BACKGROUNDRadiation is a promising treatment for in stent restenosis and restenosis following percutaneous transluminal coronary angioplasty, which has troubled interventional cardiologists for a long time. It inhibits neointima hyperplasia, vascular remodeling, and increases the mean luminal diameter. The mechanism of intracoronary brachytherapy for restenosis is not well understood. Endogenous gaseous transmitters including nitric oxide and carbon monoxide are closely related to restenosis. Hydrogen sulfide, a new endogenous gaseous transmitter, is able to inhibit the proliferation of vascular smooth muscle cells and vascular remodeling. This study aimed to clarify the effect of radiation on cystathionine-gamma-lyase/hydrogen sulfide pathway in rat smooth muscle cells.

METHODSWe studied the effect of radiation on the cystathionine-gamma-lyase/hydrogen sulfide pathway. Rat vascular smooth muscle cells were radiated with (60)Co gamma at doses of 14 Gy and 25 Gy respectively. Then the mRNA level of cystathionine-gamma-lyase was studied by quantitative reverse-transcription competitive polymerase chain reaction. Hydrogen sulfide concentration in culture medium was determined by methylene blue spectrophotometry. Cystathionine-gamma-lyase activity in vascular smooth muscle cells was also studied.

RESULTS(60)Co gamma radiation at a dose of 1 Gy did not affect the cystathionine-gamma-lyase/hydrogen sulfide pathway significantly. However, (60)Co gamma radiation at doses of 14 Gy and 25 Gy decreased the hydrogen sulfide synthesis by 21.9% (P<0.05) and 26.8% (P<0.01) respectively. At the same time, they decreased the cystathionine-gamma-lyase activity by 15.1% (P<0.05) and 20.5% (P<0.01) respectively, and cystathionine-gamma-lyase mRNA expression by 29.3% (P<0.01) and 38.2% (P<0.01) respectively.

CONCLUSIONAppropriate (60)Co gamma radiation inhibits the H(2)S synthesis by inhibiting the gene expression of cystathionine-gamma-lyase and the cystathionine-gamma-lyase activity.

Animals ; Cells, Cultured ; Cobalt Radioisotopes ; Cystathionine gamma-Lyase ; genetics ; metabolism ; Enzyme Activation ; drug effects ; radiation effects ; Gamma Rays ; Hydrogen Sulfide ; metabolism ; Male ; Muscle, Smooth, Vascular ; cytology ; Myocytes, Smooth Muscle ; drug effects ; metabolism ; radiation effects ; Rats ; Rats, Wistar ; Reverse Transcriptase Polymerase Chain Reaction ; Signal Transduction ; drug effects ; radiation effects

NF-kappa B promotes cell survival against external stress such as radiation. We examined whether NF-kappa B decoy transfection enhances the antiproliferative effects of radiation on vascular smooth muscle cells (VSMCs) in vitro. The irradiation induced activation or nuclear translocation of NF-kappa B p65 in VSMCs was confirmed by immunofluorescence. NF-kB decoy transfection resulted in inhibition of the radiation-induced NF-kB activation in VSMCs and the subsequent reduction of transcription and translocation of ICAM, iNOS, and TNF-alpha, downstream molecules under the control of NF-kappa B. By using MTT assay, NF-kappa B decoy augmented the antiproliferative effects of radiation, where the effect of low dose radiation (2 and 8-Gy) of the cells transfected with NF-kappa B decoy was equivalent to the high dose (16-Gy) irradiated non-transfected cells at 48 h after irradiation: 1.06+/-0.16, 1.11+/-0.22, 1.20+/-0.25, respectively. The decrease in proliferation and survival of the radiation treated cells by flow cytometry analysis showed that NF-kappa B inhibition did not show any additive effects on the cell cycle of the irradiated VSMCs, while apoptosis was significantly increased after NF-kappa B decoy transfection in the irradiated VSMCs (apoptosis fraction: 13.33+/-2.08% vs. 26.29+/-7.43%, for radiation only vs. radiation+NF-kappa B decoy transfection, P < 0.05). In addition, at 48 h, NF-kappa B decoy transfection dose dependently (10 mM vs. 20 mM) inhibited proliferation of 16Gy-irradiated VSMCs, and showed greater antiproliferative efficacy than 100 mM sulfasalazine, a specific NF-kappa B inhibitor. These results indicate that NF-kappa B inhibition reduces proliferation and survival of irradiated VSMCs, likely by increased apoptosis rather than additive cell cycle arrest and suggest the possibility of adjunctive gene therapy using NF-kappa B decoy to improve efficacy and to decrease the adverse effects of intracoronary radiation therapy.
Animals ; Aorta/cytology/radiation effects ; *Apoptosis ; Cell Cycle/physiology/radiation effects ; Cell Proliferation/radiation effects ; Cells, Cultured ; Gamma Rays ; Intercellular Adhesion Molecule-1/metabolism ; Male ; Muscle, Smooth, Vascular/cytology/physiology/*radiation effects ; Myocytes, Smooth Muscle/cytology/radiation effects ; NF-kappa B/*antagonists & inhibitors/metabolism ; Nitric-Oxide Synthase/metabolism ; Protein Transport ; Rats ; Rats, Sprague-Dawley ; Research Support, Non-U.S. Gov't ; Transcription, Genetic ; Transfection ; Tumor Necrosis Factor-alpha/metabolism

OBJECTIVETo discuss the expression and significance of caspase-3 gene in the apoptotic muscle cells in gamma-radiation-induced muscle cell lines.

METHODSThe caspase-3 mRNA in the control and gamma-radiation induced apoptotic muscle cells was analysed by RT-PCR.

RESULTSThe expression of caspase-3 gene transcript was higher in 103Pd radioactive stent dog bile duct than in general stent dog bile duct, and apoptotic muscle cells were higher in 103Pd radioactive stent dog bile duct than in general stent dog bile duct.

CONCLUSIONSThe high level expression of caspase-3 gene may help to understand the muscle cells sensitivity to gamma-radiation apoptosis. 103Pd radioactive stent may increase the expression of caspase-3 gene in dog bile duct and prevent the billiary narrow when dog bile duct was injured by balloon.

Animals ; Apoptosis ; radiation effects ; Apoptosis Regulatory Proteins ; Bile Ducts ; enzymology ; radiation effects ; Caspase 3 ; Caspases ; genetics ; radiation effects ; Dogs ; Myocytes, Smooth Muscle ; cytology ; radiation effects ; Palladium ; administration & dosage ; RNA, Messenger ; genetics ; radiation effects ; Radioisotopes ; administration & dosage ; Reverse Transcriptase Polymerase Chain Reaction ; Stents