Methylation of tumor-suppressor genes in neuroblastoma: The RASSF1A gene is almost always methylated in primary tumors.
BACKGROUND
Currently, the best characterized genetic aberration in neuroblastoma (NB) is MYCN amplification, which has been clearly related to prognosis. In the present study, we investigated whether specific epigenetic alterations are associated with stage of disease.


METHODS
Sixty-two NBs (45 primary tumors and 17 NBs at relapse) were studied in terms of the methylation status of 19 genes (p15INK4a, p16INK4a, p14ARF, APC, RB1, RASSF1A, BLU, FHIT, RARbeta, INI1, TIMP3, NF2, MGMT, DAPK, FLIP, ECAD, CASP8, and the receptors DcR1 and DcR2).


RESULTS
At diagnosis, we found hypermethylation of RASSF1A in 93% of these tumors, hypermethylation of TIMP3 in 51%, of CASP8 in 38%, of BLU in 34%, of DcR2 in 25%, and of DcR1 in 11%. All 17 tumors tested at relapse showed hypermethylation of RASSF1A (100%), while 10 showed hypermethylation of TIMP3 (59%), six of CASP8 (35%), five of DcR2 (29%), four of BLU (24%), and three of DcR1 (18%). Hypermethylation was related to clinical stage; NBs at stages 1, 2, and 4s were less frequently methylated than stages 3 and 4 disease (P = 0.002).


CONCLUSIONS
These results from our series indicate that hypermethylation of tumor-suppressor genes may be important in the development and evolution of NB. These epigenetic alterations could be used as a marker of the disease and genes regulating methylation should be considered as possible therapeutic targets in NB.
Michalowski
Mariana Bohns
MB
Centre d'Innovation en Biologie, Centre Hospitalier Universitaire de Grenoble, France.
de Fraipont
Florence
F
Plantaz
Dominique
D
Michelland
Sylvie
S
Combaret
Valérie
V
Favrot
Marie-Christine
MC
D053181:Caspase 8 / Q000235:genetics / Q000378:metabolism; D002675:Child, Preschool; D003598:Cytoskeletal Proteins; D019175:DNA Methylation; D044127:Epigenesis, Genetic; D058851:GPI-Linked Proteins; D016147:Genes, Tumor Suppressor / Q000502:physiology*; D006801:Humans; D007223:Infant; D009447:Neuroblastoma / Q000235:genetics*; D053320:Receptors, Tumor Necrosis Factor, Member 10c; D019717:Tissue Inhibitor of Metalloproteinase-3 / Q000235:genetics / Q000378:metabolism; D053319:Tumor Necrosis Factor Decoy Receptors / Q000235:genetics; D025521:Tumor Suppressor Proteins / Q000235:genetics* / Q000378:metabolism
D003598:Cytoskeletal Proteins; D058851:GPI-Linked Proteins; C411762:RASSF1 protein, human; D053320:Receptors, Tumor Necrosis Factor, Member 10c; C088390:TIMP3 protein, human; C108661:TNFRSF10C protein, human; C451501:TNFRSF10D protein, human; D019717:Tissue Inhibitor of Metalloproteinase-3; D053319:Tumor Necrosis Factor Decoy Receptors; D025521:Tumor Suppressor Proteins; C472720:ZMYND10 protein, human; C505530:CASP8 protein, human; D053181:Caspase 8