An emerging role for the nuclear localization of maspin in the suppression of tumor progression and metastasis1This article is part of Special Issue entitled Asilomar Chromatin and has undergone the Journal’s usual peer review process.

2012 ◽  
Vol 90 (1) ◽  
pp. 22-38 ◽  
Author(s):  
Brigitte Goulet ◽  
Gabriel Chan ◽  
Ann F. Chambers ◽  
John D. Lewis
Keyword(s):  
Tumor Suppressor ◽  
Nuclear Localization ◽  
Molecular Mechanisms ◽  
Additional Data ◽  
Mammary Epithelial Cells ◽  
Peer Review Process ◽  
Mammary Epithelial ◽  
Suppressor Activity ◽  
Tumor Suppressor Activity ◽  
Normal Mammary Epithelial

Maspin, a member of the serpin family of serine protease inhibitors, was originally identified as a tumor suppressor that is expressed in normal mammary epithelial cells but is reduced or absent in breast carcinomas. Early enthusiasm for maspin as a biomarker for disease progression has been tempered by clinical data that associates maspin with favourable outcomes in some studies and poor prognosis in others. Here, we review all of the published clinical studies for maspin in breast and ovarian cancers and propose that the apparent discordance between clinical reports is a consequence of differential cellular distribution of maspin. Indeed, it was thought that an extracellular pool of maspin possessed tumor suppressor activity, acting by inhibiting migration and increasing cell adhesion. Recent evidence from our group and others indicates, however, that the nuclear localization of maspin in cancer cells is necessary for its tumor suppressor activity. We provide additional data here to demonstrate that nuclear-localized maspin binds to chromatin and is required to effectively prevent cells from metastasizing. Our knowledge of other serpins that localize to the nucleus should help to inform future studies of nuclear maspin. Elucidation of the molecular mechanisms regulating the localization and activities of maspin should pave the way for the development of improved diagnostics and therapies for cancer.

scholarly journals Nuclear Localization Is Not Required for Tip60 Tumor Suppressor Activity in Breast and Lung Cancer Cells

2020 ◽  
Vol 39 (11) ◽  
pp. 2077-2084
Author(s):  
Priyadarshini Ravichandran ◽  
Simon A. Davis ◽  
Himali Vashishtha ◽  
Azad L. Gucwa ◽  
Daniel S. Ginsburg
Keyword(s):  
Lung Cancer ◽  
Tumor Suppressor ◽  
Cancer Cells ◽  
Nuclear Localization ◽  
Lung Cancer Cells ◽  
Suppressor Activity ◽  
Tumor Suppressor Activity

scholarly journals The TGF-β Family: Signaling Pathways, Developmental Roles, and Tumor Suppressor Activities

2002 ◽  
Vol 2 ◽  
pp. 892-925 ◽  
Author(s):  
Aaron N. Johnson ◽  
Stuart J. Newfeld
Keyword(s):  
Tumor Suppressor ◽  
Signaling Pathways ◽  
Molecular Mechanisms ◽  
Transforming Growth Factor ◽  
Family Members ◽  
Transforming Growth Factor Β ◽  
Suppressor Activity ◽  
Wide Range ◽  
Tumor Suppressor Activity ◽  
Multicellular Organisms

Intercellular communication is a critical process for all multicellular organisms, and communication among cells is required for proper embryonic development and adult physiology. Members of the Transforming Growth Factor-β (TGF-β) family of secreted proteins communicate information between cells via a complex signaling pathway, and family members are capable of inducing a wide range of cellular responses. The purpose of this review is to provide the reader with a broad introduction to our current understanding of three aspects of the TGF-β family. These are the molecular mechanisms utilized by TGF-β signaling pathways, the developmental roles played by TGF-β family members in a variety of species, and the growing list of cancers in which various TGF-β signaling pathways display tumor suppressor activity.

Targeting the p53 tumor suppressor activity in glioblastomas using small molecule MDM2-inhibitor

2011 ◽  
Vol 42 (01) ◽  
Author(s):  
P. Monfared ◽  
T. Viel ◽  
G. Schneider ◽  
Y. Waerzeggers ◽  
S. Rapic ◽  
...  
Keyword(s):  
Tumor Suppressor ◽  
Small Molecule ◽  
Suppressor Activity ◽  
P53 Tumor Suppressor ◽  
Tumor Suppressor Activity ◽  
Mdm2 Inhibitor

Merlin cooperates with neurofibromin and Spred1 to suppress the Ras–Erk pathway

2020 ◽  
Author(s):  
Yan Cui ◽  
Lin Ma ◽  
Stephan Schacke ◽  
Jiani C Yin ◽  
Yi-Ping Hsueh ◽  
...  
Keyword(s):  
Tumor Suppressor ◽  
Binding Sites ◽  
Neurofibromatosis Type ◽  
Kinase Domain ◽  
Erk Pathway ◽  
Suppressor Activity ◽  
The Third ◽  
Tumor Suppressor Activity ◽  
Multiple Signaling

