Biomedical subjects

Kazuo Maruyama

Publications and source records attributed to Kazuo Maruyama.

6 recordsLinked to original sources

PubMed2003

Gene structure, dual-promoters and mRNA alternative splicing of the human and mouse regulator of G protein signaling GAIP/RGS19.

Here we report the gene structure and transcription regulation of the human and mouse G protein-signaling regulator GAIP/RGS19. The GAIP/RGS19 gene is adjacent to and in an opposite orientation to the opioid-receptor-like receptor 1 (ORL1) gene. In both human and mouse, the GAIP/RGS19 gene is composed of seven exons. The first two exons are under the control of two different promoters and are alternatively employed to start the transcription of two 5' distinctive mRNAs. The two promoters appear to compete with and inhibit each other. We have also identified in mice an alternatively spliced short GAIP/RGS19 mRNA that lacks the exon 2 region and utilizes an ATG in exon 3 as its translation initiation codon. As a result, the short GAIP/RGS19 protein does not have the N-terminal 22 amino acid residues of a full-length isoform. GAIP/RGS19 alternative splicing patterns are differentially expressed in various tissues. The mRNA alternative splicing to produce multiple isoforms may play a significant role in regulating the function and selectivity of GAIP/RGS19.

Alternative Splicing↗

PubMed2002

The human DNA methyltransferases DNMT3A and DNMT3B have two types of promoters with different CpG contents.

DNA modification that is established by de novo methylation is involved in the epigenetic control of genome functions. The DNMT3A and DNMT3B genes encode putative de novo methyltransferases. In this paper, we investigated the transcriptional regulatory regions of the human DNMT3A and DNMT3B genes. We found that the DNMT3A and DNMT3B genes have multiple transcriptional start points (TSPs) that are separated on the chromosome and the expressions of these genes are controlled by multiple promoters. The DNMT3A gene has at least four TSPs and the expression is controlled by three different promoters. All three promoters lack typical TATA sequences adjacent to the TSPs. Two of them bear CpG-rich promoters and the other a CpG-poor promoter. The DNMT3B gene has at least two TSPs which exist in different exons and the expression is controlled by different promoters. Both promoter regions of the DNMT3B gene lack typical TATA sequences, where one promoter contains a CpG-rich area near the TSP, the other promoter is CpG-poor. Together with the data that the human DNMT1 gene has both CpG-rich and CpG-poor promoters, it is suggested that transcriptional regulation by two types of promoters, CpG-rich and CpG-poor, might be common characteristics in the DNMT gene family.

5' Flanking Region↗

PubMed2002

Intracellular targeting therapy of cisplatin-encapsulated transferrin-polyethylene glycol liposome on peritoneal dissemination of gastric cancer.

Peritoneal dissemination in gastric cancer is a common fatal clinical condition with few effective therapies available. We studied the therapeutic effect of a tumor-targeting drug delivery system that uses cisplatin-encapsulated and Tf-conjugated PEG liposomes (Tf-PEG liposomes) in nude mice with peritoneal dissemination of human gastric cancer cells. Small unilamellar Tf-PEG, PEG or DSPC/CH liposomes (bare liposomes) encapsulating cisplatin were prepared by reverse-phase evaporation followed by extrusion. Electron microscopic studies revealed that Tf-PEG liposomes were internalized into tumor cells by receptor-mediated endocytosis. To examine the biodistribution of each liposome and cisplatin level, nude mice were inoculated i.p. with 10(7) MKN45P human gastric tumor cells. On the fourth day after tumor inoculation, (3)H-CHE-labeled and cisplatin-encapsulated Tf-PEG, PEG or bare liposome were inoculated i.p. The Tf-PEG liposome-administered group maintained high liposome and cisplatin levels in ascites and showed a prolonged residence time in the peripheral circulation. Uptake of Tf-PEG liposomes into the liver and spleen was significantly lower than that of bare liposomes. Uptake of Tf-PEG liposomes in disseminated tumor cells of ascites and the greater omentum was significantly higher than that of PEG or bare liposomes and a significant increase in cisplatin levels was observed in these tumor cells. Mice receiving Tf-PEG liposomes 1 and 4 days after the day of tumor inoculation showed significantly higher survival rates compared with those receiving PEG liposomes without Tf, bare liposomes or free cisplatin solution. These results suggest that cisplatin-encapsulated Tf-PEG liposomes may be useful as a new intracellular targeting carrier for treatment of gastric cancer with peritoneal dissemination.

Animals↗

PubMed2002

Targetability and intracellular delivery of anti-BCG antibody-modified, pH-sensitive fusogenic immunoliposomes to tumor cells.

