Alternative reading frames of the INK4a tumor suppressor gene encode two unrelated proteins capable of inducing cell cycle arrest

The tumor suppressor gene p53 prevents the initiation of tumor formation by inducing cell cycle arrest, senescence, DNA repair, and apoptosis. Recently, the absence or mutation of p53 was described to facilitate nuclear reprogramming. These findings suggest an influence of p53 on the de-differentiation process, and highlight the similarities between induction of pluripotency and tumor formation.

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Neuroradiology Manifestations of Li-Fraumeni Syndrome: Epidemiology, Genetics, Imaging Findings, and Management

Neurographics ◽

10.3174/ng.2000003 ◽

2020 ◽

Vol 10 (4) ◽

pp. 228-235

Author(s):

S. Naganawa ◽

T. Donohue ◽

A. Capizzano ◽

Y. Ota ◽

J. Kim ◽

...

Keyword(s):

Cell Cycle ◽

Tumor Suppressor ◽

Tumor Suppressor Gene ◽

Soft Tissue Sarcomas ◽

Suppressor Gene ◽

Imaging Findings ◽

Li Fraumeni Syndrome ◽

Increased Risk ◽

Li Fraumeni ◽

Risk Of Cancer

Li-Fraumeni syndrome is a familial cancer predisposition syndrome associated with germline mutation of the tumor suppressor gene 53, which encodes the tumor suppressor p53 protein. Affected patients are predisposed to an increased risk of cancer development, including soft-tissue sarcomas, breast cancer, brain tumors, and adrenocortical carcinoma, among other malignancies. The tumor suppressor gene TP53 plays an important, complex role in regulating the cell cycle, collaborating with transcription factors and other proteins. The disruption of appropriate cell cycle regulation by mutated TP53 is considered to be the cause of tumorigenesis in Li-Fraumeni syndrome. Appropriate surveillance, predominantly by using MR imaging, is used for early malignancy screening in an effort to improve the survival rate among individuals who are affected. Patients with Li-Fraumeni syndrome are also at increased risk for neoplasm development after radiation exposure, and, therefore, avoiding unnecessary radiation in both the diagnostic and therapeutic settings is paramount. Here, we review the epidemiology, genetics, imaging findings, and the current standard surveillance protocol for Li-Fraumeni syndrome from the National Comprehensive Cancer Network as well as potential treatment options.Learning Objective: Describe the cause of second primary malignancy among patients with Li-Fraumeni syndrome.

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Tumor Suppressor Inactivation in the Pathogenesis of Adult T-Cell Leukemia

Journal of Oncology ◽

10.1155/2015/183590 ◽

2015 ◽

Vol 2015 ◽

pp. 1-11 ◽

Cited By ~ 5

Author(s):

Christophe Nicot

Keyword(s):

Cell Cycle ◽

T Cell ◽

Tumor Suppressor ◽

Cell Cycle Arrest ◽

Tumor Suppressors ◽

Epigenetic Mechanisms ◽

T Cell Leukemia ◽

Cell Leukemia ◽

Adult T Cell Leukemia ◽

Cycle Arrest

Tumor suppressor functions are essential to control cellular proliferation, to activate the apoptosis or senescence pathway to eliminate unwanted cells, to link DNA damage signals to cell cycle arrest checkpoints, to activate appropriate DNA repair pathways, and to prevent the loss of adhesion to inhibit initiation of metastases. Therefore, tumor suppressor genes are indispensable to maintaining genetic and genomic integrity. Consequently, inactivation of tumor suppressors by somatic mutations or epigenetic mechanisms is frequently associated with tumor initiation and development. In contrast, reactivation of tumor suppressor functions can effectively reverse the transformed phenotype and lead to cell cycle arrest or death of cancerous cells and be used as a therapeutic strategy. Adult T-cell leukemia/lymphoma (ATLL) is an aggressive lymphoproliferative disease associated with infection of CD4 T cells by the Human T-cell Leukemia Virus Type 1 (HTLV-I). HTLV-I-associated T-cell transformation is the result of a multistep oncogenic process in which the virus initially induces chronic T-cell proliferation and alters cellular pathways resulting in the accumulation of genetic defects and the deregulated growth of virally infected cells. This review will focus on the current knowledge of the genetic and epigenetic mechanisms regulating the inactivation of tumor suppressors in the pathogenesis of HTLV-I.

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ei24, a p53 Response Gene Involved in Growth Suppression and Apoptosis

Molecular and Cellular Biology ◽

10.1128/mcb.20.1.233-241.2000 ◽

2000 ◽

Vol 20 (1) ◽

pp. 233-241 ◽

Cited By ~ 72

Author(s):

Zhengming Gu ◽

Cathy Flemington ◽

Thomas Chittenden ◽

Gerard P. Zambetti

Keyword(s):

Cell Cycle ◽

Cell Growth ◽

Tumor Suppressor ◽

Cell Cycle Arrest ◽

Apoptotic Cell ◽

Functional Characterization ◽

Growth Control ◽

P53 Tumor Suppressor ◽

Cycle Arrest ◽

P53 Response

ABSTRACT DNA damage and/or hyperproliferative signals activate the wild-type p53 tumor suppressor protein, which induces a G1 cell cycle arrest or apoptosis. Although the mechanism of p53-mediated cell cycle arrest is fairly well defined, the p53-dependent pathway regulating apoptosis is poorly understood. Here we report the functional characterization of murine ei24 (also known asPIG8), a gene directly regulated by p53, whose overexpression negatively controls cell growth and induces apoptotic cell death. Ectopic ei24 expression markedly inhibits cell colony formation, induces the morphological features of apoptosis, and reduces the number of β-galactosidase-marked cells, which is efficiently blocked by coexpression of Bcl-XL. Theei24/PIG8 gene is localized on human chromosome 11q23, a region frequently altered in human cancers. These results suggest that ei24 may play an important role in negative cell growth control by functioning as an apoptotic effector of p53 tumor suppressor activities.

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