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Comel A.,Laboratorio Nazionale CIB LNCIB | Sorrentino G.,University of Trieste | Capaci V.,University of Trieste | Del Sal G.,Laboratorio Nazionale CIB LNCIB
FEBS Letters | Year: 2014

The tumor suppressor p53 is a transcription factor that in response to a plethora of stress stimuli activates a complex and context-dependent cellular response ultimately protecting genome integrity. In the last two decades, the discovery of cytoplasmic p53 localization has driven an intense research on its extra-nuclear functions. The ability to induce apoptosis acting directly at mitochondria and the related mechanisms of p53 localization and translocation in the cytoplasm and mitochondria have been dissected. However, recent works indicate the involvement of cytoplasmic p53 also in biological processes such as autophagy, metabolism, oxidative stress and drug response. This review will focus on the mechanisms of cytoplasmic p53 activation and the pathophysiological role of p53's transcription-independent functions, highlighting possible therapeutic implications. © 2014 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Girardini J.E.,CONICET | Walerych D.,Laboratorio Nazionale CIB LNCIB | Walerych D.,University of Trieste | Del Sal G.,Laboratorio Nazionale CIB LNCIB | Del Sal G.,University of Trieste
Sub-Cellular Biochemistry | Year: 2014

Following the initial findings suggesting a pro-oncogenic role for p53 point mutants, more than 30 years of research have unveiled the critical role exerted by these mutants in human cancer. A growing body of evidence, including mouse models and clinical data, has clearly demonstrated a connection between mutant p53 and the development of aggressive and metastatic tumors. Even if the molecular mechanisms underlying mutant p53 activities are still the object of intense scrutiny, it seems evident that full activation of its oncogenic role requires the functional interaction with other oncogenic alterations. p53 point mutants, with their pleiotropic effects, simultaneously activating several mechanisms of aggressiveness, are engaged in multiple cross-talk with a variety of other cancer-related processes, thus depicting a complex molecular landscape for the mutant p53 network. In this chapter revealing evidence illustrating different ways through which this cooperation may be achieved will be discussed. Considering the proposed role for mutant p53 as a driver of cancer aggressiveness, disarming mutant p53 function by uncoupling the cooperation with other oncogenic alterations, stands out as an exciting possibility for the development of novel anti-cancer therapies. © Springer Science+Business Media Dordrecht 2014.

Pegoraro S.,University of Trieste | Ros G.,University of Trieste | Ciani Y.,University of Trieste | Ciani Y.,Laboratorio Nazionale CIB LNCIB | And 3 more authors.
Oncotarget | Year: 2015

High Mobility Group A1 (HMGA1) is an architectural chromatin factor that promotes neoplastic transformation and progression. However, the mechanism by which HMGA1 exerts its oncogenic function is not fully understood. Here, we show that cyclin E2 (CCNE2) acts downstream of HMGA1 to regulate the motility and invasiveness of basal-like breast cancer cells by promoting the nuclear localization and activity of YAP, the downstream mediator of the Hippo pathway. Mechanistically, the activity of MST1/2 and LATS1/2, the core kinases of the Hippo pathway, are required for the HMGA1- and CCNE2-mediated regulation of YAP localization. In breast cancer patients, high levels of HMGA1 and CCNE2 expression are associated with the YAP/TAZ signature, supporting this connection. Moreover, we provide evidence that CDK inhibitors induce the translocation of YAP from the nucleus to the cytoplasm, resulting in a decrease in its activity. These findings reveal an association between HMGA1 and the Hippo pathway that is relevant to stem cell biology, tissue homeostasis, and cancer.

Girardini J.,Laboratorio Nazionale CIB LNCIB | Girardini J.,University of Trieste | Napoli M.,Laboratorio Nazionale CIB LNCIB | Napoli M.,University of Trieste | And 24 more authors.
Cancer Cell | Year: 2011

TP53 missense mutations dramatically influence tumor progression, however, their mechanism of action is still poorly understood. Here we demonstrate the fundamental role of the prolyl isomerase Pin1 in mutant p53 oncogenic functions. Pin1 enhances tumorigenesis in a Li-Fraumeni mouse model and cooperates with mutant p53 in Ras-dependent transformation. In breast cancer cells, Pin1 promotes mutant p53 dependent inhibition of the antimetastatic factor p63 and induction of a mutant p53 transcriptional program to increase aggressiveness. Furthermore, we identified a transcriptional signature associated with poor prognosis in breast cancer and, in a cohort of patients, Pin1 overexpression influenced the prognostic value of p53 mutation. These results define a Pin1/mutant p53 axis that conveys oncogenic signals to promote aggressiveness in human cancers. © 2011 Elsevier Inc.

Collavin L.,Laboratorio Nazionale CIB LNCIB | Collavin L.,University of Trieste | Lunardi A.,Laboratorio Nazionale CIB LNCIB | Lunardi A.,University of Trieste | And 3 more authors.
Cell Death and Differentiation | Year: 2010

The tumor suppressor p53 is a central hub in a molecular network controlling cell proliferation and death in response to potentially oncogenic conditions, and a wide array of covalent modifications and protein interactions modulate the nuclear and cytoplasmic activities of p53. The p53 relatives, p73 and p63, are entangled in the same regulatory network, being subject at least in part to the same modifications and interactions that convey signals on p53, and actively contributing to the resulting cellular output. The emerging picture is that of an interconnected pathway, in which all p53-family proteins are involved in the response to oncogenic stress and physiological inputs. Therefore, common and specific interactors of p53-family proteins can have a wide effect on function and dysfunction of this pathway. Many years of research have uncovered an impressive number of p53-interacting proteins, but much less is known about protein interactions of p63 and p73. Yet, many interactors may be shared by multiple p53-family proteins, with similar or different effects. In this study we review shared interactors of p53-family proteins with the aim to encourage research into this field; this knowledge promises to unveil regulatory elements that could be targeted by a new generation of molecules, and allow more efficient use of currently available drugs for cancer treatment. © 2010 Macmillan Publishers Limited All rights reserved.

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