Clinical implications of a slight increase in the gene dosage of MYCN in neuroblastoma determined using quantitative PCR

More Abundant Superoxide Dismutase2 Protein Levels in Blood May Act as a Prognostic Marker for High-Risk Neuroblastoma Patients

Purpose: Determination of proteomic differences plays an important role in biomarker investigations. Due to its heterogenic molecular background, identification of certain biomarkers is still a demand both for diagnosis and for prognosis of neuroblastoma. In this study, it is aimed to identify some marker proteins/mechanisms that may play role in neuroblastoma prognosis. Methods: A proteomic approach was performed for different risk groups of the disease by using matrix-assisted laser desorption ionization–time of flight (MALDI-TOF/TOF) approach. Mononuclear cell pools from blood samples of patients for risk groups were constructed and protein expression changes for different groups were identified. Real-time PCR analysis were performed for N-MYC, 11q, 1p and 17q status of these patients and risk groups were determined from tumor samples. Results: Manganese-superoxide dismutase (SOD2) protein was significantly increased in high-risk group of neuroblastoma patients. Conclusion: SOD2 may play an important role in neuroblastoma progression and be a candidate prognostic peripheral blood marker for neuroblastoma patients.

Correlation between the number of segmental chromosome aberrations and the age at diagnosis of diploid neuroblastomas without MYCN amplification

BACKGROUND

In neuroblastomas (NBs) without MYCN amplification, segmental chromosome aberrations SCAs such as 1p loss, 11q loss, and 17q gain have been suggested to be associated with the prognosis of the patients. We assessed the correlation between the number of SCAs and other biological factors in primary NBs samples.

METHOD

The status of SCAs in 54 primary NBs samples was analyzed using the single-nucleotide polymorphism (SNP) array (Human CMV370-Duo; Illumina, San Diego, CA). The status of MYCN amplification was determined by an SNP array and the fluorescence in situ hybridization method. The DNA ploidy was determined by flow cytometry.

RESULTS

Nine of 54 samples showed MYCN amplification. All 9 samples with MYCN amplification and 20 of 45 samples without MYCN amplification showed diploidy/tetraploidy, and the other 25 samples without MYCN amplification showed aneuploidy. The most frequent SCAs were 17q gain (26/54; 48.1%) and 11q loss (16/54; 29.6%), followed by 1p loss (15/54; 27.8%). The number of SCAs in diploidy/tetraploidy NBs without MYCN amplification (7.00 ± 4.67) was higher than that in NBs with MYCN amplification (4.78 ± 2.82) and in aneuploid NBs (1.64 ± 2.78) (P < .05). In diploid/tetraploid NBs without MYCN amplification, there was a significant difference between an age at diagnosis less than 12 months (n = 7) and over 12 months (n = 13) (4.14 ± 3.63 vs 8.54 ± 4.54; P = .04). Moreover, the number of SCAs correlated with the age at diagnosis in diploid/tetraploid samples without MYCN amplification (r = 0.70, P = .0006). In NBs with MYCN amplification, the number of SCAs did not correlate with the age at diagnosis.

CONCLUSION

The number of SCAs significantly increased in proportion to age at diagnosis in diploid/tetraploid NBs without MYCN amplification. The increase in the number of these SCAs may play an important role in the prognosis of patients without MYCN amplification over 12 months of age.

The genetic and clinical significance of MYCN gain as detected by FISH in neuroblastoma

PURPOSE

MYCN amplification (MYCN-A) is a strong prognostic factor in neuroblastoma (NB). MYCN gain which is a low level of MYCN-A as determined by FISH. It is unclear whether the MYCN gain is the pre-status of MYCN-A. This study assessed the status of MYCN gene and chromosome 2p of MYCN-A, MYCN gain and no MYCN amplification using a single nucleotide polymorphism (SNP) array, and the clinical implication of MYCN gain in NB.

METHODS

The status of the MYCN gene was determined by FISH in 47 primary NB samples and the status of chromosome 2p in all cases was analyzed using an SNP array.

