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The PTTG1-binding factor (PBF/PTTG1IP) regulates p53 activity in thyroid cells.

ABSTRACT: The PTTG1-binding factor (PBF/PTTG1IP) has an emerging repertoire of roles, especially in thyroid biology, and functions as a protooncogene. High PBF expression is independently associated with poor prognosis and lower disease-specific survival in human thyroid cancer. However, the precise role of PBF in thyroid tumorigenesis is unclear. Here, we present extensive evidence demonstrating that PBF is a novel regulator of p53, a tumor suppressor protein with a key role in maintaining genetic stability, which is infrequently mutated in differentiated thyroid cancer. By coimmunoprecipitation and proximity-ligation assays, we show that PBF binds specifically to p53 in thyroid cells and significantly represses transactivation of responsive promoters. Further, we identify that PBF decreases p53 stability by enhancing ubiquitination, which appears dependent on the E3 ligase activity of Mdm2. Impaired p53 function was evident in a transgenic mouse model with thyroid-specific PBF overexpression (transgenic PBF mice), which had significantly increased genetic instability as indicated by fluorescent inter simple sequence repeat-PCR analysis. Consistent with this, approximately 40% of all DNA repair genes examined were repressed in transgenic PBF primary cultures, including genes with critical roles in maintaining genomic integrity such as Mgmt, Rad51, and Xrcc3. Our data also revealed that PBF induction resulted in up-regulation of the E2 enzyme Rad6 in murine thyrocytes and was associated with Rad6 expression in human thyroid tumors. Overall, this work provides novel insights into the role of the protooncogene PBF as a negative regulator of p53 function in thyroid tumorigenesis, in which PBF is generally overexpressed and p53 mutations are rare compared with other tumor types.

SUBMITTER: Read ML

PROVIDER: S-EPMC4759943 | biostudies-literature | 2014 Apr

REPOSITORIES: biostudies-literature

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The PTTG1-binding factor (PBF/PTTG1IP) regulates p53 activity in thyroid cells.

Read Martin L ML Seed Robert I RI Fong Jim C W JC Modasia Bhavika B Ryan Gavin A GA Watkins Rachel J RJ Gagliano Teresa T Smith Vicki E VE Stratford Anna L AL Kwan Perkin K PK Sharma Neil N Dixon Olivia M OM Watkinson John C JC Boelaert Kristien K Franklyn Jayne A JA Turnell Andrew S AS McCabe Christopher J CJ

Endocrinology 20140207 4

The PTTG1-binding factor (PBF/PTTG1IP) has an emerging repertoire of roles, especially in thyroid biology, and functions as a protooncogene. High PBF expression is independently associated with poor prognosis and lower disease-specific survival in human thyroid cancer. However, the precise role of PBF in thyroid tumorigenesis is unclear. Here, we present extensive evidence demonstrating that PBF is a novel regulator of p53, a tumor suppressor protein with a key role in maintaining genetic stabil ...[more]

PMID: 24506068

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Project description:ObjectiveAn oncogenic protein, pituitary tumor transforming gene 1 binding factor (PTTG1IP, also called PBF), has been found to be expressed in various cancers. However, few studies have explored its prognostic significance and biologic function in epithelial ovarian cancer (EOC).MethodsBased on the Cancer Genome Atlas (TCGA) database, this study determined the differential expression of PBF at the mRNA level in EOC and normal tissues, which was then verified using real-time PCR and western blotting. Moreover, the Kaplan-Meier method and the Cox regression method were adopted to assess the clinical value of PBF in EOC. A nomogram model was constructed to evaluate the prognostic performance of PBF in EOC. Gene set enrichment analysis (GSEA) was employed to evaluate the signaling and pathway enrichment of PBF in EOC. The association between PBF expression and tumor-infiltrating immune cells (TIICs) in EOC was examined by single-sample GSEA and TIMER.ResultsPBF was significantly higher in EOC than normal tissues as shown through TCGA database, and this result was verified by qRT-PCR and western blotting of EOC tissues and different cell lines. High PBF was associated with tumor size and lymphatic metastasis status. Kaplan-Meier (KM) analysis indicated that high PBF expression correlated with poor prognosis in patients with EOC (P < 0.0001). Moreover, multivariate Cox regression analysis was used to verify that PBF is an independent prognostic factor for EOC. The nomogram model exhibited moderate predictive accuracy and clinical utility in predicting EOC prognosis. The GSEA revealed that the expression of signaling pathways, such DNA damage replication, p53 pathway, Akt phosphorylation pathway, and estrogen-dependent nuclear pathway, were increased in the phenotype with high PBF expression. PBF expression was associated with neutrophil cells, iDC cells, NK cells, and Tem cells.ConclusionAs a prognostic biomarker for EOC, PBF was found to be correlated with immune infiltration, and may therefore be a promising target for immunotherapy for EOC.

Dataset Information

The PTTG1-binding factor (PBF/PTTG1IP) regulates p53 activity in thyroid cells.

Publications

The PTTG1-binding factor (PBF/PTTG1IP) regulates p53 activity in thyroid cells.

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