryos. Although PEBP2beta/CBFbeta was detected in various tissues to various degrees, interesting features of expression were observed in the skeletal myogenic cells. Here PEBP2beta/CBFbeta was found mainly to occur as cytoplasmic staining and the intensity of this staining increased depending on the differentiation stage of the cells. In the undifferentiated myoblasts PEBP2beta/CBFbeta was undetectable, whereas moderate levels of PEBP2beta/ CBFbeta were detected in the elongated and aligned myocytes. PEBP2beta/CBFbeta appeared to accumulate further when the cells fused to each other to become multinucleated myotubes. Once the muscle fibers were established, PEBP2beta/CBFbeta was relocated onto or around the Z-lines. PEBP2beta/CBFbeta was also detected in the cytoplasm of cardiac myocytes and in the smooth muscle cells of the digestive tract. In all the above, the skeletal myotubes were the only case that showed both nuclear and cytoplasmic staining of PEBP2beta/CBFbeta. Thus, we could show differentiation dependent pattern of PEBP2beta/CBFbeta expression in muscle development and establish PEBP2beta/CBFbeta to be a cytoplasmic as well as nuclear protein in vivo.

Actinin↗

PubMed1997

Differential contributions of BRCA1 and BRCA2 to early-onset breast cancer.

BACKGROUND: Germ-line mutations in the BRCA1 and BRCA2 genes predispose women to breast cancer. BRCA1 mutations are found in approximately 12 percent of women with breast cancer of early onset, and the specific mutation causing a deletion of adenine and guanine (185delAG), which is present in 1 percent of the Ashkenazi Jewish population, contributes to 21 percent of breast cancers among young Jewish women. The contribution of BRCA2 mutations to breast cancer of early onset is unknown. METHODS: Lymphocyte specimens from 73 women with breast cancer diagnosed by the age of 32 were studied for heterozygous mutations of BRCA2 by a complementary-DNA-based protein-truncation assay, followed by automated nucleotide sequencing. In addition, specimens from 39 Jewish women with breast cancer diagnosed by the age of 40 were tested for specific mutations by an allele-specific polymerase chain reaction. RESULTS: Definite BRCA2 mutations were found in 2 of the 73 women with early-onset breast cancer (2.7 percent; 95 percent confidence interval, 0.4 to 9.6 percent), suggesting that BRCA2 is associated with fewer cases than BRCA1 (P=0.03). The specific BRCA2 mutation causing a deletion of thymine (6174delT), which is found in 1.3 percent of the Ashkenazi Jewish population, was observed in 1 of the 39 young Jewish women with breast cancer (2.6 percent; 95 percent confidence interval, 0.09 to 13.5 percent), indicating that it has a small role as a risk factor for early-onset breast cancer. Among young women with breast cancer, there are BRCA2 mutations that cause truncation of the extreme C terminus of the protein and that may be functionally silent, along with definite truncating mutations. CONCLUSIONS: Germ-line mutations in BRCA2 contribute to fewer cases of breast cancer among young women than do mutations in BRCA1. Carriers of BRCA2 mutations may have a smaller increase in the risk of early-onset breast cancer.

Adult↗

PubMed1997

Detection of heterozygous truncating mutations in the BRCA1 and APC genes by using a rapid screening assay in yeast.

The detection of inactivating mutations in tumor suppressor genes is critical to their characterization, as well as to the development of diagnostic testing. Most approaches for mutational screening of germ-line specimens are complicated by the fact that mutations are heterozygous and that missense mutations are difficult to interpret in the absence of information about protein function. We describe a novel method using Saccharomyces cerevisiae for detecting protein-truncating mutations in any gene of interest. The PCR-amplified coding sequence is inserted by homologous recombination into a yeast URA3 fusion protein, and transformants are assayed for growth in the absence of uracil. The high efficiency of homologous recombination in yeast ensures that both alleles are represented among transformants and achieves separation of alleles, which facilitates subsequent nucleotide sequencing of the mutated transcript. The specificity of translational initiation of the URA3 gene leads to minimal enzymatic activity in transformants harboring an inserted stop codon, and hence to reliable distinction between specimens with wild-type alleles and those with a heterozygous truncating mutation. This yeast-based stop codon assay accurately detects heterozygous truncating mutations in the BRCA1 gene in patients with early onset of breast cancer and in the APC gene in patients with familial adenomatous polyposis. This approach offers a rapid and reliable method for genetic diagnosis in individuals at high risk for germ-line mutations in cancer susceptibility genes.

