The p53 pathway and its inactivation in neuroblastoma

doi:10.1016/S0304-3835(03)00088-0

Cancer Letters

Volume 197, Issues 1–2, 18 July 2003, Pages 93-98

https://doi.org/10.1016/S0304-3835(03)00088-0 Get rights and content

Abstract

Early studies of p53 in neuroblastoma reported infrequent mutations in tumours and cell lines. Cytoplasmic sequestration was later proposed as an alternative mechanism of inactivation, but many studies have since reported an intact p53 pathway in neuroblastoma cell lines, as detected by nuclear p53 accumulation after DNA damage, intact DNA binding, transcriptional activation of target genes and the induction of apoptosis. In some MYCN amplified cell lines however, an irradiation induced G₁ arrest does not occur, despite the presence of normal p53. Neuroblastoma usually responds to chemotherapy but frequently relapses, and there is evidence from tumours, and cell lines that p53 inactivation via mutation or MDM2amplification occurs at relapse and is sometimes associated with multidrug resistance. If p53 inactivation occurs frequently in relapsed tumours it may be appropriate to include p53 independent therapies in the initial management of high-risk neuroblastoma.

Introduction

Unlike the improvements in survival in many childhood cancers, high-risk neuroblastoma is still one of the most difficult tumours to cure, with only 30% long-term survival despite intensive multi-modal therapy. New treatments and a better understanding of drug resistance mechanisms are required before the survival rates can significantly improve.

An important mechanism of resistance to cytotoxic therapy in many tumour cells is an abnormality in the p53 tumour suppressor gene pathway [1]. The subject of p53 inactivation in neuroblastoma has been one of the most controversial areas in neuroblastoma research to date. This review draws together the apparently conflicting data and concludes that knowledge of p53 function in neuroblastoma may help in planning appropriate therapy in the future.

Section snippets

The p53 pathway

The nuclear phosphoprotein, p53, is usually present at low levels in the cell, due to a short half-life (approx. 30 min), but accumulates in response to cellular stress such as DNA damage from irradiation. It binds DNA in a sequence-specific manner to activate the transcription of a number of genes including p21WAF1, MDM2 and BAX. p21^WAF1 inhibits G₁ cyclin dependent kinases, blocking cell cycle progression from G₁ into S phase. MDM2 binds to p53, blocking its transcriptional function and

History of the study of p53 in neuroblastoma

The first studies of p53 in neuroblastoma reported high levels of p53mRNA and a stabilised p53 protein in four wild-type p53 neuroblastoma cell lines compared to bovine adrenal medulla (reviewed in [3]). The pulse chase method used to measure p53 half-life in these cell lines however, has recently been reported to elicit a DNA damage response and stabilisation of p53 [4], but this would not account for the increased mRNA levels.

It is possible that the presence of p53 in neuroblastoma cell lines

Does p53 function normally in neuroblastoma?

p53 function is best assessed by testing whether the p53 pathway is intact after DNA damage. This process can be separated into nuclear p53 translocation, DNA binding and transcriptional transactivation of target genes, and testing the downstream functional endpoints of cell cycle arrest and apoptosis.

Evidence for p53 inactivation after cytotoxic therapy

Unlike many adult malignancies most neuroblastomas do initially respond to chemotherapy and it is likely that the presence of functionally active p53 is at least partly involved in this initial chemosensitivity. However, over half of previously responsive neuroblastomas eventually relapse with chemoresistant disease and there is evidence for p53 inactivation at this stage in some cases.

Conclusions

The study of p53 in neuroblastoma has evolved from reports of p53 accumulation and possible inactivation by cytoplasmic sequestration, through studies demonstrating an intact p53 pathway, to recent evidence showing that p53 inactivation may be the most frequent mechanism of drug resistance identified in neuroblastoma cell lines to date. If this is confirmed in tumours, it may be appropriate to include novel p53-independent chemotherapeutic agents in the management of high-risk neuroblastoma.

Acknowledgements

DAT is the recipient of a UK Department of Health Clinician Scientist Award. Work in the Cancer Research Unit is funded by Cancer Research UK and the North of England Children's Cancer Research Fund. Children's Cancer Institute Australia for Medical Research is affiliated with the University of New South Wales and Sydney Children's Hospital. This work was supported by grants from the National Health and Medical Research Council (Australia) and the New South Wales Cancer Council (Australia).

