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.
Consistent with its role as an important neurodevelopmental gene, forced overexpression of wild-type PHOX2B in neuroblastoma cell lines suppressed cell proliferation and synergized with all-trans retinoic acid to promote differentiation.
Consistent with its role as an important neurodevelopmental gene, forced overexpression of wild-type PHOX2B in neuroblastoma cell lines suppressed cell proliferation and synergized with all-trans retinoic acid to promote differentiation.
These experiments describe for the first time regulation of the Delta-Notch pathway by MSX1, and connect these genes to the PHOX2B oncogene, indicative of a role in neuroblastoma biology.
Transient transfections and electrophoretic-mobility-shift assays suggested that PHOX2B is able to bind the cell-specific element in the 5' regulatory region of the TLX2 gene, determining its transactivation in neuroblastoma cells.