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Biotinylation of the c‐myc promoter binding protein MBP‐1 decreases c‐myc expression in mammary carcinoma MCF‐7 cells
Author(s) -
Zhou Jie,
Wijeratne Subhashinee S. K.,
Zempleni Janos
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.639.8
Subject(s) - biotinylation , biotin , metastasis , oncogene , microbiology and biotechnology , cancer research , transfection , biology , transactivation , mcf 7 , gene expression , cancer cell , cancer , gene , biochemistry , genetics , cell cycle , human breast
Biotin feeding studies in mice predisposed to developing breast cancer suggest that the tumor load increases by ~100% in biotin‐deficient mice compared with controls, and that the increase is associated with metastasis rather than new tumors. The oncogene c‐myc is implicated in cancer metastasis, and its expression is repressed by binding of MBP‐1 to the c‐myc promoter. Discovery‐based studies for identifying novel biotin‐containing proteins suggest that MBP‐1 contains covalently bound biotin, judged by mass spectrometry. We hypothesized that biotinylation of MBP‐1 increases the binding of MBP‐1 to the c‐myc promoter, thereby decreasing c‐myc expression and metastasis. MCF‐7 cells were cultured in biotin‐defined media (deficient, sufficient, supplemented) and transfected with a reporter gene construct for the c‐myc promoter. Reporter activity was ~100% greater in biotin‐deficient cells compared with sufficient and supplemented controls. Likewise, c‐myc mRNA levels were 10% higher in deficient compared with sufficient cells, and 10% high in sufficient compared with supplemented cells. Biotinylation of MBP‐1 is an enzymatic process, judged by streptavidin blots. These observations are consistent with our hypothesis and preliminary studies, suggesting that biotin depletion causes an increased expression of the oncogene c‐myc, thereby increasing cancer risk. Grant Funding Source : ARD Hatch, NIFA, and NIH