References (18)

A. Levine
p53, the cellular gatekeeper for growth and division
Cell
(1997)
J.S. Isaacs et al.
Requirement for HDM2 activity in the rapid degradation of p53 in neuroblastoma
J. Biol. Chem.
(2001)
D.A. Tweddle et al.
p53 cellular localisation and function in neuroblastoma: Evidence for defective G₁ arrest despite WAF1 induction in MYCN amplified cells
Am. J. Pathol.
(2001)
S. Gangopadhyay et al.
Expression of different mutant p53 transgenes in neuroblastoma cells leads to different cellular responses to genotoxic agents
Exp. Cell Res.
(2002)
B. Vogelstein et al.
Surfing the p53 network
Nature
(2000)
A. Davidoff et al.
Expression of p53 in neuroblastoma and neuroepithelioma-derived cell lines
Oncogene
(1992)
D.E. MacCallum et al.
The p53 response to ionising radiation in adult and developing murine tissues
Oncogene
(1996)
D.A. Tweddle et al.
Evidence for the development of p53 mutations after cytotoxic therapy in a neuroblastoma cell line
Cancer Res.
(2001)
U. Moll et al.
Wild-type p53 undergoes cytoplasmic sequestration in undifferentiated neuroblastomas but not differentiated tumors
Proc. Natl. Acad. Sci. USA
(1995)

There are more references available in the full text version of this article.

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Prostaglandin E₂ (PGE₂) promotes tumor cell proliferation, migration, and invasion, fostering an inflammation-enriched microenvironment that facilitates angiogenesis and immune evasion. However, the PGE₂ receptor subtype (EP1–EP4) involved in neuroblastoma (NB) growth remains elusive. Herein, we show that the EP2 receptor highly correlates with NB aggressiveness and acts as a predominant Gα_s-coupled receptor mediating PGE₂-initiated cyclic AMP (cAMP) signaling in NB cells with high-risk factors, including 11q deletion and MYCN amplification. Knockout of EP2 in NB cells blocks the development of xenografts, and its conditional knockdown prevents established tumors from progressing. Pharmacological inhibition of EP2 by our recently developed antagonist TG6-129 suppresses the growth of NB xenografts in nude mice and syngeneic allografts in immunocompetent hosts, accompanied by anti-inflammatory, antiangiogenic, and apoptotic effects. This proof-of-concept study suggests that the PGE₂/EP2 signaling pathway contributes to NB malignancy and that EP2 inhibition by our drug-like compounds provides a promising strategy to treat this deadly pediatric cancer.
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Despite intensive treatment protocols and recent advances, neuroblastomas still account for approximately 15% of all childhood cancer deaths. In contrast with adult cancers, p53 pathway inactivation in neuroblastomas is rarely caused by p53 mutation but rather by altered MDM2 or p14ARF expression. Moreover, neuroblastomas are characterised by high proliferation rates, frequently triggered by pRb pathway dysfunction due to aberrant expression of cyclin D1, CDK4 or p16INK4a. Simultaneous disturbance of these pathways can occur via co-amplification of MDM2 and CDK4 or homozygous deletion of CDKN2A, which encodes both p14ARF and p16INK4a.
We examined whether both single and combined inhibition of MDM2 and CDK4/6 is effective in reducing neuroblastoma cell viability. In our panel of ten cell lines with a spectrum of aberrations in the p53 and pRb pathway, idasanutlin and abemaciclib were the most potent MDM2 and CDK4/6 inhibitors, respectively. No correlation was observed between the genetic background and response to the single inhibitors. We confirmed this lack of correlation in isogenic systems overexpressing MDM2 and/or CDK4. In addition, combined inhibition did not result in synergistic effects. Instead, abemaciclib diminished the pro-apoptotic effect of idasanutlin, leading to slightly antagonistic effects. In vivo treatment with idasanutlin and abemaciclib led to reduced tumour growth compared with single drug treatment, but no synergistic response was observed.
We conclude that p53 and pRb pathway aberrations cannot be used as predictive biomarkers for neuroblastoma sensitivity to MDM2 and/or CDK4/6 inhibitors. Moreover, we advise to be cautious with combining these inhibitors in neuroblastomas.
Targeting the p53-MDM2 pathway for neuroblastoma therapy: Rays of hope
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Citation Excerpt :
In addition to p53 inactivation via mutation, there are other non-mutational mechanisms which can inactivate p53 in neuroblastoma cells. For instance, neuroblastoma cell lines derived from tumors at relapse may have MDM2 amplification, and such cells are more chemoresistant and have reduced p53 function compared to normal cell lines [27]. Thus, chemotherapeutic drugs that can exert their effects independent of functional p53 should be used against neuroblastoma, especially in patients with relapsed or progressive tumors.
Despite being the subject of extensive research and clinical trials, neuroblastoma remains a major therapeutic challenge in pediatric oncology. The p53 protein is a central safeguard that protects cells against genome instability and malignant transformation. Mutated TP53 (the gene encoding p53) is implicated in many human cancers, but the majority of neuroblastomas have wild type p53 with intact transcriptional function. In fact, the TP53 mutation rate does not exceed 1–2% in neuroblastomas. However, overexpression of the murine double minute 2 (MDM2) gene in neuroblastoma is relatively common, and leads to inhibition of p53. It is also associated with other non-canonical p53-independent functions, including drug resistance and increased translation of MYCN and VEGF mRNA. The p53-MDM2 pathway in neuroblastoma is also modulated at several different molecular levels, including via interactions with other proteins (MYCN, p14^ARF). In addition, the overexpression of MDM2 in tumors is linked to a poorer prognosis for cancer patients. Thus, restoring p53 function by inhibiting its interaction with MDM2 is a potential therapeutic strategy for neuroblastoma. A number of p53-MDM2 antagonists have been designed and studied for this purpose. This review summarizes the current understanding of p53 biology and the p53-dependent and -independent oncogenic functions of MDM2 in neuroblastoma, and also the regulation of the p53-MDM2 axis in neuroblastoma. This review also highlights the use of MDM2 as a molecular target for the disease, and describes the MDM2 inhibitors currently being investigated in preclinical and clinical studies. We also briefly explain the various strategies that have been used and future directions to take in the development of effective MDM2 inhibitors for neuroblastoma.
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Neuroblastoma is a solid embryonal tumor of the sympathetic nervous system. The clinical course of patients with neuroblastoma is highly heterogeneous, from localized tumors and spontaneous regression to early metastasizing, rapid progression, and therapy resistance. This clinical heterogeneity can be attributed largely to the interaction of multiple genetic and epigenetic factors, including both sequence and copy number variants that occur in neuroblastoma cells. Recent methodological advances have enabled the detailed analysis of the neuroblastoma genome, leading to the identification of new prognostic markers and better patient stratification.
Amplification of MYCN gene and DNA ploidy have been used as the most reliable indicators of aggressive and treatment-resistant neuroblastoma, yet few of the high-risk tumors lack these features [1]. Candidate tumor suppressor genes have been identified on chromosomes 1p, 3p, and 11q that are deleted in some neuroblastomas. Despite extensive knowledge of somatically acquired genomic rearrangements in neuroblastoma and their association with the clinical tumor phenotype, very few data are available about the factors leading to these genetic events. While genetic alterations are almost impossible to reverse, epigenetic changes can dynamically respond to signals from physical, biological, and social environments [2]. New functional studies suggest that microRNAs regulate important genes involved in neuroblastoma pathogenesis [3].
AF1q is a universal marker of neuroblastoma that sustains N-Myc expression and drives tumorigenesis
2024, Oncogene
p53 stabilisation potentiates [<sup>177</sup>Lu]Lu-DOTATATE treatment in neuroblastoma xenografts
2024, European Journal of Nuclear Medicine and Molecular Imaging

