NF-kappaB decoy potentiates the effects of radiation on vascular smooth muscle cells by enhancing apoptosis.
NF-kappaB promotes cell survival against external stress such as radiation. We examined whether NF-kappaB 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-kappaB p65 in VSMCs was confirmed by immunofluorescence. NF-kappaB decoy transfection resulted in inhibition of the radiation-induced NF-kappaB activation in VSMCs and the subsequent reduction of transcription and translocation of ICAM, iNOS, and TNF-alpha, downstream molecules under the control of NF-kappaB. By using MTT assay, NF-kappaB decoy augmented the antiproliferative effects of radiation, where the effect of low dose radiation (2 and 8-Gy) of the cells transfected with NF-kappaB 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-kappaB inhibition did not show any additive effects on the cell cycle of the irradiated VSMCs, while apoptosis was significantly increased after NF-kappaB decoy transfection in the irradiated VSMCs (apoptosis fraction: 13.33+/-2.08% vs. 26.29+/-7.43%, for radiation only vs. radiation+NF-kappaB decoy transfection, P < 0.05). In addition, at 48 h, NF-kappaB decoy transfection dose dependently (10 microM vs. 20 microM) inhibited proliferation of 16Gy-irradiated VSMCs, and showed greater antiproliferative efficacy than 100 microM sulfasalazine, a specific NF-kappaB inhibitor. These results indicate that NF-kappaB 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-kappaB decoy to improve efficacy and to decrease the adverse effects of intracoronary radiation therapy.
Zhang
Shu-Ying
SY
Cardiovascular Laboratory, Clinical Research Institute, Seoul National University Hospital, Seoul 110-744, Korea.
Park
Kyung-Woo
KW
Oh
Seil
S
Cho
Hyun-Ju
HJ
Cho
Hyun-Jai
HJ
Park
Jin-Shik
JS
Cho
Young-Seok
YS
Koo
Bon-Kwon
BK
Chae
In-Ho
IH
Choi
Dong-Joo
DJ
Kim
Hyo-Soo
HS
Lee
Myoung-Mook
MM
D000818:Animals; D001011:Aorta / Q000166:cytology / Q000528:radiation effects; D017209:Apoptosis; D002453:Cell Cycle / Q000502:physiology / Q000528:radiation effects; D049109:Cell Proliferation / Q000528:radiation effects; D002478:Cells, Cultured; D005720:Gamma Rays; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000502:physiology / Q000528:radiation effects*; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000528:radiation effects; D016328:NF-kappa B / Q000037:antagonists & inhibitors* / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D021381:Protein Transport; D051381:Rats; D017207:Rats, Sprague-Dawley; D014158:Transcription, Genetic; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; D018799:Intercellular Adhesion Molecule-1; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat