Our findings demonstrate that PHOX2A expression is finely controlled during retinoic acid differentiation and this, together with PHOX2B down-regulation, reinforces the idea that they may be useful biomarkers for NB staging, prognosis and treatment decision making.
These findings confirmed that PHOX2B is a key regulator of neuroblastoma differentiation and stemness maintenance and indicated that PHOX2B might serve as a potential therapeutic target in neuroblastoma patients.
Therefore, post-transcriptional down-regulation of the PHOX2B gene takes place in NB cell lines and miRNA-204 participates in such a 3'UTR mediated control.
This case highlights the need to consider neuroblastoma in patients with CCHS and the longest PHOX2B PARMs and to individualize treatment based on co-morbidities.
Starting from these observations, we have performed in vitro drug screening approaches targeting PHOX2B overexpression as a potential pharmacological means in NB.
PCR-based detection of minimal residual disease (MRD) in neuroblastoma is currently based on RNA markers; however, expression of these targets can vary, and only paired-like homeobox 2b has no background expression.
Our results suggest that certain PHOX2B variants associated with neuroblastoma pathogenesis, because of their inability to bind to key interacting proteins such as HPCAL1, may predispose to this malignancy by impeding the differentiation of immature sympathetic neurons.
In the present study, we validated the ability of 14 commonly used real-time RT-PCR markers to detect MRD based on their expression in neuroblastoma TICs, and we developed a novel MRD detection protocol, which scored the samples as MRD-positive when the expression of one of the 11 real-time RT-PCR markers (CHRNA3, CRMP1, DBH, DCX, DDC, GABRB3, GAP43, ISL1, KIF1A, PHOX2B and TH) exceeded the normal range.
Heterozygous germline mutations and deletions in PHOX2B, a key regulator of autonomic neuron development, predispose to neuroblastoma, a tumor of the peripheral sympathetic nervous system.
PHOX2B plays a key function in the development of neural crest derivatives, and heterozygous mutations cause a complex dysautonomia associating HSCR, Congenital Central Hypoventilation Syndrome (CCHS) and neuroblastoma (NB) in various combinations.
For instance, discoveries in familial NBL have identified genetic aberrations in Phox2b and Alk that predispose to NBL, while advances in epigenetics and MYCN regulation have also offered insight into NBL pathogenesis and future treatment.
In neuroblastoma (NB) patients, minimal residual disease (MRD) can be detected by real-time quantitative PCR (qPCR) using NB-specific target genes, such as PHOX2B and TH.
We then assessed the results of PHOX2B immunohistochemistry in 12 cases of undifferentiated pediatric neoplasms: PHOX2B was expressed in 6/6 undifferentiated neuroblastomas and in no other small round blue-cell tumors.
Universal mass screening for neuroblastoma is not indicated but targeted screening of infants at risk of hereditary neuroblastoma with germline ALK or PHOX2B mutations is appropriate.
We undertook mutational analysis of the genes known to predispose to non-syndromic familial Wilms tumor (WT1) or neuroblastoma (PHOX2B, ALK) which excluded these as the underlying predisposition genes in the nine families.
Following this possibility, we first confirmed a striking correlation between the transcription levels of ALK, PHOX2B and its direct target PHOX2A in a panel of NB cell lines.
We did not find any conclusive association of the polymorphisms or mutations in PHOX2b with the development of NB, although the large confidence intervals neither substantiate nor exclude a role for this gene in the tumor etiology.
The PHOX2B gene is implicated in the development of the autonomic nervous system and has been found to be infrequently mutated in sporadic neuroblastoma tumours and in some patients with hereditary neuroblastoma.