Masazumi Eriguchi

Liposomes bearing polyethyleneglycol-coupled transferrin with intracellular targeting property to the solid tumors in vivo

AbstractPurpose. The purpose of this study was to determine the usefulness of transferrin (TF)-pendant-type polyethyleneglycol (PEG)-liposomes (TF-PEG-liposomes), in which TF was covalently linked to the distal terminal of PEG chains on the external surface of PEG-liposomes as a carrier for in vivo cytoplasmic targeting to tumor cells. Methods. Small unilamellar TF-PEG-liposomes (100-140 nm in diameter) were prepared from DSPC, CH, DSPE-PEG, and DSPE-PEG-COOH (2:1:0.11:0.021, molar ratio), and were conjugated to TF via the carboxyl residue of DSPE-PEG-COOH. The intracellular targeting ability of TF-PEG-liposomes to tumor cells was examined in vitro and in Colon 26 tumor-bearing mice. Results. TF-PEG-liposomes, bearing approximately 25 TF molecules per liposome, readily bound to mouse Colon 26 cells in vitro and were internalized by receptor-mediated endocytosis. TF-PEG-liposomes showed a prolonged residence time in the circulation and low RES uptake in Colon 26 tumor-bearing mice, resulting in enhanced extravasation of the liposomes into the solid tumor tissue. Electron microscopic studies in Colon 26 tumor-bearing mice revealed that the extravasated TF-PEG-liposomes were internalized into tumor cells by receptor-mediated endocytosis. Conclusion. TF-PEG-liposomes had the capabilities of specific receptor binding and receptor-mediated endocytosis to target cells after extravasation into solid tumors in vivo. Such liposomes should be useful for in vivo cytoplasmic targeting of chemotherapeutic agents or plasmid DNAs to target cells.

Oxalato-platinum or 1-OHP, a third-generation platinum complex: an experimental and clinical appraisal and preliminary comparison with cis-platinum and carboplatinum

A new platinum complex, oxalatoplatin or l-OHP, which, at the same metal dose in experimental tests is as efficient as cisplatin, and is more so at a lower metal dose than carboplatin; which is as efficient in human tumors of the testis and ovary as these other analogs, and more so in melanoma and breast cancer; which is not nephrotoxic, cardiotoxic or mutagenic, and hardly hematotoxic and neurotoxic, is described and compared with the above-mentioned platinum complexes. Combined with 5Fu, it induces a high number of remissions in colorectal cancer, and has brought about cures in inoperable gastric cancers. Combined with carboplatin, it has resulted in a high proportion of cures in L1210-carrying mice, which no other two-by-two combination of these complexes has achieved.

Antitumour effect of polyoxomolybdates : induction of apoptotic cell death and autophagy in in vitro and in vivo models

Polyoxomolybdates (PMs) as discrete molybdenum-oxide cluster anions have been investigated in the course of study of their medical applications. Here, we show the significant antitumour potency of the polyoxomolybdate [Me3NH]6[H2MoV12O28(OH)12(MoVIO3)4]·2H2O (PM-17), which is a photo-reduced compound of [NH3Pri]6[Mo7O24]·3H2O. The effect of PM-17 on the growth of cancer cell lines and xenografts was assessed by a cell viability test and analysis of tumour expansion rate. Morphological analysis was carried out by Hoechst staining, flow-cytometric analysis of Annexin V staining, terminal deoxynucleotidyl transferase-mediated ‘nick-end’ labelling staining, and electron-microscopic analysis. Activation of autophagy was detected by western blotting and fluorescence-microscopic analysis of the localisation of GFP-LC3 in transfected tumour cells. PM-17 inhibited the growth of human pancreatic cancer (AsPC-1) xenografts in a nude mice model, and induced morphological alterations in tumour cells. Correspondingly, PM-17 repressed the proliferation of AsPC-1 cells and human gastric cancer cells (MKN45) depending on the dose in vitro. We observed apoptotic patterns as the formation of apoptotic small bodies and translocation of phosphatidylserine by Hoechst staining and flow-cytometric analysis following Annexin V staining, and in parallel, autophagic conformation by the formulation of autophagosomes and localisation of GFP-LC3 by electron- and fluorescence-microscopic analysis.

Gene transfer by DNA/mannosylated chitosan complexes into mouse peritoneal macrophages.

