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M Suenaga

Publications and source records attributed to M Suenaga.

At least 19 recordsLinked to original sources
PubMed2001

Characteristics and distribution of endogenous RFamide-related peptide-1.

We have recently identified RFamide-related peptide (RFRP) gene that would encode three peptides (i.e., RFRP-1, -2, and -3) in human and bovine, and demonstrated that synthetic RFRP-1 and -3 act as specific agonists for a G protein-coupled receptor OT7T022. However, molecular characteristics and tissue distribution of endogenous RFRPs have not been determined yet. In this study, we prepared a monoclonal antibody for the C-terminal portion of rat RFRP-1. As this antibody could recognize a consensus sequence among the C-terminal portions of rat, human, and bovine RFRP-1, we purified endogenous RFRP-1 from bovine hypothalamus on the basis of immunoreactivity to the antibody. The purified bovine endogenous RFRP-1 was found to have 35-amino-acid length that corresponds to 37-amino-acid length in human and rat. We subsequently constructed a sandwich enzyme immunoassay using the monoclonal antibody and a polyclonal antibody for the N-terminal portion of rat RFRP-1, and analyzed the tissue distribution of endogenous RFRP-1 in rats. Significant levels of RFRP-1 were detected only in the central nervous system, and the highest concentration of RFRP-1 was detected in the hypothalamus. RFRP-1-positive nerve cells were detected in the rat hypothalamus by immunohistochemical analyses using the monoclonal antibody. In culture, RFRP-1 lowered cAMP production in Chinese hamster ovary cells expressing OT7T022 and it was abolished by pre-treatment with pertussis toxin, suggesting that OT7T022 couples G(i)/G(o) in the signal transduction pathway.

Amino Acid Sequence↗
PubMed2001

Metastin suppresses the motility and growth of CHO cells transfected with its receptor.

We recently reported having identified of the ligand for an orphan G-protein-coupled receptor, hOT7T175, as the gene product (68-121)-amide of the metastasis suppressor gene KiSS-1. We further showed that the ligand, which we named "metastin," inhibits chemotaxis and invasion of Chinese hamster ovary (CHO) cells transfected with hOT7T175 cDNA (CHO/h175) in vitro, and pulmonary metastasis of hOT7T175-transfected B16-BL6 melanomas in vivo. In the present study, we investigated the activity of metastin in CHO/h175 cells in greater detail. Metastin significantly suppressed motility in a chemotaxis assay and wound healing assay at 10-100 nM order concentrations. Two N-terminally truncated peptides, metastin(40-54) and metastin(45-54) inhibited the migration of CHO/h175 cells as potently as metastin itself. Metastin also inhibited the spreading, monolayer growth and colony formation in agar (0.8%) of CHO/h175 cells at 10-100 nM concentrations. These results indicate that metastin is a potent inhibitor of cell motility, leading to suppression of cell growth and antimetastatic activity, and suggest that low molecular chemical compounds could replace its activity as a novel antimetastatic agent.

Animals↗
PubMed2001

Novel betacellulin derivatives. Separation of the differentiation activity from the mitogenic activity.

Betacellulin (BTC) is a member of the epidermal growth factor family. It has two biological activities: mitogenic activity in fibroblasts and vascular smooth muscle cells, and differentiation activity for the differentiation of pancreatic acinar AR42J cells into insulin-secreting cells. The previous finding that recombinant BTC promotes the neogenesis of beta-cells in a mouse model supports the possibility that BTC is a therapeutic protein. However, the mitogenic activity of BTC may not be needed for differentiation into beta-cells and may cause a side effect in clinical use. We prepared several derivatives of BTC to segregate the two activities, to decrease the mitogenic activity, and to maintain the differentiation activity. We succeeded in obtaining BTC derivatives segregated by the two biological activities by preparing truncated-type derivatives. A derivative of BTC, BTC24-76, with a truncated N-terminal 23 amino acids and C-terminal 4 amino acids, was 2.5-fold more active in differentiation and had one-tenth of the mitogenic activity. The derivatives described in the present study should be helpful in future applications as therapeutic proteins and in basic research for discovery of a BTC-specific receptor.

Amino Acid Sequence↗
PubMed2001

Metastasis suppressor gene KiSS-1 encodes peptide ligand of a G-protein-coupled receptor.

