Induction of p53-Dependent Senescence by the MDM2 Antagonist Nutlin-3a in Mouse Cells of Fibroblast Origin

Molecular Oncology Program, Spanish National Cancer Research Center (CNIO), Madrid, Spain.
Cancer Research (Impact Factor: 9.33). 09/2007; 67(15):7350-7. DOI: 10.1158/0008-5472.CAN-07-0200
Source: PubMed


Cellular senescence is emerging as an important in vivo anticancer response elicited by multiple stresses, including currently used chemotherapeutic drugs. Nutlin-3a is a recently discovered small-molecule antagonist of the p53-destabilizing protein murine double minute-2 (MDM2) that induces cell cycle arrest and apoptosis in cancer cells with functional p53. Here, we report that nutlin-3a induces cellular senescence in murine primary fibroblasts, oncogenically transformed fibroblasts, and fibrosarcoma cell lines. No evidence of drug-induced apoptosis was observed in any case. Nutlin-induced senescence was strictly dependent on the presence of functional p53 as revealed by the fact that cells lacking p53 were completely insensitive to the drug, whereas cells lacking the tumor suppressor alternative reading frame product of the CDKN2A locus underwent irreversible cell cycle arrest. Interestingly, irreversibility was achieved in neoplastic cells faster than in their corresponding parental primary cells, suggesting that nutlin-3a and oncogenic signaling cooperate in activating p53. Our current results suggest that senescence could be a major cellular outcome of cancer therapy by antagonists of the p53-MDM2 interaction, such as nutlin-3a.

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    • "Another interesting discovery is that p53-triggered senescence selectively affects tumor cells, leaving normal tissue totally unchanged (86). Novel p53-targeting compounds developed to date include Ellipticine and PRIMA-1, which restore wild-type activity to p53 mutants, and nutlins, which inhibit the binding of p53 to MDM2 (87-89). "
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    ABSTRACT: Cellular senescence is a physiological process of irreversible cell-cycle arrest that contributes to various physiological and pathological processes of aging. Whereas replicative senescence is associated with telomere attrition after repeated cell division, stress-induced premature senescence occurs in response to aberrant oncogenic signaling, oxidative stress, and DNA damage which is independent of telomere dysfunction. Recent evidence indicates that cellular senescence provides a barrier to tumorigenesis and is a determinant of the outcome of cancer treatment. However, the senescence-associated secretory phenotype, which contributes to multiple facets of senescent cancer cells, may influence both cancer-inhibitory and cancer-promoting mechanisms of neighboring cells. Conventional treatments, such as chemo- and radiotherapies, preferentially induce premature senescence instead of apoptosis in the appropriate cellular context. In addition, treatment-induced premature senescence could compensate for resistance to apoptosis via alternative signaling pathways. Therefore, we believe that an intensive effort to understand cancer cell senescence could facilitate the development of novel therapeutic strategies for improving the efficacy of anticancer therapies. This review summarizes the current understanding of molecular mechanisms, functions, and clinical applications of cellular senescence for anticancer therapy.
    BMB reports 02/2014; 47(2). DOI:10.5483/BMBRep.2014.47.2.005 · 2.60 Impact Factor
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    • "Moreover, they confirmed that Nutlin-3a requires p53 and p21 expression to work as an anti- PH drug showing that Nutlin-3a exerts no effects on hypoxia-exposed p53 −/− and p21 −/− mice. Intriguingly, the paper also shows that Nutlin-3a treatment of cultured human PASMCs results in cell growth arrest but not apoptosis, which is consistent with other reports using fibroblasts from mice and humans (Efeyan et al., 2007; Kumamoto et al., 2008). Therefore, it appears that Nutlin-3a has a totally different mechanism of action from currently available drugs and that it is not directly associated with relaxation of smooth muscle and vasodilation of the pulmonary arteries, which lessens the concern about the side effects related to vasodilation. "

    Frontiers in Pharmacology 07/2013; 4:87. DOI:10.3389/fphar.2013.00087 · 3.80 Impact Factor
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    • "To activate p53, we used the small molecule MDM2-antagonist nutlin-3a, which causes an accumulation of p53 protein (Efeyan et al., 2007; Kumamoto et al., 2008). To activate the pRB pathway, FIGURE 3: p53 or p16 expression is sufficient to cause lamin B1 loss, which is regulated at the mRNA level. "
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    ABSTRACT: Cellular senescence is a potent tumor-suppressive mechanism that arrests cell proliferation and has been linked to aging. However, studies of senescence have been impeded by the lack of simple, exclusive biomarkers of the senescent state. Senescent cells develop characteristic morphological changes, which include enlarged and often irregular nuclei and chromatin reorganization. Because alterations to the nuclear lamina can affect both nuclear morphology and gene expression, we examined the nuclear lamina of senescent cells. We show here than lamin B1 is lost from primary human and murine cell strains when they are induced to senesce by DNA damage, replicative exhaustion, or oncogene expression. Lamin B1 loss did not depend on the p38 mitogen-activated protein kinase, nuclear factor-κB, ataxia telangiectasia-mutated kinase, or reactive oxygen species signaling pathways, which are positive regulators of senescent phenotypes. However, activation of either the p53 or pRB tumor suppressor pathway was sufficient to induce lamin B1 loss. Lamin B1 declined at the mRNA level via a decrease in mRNA stability rather than by the caspase-mediated degradation seen during apoptosis. Last, lamin B1 protein and mRNA declined in mouse tissue after senescence was induced by irradiation. Our findings suggest that lamin B1 loss can serve as biomarker of senescence both in culture and in vivo.
    Molecular biology of the cell 04/2012; 23(11):2066-75. DOI:10.1091/mbc.E11-10-0884 · 4.47 Impact Factor
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