Circulating methylated-DCR2 gene in serum as an indicator of prognosis and therapeutic efficacy in patients with MYCN nonamplified neuroblastoma.
BACKGROUND
MYCN amplification (MNA) in neuroblastoma is a strong indicator of poor prognosis. However, some MYCN nonamplified (non-MNA) cases show poor outcomes, and examining the status of the gene requires an operation, which may have surgical complications. Therefore, a new marker is needed to identify cases of non-MNA neuroblastomas with poor prognoses using less risky procedures. Aberrant hypermethylation of the DCR2 promoter has recently been associated with rapidly progressing neuroblastoma. We aimed to develop a noninvasive DCR2 methylation assay for patients with neuroblastoma using serum DNA, which predominantly originates from tumor-released DNA.


METHODS
Using DNA-based real-time PCR, we simultaneously quantified a methylated-DCR2 specific sequence (M) and a reference sequence (R) located in the promoter region in serum DNA, and evaluated DCR2 methylation status as M/R ratios in 86 patients with neuroblastoma.


RESULTS
Serum DCR2 M/R ratios were strongly correlated with those in the tumor (r=0.67; P=0.002). DCR2 methylation was associated with stage both in the whole neuroblastoma group and in the non-MNA group (P<0.001), and DCR2-methylated patients showed significantly poorer 5-year event-free survival in the whole neuroblastoma group (43% versus 84%; P<0.001), especially in the non-MNA group (12% versus 96%;P<0.001). Among five DCR2-methylated patients whose clinical courses were followed, serum M/R ratios were close to 0 in the patients in remission, whereas the ratios increased in patients who relapsed.


CONCLUSIONS
Detection of methylated-DCR2 in serum DNA has promise as a noninvasive assay for predicting prognosis and therapeutic efficacy in neuroblastoma, especially in non-MNA cases. Furthermore, it might be a sensitive marker of tumor recurrence in DCR2-methylated cases.
Yagyu
Shigeki
S
Department of Pediatrics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kamigyo-ku, Kyoto, Japan.
Gotoh
Takahiro
T
Iehara
Tomoko
T
Miyachi
Mitsuru
M
Katsumi
Yoshiki
Y
Tsubai-Shimizu
Satoko
S
Kikuchi
Ken
K
Tamura
Shinichi
S
Tsuchiya
Kunihiko
K
Imamura
Toshihiko
T
Misawa-Furihata
Akiko
A
Sugimoto
Tohru
T
Sawada
Tadashi
T
Hosoi
Hajime
H
D019175:DNA Methylation; D005260:Female; D005784:Gene Amplification; D006801:Humans; D007223:Infant; D008297:Male; D000071447:N-Myc Proto-Oncogene Protein; D009447:Neuroblastoma / Q000097:blood / Q000175:diagnosis / Q000235:genetics* / Q000628:therapy; D009687:Nuclear Proteins / Q000235:genetics*; D015513:Oncogene Proteins / Q000235:genetics*; D011379:Prognosis; D016896:Treatment Outcome; D053319:Tumor Necrosis Factor Decoy Receptors / Q000235:genetics*
C459801:MYCN protein, human; D000071447:N-Myc Proto-Oncogene Protein; D009687:Nuclear Proteins; D015513:Oncogene Proteins; C451501:TNFRSF10D protein, human; D053319:Tumor Necrosis Factor Decoy Receptors