Metastasis is a major cause of death in cancer patients and involves a multistep process including detachment of cancer cells from a primary cancer, invasion of surrounding tissue, spread through circulation, re-invasion and proliferation in distant organs. KiSS-1 is a human metastasis suppressor gene, that suppresses metastases of human melanomas and breast carcinomas without affecting tumorigenicity. However, its gene product and functional mechanisms have not been elucidated. Here we show that KiSS-1 (refs 1, 4) encodes a carboxy-terminally amidated peptide with 54 amino-acid residues, which we have isolated from human placenta as the endogenous ligand of an orphan G-protein-coupled receptor (hOT7T175) and have named 'metastin'. Metastin inhibits chemotaxis and invasion of hOT7T175-transfected CHO cells in vitro and attenuates pulmonary metastasis of hOT7T175-transfected B16-BL6 melanomas in vivo. The results suggest possible mechanisms of action for KiSS-1 and a potential new therapeutic approach.

Amino Acid Sequence↗
PubMed2001

Phase I study of second-line chemotherapy with docetaxel and carboplatin in advanced non-small-cell lung cancer.

PURPOSE: Docetaxel and carboplatin have a broad spectrum of antitumor activity. We conducted a phase I study of docetaxel and carboplatin as second-line chemotherapy in previously treated non-small-cell lung cancer (NSCLC). This study aimed to determine the maximum tolerated dose (MTD) and the dose-limiting toxicities in this second-line combination chemotherapy. METHODS: Patients with advanced NSCLC were treated with escalating docetaxel doses in combination with a fixed-target area under the concentration-time curve (AUC) of 5 mg min/ml of carboplatin on day 1 of a 3-4-week cycle. The carboplatin dose was determined by multiplying the AUC by the clearance predicted using the Chatelut formula. The docetaxel dose was escalated from 40 mg/m2 to the MTD by 10 mg/m2 increments. RESULTS: A total of 16 patients previously treated with anticancer drugs were enrolled through three dose levels (40, 50 and 60 mg/m2 of docetaxel). All patients were assessable for toxicity and response. The MTD was docetaxel 60 mg/m2 with a carboplatin target AUC of 5 mg min/ml, and the dose-limiting toxicities in two of four patients were neutropenia and thrombocytopenia. Overall, neutropenia and thrombocytopenia of grade 3/4 occurred in eight patients (50%) and three patients (19%), respectively. Four patients (25%) and two patients (13%) experienced both grade 1 diarrhea and dermatitis, respectively. Allergic reactions, fluid retention, pneumonitis, neurotoxicity and mucositis were not observed. Of 16 patients, 5 showed an objective response (response rate 31%; 95% CI 14-56%). CONCLUSIONS: The combination of docetaxel and carboplatin is a feasible and well-tolerated second-line chemotherapy regimen in the treatment of NSCLC. Docetaxel 50 mg/m2 under the carboplatin target AUC of 5 mg x min/ml using the Chatelut formula was the recommended dose for phase II study.

Adult↗
PubMed2000

Acute cerebellar ataxia of a patient with SLE.

We described a 28-year-old woman with systemic lupus erythematosus (SLE) presented with digestive tract, skin and renal symptoms and afterwards developed acute cerebellar ataxia, a paresis of the right inferior rectus muscle, left abducens paralysis and left facial palsy which seemed to be consistent with a brainstem lesion visible on magnetic resonance imaging (MRI). This lesion disappeared within 9 days of corticosteroid treatment. It is suggested that this lesion is focal edema induced by acute changes in the blood brain barrier secondary to a vasculopathy. Other causes, including local infarction, are unlikely.

Acute Disease↗
PubMed2000

Birth cohort effects on incidence of lung cancers: a population-based study in Nagasaki, Japan.

Smoking prevalence remains high (around 60%) among Japanese males, but smoking initiation among males born in the 1930s decreased by approximately 10% due to economic difficulties following World War II. The present study was designed to examine whether this temporary decline in smoking initiation influenced the subsequent incidence of lung cancers, especially adenocarcinoma. Trends of lung cancer incidence by histological type in both sexes were investigated using data from the population-based cancer registry in Nagasaki, Japan, from 1986 through 1995. During this period, 5668 males and 2309 females were diagnosed as having lung cancer, and the overall incidence of lung cancers among both sexes remained stable. However, males aged 55 - 59 years showed a decrease in the age-specific incidence of adenocarcinoma and squamous-cell carcinoma (P < 0.05 and P < 0.01, respectively). In birth cohort analyses, the incidence of adenocarcinoma and squamous-cell carcinoma was lower in the 1935 - 1939 birth male cohort than in the successive cohorts. The incidence of lung cancers among females with low smoking prevalence did not change with birth cohort. The low smoking initiation among the 1935 - 1939 birth male cohort appeared to have resulted in a decreased incidence of adenocarcinoma and squamous cell carcinoma among middle-aged Japanese males. The present study suggests that smoking prevention has an effect in reducing the incidence of lung adenocarcinoma, as well as squamous-cell carcinoma, among smokers.