We prepared tumor-specific immunoliposomes by coupling anti-BCG monoclonal antibodies to pH-sensitive fusogenic liposomes modified with succinylated polyglycidol (sucPG), in order to obtain efficient binding to, and endocytotic internalization into, the tumor cells. Mouse colon carcinoma 26 cells, which are known to share a common antigen with BCG, were used in in vitro experiments. BCG-sucPG immunoliposomes showed fusion ability under acidic conditions. Fluorescence microscopic observation indicated that BCG-sucPG immunoliposomes bound to colon 26 tumor cells and induced receptor-mediated endocytosis at 37 degrees C. Fusion assay by resonance energy transfer using N-(7-nitro-2-1,3-benzoxadiazol-4-yl) diacyl phosphatidylethanolamine and N-(lissamine rhodamine B sulfonyl) diacyl phosphatidylethanolamine suggested that fusion between BCG-sucPG immunoliposomes and endosomal and/or lysozomal membrane did occur. These results imply that the BCG-sucPG immunoliposomes transfer their content into the cytoplasm by fusing with the endosomal and/or lysozomal membrane after recognition of target cells and subsequent internalization into the cells by endocytosis.

Animals↗

PubMed2002

PEG-immunoliposome.

This review deals with the current status of newly developed pendant-type PEG-immunoliposomes (Type C), carrying monoclonal antibodies or their fragments (Fab') at the distal ends of the PEG chains. In terms of target binding of Type C, two different anatomical compartments are considered. They are mouse lung endothelium as a readily accessible site via the intravascular route and the implanted solid tumor as a much less accessible target site reached via extravasation. Small unilamellar liposomes (90-130 nm in diameter) were prepared from phosphatidycholine and cholesterol (2:1, m/m) containing 6mol.% of DSPE-PEG-COOH or DPPE-PEG-Mal. For targeting to the vascular endothelial surface in the lung, 34A antibody, which is highly specific to mouse pulmonary endothelial cells, was conjugated to PEG-liposomes (34A-Type C). The degree of lung binding of 34A-Type C in BALB/c mouse was significantly higher than that of 34A-Type A, which is an ordinary type of immunoliposome (without PEG derivatives). For targeting to solid tumor tissue, 21 B2 antibody (anti-human CEA) and its Fab' fragment were used. The targeting ability of Fab'-Type C was examined by using CEA-positive human gastric cancer strain MKN-45 cells inoculated into BALB/c nu/nu mice. Fab'-Type C showed low RES uptake and a long circulation time, and enhanced accumulation of the liposomes in the solid tumor was seen. The small Fab'-Type C predominantly passed through the leaky tumor endothelium by passive convective transport. These studies offer important insights into the potential of Type C liposomes for target-specific drug delivery.

Adenocarcinoma↗

PubMed2002

Pharmaceutical design of the liposomal antimicrobial agents for infectious disease.

From the point of view of pharmaceutical design, development of carrier system of antimicrobial agents with functional properties should be required. We introduced here the development-process of liposomal formulations of polyene macrolide antibiotics, amphotericin B (AmB) and nystatin as injectable dosage forms. Both development of the effective encapsulation method of these drugs in liposomes and investigation of the encapsulation mechanism and the molecular states of them are important to determine the optimum lipid composition for therapeutic uses. Enhanced encapsulation of these hydrophobic drugs, long-circulation in blood and high targetability are the required functional properties for the carrier system. Low encapsulation of AmB in liposomes has been overcome by the incorporation of polyethylene glycol-lipid derivatives, DSPE-PEG. Both the hydration with 9% sucrose solution and the complex formation between AmB and DSPE-PEG contribute not only to the enhanced encapsulation of AmB in liposomes but also to the stability and long-circulation properties in blood. Encapsulation mechanism and the molecular states of AmB in liposomes were also investigated by several methods. AmB-encapsulating PEG liposomes (PEG-L-AmB) with optimum lipid composition also showed reduced toxicity and higher therapeutic efficacy on murine model of pulmonary aspergillosis than that of conventionally used AmB formulations. Further enhanced therapeutic effects was observed by using AmB-encapsulating PEG immunoliposomes (34A-PEG-L-AmB) carrying monoclonal antibodies at the distal ends of the PEG chains. On the contrary to AmB, encapsulation characteristics of nystatin were apparently different from that of AmB, though the chemical structure is very similar. Self-association of nystatin with sterol-free lipid membrane dominantly influences on the encapsulation characteristics. Many experiments about the encapsulation of antimicrobial agents in liposomes have been demonstrated by many researchers, but there are not so much drugs developed for commercially used. Optimization of the formulation of functional drug-carrier system should be important for the practical uses.

Amphotericin B↗