Chitosan is a biodegradable and biocompatible polymer and is useful as a non-viral vector for gene delivery. In order to deliver pDNA/chitosan complex into macrophages expressing a mannose receptor, mannose-modified chitosan (man-chitosan) was employed. The cellular uptake of pDNA/man-chitosan complexes through mannose recognition was then observed. The pDNA/man-chitosan complexes showed no significant cytotoxicity in mouse peritoneal macrophages, while pDNA/man-PEI complexes showed strong cytotoxicity. The pDNA/man-chitosan complexes showed much higher transfection efficiency than pDNA/chitosan complexes in mouse peritoneal macrophages. Observation with a confocal laser microscope suggested differences in the cellular uptake mechanism between pDNA/chitosan complexes and pDNA/man-chitosan complexes. Mannose receptor-mediated gene transfer thus enhances the transfection efficiency of pDNA/chitosan complexes.

Highly efficient in vivo gene transfection by plasmid/PEI complexes coated by anionic PEG derivatives bearing carboxyl groups and RGD peptide

A new class of an anionic poly (ethylene glycol) derivative, PEG-Suc, bearing 17.7 pairs of carboxylic acid-side chains was synthesized. PEG-Suc deposited onto the DNA/polyethyleneimine complexes without destroying them even at high dose ratio. Coating of the DNA complexes by PEG-Suc recharged their surface to negative, and effectively protected them from the albumin-induced aggregation. Paired carboxyl groups in the side chains showed higher proton sponge effect. Negatively charged surface would diminish the electrostatic binding of the complexes to the cells, and the transfection efficiency on the cultured cells was not high. RGD peptide side chain as a ligand to malignant cell surfaces was then introduced to compensate the reduced electrical adhesion. RGD-PEG-Suc-coated plasmid/PEI complex brought about more than 3 times higher reporter protein activity on the cultured B16 cells. Those bio-compatible DNA complexes with ligand attained very high gene expression in tumor, lung, and liver after injection into mouse tail vein.

A molecular biological study of anti-tumor mechanisms of an anti-cancer agent Oxaliplatin against established human gastric cancer cell lines

We report that preoperative administration of Oxaliplatin, a new anti-cancer platinum agent, is an effective treatment for gastric cancer. The purpose of this in vitro study is to determine whether Oxaliplatin induces apoptosis in established human gastric cancer cell lines. Five established gastric cancer cell lines are used: MNK45, KATO-III, OKAJIMA, MNK28 and MNK74. Chemosensitivity to l-OHP is studied using a growth inhibition test. Induction of apoptosis in gastric cancer cells is analyzed by assessing DNA ladder formation, DNA fragmentation and actin cleavage. While all five gastric cancer cell lines are sensitive to Oxaliplatin, the poorly differentiated lines are the most sensitive. DNA ladder formation and/or DNA fragmentation are detected in all gastric cancer cell lines. However, actin cleavage is not detected in any of the cell lines. Oxaliplatin has an anti-cancer effect on human gastric cancer cell lines, particularly cell lines of poorly differentiated adenocarcinoma, indicating that Oxaliplatin would be an effective treatment for poorly differentiated gastric cancer. Oxaliplatin induces apoptosis in gastric cancer cell lines, but actin cleavage is not detected in cancer cells. This finding suggests that (1) the apoptotic caspase pathway leads mainly to DNA condensation and fragmentation, and (2) caspase-independent apoptotic pathways may be activated when gastric cancer cells are treated with Oxaliplatin.

Targeting Chemotherapy to Solid Tumors with Long-circulating Thermosensitive Liposomes and Local Hyperthermia

The effectiveness of the combination of long‐circulating, thermosensitive liposomes and hyperthermia is described. Small‐sized, thermosensitive liposomes that encapsulate doxorubicin (DXR‐PEGTSL (SUV)) have a prolonged circulation time and are extravasated to targeted solid tumors in vivo, where they preferentially release the agent in an anatomical site subjected to local hyperthermia. Liposomes were prepared by the incorporation of amphipathic polyethyleneglycol (PEG) to prolong their circulation time. DXR‐PEG‐TSL (SUV) was retained longest and was accumulated most efficiently in solid tumors in Balb/c mice. The combination of DXR‐PEG‐TSL (SUV) and hyperthermia at the tumor sites 3 h after injection, gave high concentrations of doxorubicin in tumor tissue and resulted in more effective tumor retardation and increased survival time. A large amount of DXR‐PEG‐TSL (SUV) was extravasated into the tumors during circulation for 3 h after injection, suggesting that the encapsulated drug was released into the interstitial spaces of the lesions by local hyperthermia. This system is expected to be clinically valuable for the delivery of a wide range of chemotherapeutic agents in the treatment of solid tumors.

