Activation of the insulin-like growth factor II transcription by aflatoxin B1 induced p53 mutant 249 is caused by activation of transcription complexes; implications for a gain-of-function during the formation of hepatocellular carcinoma

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Title
Activation of the insulin-like growth factor II transcription by aflatoxin B1 induced p53 mutant 249 is caused by activation of transcription complexes; implications for a gain-of-function during the formation of hepatocellular carcinoma
Author(s)
Young Ik Lee; Sook Lee; Gokul C Das; Ui Sun Park; Sook Mi Park; Yoon Ik Lee
Bibliographic Citation
Oncogene, vol. 19, no. 33, pp. 3717-3726
Publication Year
2000
Abstract
Aflatoxin B1 (AFB1) induced mutation of the p53 gene at codon 249 (p53mt249) is critical during the formation of hepatocellular carcinoma (HCC) following hepatitis B virus (HBV) infection. p53mt249 markedly increases insulin-like growth factor II (IGF-II) transcription largely from promoter 4, accumulating the fetal form of IGF-II. Modulation of the transcription factor binding to IGF-II P4 by wild-type p53 and p53mt249 was identified. Wild-type p53 inhibited binding of transcription factors Sp1 and TBP on the P4 promoter, while p53mt249 enhanced the formation of transcriptional complexes through enhanced DNA-protein (Sp1 or TBP) and protein-protein (Sp1 and TBP) interactions. p53mt249 stimulates transcription factor Sp1 phosphorylation which might be a cause of increased transcription factor binding on the P4 promoter while wild-type p53 does not. Transfection of hepatocytes with p53mt249 impaired induction of apoptosis by the HBV-X protein and TNF-α. Therefore, the blocking of apoptosis through enhanced production of IGF-II should provide a favorable opportunity for the selection of transformed hepatocytes. These results ex;plain the molecular basis for the genesis of HCC by p53mt249 which was found to be induced by a potent mutagen, AFB1.
Keyword
insulin-like growth factor IIp53 mutanttranscriptional activationhepatocellular carcinoma
ISSN
0950-9232
Publisher
Springer-Nature Pub Group
DOI
http://dx.doi.org/10.1038/sj.onc.1203694
Type
Article
Appears in Collections:
1. Journal Articles > Journal Articles
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