Base Sequence↗

PubMed1997

Oligomerization is not essential for growth suppression by p53 in p53-deficient osteosarcoma Saos-2 cells.

The carboxy-terminal portion of the p53 protein contains the tetramerization domain, and the introduction of multiple missense mutations in this domain disrupts the formation of p53 tetramers, resulting in the production of dimeric or monomeric forms of p53. It has recently been shown that a single missense or nonsense mutation in this domain affects the functional properties of p53 both in yeast and in mammalian cells. In this study, we tested the oligomerization of p53 with mutations in the oligomerization domain, when expressed in a human osteosarcoma cell line, Saos-2, in vivo. We found that single point mutations, including two missense and two nonsense mutations, in the alpha-helix of the oligomerization domain disrupted the oligomerization of p53, but that p53 still retained its ability to inhibit colony formation of cells to some degree. These results suggest that oligomerization and the carboxy-terminal basic domain are not prerequisite for p53-dependent tumor suppression, and this may explain why few of the tumor-derived p53 mutations that have been examined so far are carboxy-terminal mutations.

Biopolymers↗

PubMed1997

Screening the p53 status of human cell lines using a yeast functional assay.

We have screened the p53 status of 156 human cell lines, including 142 tumor cell lines from 27 different tumor types and 14 cell lines from normal tissues by using functional analysis of separated alleles in yeast. This assay enables us to score wild-type p53 expression on the basis of the ability of expressed p53 to transactivate the reporter gene HIS3 via the p53-responsive GAL1 promotor in Saccharomyces cerevisiae. Of 142 tumor cell lines, at least 104 lines (73.2%) were found to express the mutated p53 gene: 94 lines (66.2%) were mutated in both alleles, three lines (2.1%) were heterozygous, and no p53 cDNA was amplified from seven lines (4.9%). Of the 14 cell lines originating from normal tissues, all the transformed or immortalized cell lines expressed mutant p53 only. Yeast cells expressing mutant p53 derived from 94 cell lines were analyzed for temperature-sensitive growth. p53 cDNA from eight cell lines showed p53-dependent temperature-sensitive growth, growing at 30 degrees C but not at 37 degrees C. Four temperature-sensitive p53 mutations were isolated: CAT-->CGT at codon 214 (H214R), TAC-->TGC at codon 234 (Y234C), GTG-->ATG at codon 272 (V272M), and GAG-->AAG (E285K). Functionally wild-type p53 was detected in 38 tumor cell lines (26.8%) and all of the diploid fibroblasts at early and late population doubling levels. These results strongly support the previous findings that p53 inactivation is one of the most frequent genetic events that occurs during carcinogenesis and immortalization.

Alleles↗

PubMed1997

Performance study of a miniature gamma ray scintillation vivo probe for tumor localization.

UNLABELLED: We have developed a miniature gamma-ray endoscopic probe consisting of dual BGO detector probes for tumor detection inside the body cavities. The dual detector system was coupled with random coincidence to decrease the distant background radiation and to improve its spatial resolution for tumor localization. METHOD: The performance of the probe was investigated with a point source and a water phantom. A solution of positron emitting 18F isotope was used as the source. Clinical trials of the probe were done to localize tumors on the skin surface of four subjects carrying tumors close to the body surfaces, into whom 67Ga-citrate and 18F-FDG radiopharmaceuticals were injected. RESULTS: Measurements indicated that the spatial resolution of the dual detector probes is around 1.5 times better than the single detector probe, and both single and dual detector endoscopic probe systems are capable of localizing a tumor on a large photon background. CONCLUSION: The endoscopic probe may be easier to insert inside body cavities due to the small crystal size and the flexible light guides. A single detector probe with higher sensitivity may be useful in searching for tumors over a wide intracavity area but a dual detector probe can be used for precise tumor localization. The detector probe may also be suitable for intraoperative observation.

Adult↗