Adenocarcinoma↗
PubMed2000

Interactions of ofloxacin and erythromycin with the multidrug resistance protein (MRP) in MRP-overexpressing human leukemia cells.

To investigate interactions between the multidrug resistance protein (MRP) and antimicrobial agents, we examined the effects of 12 agents on vincristine sensitivity and efflux of the calcein acetoxy-methyl ester (calcein-AM) of a MRP substrate in MRP-overexpressing cells. Only ofloxacin and erythromycin enhanced sensitivity with increased intracellular vincristine accumulation and inhibited the calcein-AM efflux. Our findings suggest that the two agents are possible MRP substrates and may competitively inhibit MRP function as a drug efflux pump.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1998

Synthesis of new peptides with prolactin-releasing activity by a combination of recombinant DNA technology and a cysteine-specific cyanylation reaction.

A newly isolated peptide from bovine hypothalamus with prolactin-releasing activity (prolactin-releasing peptide; PrRP) was synthesized by a combination of recombinant DNA technology and a cysteine-specific cyanylation reaction, together with rat and human homologs. The peptides were expressed in the form of fusion proteins with basic fibroblast growth factor mutein, which were purified by heparin-affinity chromatography. The fusion proteins were cleaved at the cysteine residues of the junction site by cyanylation, followed by treatment with ammonia for C-terminal amidation. Purification of the resulting crude peptides was performed using chromatography on a gel-filtration column, a cation-exchange column, and a reversed-phase column. As an example, about 90 mg of bovine PrRP (bPrRP) was obtained from 201 of culture bloth. The purified b PrRP showed full biological activities in binding to its receptor expressed on CHO cells and releasing arachidonic acid metabolite from the same cells, while the C-terminal acid form of bPrRP had little of these activities. These results indicate that the C-terminal amide structure is very important for expressing biological activity. The peptides obtained here might be very useful for studies on their biological significance and roles in vivo.

Amino Acid Sequence↗
PubMed1998

Renaturation of recombinant human neurotrophin-3 from inclusion bodies using a suppressor agent of aggregation.

Escherichia coli has been widely used in the production of recombinant proteins. One of the drawbacks inherent in this method is that the proteins produced in the cells often form inactive inclusion bodies. Usually, the inclusion bodies can be separated from other cell components, solubilized by denaturants such as guanidine hydrochloride or urea, and then renatured through a refolding process such as dilution or dialysis. However, it has been shown that biologically active recombinant human neurotrophin-3 cannot be obtained at high yield by this procedure due to aggregation and precipitation of the protein. We applied the refolding process using the aggregation suppressor L-arginine in the renaturation of neurotrophin-3, and obtained biologically active neurotrophin-3 at high yield from the inclusion bodies. Consequently, about 10 mg of purified neurotrophin-3 was prepared from 1 litre of culture broth.

Amino Acids↗
PubMed1995

[Strategy for the treatment of hepatocellular carcinoma].

Hepatocellular carcinoma is a refractory cancer for the following two reasons: the tumor characteristics, including formation of tumor thrombus in the portal vein, metastasis within the liver and multicentricity of growth; and liver function disturbance due to cirrhotic change by B- or C-type viral infection. The most desirable treatment is hepatic resection, the only method producing a disease-free condition. However, there are not many cases that meet the indications for hepatic resection, since they have advanced lesions and/or liver dysfunction. If one cannot perform a hepatic resection, other suitable therapies should be selected, including transcatheter arterial embolization, percutaneous ethanol injection therapy, ligation of hepatic artery, irradiation, chemotherapy from hepatic artery via reservoir and so on. Combined therapy may sometimes be necessary for satisfactory efficacy. For long-term survival it is very important to do a close follow-up study over a long period. This encourages us to detect new lesions earlier and then perform suitable therapy again. Notifying patients of the disease and obtaining informed consent are needed for this long-term follow-up and treatment. When patients were examined who had first undergone hepatic resection and then hepatic re-resection for recurrence, we found that their survival rate was not different from that in the non-recurrent cases. This result indicates that overcoming refractory hepatocellular carcinoma requires a multidisciplinary treatment in which hepatic resection is the main means.

Antineoplastic Agents↗