AF1q enhancement of gamma irradiation-induced apoptosis by up-regulation of BAD expression via NF-kappaB in human squamous carcinoma A431 cells.
BAD (BCL-2 antagonist of cell death) is a pro-apoptotic BCL-2 family protein that plays a critical role in the regulation of apoptotic response. This study presents direct evidence that AF1q increased the radiation-induced apoptosis through up-regulation of BAD in human squamous carcinoma A431 cells and the key transcription factor involved is NF-kappaB. The minimal promoter sequence of BAD was identified; the activity was increased in AF1q stable transfectants and decreased upon AF1q siRNA transfection. The NF-kappaB consensus binding sequence is detected on BAD promoter. Inactivation of NF-kappaB by NF-kappaB inhibitor Bay 11-7082 or NF-kappaB p65 siRNA suppressed the expression and promoter activity of BAD; the suppression is more obvious in AF1q stable transfectants which also have an elevated NF-kappaB level. Mutation of putative NF-kappaB motif decreased the BAD promoter activity. The binding of NF-kappaB to the BAD promoter was confirmed by chromatin-immunoprecipitation. These findings indicate that AF1q up-regulation of BAD is through its effect on NF-kappaB and this may hint of its oncogenic mechanism in cancer.
Co
Ngai Na
NN
Faculty of Medicine, School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong SAR, PR China.
Tsang
Wing Pui
WP
Tsang
Tsun Yee
TY
Yeung
Chi Lam Au
CL
Yau
Pak Lun
PL
Kong
Siu Kai
SK
Kwok
Tim Tak
TT
D017209:Apoptosis / Q000187:drug effects / Q000235:genetics* / Q000528:radiation effects*; D001483:Base Sequence; D001798:Blood Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D002294:Carcinoma, Squamous Cell / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D045744:Cell Line, Tumor; D005720:Gamma Rays; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects / Q000528:radiation effects; D006801:Humans; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D011518:Proto-Oncogene Proteins; D034741:RNA, Small Interfering / Q000494:pharmacology; D014158:Transcription, Genetic / Q000187:drug effects / Q000235:genetics; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics; D051025:bcl-Associated Death Protein / Q000235:genetics* / Q000378:metabolism
C494819:BAD protein, human; D001798:Blood Proteins; C091736:MLLT11 protein, human; D016328:NF-kappa B; D009363:Neoplasm Proteins; D011518:Proto-Oncogene Proteins; D034741:RNA, Small Interfering; D051025:bcl-Associated Death Protein