Adenovirus-mediated gene transduction of truncated I kappa B alpha enhances radiosensitivity in human colon cancer cells.
Nuclear factor kappa B (NF-kappa B) is a transcription factor that is known to regulate apoptosis when cells are exposed to DNA-damaging agents such as ionizing radiation and cytotoxic drugs. We sought to determine if inhibition of NF-kappa B could enhance radiosensitivity in human colon cancer cells in vitro and in vivo. To inhibit NF-kappa B activation specifically, we constructed a recombinant adenovirus vector expressing a truncated form of the inhibitor protein I kappa B alpha (I kappa B alpha Delta N) that lacks the phosphorylation sites essential for activation of NF-kappa B, and transfected two human colon cancer cell lines (HT29 and HCT15) with this vector. In vitro colony-forming assays revealed that the overexpression of the stable I kappa B alpha by AxI kappa B alpha Delta N infection significantly suppressed cell growth after irradiation in both cell lines as compared to infection with a control vector, AxLacZ. Treatment with AxI kappa B alpha Delta N and irradiation successfully inhibited the growth of HT29 xenografted subcutaneous tumors in nude mice with an 83.8% volume reduction on day 38 as compared to the untreated tumors. Furthermore, it was demonstrated that apoptosis was increased by adenovirus-mediated gene transduction of I kappa B alpha Delta N in vitro and in vivo. These results indicated that inhibition of NF-kappa B could enhance radiosensitivity through an increase in radiation-induced apoptosis. We believe that radio-gene therapy using adenovirus-mediated gene transduction of I kappa B alpha Delta N could be an attractive candidate as a treatment strategy for colorectal cancer.
Mukogawa
Tomohide
T
First Department of Surgery, Nara Medical University, Kashihara, Nara 634-8522, Japan. tmuko@naramed-u.ac.jp
Koyama
Fumikazu
F
Tachibana
Masaaki
M
Takayanagi
Atsushi
A
Shimizu
Nobuyoshi
N
Fujii
Hisao
H
Ueno
Masato
M
Matsumoto
Hiroshi
H
Takeuchi
Taku
T
Nakajima
Yoshiyuki
Y
D000256:Adenoviridae / Q000235:genetics*; D002460:Cell Line; D002470:Cell Survival / Q000528:radiation effects; D003110:Colonic Neoplasms / Q000235:genetics* / Q000821:virology; D004307:Dose-Response Relationship, Radiation; D005822:Genetic Vectors; D006801:Humans; D020672:I-kappa B Proteins / Q000235:genetics* / Q000378:metabolism; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000037:antagonists & inhibitors; D011836:Radiation Tolerance / Q000235:genetics*; D011994:Recombinant Proteins / Q000378:metabolism; D014162:Transfection; D014407:Tumor Cells, Cultured; D014965:X-Rays
D020672:I-kappa B Proteins; D016328:NF-kappa B; C000606204:NFKBIA protein, human; C000606205:Nfkbia protein, mouse; D011994:Recombinant Proteins; D000072000:NF-KappaB Inhibitor alpha