ABSTRACT
UNLABELLED: Auger electrons can create breaks in nucleic acids, giving them possible therapeutic utility. We investigated the therapeutic effect of Auger electrons emitted by 111In-labeled phosphorothioate antisense oligonucleotides on human neuroblastoma cells in which N-myc was overexpressed. METHODS: Human SK-N-DZ neuroblastoma cells (5 x 10(6) cells) were treated with cationic reverse-phase evaporation vesicles (REVs) encapsulating 111In-labeled antisense (40 MBq/2 nmol of oligonucleotides/mumol of total phospholipids) that had an average diameter of 250 nm. Hybridization of the radiolabeled oligonucleotides with N-myc messenger RNA (mRNA), N-myc expression, and cell proliferation were investigated. The tumorigenicity of treated cells was analyzed in nude mice. Nonradiolabeled antisense, 111In-labeled sense, or empty cationic REVs were used as controls. RESULTS: 111In-Labeled antisense, which hybridized with N-myc mRNA, was detected in cells at 12 and 24 h after the initiation of treatment. Reduced N-myc expression and inhibited cell proliferation were shown in the same cells at 48 h after the completion of treatment. N-myc expression-suppressed cells produced intraperitoneal tumors in nude mice, but the average weight of the tumors was lower than that of tumors in control mice. CONCLUSION: Auger electrons emitted from 111In in close proximity to their target N-myc mRNA may prolong the time to cell proliferation in human neuroblastoma cells due to inhibition of the translation of N-myc. Auger electron therapy therefore has potential as an internally delivered molecular radiotherapy targeting the mRNA of a tumor cell.
Subject(s)
Electrons , Genes, myc , Indium Radioisotopes/therapeutic use , Neuroblastoma/radiotherapy , Oligonucleotides, Antisense , Animals , Cell Line, Tumor , Cell Proliferation , Female , Humans , Mice , Mice, Inbred BALB C , Mice, Nude , Neoplasm Transplantation , Neuroblastoma/pathology , Nucleic Acid Hybridization , Oligonucleotides, Antisense/chemistry , RNA, Messenger/chemistry , Transplantation, HeterologousABSTRACT
Determination of whether the steroid-induced cataract formation is caused through glucocorticoid (GC) receptor-mediated process was conducted by using GC antagonist (RU486) and anti-GC receptor antibody, and by sucrose density gradient ultracentrifugation analysis. (1) When 15 day-old chick embryos were treated with dexamethasone (DEX, 0.025 micromol per egg), their lenses started to form an opaque ring around the peri-nuclear region (stage II-III) after 12 hr and developed into nuclear-like cataract (stage IV-V) after 44 hr. The cataract formation examined at the 44 hr could be effectively prevented by administration of RU486 (0.2 micromol per egg) ranging from 2 hr before to 12 hr after the DEX administration. (2) GC receptor was present in liver, but could not be determined in lens by western blot analysis using monoclonal anti-GC receptor antibody. (3) Sucrose gradient ultracentrifugation analysis indicated that the receptor (9S) in the liver could be transformed to the 4S form after 0.4M NaCl treatment. Combined with our previous data, this suggests that changes in hepatic functions mediated by the GC receptor after the GC administration may be involved in the process of the cataract formation.
