Overexpressed Pituitary Tumor-Transforming Gene Causes Aneuploidy in Live Human Cells

Abstract The mammalian securin, pituitary tumor-transforming gene (PTTG), is overexpressed in several tumors and transforms cells in vitro and in vivo. To test the hypothesis that PTTG overexpression causes aneuploidy, enhanced green fluorescent protein (EGFP)-tagged PTTG (PTTG-EGFP) was expressed in human H1299 cancer cells (with undetectable endogenous PTTG expression) and mitosis of individual live cells observed. Untransfected cells and cells expressing EGFP alone exhibited appropriate mitosis. PTTG-EGFP markedly prolonged prophase and metaphase, indicating that PTTG blocks progression of mitosis to anaphase. In cells that underwent apparently normal mitosis (35 of 65 cells), PTTG-EGFP was degraded about 1 min before anaphase onset. Cells that failed to degrade PTTG-EGFP exhibited asymmetrical cytokinesis without chromosome segregation (18 of 65 cells) or chromosome decondensation without cytokinesis (9 of 65 cells), resulting in appearance of a macronucleus. Fifty-one of 55 cells expressing a nondegradable mutant PTTG exhibited asymmetrical cytokinesis without chromosome segregation, and some (4 of 55) decondensed chromosomes, both resulting in macronuclear formation. During this abnormal cytokinesis, all chromosomes and spindles and both centrosomes moved to one daughter cell, suggesting potential chaos in the subsequent mitosis. In conclusion, failure of PTTG degradation or enhanced PTTG accumulation, as a consequence of overexpression, inhibits mitosis progression and chromosome segregation but does not directly affect cytokinesis, resulting in aneuploidy. These results demonstrate that PTTG induces aneuploidy in single, live, human cancer cells.

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Pituitary tumor-transforming gene and its binding factor in endocrine cancer

Expert Reviews in Molecular Medicine ◽

10.1017/s1462399410001699 ◽

2010 ◽

Vol 12 ◽

Cited By ~ 31

Author(s):

Vicki E. Smith ◽

Jayne A. Franklyn ◽

Christopher J. McCabe

Keyword(s):

Pituitary Tumor ◽

Current Knowledge ◽

Cellular Transformation ◽

Ovarian Carcinomas ◽

Pituitary Tumor Transforming Gene ◽

Multifunctional Protein ◽

Binding Factor ◽

Transforming Gene

The pituitary tumor-transforming gene (PTTG1) encodes a multifunctional protein (PTTG) that is overexpressed in numerous tumours, including pituitary, thyroid, breast and ovarian carcinomas. PTTG induces cellular transformation in vitro and tumourigenesis in vivo, and several mechanisms by which PTTG contributes to tumourigenesis have been investigated. Also known as the human securin, PTTG is involved in cell cycle regulation, controlling the segregation of sister chromatids during mitosis. This review outlines current information regarding PTTG structure, expression, regulation and function in the pathogenesis of neoplasia. Recent progress concerning the use of PTTG as a prognostic marker or therapeutic target will be considered. In addition, the PTTG binding factor (PBF), identified through its interaction with PTTG, has also been established as a proto-oncogene that is upregulated in several cancers. Current knowledge regarding PBF is outlined and its role both independently and alongside PTTG in endocrine and related cancers is discussed.

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A New Smoothened Antagonist Bearing the Purine Scaffold Shows Antitumour Activity In Vitro and In Vivo

International Journal of Molecular Sciences ◽

10.3390/ijms22168372 ◽

2021 ◽

Vol 22 (16) ◽

pp. 8372

Author(s):

Ana María Zárate ◽

Christian Espinosa-Bustos ◽

Simón Guerrero ◽

Angélica Fierro ◽

Felipe Oyarzún-Ampuero ◽

...

Keyword(s):

Cancer Cells ◽

Human Cancer ◽

Antitumour Activity ◽

Anticancer Compounds ◽

Human Cancer Cells ◽

Cycle Arrest ◽

Apoptosis Inducer ◽

Purine Ring

The Smoothened (SMO) receptor is the most druggable target in the Hedgehog (HH) pathway for anticancer compounds. However, SMO antagonists such as vismodegib rapidly develop drug resistance. In this study, new SMO antagonists having the versatile purine ring as a scaffold were designed, synthesised, and biologically tested to provide an insight to their mechanism of action. Compound 4s was the most active and the best inhibitor of cell growth and selectively cytotoxic to cancer cells. 4s induced cell cycle arrest, apoptosis, a reduction in colony formation and downregulation of PTCH and GLI1 expression. BODIPY-cyclopamine displacement assays confirmed 4s is a SMO antagonist. In vivo, 4s strongly inhibited tumour relapse and metastasis of melanoma cells in mice. In vitro, 4s was more efficient than vismodegib to induce apoptosis in human cancer cells and that might be attributed to its dual ability to function as a SMO antagonist and apoptosis inducer.