Application of drug delivery system to boron neutron capture therapy for cancer

Background: Tumor cell destruction in boron neutron capture therapy (BNCT) is due to the nuclear reaction between 10B and thermal neutrons (10B + 1n → 7Li + 4He (α) + 2.31 MeV (93.7 %)/2.79 MeV (6.3 %)). The resulting lithium ions and αparticles are high linear energy transfer (LET) particles which give a high biological effect. Their short range in tissue (5 – 9 μm) restricts radiation damage to those cells in which boron atoms are located at the time of neutron irradiation. BNCT has been applied clinically for the treatment of malignant brain tumors, malignant melanoma, head and neck cancer and hepatoma. Sodium mercaptoundecahydro-dodecaborate (Na210B12H11SH: BSH) and borono-phenylalanine (10BPA) are currently being used in clinical treatments. These low molecule compounds are easily cleared from cancer cells and blood, so high accumulation and selective delivery of boron compounds into tumor tissues and cancer cells are most important to achieve effective BNCT and to avoid damage to adjacent healthy cells. Objective: In order to achieve the selective delivery of boron atoms to cancer cells, a drug delivery system (DDS) is an attractive intelligent technology for targeting and controlled release of drugs. Methods: We performed literature searches related to boron delivery systems in vitro and in vivo Results: We describe several DDS technologies for boron delivery to cancer tissues and cancer cells from the past to current status. We are convinced that it will be possible to use liposomes, monoclonal antibodies and WOW emulsions as boron delivery systems for BNCT clinically in accordance with the preparation of good commercial product (GCP) grade materials.

Progress reports on immune gene therapy for stage IV renal cell cancer using lethally irradiated granulocyte-macrophage colony-stimulating factor-transduced autologous renal cancer cells

Abstract There is no effective treatment for patients with stage IV renal cell cancer (RCC), although the introduction of new therapy is imminent. Cancer gene therapy is currently considered to be one of the most promising therapeutic modalities in the field of cancer treatment. Based on the results of animal studies, vaccination using autologous granulocyte-macrophage colony-stimulating factor-transduced renal cancer cells appears promising. Before initiating a clinical study using an ex vivo gene-transduced autologous cell vaccine-based immunogene therapy for RCC in Japan, in 1992 we initially planned a Japanese version of a clinical protocol in collaboration with a US group. In 1993, the original protocol was refined. We performed five preclinical qualification studies using RCC nephrectomy specimens from patients in 1997, and the results showed that preparation of RCC cells for autologous vaccines at the Clinical Cell Technology Facility, Research Hospital of the Institute of Medical Science, University of Tokyo, was feasible. Subsequently in August 1998, the Ministry of Health and Welfare and the Ministry of Education, Science, Culture, and Sport approved our clinical protocol. We have recruited two patients with stage IV RCC to our study so far. Here we report the background to the initiation of cancer gene therapy in Japan.

Neutron capture autoradiographic determination of 10B distributions and concentrations in biological samples for boron neutron capture therapy

Abstract It is necessary for effective boron neutron capture therapy (BNCT) to accumulate 10 B atoms in the tumor cells. We prepared a cationic liposome entrapped 10 B compound for the delivery system and examined the delivery capacity of 10 B atoms to pancreatic cancer cell, AsPC-1, in vivo. It is required to achieve an accurate measurement of 10 B distributions and concentrations in biological samples with a sensitivity in the ppm range for BNCT. We applied CR-39 (polyallyldiglycol carbonate) plastic track detectors to α-autoradiographic measurements of the 10 B biodistribution in sliced whole-body samples of mice. To selectively desensitize undesirable proton tracks, we applied PEW (KOH+C2H5OH+H2O) solution to the etching of CR-39 detector. The subsequent use of an alpha-track radiographic image analysis system enabled a discrimination between alpha tracks and recoiled proton tracks by the track size selection method. This enabled us to estimate quantitatively the distributions of 10 B concentrations within the tissue sections by comparing with suitable standards.