Promoter hypermethylation profile of RASSF1A, FHIT, and sFRP1 in intracranial primitive neuroectodermal tumors.
Medulloblastomas (MBs) and supratentorial primitive neuroectodermal tumors (SPNETs) are histologically alike intracranial PNETs found in different anatomical locations of the brain. Current evidence suggests that hypermethylation of promoter CpG islands is a common epigenetic event in a variety of human cancers. The aim of this study was to investigate whether promoter hypermethylation of putative tumor suppressor genes was involved in both types of intracranial PNETs. We examined the methylation status at promoter regions of RASSF1A, FHIT, and sFRP1 by methylation-specific polymerase chain reaction in a cohort of 25 primary MBs, 9 primary SPNETs, and 3 MB and 2 SPNET cell lines. Our results revealed no promoter hypermethylation of RASSF1A, FHIT, and sFRP1 in 2 normal cerebellar and 5 normal cerebral tissue specimens examined. In contrast, promoter hypermethylation of RASSF1A was detected in 100% of primary MBs, 67% (6/9) of primary SPNETs, and all PNET cell lines. The frequency of promoter hypermethylation of RASSF1A was significantly lower in SPNETs than in MBs (Fisher exact test, P = .014). Treatment of RASSF1A-deficient PNET cell lines with 5-aza-2'deoxycytidine, a demethylating agent, restored RASSF1A expression, providing evidence that promoter hypermethylation contributes to transcriptional silencing. In addition, promoter hypermethylation of FHIT and sFRP1 was detected in 22% (2/9) and 11% (1/9) of SPNETs, respectively, but not in any MBs studied. In conclusion, our study demonstrates that promoter hypermethylation of RASSF1A is a common event in intracranial PNETs, whereas FHIT and sFRP1 are epigenetically affected in a fraction of SPNETs.
Chang
Qing
Q
Department of Anatomical and Cellular Pathology, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong SAR, People's Republic of China.
Pang
Jesse Chung-Sean
JC
Li
Kay Ka Wai
KK
Poon
Wai Sang
WS
Zhou
Liangfu
L
Ng
Ho-Keung
HK
D017766:Acid Anhydride Hydrolases / Q000235:genetics* / Q000378:metabolism; D000293:Adolescent; D000328:Adult; D000368:Aged; D064007:Ataxia Telangiectasia Mutated Proteins; D001932:Brain Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D018797:Cell Cycle Proteins / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D002648:Child; D002675:Child, Preschool; D019175:DNA Methylation; D017931:DNA Primers / Q000737:chemistry; D004273:DNA, Neoplasm / Q000032:analysis; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D009363:Neoplasm Proteins / Q000235:genetics* / Q000378:metabolism; D018242:Neuroectodermal Tumors, Primitive / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D025521:Tumor Suppressor Proteins / Q000235:genetics* / Q000378:metabolism; D000099170:Bis(5'-adenosyl)triphosphatase
D017766:Acid Anhydride Hydrolases; D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins; D017931:DNA Primers; D004273:DNA, Neoplasm; D009363:Neoplasm Proteins; D017346:Protein Serine-Threonine Kinases; D025521:Tumor Suppressor Proteins; D000099170:Bis(5'-adenosyl)triphosphatase; C411762:RASSF1 protein, human; C576597:ATR protein, human