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Murine pituitary tumor-transforming gene functions as a securin protein in insulin-secreting cells

Journal of Endocrinology ◽

10.1677/joe.1.06885 ◽

2006 ◽

Vol 191 (1) ◽

pp. 45-53 ◽

Cited By ~ 8

Author(s):

Run Yu ◽

Martha Cruz-Soto ◽

Sergio Li Calzi ◽

Hongxiang Hui ◽

Shlomo Melmed

Keyword(s):

Cell Proliferation ◽

Pituitary Tumor ◽

Cell Cycle Progression ◽

Fluorescent Protein ◽

Cell System ◽

Β Cell ◽

Human Pituitary ◽

Pituitary Tumor Transforming Gene ◽

Expression Levels ◽

Transforming Gene

Human pituitary tumor-transforming gene 1 (PTTG1) encodes a securin protein critically important in regulating chromosome separation. Murine PTTG (mPTTG) is 66% homologous to human PTTG1 and PTTG-null (PTTG−/−) mice exhibit pancreatic β-cell hypoplasia and abnormal nuclear morphology with resultant diabetes. As we show that ductal β-cell neogenesis is intact in PTTG−/− mice, we explored mechanism for defective β-cell replication. We tested whether mPTTG exhibits securin properties in mouse insulin-secreting insulinoma MIN6 cells, using a live-cell system to monitor mitosis in cells transfected with an enhanced green fluorescent protein (EGFP)-tagged mPTTG conjugate (mPTTG-EGFP). To fulfill the criteria for securin properties, the protein should undergo degradation immediately before the metaphase-to-anaphase transition when expression levels are low, and should inhibit metaphase-to-anaphase transition when expression levels are high. EGFP itself did not undergo degradation throughout mitosis and high levels of EGFP per se did not affect normal mitosis progression (n=25). However, mPTTG-EGFP was degraded 2 min before the metaphase-to-anaphase transition when expression levels were low (n=19), and high mPTTG-EGFP levels blocked metaphase-to-anaphase transition in 13 cells. mPTTG-EGFP inhibited MIN6 cell proliferation and caused apoptosis. Immunocoprecipitation demonstrated binding of mPTTG-EGFP and separase. These results show that mPTTG exhibits properties consistent with a murine securin in insulin-secreting mouse cells and mPTTG overexpression inhibits cell proliferation, suggesting that defective β-cell proliferation observed in PTTG−/− mice is likely due to abnormal cell-cycle progression.

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Cancer-Associated Fibroblasts Induce Epithelial-Mesenchymal Transition in Endometrial Cancer Cells by Regulating Pituitary Tumor Transforming Gene

Cancer Investigation ◽

10.1080/07357907.2019.1575969 ◽

2019 ◽

Vol 37 (3) ◽

pp. 134-143 ◽

Cited By ~ 2

Author(s):

Xiaoyun Wang ◽

Xiwen Sun ◽

Lin Mu ◽

Wei Chen

Keyword(s):

Endometrial Cancer ◽

Cancer Cells ◽

Pituitary Tumor ◽

Epithelial Mesenchymal Transition ◽

Cancer Associated Fibroblasts ◽

Pituitary Tumor Transforming Gene ◽

Mesenchymal Transition ◽

Transforming Gene

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2, 3-Dihydro-3β-methoxy Withaferin-A Lacks Anti-Metastasis Potency: Bioinformatics and Experimental Evidences

Scientific Reports ◽

10.1038/s41598-019-53568-6 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 2

Author(s):

Anupama Chaudhary ◽

Rajkumar S. Kalra ◽

Vidhi Malik ◽

Shashank P. Katiyar ◽

Durai Sundar ◽

...

Keyword(s):

Cell Migration ◽

Cancer Cells ◽

Cancer Cell ◽

Human Cancer ◽

Effector Proteins ◽

Withaferin A ◽

Migration And Invasion ◽

Cell Metastasis

AbstractWithaferin-A is a withanolide, predominantly present in Ashwagandha (Withania somnifera). It has been shown to possess anticancer activity in a variety of human cancer cells in vitro and in vivo. Molecular mechanism of such cytotoxicity has not yet been completely understood. Withaferin-A and Withanone were earlier shown to activate p53 tumor suppressor and oxidative stress pathways in cancer cells. 2,3-dihydro-3β-methoxy analogue of Withaferin-A (3βmWi-A) was shown to lack cytotoxicity and well tolerated at higher concentrations. It, on the other hand, protected normal cells against oxidative, chemical and UV stresses through induction of anti-stress and pro-survival signaling. We, in the present study, investigated the effect of Wi-A and 3βmWi-A on cell migration and metastasis signaling. Whereas Wi-A binds to vimentin and heterogeneous nuclear ribonucleoprotein K (hnRNP-K) with high efficacy and downregulates its effector proteins, MMPs and VEGF, involved in cancer cell metastasis, 3βmWi-A was ineffective. Consistently, Wi-A, and not 3βmWi-A, caused reduction in cytoskeleton proteins (Vimentin, N-Cadherin) and active protease (u-PA) that are essential for three key steps of cancer cell metastasis (EMT, increase in cell migration and invasion).

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