Transcriptional activation of the MUC2 gene by p53.
MUC2 is one of the major components of mucins that provide a protective barrier between epithelial surfaces and the gut lumen. We investigated possible alterations of MUC2 gene expression by p53 and p21(Sdi1/Waf1/Cip1) in a human colon cancer cell line, DLD-1, establishing subclones in which a tetracycline-regulatable promoter controls exogenous p53 and p21 expression. MUC2 mRNA more significantly increased in response to p53 than to p21. Unexpectedly, MUC2 expression was also induced in human osteosarcoma cells, U-2OS and Saos-2, by exogenous p53. We next performed a reporter assay to test the direct regulation of MUC2 gene expression by p53. Deletion and mutagenesis of the MUC2 promoter region showed that it contains two sites for transactivation by p53. Furthermore, an electrophoretic mobility shift assay indicated that p53 binds to those elements. We analyzed MUC2 expression in other cell types possessing a functional p53 after exposure to various forms of stress. In MCF7 breast cancer and A427 lung cancer cells, MUC2 expression was increased along with the endogenous p53 level by actinomycin D, UVC, and x-ray, but not in RERF-LC-MS lung cancer cells carrying a mutated p53. These results suggest that p53 directly activates the MUC2 gene in many cell types.
Ookawa
Keizou
K
Second Department of Biochemistry, Hirosaki University School of Medicine, Zaifucho 5, Aomori 036-8562, Japan. kookawa@cc.hirosaki-u.ac.jp
Kudo
Toshihiro
T
Aizawa
Shu
S
Saito
Hiroshi
H
Tsuchida
Shigeki
S
D001483:Base Sequence; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000502:physiology; D017931:DNA Primers; D006801:Humans; D055262:Mucin-2; D009077:Mucins / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012689:Sequence Homology, Nucleic Acid; D015533:Transcriptional Activation / Q000502:physiology*; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000502:physiology*
C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D017931:DNA Primers; C524625:MUC2 protein, human; D055262:Mucin-2; D009077:Mucins; D012333:RNA, Messenger; D016159:Tumor Suppressor Protein p53