Pituitary tumor transforming gene 1 regulates Aurora kinase A activity

Department of Medicine, Cedars-Sinai Research Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA 90048, USA.
Oncogene (Impact Factor: 8.46). 08/2008; 27(49):6385-95. DOI: 10.1038/onc.2008.234
Source: PubMed


Pituitary tumor transforming gene 1 (PTTG1), a transforming gene highly expressed in several cancers, is a mammalian securin protein regulating both G1/S and G2/M phases. Using protein array screening, we showed PTTG1 interacting with Aurora kinase A (Aurora-A), and confirmed the interaction using co-immunoprecipitation, His-tagged pull-down assays and intracellular immunofluorescence colocalization. PTTG1 transfection into HCT116 cells prevented Aurora-A T288 autophosphorylation, inhibited phosphorylation of the histone H3 Aurora-A substrate and resulted in abnormally condensed chromatin. PTTG1-null cell proliferation was more sensitive to Aurora-A knock down and to Aurora kinase Inhibitor III treatment. The results indicate that PTTG1 and Aurora-A interact to regulate cellular responses to anti-neoplastic drugs. PTTG1 knockdown is therefore a potential approach to improve the efficacy of tumor Aurora kinase inhibitors.

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Available from: Kolja A Wawrowsky, Mar 04, 2015
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    • "AurA activity (Saskova et al., 2008; Tong et al., 2008). However , three studies suggest that T288 phosphorylation is not an absolute readout to evaluate AurA activity. "
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    ABSTRACT: Aurora A (AurA) is a major mitotic protein kinase involved in centrosome maturation and spindle assembly. Nucleophosmin/B23 (NPM) is a pleiotropic nucleolar protein involved in a variety of cellular processes including centrosome maturation. In the present study, we report that NPM is a strong activator of AurA kinase activity. NPM and AurA coimmunoprecipitate and colocalize to centrosomes in G2 phase, where AurA becomes active. In contrast with previously characterized AurA activators, NPM does not trigger autophosphorylation of AurA on threonine 288. NPM induces phosphorylation of AurA on serine 89, and this phosphorylation is necessary for activation of AurA. These data were confirmed in vivo, as depletion of NPM by ribonucleic acid interference eliminated phosphorylation of CDC25B on S353 at the centrosome, indicating a local loss of AurA activity. Our data demonstrate that NPM is a strong activator of AurA kinase activity at the centrosome and support a novel mechanism of activation for AurA.
    Full-text · Article · Mar 2012 · The Journal of Cell Biology
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    • "The effect of PTTG1 on centrosomal MT nucleation, together with its interaction with γ-tubulin and AKAP450, suggests a role of PTTG1 at the centrosome. Actually, the intracellular location of GFP-PTTG1 fusion protein in the centrosome was reported in HCT116 cells (Tong et al., 2008); in addition, using our PTTG1 antibody, we localized endogenous PTTG1 in the centrosome in both Cos-7 and RPE1 cells (Figure 9). This intracellular location supports an effective interaction of PTTG1 with γ-tubulin and AKAP450 centrosomal proteins. "
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    ABSTRACT: Pituitary tumor transforming gene 1 (PTTG1), also known as securin, has been implicated in many biological functions, including inhibition of sister chromatid separation, DNA repair, organ development, and regulation of the expression and secretion of angiogenic and metastatic factors. Although most of these functions of securin seem to depend on the localization of PTTG1 in the nucleus of the cell, a fraction of the protein has been also detected in the cytoplasm. Here we demonstrate that, in different cell types, a portion of cytoplasmic PTTG1 is associated with the cis face of the Golgi apparatus and that this localization depends on PTTG1 phosphorylation status. In this organelle, PTTG1 forms a complex with proteins involved in microtubule nucleation, including GM130, AKAP450, and γ-tubulin. RNA interference-mediated depletion of PTTG1 produces a delay in centrosomal and noncentrosomal microtubule nucleation. Cells lacking PTTG1 show severe defects in both cell polarization and migration in wound-healing assays. To our knowledge, this is the first study reporting the role of PTTG1 in microtubule nucleation and cell polarization, two processes directly involved in cell migration. We believe that these findings will contribute to understanding the mechanisms underlying PTTG1-mediated biological functions.
    Full-text · Article · Sep 2011 · Molecular biology of the cell
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    • "PTTG1 is a natively unfolded protein [8] which binds to ∼700 gene promoters as indicated by ChIP-on-Chip assay [9], and interacts with ∼80 proteins [10]. In addition to its securin function [11], PTTG1 regulates G2/M phase transition by inhibiting separase cleavage and aurora kinase A activity [10], [12]. PTTG1 also regulates G1/S transition by inducing cyclin D3 and repressing p21 expression [9]. "
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    ABSTRACT: As PTTG1 (pituitary tumor transforming gene) abundance correlates with adverse outcomes in cancer treatment, we determined mechanisms underlying this observation by assessing the role of PTTG1 in regulating cell response to anti-neoplastic drugs. HCT116 cells devoid of PTTG1 (PTTG1(-/-)) exhibited enhanced drug sensitivity as assessed by measuring BrdU incorporation in vitro. Apoptosis, mitosis catastrophe or DNA damage were not detected, but features of senescence were observed using low doses of doxorubicin and TSA. The number of drug-induced PTTG1(-/-) senescent cells increased ∼4 fold as compared to WT PTTG1-replete cells (p<0.001). p21, an important regulator of cell senescence, was induced ∼3 fold in HCT116 PTTG1(-/-) cells upon doxorubicin or Trichostatin A treatment. Binding of Sp1, p53 and p300 to the p21 promoter was enhanced in PTTG1(-/-) cells after treatment, suggesting transcriptional regulation of p21. p21 knock down abrogated the observed senescent effects of these drugs, indicating that PTTG1 likely suppresses p21 to regulate drug-induced senescence. PTTG1 also regulated SW620 colon cancer cells response to doxorubicin and TSA mediated by p21. Subcutaneously xenografted PTTG1(-/-) HCT116 cells developed smaller tumors and exhibited enhanced responses to doxorubicin. PTTG1(-/-) tumor tissue derived from excised tumors exhibited increased doxorubicin-induced senescence. As senescence is a determinant of cell responses to anti-neoplastic treatments, these findings suggest PTTG1 as a tumor cell marker to predict anti-neoplastic treatment outcomes.
    Full-text · Article · Jan 2011 · PLoS ONE
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