TAp73α increases p53 tumor suppressor activity in thyroid cancer cells via the inhibition of Mdm2-mediated degradation
| Autor: | Mariangela Sanfilippo, Riccardo Vigneri, Veronica Vella, Francesco Frasca, Vincenzo Pezzino, Giuseppe Pandini, Roberta Malaguarnera |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2008 |
| Předmět: |
Cyclin-Dependent Kinase Inhibitor p21
Small interfering RNA Cancer Research Transcription Genetic Biology Binding Competitive Cell Line Promoter Regions Bcl-2-associated X protein Proto-Oncogene Proteins c-mdm2 Competitive Genetic Transcription (biology) Cell Line Tumor medicine Humans Thyroid Neoplasms Nuclear protein Promoter Regions Genetic neoplasms Thyroid cancer Molecular Biology Protein Processing bcl-2-Associated X Protein Regulation of gene expression Neoplastic Binding Sites Tumor Tumor Suppressor Proteins Post-Translational Nuclear Proteins Binding medicine.disease Gene Expression Regulation Neoplastic DNA-Binding Proteins Oncology Gene Expression Regulation Cancer research biology.protein Mdm2 Thermodynamics Protein Binding Tumor Suppressor Protein p53 Protein Processing Post-Translational Transcription |
| Popis: | p53 family proteins include p53 tumor suppressor, p63, and p73. Despite the high similarity in structure and function with p53, p63, and p73 function in tumor suppression is still controversial. Here, we show that TAp73α, a transcriptionally active p73 isoform, is able to synergize p53 tumor suppressor function in thyroid cancer cells. Indeed, depletion of p73 by small interfering RNA in thyroid cancer cells resulted in a reduced transcriptional activity of p53. Ectopic coexpression of both p53 and TAp73α in thyroid cancer cells resulted in increased transcription and tumor suppressor function compared with p53 or TAp73α alone, as well as in increased p53 protein levels. The enhancing effect of TAp73α on p53 activity is Mdm2 dependent because it is prevented by Mdm2 depletion by small interfering RNA. At least two mechanisms may explain the interference of TAp73α with p53 function. First, in thyroid cancer cells, TAp73α inhibits the effect of p53 on Mdm2 induction by antagonizing p53 at the Mdm2 promoter level. Second, a TAp73α mutant (G264W), which is devoid of DNA binding capability, is still able to increase p53 protein levels by competing with p53 for Mdm2 protein binding. Taken together, these results indicate that in thyroid cancer cells, TAp73α is able to increase p53 protein level and function by interfering with Mdm2-mediated p53 degradation. These results may be useful for designing gene therapies aimed at restoring a normal p53 function in thyroid cancer cells. (Mol Cancer Res 2008;6(1):64–77) |
| Databáze: | OpenAIRE |
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