Disruption of the ARF-Mdm2-p53 tumor suppressor pathway in Myc-induced lymphomagenesis (original) (raw)
Related papers
Myc signaling via the ARF tumor suppressor regulates p53-dependent apoptosis and immortalization
Genes & Development, 1998
Establishment of primary mouse embryo fibroblasts (MEFs) as continuously growing cell lines is normally accompanied by loss of the p53 or p19 ARF tumor suppressors, which act in a common biochemical pathway. myc rapidly activates ARF and p53 gene expression in primary MEFs and triggers replicative crisis by inducing apoptosis. MEFs that survive myc overexpression sustain p53 mutation or ARF loss during the process of establishment and become immortal. MEFs lacking ARF or p53 exhibit an attenuated apoptotic response to myc ab initio and rapidly give rise to cell lines that proliferate in chemically defined medium lacking serum. Therefore, ARF regulates a p53-dependent checkpoint that safeguards cells against hyperproliferative, oncogenic signals.
Oncogene, 2004
The tumor suppressor p19 ARF inhibits Mdm2, which restricts the activity of p53. Complicated feedback and control mechanisms regulate ARF, Mdm2, and p53 interactions. Here we report that ARF haploinsufficiency completely rescued the p53-dependent effects of Mdm2 haploinsufficiency on B-cell development, survival, and transformation. In contrast to Mdm2 þ /À B cells, Mdm2 þ /À B cells deficient in ARF were similar to wild-type B cells in their rates of growth and apoptosis and activation of p53. Consequently, the profoundly reduced numbers of B cells in Mdm2 þ /À El-myc transgenic mice were restored to normal levels in ARF þ /À Mdm2 þ /À El-myc transgenics. Additionally, ARF þ /À Mdm2 þ /À El-myc transgenics developed lymphomas at rates analogous to those observed for wild-type El-myc transgenics, demonstrating that loss of one allele of ARF rescued the protracted lymphoma latency in Mdm2 þ /À El-myc transgenics. Importantly, in ARF þ /À Mdm2 þ /À El-myc transgenic lymphomas, p53 was inactivated at the frequency observed in lymphomas of wild-type El-myc transgenics. Collectively, these results support a model whereby the stoichiometry of Mdm2 and ARF controls apoptosis and tumor development, which should have significant implications in the treatment of malignancies that have inactivated ARF.
Mdm2 haplo-insufficiency profoundly inhibits Myc-induced lymphomagenesis
The EMBO journal, 2003
Mdm2 harnesses the p53 tumor suppressor, yet loss of one Mdm2 allele in Mdm2(+/-) mice has heretofore not been shown to impair tumor development. Here we report that Mdm2 haplo-insufficiency profoundly suppresses lymphomagenesis in E micro -myc transgenic mice. Mdm2(+/-)E micro -myc transgenics had greatly protracted rates of B cell lymphoma development with life spans twice that of wild-type transgenic littermates. Im paired lymphoma development was associated with drastic reductions in peripheral B cell numbers in Mdm2(+/-)E micro -myc transgenics, and primary pre-B cells from Mdm2(+/-)E micro -myc transgenics and Mdm2(+/-) littermates were extremely susceptible to spontaneous apoptosis. Loss of p53 rescued all of the effects of Mdm2 haplo-insufficiency, indicating they were p53 dependent. Furthermore, half of the lymphomas that ultimately emerged in Mdm2(+/-)E micro -myc transgenics harbored inactivating mutations in p53, and the majority overcame haplo-insufficiency by overexpre...
