Abstract |
Testicular germ cell tumors (TGCTs) arise despite possessing high levels of wild-type p53, suggesting p53 latency. We have previously shown that p53 repression in TGCT-derived human embryonal carcinoma (EC) is relieved upon treatment with all-trans retinoic acid (RA), resulting in enhanced p53 transactivation activity. To further investigate p53 repression in EC, a series of gal4-p53 truncation constructs were generated. Deletion of the core DNA-binding region, residues 117-274, had no effect on basal or RA-induced p53 activity. Progressively, larger truncations were made in the C- or N-terminal direction. Deletion of residues toward the C-terminus of p53 as far as residue 354 did not affect either the basal or RA-inducible activity of gal4-p53. When a small region in the N-terminus was deleted (residues 105-116), relief of the basal repression of p53 activity characteristic of EC was observed. Fusion of this region to the VP16 activation domain (VPAD) resulted in a 10-20-fold repression of VPAD activity in NT2/D1 human EC cells, indicating that this region acts as a heterologous repressor. Owing to its location in the N-terminal half of p53, we have named this region the p53 N-terminal Repression Domain (p53-NRD). The p53-NRD mediated repression in a variety of cell lines, with the most prominent repression observed in human EC cells. While RA alone had no effect on p53-NRD activity, cotreatment with RA and the histone deacetylase inhibitor trichostatin-A ( TSA) completely relieved p53-NRD-mediated repression. In contrast, NRD-mediated repression was not sensitive to RA and TSA in a derived RA-resistant cell line with a retinoic acid receptor gamma (RARgamma) defect, but sensitivity could be restored with transfection of RARgamma. These data indicate that a unique repressor domain resides in p53 at residues 90-116 whose activity can be modulated in the presence of 'differentiation therapy' and 'transcription therapy' agents.
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Authors | Joshua C Curtin, Michael J Spinella |
Journal | Oncogene
(Oncogene)
Vol. 24
Issue 9
Pg. 1481-90
(Feb 24 2005)
ISSN: 0950-9232 [Print] England |
PMID | 15674351
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)
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Chemical References |
- Tumor Suppressor Protein p53
- Tretinoin
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Topics |
- Amino Acid Sequence
- Animals
- Breast Neoplasms
- CHO Cells
- COS Cells
- Carcinoma, Embryonal
(genetics)
- Cell Division
(drug effects)
- Cell Line, Tumor
- Chlorocebus aethiops
- Cricetinae
- Gene Expression Regulation, Neoplastic
- Humans
- Molecular Sequence Data
- Transcription, Genetic
(genetics)
- Transfection
- Tretinoin
(pharmacology)
- Tumor Suppressor Protein p53
(chemistry, genetics)
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