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Cancer Letters

Abstract

Introduction

Section snippets

The p53 pathway

History of the study of p53 in neuroblastoma

Does p53 function normally in neuroblastoma?

Evidence for p53 inactivation after cytotoxic therapy

Conclusions

Acknowledgements

References (18)

p53, the cellular gatekeeper for growth and division

Cell

Requirement for HDM2 activity in the rapid degradation of p53 in neuroblastoma

J. Biol. Chem.

p53 cellular localisation and function in neuroblastoma: Evidence for defective G₁ arrest despite WAF1 induction in MYCN amplified cells

Am. J. Pathol.

Expression of different mutant p53 transgenes in neuroblastoma cells leads to different cellular responses to genotoxic agents

Exp. Cell Res.

Surfing the p53 network

Nature

Expression of p53 in neuroblastoma and neuroepithelioma-derived cell lines

Oncogene

The p53 response to ionising radiation in adult and developing murine tissues

Oncogene

Evidence for the development of p53 mutations after cytotoxic therapy in a neuroblastoma cell line

Cancer Res.

Wild-type p53 undergoes cytoplasmic sequestration in undifferentiated neuroblastomas but not differentiated tumors

Proc. Natl. Acad. Sci. USA

Cited by (146)

Targeting EP2 receptor with multifaceted mechanisms for high-risk neuroblastoma

Combined targeting of the p53 and pRb pathway in neuroblastoma does not lead to synergistic responses

Targeting the p53-MDM2 pathway for neuroblastoma therapy: Rays of hope

Role of genetic and epigenetic alterations in pathogenesis of neuroblastoma

AF1q is a universal marker of neuroblastoma that sustains N-Myc expression and drives tumorigenesis

p53 stabilisation potentiates [<sup>177</sup>Lu]Lu-DOTATATE treatment in neuroblastoma xenografts

Mini-reviewThe p53 pathway and its inactivation in neuroblastoma

Abstract

Introduction

Section snippets

The p53 pathway

History of the study of p53 in neuroblastoma

Does p53 function normally in neuroblastoma?

Evidence for p53 inactivation after cytotoxic therapy

Conclusions

Acknowledgements

Cell

J. Biol. Chem.

Am. J. Pathol.

Exp. Cell Res.

Surfing the p53 network

Nature

Expression of p53 in neuroblastoma and neuroepithelioma-derived cell lines

Oncogene

The p53 response to ionising radiation in adult and developing murine tissues

Oncogene

Evidence for the development of p53 mutations after cytotoxic therapy in a neuroblastoma cell line

Cancer Res.

Wild-type p53 undergoes cytoplasmic sequestration in undifferentiated neuroblastomas but not differentiated tumors

Proc. Natl. Acad. Sci. USA

Mini-review
The p53 pathway and its inactivation in neuroblastoma