Author
Guillermina Lozano
Bio: Guillermina Lozano is an academic researcher from University of Texas MD Anderson Cancer Center. The author has contributed to research in topics: Regulation of gene expression & Mdm2. The author has an hindex of 7, co-authored 8 publications receiving 1318 citations.
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Journal Article•
TL;DR: The murine double minute 2 (mdm2) gene encodes a negative regulator of the p53 tumor suppressor, which functions as an E3 ubiquitin ligase to degrade p53, and also binds another tumor suppressing protein, ARF.
Abstract: The murine double minute 2 (mdm2) gene encodes a negative regulator of the p53 tumor suppressor. Amplification of mdm2 or increased expression by unknown mechanisms occurs in many tumors. Thus, increased levels of MDM2 would inactivate the apoptotic and cell cycle arrest functions of p53, as do deletion or mutation of p53, common events in the genesis of many kinds of tumors. MDM2 functions as an E3 ubiquitin ligase to degrade p53. MDM2 also binds another tumor suppressor, ARF. This interaction sequesters MDM2 in the nucleolus away from p53, thus activating p53. Many additional MDM2 interacting proteins have been identified. Functions of MDM2 independent of p53 have also been identified. This article is an introduction to MDM2, its structure and biological functions, as well as its relationship to its binding partners.
427 citations
TL;DR: This work presents a novel and scalable approach to gene expression engineering that allows for real-time annotation of gene expression changes in response to cancerigenicity and shows promise in finding novel and efficient treatments for cancer.
Abstract: 1 Laboratory For Molecular Cancer Biology, Flanders Interuniversity Institute for Biotechnology (VIB), University of Ghent, Technologiepark, 927, Ghent B9052, Belgium 2 Salk Institute for Biological Studies, Gene Expression Laboratory, La Jolla, CA 92037, USA 3 Gene Expression and Diseases Unit, Institut Pasteur, Paris, France 4 The University of Texas Graduate School of Biomedical Sciences and department of Molecular Genetics, Section of Cancer Genetics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA * Corresponding author: J-C Marine, Laboratory For Molecular Cancer Biology, VIB, Technologiepark, 927, Ghent B-9052, Belgium. Tel: þ 32-93-313-640; Fax: þ 32-93-313-516; E-mail: chris.marine@dmbr.ugent.be
335 citations
TL;DR: Advances in Mdm2-mediated regulation of p53 and how the physical and functional interactions between these two proteins are regulated are evaluated and their potential implications for the development of new cancer therapeutic strategies are reviewed.
Abstract: The really interesting genes (RING)-finger-containing oncoprotein, Mdm2, is a promising drug target for cancer therapy. A key Mdm2 function is to promote ubiquitylation and proteasomal-dependent degradation of the tumor suppressor protein p53. Recent reports provide novel important insights into Mdm2-mediated regulation of p53 and how the physical and functional interactions between these two proteins are regulated. Moreover, a p53-independent role of Mdm2 has recently been confirmed by genetic data. These advances and their potential implications for the development of new cancer therapeutic strategies form the focus of this review.
304 citations
TL;DR: High levels of HDM2 in the cytoplasm in 25% of lung tumors as opposed to its normal localization in the nucleus suggest the existence of another level of regulation ofHDM2 which increases the activity of p53.
Abstract: The human counterpart hdm2 of the murine double-minute 2 (mdm2) gene encodes a 90-kD protein (HDM2) that inhibits the function of the p53 tumor suppressor. Hdm2 is amplified in approximately 30% of sarcomas, leading to overproduction of HDM2 and inactivation of p53. Using immunohistochemistry to screen a panel of human tumors for HDM2 overproduction, we detected high levels of HDM2 in the cytoplasm in 25% of lung tumors as opposed to its normal localization in the nucleus. These samples contained full-length hdm2 and several alternate-splice forms of hdm2 mRNA. Sequence analysis revealed deletions in the alternate-splice forms of the p53 binding domain and absence of a nuclear localization signal. In transient transfection assays, one of the alternate-splice forms, HDM2ALT1, bound and sequestered full-length HDM2 in the cytoplasm. In addition, the binding of HDM2ALT1 to HDM2 inhibited the interaction of HDM2 with p53, thus enhancing p53 transcriptional activity. These data suggest the existence of another level of regulation of HDM2 which increases the activity of p53.
140 citations
TL;DR: The data show that Mdm2 is required for rescuing erythroid progenitors from p53-mediated apoptosis during primitive erythropoiesis, and Mdm4 only contributes to p53 regulation at a specific phase of the differentiation program.
71 citations
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TL;DR: Control of p53's transcriptional activity is crucial for determining which p53 response is activated, a decision that must be understood if the next generation of drugs that selectively activate or inhibit p53 are to be exploited efficiently.
2,775 citations
TL;DR: It is now becoming clear that p53 can have a much broader role and can contribute to the development, life expectancy and overall fitness of an organism.
Abstract: p53 is best known as a tumour suppressor, although recent studies have challenged the view that this is its only role. Instead, p53 has important functions in organismal development, and might contribute to a number of diseases other than cancer.
2,096 citations
TL;DR: It is shown that p53 inhibits cystine uptake and sensitizes cells to ferroptosis, a non-apoptotic form of cell death, by repressing expression of SLC7A11, a key component of the Cystine/glutamate antiporter.
Abstract: Although p53-mediated cell-cycle arrest, senescence and apoptosis serve as critical barriers to cancer development, emerging evidence suggests that the metabolic activities of p53 are also important. Here we show that p53 inhibits cystine uptake and sensitizes cells to ferroptosis, a non-apoptotic form of cell death, by repressing expression of SLC7A11, a key component of the cystine/glutamate antiporter. Notably, p53(3KR), an acetylation-defective mutant that fails to induce cell-cycle arrest, senescence and apoptosis, fully retains the ability to regulate SLC7A11 expression and induce ferroptosis upon reactive oxygen species (ROS)-induced stress. Analysis of mutant mice shows that these non-canonical p53 activities contribute to embryonic development and the lethality associated with loss of Mdm2. Moreover, SLC7A11 is highly expressed in human tumours, and its overexpression inhibits ROS-induced ferroptosis and abrogates p53(3KR)-mediated tumour growth suppression in xenograft models. Our findings uncover a new mode of tumour suppression based on p53 regulation of cystine metabolism, ROS responses and ferroptosis.
1,677 citations
TL;DR: It is proposed that antirepression, the release of p53 from repression by factors such as Mdm2 and MdmX, is a key step in the physiological activation of p 53.
1,503 citations
TL;DR: This Review of in vitro studies, human tumour data and recent mouse models shows that p53 post-translational modifications have modulatory roles, and MDM2 andMDM4 have more profound roles for regulating p53.
Abstract: Mutations in TP53, the gene that encodes the tumour suppressor p53, are found in 50% of human cancers, and increased levels of its negative regulators MDM2 and MDM4 (also known as MDMX) downregulate p53 function in many of the rest. Understanding p53 regulation remains a crucial goal to design broadly applicable anticancer strategies based on this pathway. This Review of in vitro studies, human tumour data and recent mouse models shows that p53 post-translational modifications have modulatory roles, and MDM2 and MDM4 have more profound roles for regulating p53. Importantly, MDM4 emerges as an independent target for drug development, as its inactivation is crucial for full p53 activation.
1,277 citations