Abstract The Ras–Erk pathway is frequently over-activated in human tumors. Neurofibromatosis type 1 and 2 (NF1, NF2) are characterized by multiple tumors of Schwann cell origin. The NF1 tumor suppressor neurofibromin is a principal Ras-GAP accelerating Ras inactivation, whereas the NF2 tumor suppressor merlin is a scaffold protein coordinating multiple signaling pathways. We have previously reported that merlin interacts with Ras and p120RasGAP. Here, we show that merlin can also interact with the neurofibromin/Spred1 complex via merlin-binding sites present on both proteins. Further, merlin can directly bind to the Ras-binding domain and the kinase domain of Raf1. As the third component of the neurofibromin/Spred1 complex, merlin cannot increase the Ras-GAP activity; rather, it blocks Ras binding to Raf1 by functioning as a ‘selective Ras barrier’. Merlin-deficient Schwann cells require the Ras–Erk pathway activity for proliferation. Accordingly, suppression of the Ras–Erk pathway likely contributes to merlin’s tumor suppressor activity. Taken together, our results, and studies by others, support targeting or co-targeting of this pathway as a therapy for NF2 inactivation-related tumors.

scholarly journals c-erbB-3

2002 ◽  
Vol 157 (6) ◽  
pp. 929-940 ◽  
Author(s):  
Martin Offterdinger ◽  
Christian Schöfer ◽  
Klara Weipoltshammer ◽  
Thomas W. Grunt
Keyword(s):  
Epithelial Cells ◽  
Nuclear Localization ◽  
Nuclear Export ◽  
Mammary Epithelial Cells ◽  
Mammary Epithelial ◽  
Site Directed Mutagenesis ◽  
Receptor Protein ◽  
Erbb Receptors ◽  
Cell Fractionation ◽  
Epithelial Polarity

c-erbB receptors are usually located in cell membranes and are activated by extracellular binding of EGF-like growth factors. Unexpectedly, using immunofluorescence we found high levels of c-erbB-3 within the nuclei of MTSV1-7 immortalized nonmalignant human mammary epithelial cells. Nuclear localization was mediated by the COOH terminus of c-erbB-3, and a nuclear localization signal was identified by site-directed mutagenesis and by transfer of the signal to chicken pyruvate kinase. A nuclear export inhibitor caused accumulation of c-erbB-3 in the nuclei of other mammary epithelial cell lines as demonstrated by immunofluorescence and biochemical cell fractionation, suggesting that c-erbB-3 shuttles between nuclear and nonnuclear compartments in these cells. Growth of MTSV1-7 on permeable filters induced epithelial polarity and concentration of c-erbB-3 within the nucleoli. However, the c-erbB-3 ligand heregulin β1 shifted c-erbB-3 from the nucleolus into the nucleoplasm and then into the cytoplasm. The subcellular localization of c-erbB-3 obviously depends on exogenous stimuli and on the stage of epithelial polarity and challenges the specific function of c-erbB-3 as a transmembrane receptor protein arguing for additional, as yet unidentified, roles of c-erbB-3 within the nucle(ol)us of mammary epithelial cells.

scholarly journals The ETS Transcription Factor ESE-1 Transforms MCF-12A Human Mammary Epithelial Cells via a Novel Cytoplasmic Mechanism

2004 ◽  
Vol 24 (12) ◽  
pp. 5548-5564 ◽  
Author(s):  
Jason D. Prescott ◽  
Karen S. N. Koto ◽  
Meenakshi Singh ◽  
Arthur Gutierrez-Hartmann
Keyword(s):  
Breast Cancer ◽  
Transcription Factor ◽  
Epithelial Cells ◽  
Nuclear Localization ◽  
Human Breast Cancer ◽  
Mammary Epithelial Cells ◽  
Cell Transformation ◽  
Mammary Epithelial ◽  
Human Breast ◽  
Human Mammary Epithelial

ABSTRACT Several different transcription factors, including estrogen receptor, progesterone receptor, and ETS family members, have been implicated in human breast cancer, indicating that transcription factor-induced alterations in gene expression underlie mammary cell transformation. ESE-1 is an epithelium-specific ETS transcription factor that contains two distinguishing domains, a serine- and aspartic acid-rich (SAR) domain and an AT hook domain. ESE-1 is abundantly expressed in human breast cancer and trans-activates epithelium-specific gene promoters in transient transfection assays. While it has been presumed that ETS factors transform mammary epithelial cells via their nuclear transcriptional functions, here we show (i) that ESE-1 protein is cytoplasmic in human breast cancer cells; (ii) that stably expressed green fluorescent protein-ESE-1 transforms MCF-12A human mammary epithelial cells; and (iii) that the ESE-1 SAR domain, acting in the cytoplasm, is necessary and sufficient to mediate this transformation. Deletion of transcriptional regulatory or nuclear localization domains does not impair ESE-1-mediated transformation, whereas fusing the simian virus 40 T-antigen nuclear localization signal to various ESE-1 constructs, including the SAR domain alone, inhibits their transforming capacity. Finally, we show that the nuclear localization of ESE-1 protein induces apoptosis in nontransformed mammary epithelial cells via a transcription-dependent mechanism. Together, our studies reveal two distinct ESE-1 functions, apoptosis and transformation, where the ESE-1 transcription activation domain contributes to apoptosis and the SAR domain mediates transformation via a novel nonnuclear, nontranscriptional mechanism. These studies not only describe a unique ETS factor transformation mechanism but also establish a new paradigm for cell transformation in general.

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