Evasion of the p53 tumour surveillance network by tumour-derived MYC mutants
Nature, 2005
The c-Myc oncoprotein promotes proliferation and apoptosis, such that mutations that disable apoptotic programmes often cooperate with MYC during tumorigenesis. Here we report that two common mutant MYC alleles derived from human Burkitt's lymphoma uncouple proliferation from apoptosis and, as a result, are more effective than wild-type MYC at promoting B cell lymphomagenesis in mice. Mutant MYC proteins retain their ability to stimulate proliferation and activate p53, but are defective at promoting apoptosis due to a failure to induce the BH3-only protein Bim (a member of the B cell lymphoma 2 (Bcl2) family) and effectively inhibit Bcl2. Disruption of apoptosis through enforced expression of Bcl2, or loss of either Bim or p53 function, enables wild-type MYC to produce lymphomas as efficiently as mutant MYC. These data show how parallel apoptotic pathways act together to suppress MYC-induced transformation, and how mutant MYC proteins, by selectively disabling a p53-independent pathway, enable tumour cells to evade p53 action during lymphomagenesis.
Infrequent p53 mutation in mouse tumors with deregulated myc
Cancer research, 1992
An invariant genetic lesion in mouse plasmacytomas is deregulated expression of c-myc as a consequence of chromosomal translocation. However, retroviral and transgenic studies suggest that additional genetic lesions may contribute to the genesis of plasmacytomas. The p53 tumor suppressor gene is a likely contributor to this genetic lesion, since there is a high incidence of p53 mutation in Burkitt's lymphomas and B-ALL (L3), both of which contain translocations involving c-myc analogous to those in plasmacytomas. In addition, p53 has been shown to be a transcriptional modulator of c-myc expression. In a survey of 27 mouse plasmacytomas by single-strand conformation polymorphism, we identified a single mutation (3.7% incidence), suggesting that p53 lesions are not frequent contributors to plasmacytomagenesis. A similar study of macrophage-monocyte tumors generated by a c-myc-containing retrovirus also indicates a lack of p53 involvement in deregulated c-myc expression. These resu...
International Journal of Molecular Sciences, 2012
Transcriptional activation of MYC is a hallmark of many B cell lineage neoplasms. MYC provides a constitutive proliferative signal but can also initiate ARF-dependent activation of p53 and apoptosis. The E3 ubiquitin ligase, ARF-BP1, encoded by HUWE1, modulates the activity of both the MYC and the ARF-p53 signaling pathways, prompting us to determine if it is involved in the pathogenesis of MYC-driven B cell lymphomas. ARF-BP1 was expressed at high levels in cell lines from lymphomas with either wild type or mutated p53 but not in ARF-deficient cells. Downregulation of
Blood, 2011
In Eμ-myc transgenic animals lymphoma formation requires additional genetic alterations, which frequently comprise loss of p53 or overexpression of BCL-2. We describe that the nature of the “second hit” affects the ability of the immune system to contain lymphoma development. Tumors with disrupted p53 signaling killed the host more rapidly than BCL-2 overexpressing ones. Relaxing immunologic control, using Tyk2−/− mice or by Ab-mediated depletion of CD8+ T or natural killer (NK) cells accelerated formation of BCL-2–overexpressing lymphomas but not of those lacking p53. Most strikingly, enforced expression of BCL-2 prolonged disease latency in the absence of p53, whereas blocking p53 function in BCL-2–overexpressing tumors failed to accelerate disease. This shows that blocking apoptosis in p53-deficient cells by enforcing BCL-2 expression can mitigate disease progression increasing the “immunologic visibility.” In vitro cytotoxicity assays confirmed that high expression of BCL-2 prot...
Proceedings of the National Academy of Sciences
Cancer development is driven by activated oncogenes and loss of tumor suppressors. While oncogene inhibitors have entered routine clinical practice, tumor suppressor reactivation therapy remains to be established. For the most frequently inactivated tumor suppressor p53, genetic mouse models have demonstrated regression of p53-null tumors upon p53 reactivation. While this was shown in tumor models driven by p53 loss as the initiating lesion, many human tumors initially develop in the presence of wild-type p53, acquire aberrations in the p53 pathway to bypass p53-mediated tumor suppression, and inactivate p53 itself only at later stages during metastatic progression or therapy. To explore the efficacy of p53 reactivation in this scenario, we used a reversibly switchable p53 (p53ERTAM) mouse allele to generate Eµ-Myc–driven lymphomas in the presence of active p53 and, after full lymphoma establishment, switched off p53 to model late-stage p53 inactivation. Although these lymphomas had...