RESULTS

8 of the 47 cases analyzed using FISH showed MYCN-A, 7 cases showed MYCN gain and 32 cases showed no MYCN amplification. An SNP array analysis showed that only 2 of 8 cases with MYCN-A by FISH had both amplification of MYCN region and distal 2p gain and other 6 cases had amplification of the MYCN region without distal 2p gain. All 7 cases with MYCN gain by FISH had distal 2p gain without amplification of the MYCN region, and all 32 cases with no MYCN amplification by FISH demonstrated neither the amplification of the MYCN region nor the 2p gain. 5-year overall survival rate of patients with MYCN gain (n = 7, 71.4%) was not significant different from that of patients with no MYCN amplification (n = 32, 90.6%) by FISH (p = 0.11).

CONCLUSIONS

These results suggested that the MYCN gain detected by FISH represents the 2p gain, and the MYCN gain is not considered to represent the pre-status of MYCN amplification.

Hedgehog signaling pathway in neuroblastoma differentiation

PURPOSE

The hedgehog (Hh) signaling pathway is activated in some adult cancers. On the other hand, the Hh signaling pathway plays an important role in the development of the neural crest in embryos. The aim of this study is to show the activation of Hh signaling pathway in neuroblastoma (NB), a pediatric malignancy arising from neural crest cells, and to reveal the meaning of the Hh signaling pathway in NB development.

METHODS

This study analyzed the expression of Sonic hedgehog (Shh), GLI1, and Patched 1 (Ptch1), transactivators of Hh signaling pathway, by immunohistochemistry in 82 NB and 10 ganglioneuroblastoma cases. All 92 cases were evaluated for the status of MYCN amplification.

RESULTS

Of the 92 cases, 67 (73%) were positive for Shh, 62 cases (67%) were positive for GLI1, and 73 cases (79%) were positive for Ptch1. Only 2 (10%) of the 20 cases with MYCN amplification were positive for Shh and GLI1, and 4 cases (20%) were positive for Ptch1 (MYCN amplification vs no MYCN amplification, P ≦ .01). The percentage of GLI1-positive cells in the cases with INSS stage 1 without MYCN amplification was significantly higher than that with INSS stage 4. Of 72 cases without MYCN amplification, 60 were GLI1-positive. Twelve cases were GLI1-negative, and the prognosis of the GLI1-positive cases was significantly better than that of the GLI1-negative cases (P = .015).

CONCLUSIONS

Most of NBs without MYCN amplification were positive for Shh, GLI1, and Ptch1. In the cases without MYCN amplification, the high expression of GLI1 was significantly associated with early clinical stage and a good prognosis of the patients. In contrast to adult cancers, the activation of the Hh signaling pathway in NB may be associated with the differentiation of the NB.

Low-level copy number changes of MYC genes have a prognostic impact in medulloblastoma

High-level amplifications of MYC genes are associated with poor outcomes in childhood medulloblastoma (MB). However, the occurrence of MYCN and MYCC copy number increases below the intense amplification pattern is rarely reported, and its clinical impact has not yet been determined. Here, we describe this phenomenon and its prognostic significance in a cohort of 29 MB patients. Using interphase fluorescence in situ hybridization (I-FISH), low-level copy number alterations, i.e. gain of MYCN, were shown in 5/27 (19%) samples, whereas amplification was revealed in only 1/27 (4%) samples. MYCC gain was revealed in 6/29 (21%) MB, while amplification was disclosed in only 2/29 (7%). Hyperploidy and co-incidence of gains in both MYC loci were frequently observed in samples with copy number aberrations. Survival analysis has clearly shown that MYC copy number increases are associated with lowered event-free survival and overall survival in MB. In the case of MYCN, this negative correlation was statistically significant. We conclude that limited numerical alterations in loci 2p24 (MYCN) and 8q24 (MYCC), as assessed by I-FISH, are present in MB with a higher frequency than high-level amplifications. Poor prognoses were observed in patients with copy number increases in MYC genes. Our data illustrate the importance of further investigations in multicenter trials to better refine the emerging genomic-based prognostic stratification in MB.