Chemotherapy-Induced Apoptosis in a Transgenic Model of Neuroblastoma Proceeds Through p53 Induction 1 2

Department of Pediatrics, University of California, San Francisco, San Francisco, CA 94143, USA.
Neoplasia (New York, N.Y.) (Impact Factor: 4.25). 12/2008; 10(11):1268-74. DOI: 10.1593/neo.08778
Source: PubMed


Chemoresistance in neuroblastoma is a significant issue complicating treatment of this common pediatric solid tumor. MYCN-amplified neuroblastomas are infrequently mutated at p53 and are chemosensitive at diagnosis but acquire p53 mutations and chemoresistance with relapse. Paradoxically, Myc-driven transformation is thought to require apoptotic blockade. We used the TH-MYCN transgenic murine model to examine the role of p53-driven apoptosis on neuroblastoma tumorigenesis and the response to chemotherapy. Tumors formed with high penetrance and low latency in p53-haploinsufficient TH-MYCN mice. Cyclophosphamide (CPM) induced a complete remission in p53 wild type TH-MYCN tumors, mirroring the sensitivity of childhood neuroblastoma to this agent. Treated tumors showed a prominent proliferation block, induction of p53 protein, and massive apoptosis proceeding through induction of the Bcl-2 homology domain-3-only proteins PUMA and Bim, leading to the activation of Bax and cleavage of caspase-3 and -9. Apoptosis induced by CPM was reduced in p53-haploinsufficient tumors. Treatment of MYCN-expressing human neuroblastoma cell lines with CPM induced apoptosis that was suppressible by siRNA to p53. Taken together, the results indicate that the p53 pathway plays a significant role in opposing MYCN-driven oncogenesis in a mouse model of neuroblastoma and that basal inactivation of the pathway is achieved in progressing tumors. This, in part, explains the striking sensitivity of such tumors to chemotoxic agents that induce p53-dependent apoptosis and is consistent with clinical observations that therapy-associated mutations in p53 are a likely contributor to the biology of tumors at relapse and secondarily mediate resistance to therapy.

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    • "J. Hartley (UCL, London, UK) (Clingen et al, 2005). Neuroblastoma cell lines (SK-N-AS, KELLY and BE2C) were generously supplied by Dr. L. Chesler (ICR, Sutton, UK) (Chesler et al, 2008). All the other cell lines were obtained from the American Type Tissue Collection (ATCC). "
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    ABSTRACT: Background: This study investigates whether a histone deacetylase subtype 6 (HDAC6) inhibitor could be used in the treatment of solid tumours. Methods: We evaluated the effect of a novel inhibitor, C1A, on HDAC6 biochemical activity and cell growth. We further examined potential of early noninvasive imaging of cell proliferation by [18F]fluorothymidine positron emission tomography ([18F]FLT-PET) to detect therapy response. Results: C1A induced sustained acetylation of HDAC6 substrates, α-tubulin and HSP90, compared with current clinically approved HDAC inhibitor SAHA. C1A induced apoptosis and inhibited proliferation of a panel of human tumour cell lines from different origins in the low micromolar range. Systemic administration of the drug inhibited the growth of colon tumours in vivo by 78%. The drug showed restricted activity on gene expression with <0.065% of genes modulated during 24 h of treatment. C1A treatment reduced tumour [18F]FLT uptake by 1.7-fold at 48 h, suggesting that molecular imaging could provide value in future studies of this compound. Conclusion: C1A preferentially inhibits HDAC6 and modulates HDAC6 downstream targets leading to growth inhibition of a diverse set of cancer cell lines. This property together with the favourable pharmacokinetics and efficacy in vivo makes it a candidate for further pre-clinical and clinical development.
    British Journal of Cancer 01/2013; 108(2). DOI:10.1038/bjc.2012.576 · 4.84 Impact Factor
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    • "Several lines of evidence from published literature lend support to the notion that during the process of neuroblastoma progression there is evasion of p53-mediated tumor suppression via inactivation of the p53/MDM2/p14 ARF pathway (reviewed by Van Maerken et al., 2009b) as well as a requirement for MYCN amplified neuroblastoma to circumvent MYCN driven apoptosis (reviewed by Hogarty, 2003). In vivo studies have demonstrated the importance of the p53 pathway in neuroblastoma (Chesler et al., 2008; Chen et al., 2009). Potential mechanisms whereby MYCN amplified tumors can overcome p53-mediated tumor suppression in neuroblastoma are discussed below. "
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    ABSTRACT: Neuroblastoma is the most common extra-cranial solid tumor of childhood. Despite significant advances, it currently still remains one of the most difficult childhood cancers to cure, with less than 40% of patients with high-risk disease being long-term survivors. MYCN is a proto-oncogene implicated to be directly involved in neuroblastoma development. Amplification of MYCN is associated with rapid tumor progression and poor prognosis. Novel therapeutic strategies which can improve the survival rates whilst reducing the toxicity in these patients are therefore required. Here we discuss genes regulated by MYCN in neuroblastoma, with particular reference to p53, SKP2, and DKK3 and strategies that may be employed to target them.
    Frontiers in Oncology 11/2012; 2:173. DOI:10.3389/fonc.2012.00173
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    • "Not surprisingly, p53 is mutated in over 50% of human cancers. In sharp contrast, human NBs are almost invariably p53 wild type at diagnosis [17], with the proapoptotic pathways downstream of p53 intact and recruitable by cytotoxic drugs to induce p53-dependent cell death in NB experimental models [18], [19]. p53 is actively involved in the apoptosis-sensitive phenotype induced by MYCN. "
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    ABSTRACT: MYCN amplification occurs in about 20-25% of human neuroblastomas and characterizes the majority of the high-risk cases, which display less than 50% prolonged survival rate despite intense multimodal treatment. Somehow paradoxically, MYCN also sensitizes neuroblastoma cells to apoptosis, understanding the molecular mechanisms of which might be relevant for the therapy of MYCN amplified neuroblastoma. We recently reported that the apoptosis-sensitive phenotype induced by MYCN is linked to stabilization of p53 and its proapoptotic kinase HIPK2. In MYCN primed neuroblastoma cells, further activation of both HIPK2 and p53 by Nutlin-3 leads to massive apoptosis in vitro and to tumor shrinkage and impairment of metastasis in xenograft models. Here we report that Galectin-3 impairs MYCN-primed and HIPK2-p53-dependent apoptosis in neuroblastoma cells. Galectin-3 is broadly expressed in human neuroblastoma cell lines and tumors and is repressed by MYCN to induce the apoptosis-sensitive phenotype. Despite its reduced levels, Galectin-3 can still exert residual antiapoptotic effects in MYCN amplified neuroblastoma cells, possibly due to its specific subcellular localization. Importantly, Nutlin-3 represses Galectin-3 expression, and this is required for its potent cell killing effect on MYCN amplified cell lines. Our data further characterize the apoptosis-sensitive phenotype induced by MYCN, expand our understanding of the activity of MDM2-p53 antagonists and highlight Galectin-3 as a potential biomarker for the tailored p53 reactivation therapy in patients with high-risk neuroblastomas.
    PLoS ONE 11/2012; 7(11):e49139. DOI:10.1371/journal.pone.0049139 · 3.23 Impact Factor
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