Promoter hypermethylation of multiple genes in nasopharyngeal carcinoma.
OBJECTIVE
The methylation profile of nasopharyngeal carcinoma (NPC) has been investigated by a candidate gene approach.


METHODS
Four NPC cell lines, 4 NPC xenografts, 33 NPC primary tumors, and 6 samples of normal nasopharyngeal epithelium were subjected to methylation-specific PCR for analysis of promoter methylation of eight cancer-related genes. These eight genes were RASSF1A, RARbeta2, DAP-kinase, p16, p15, p14, MGMT, and GSTP1. The correlation between methylation status of these genes and clinical features such as stage, local-regional recurrence, distant metastasis, and survival has been analyzed.


RESULTS
The incidence of promoter methylation in NPC samples was 84% for RASSF1A, 80% for RARbeta2, 76% for DAP-kinase, 46% for p16, 17% for p15, 20% for p14, 20% for MGMT, and 3% for GSTP1. No methylation of these genes was detected in the six normal nasopharyngeal epithelium samples. All NPC tumor samples in this study displayed aberrant methylation in at least one of these eight genes. No significant correlation between methylation status of these genes and clinical parameters of the patients was found.


CONCLUSIONS
A high frequency of aberrant methylation of the 5' CpG island of the RASSF1A, RARbeta2, DAP-kinase, and p16 genes in the present study was noted. Our findings suggest that methylation of the genes in the critical pathways is common in NPC.
Kwong
Joseph
J
Department of Anatomical and Cellular Pathology, The Chinese University of Hong Kong, Hong Kong SAR, People's Republic of China. s993101@mailserv.cuhk.edu.hk
Lo
Kwok-Wai
KW
To
Ka-Fai
KF
Teo
Peter M L
PM
Johnson
Philip J
PJ
Huang
Dolly Poon
DP
D051017:Apoptosis Regulatory Proteins; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000235:genetics; D018797:Cell Cycle Proteins; D050762:Cyclin-Dependent Kinase Inhibitor p15; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics; D019175:DNA Methylation; D017931:DNA Primers / Q000737:chemistry; D064550:Death-Associated Protein Kinases; D015870:Gene Expression; D016147:Genes, Tumor Suppressor; D051549:Glutathione S-Transferase pi; D005982:Glutathione Transferase / Q000235:genetics; D015801:Helminth Proteins / Q000235:genetics; D006801:Humans; D007527:Isoenzymes / Q000235:genetics; D009124:Muscle Proteins / Q000235:genetics; D009154:Mutation; D009303:Nasopharyngeal Neoplasms / Q000235:genetics* / Q000378:metabolism; D009363:Neoplasm Proteins / Q000235:genetics* / Q000378:metabolism; D009364:Neoplasm Recurrence, Local / Q000235:genetics* / Q000401:mortality / Q000473:pathology; D019853:O(6)-Methylguanine-DNA Methyltransferase / Q000235:genetics; D016133:Polymerase Chain Reaction; D011379:Prognosis; D011401:Promoter Regions, Genetic / Q000235:genetics*; D018168:Receptors, Retinoic Acid / Q000235:genetics; D015996:Survival Rate; D014157:Transcription Factors / Q000235:genetics; D014183:Transplantation, Heterologous; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins; D000096985:Calponins
D051017:Apoptosis Regulatory Proteins; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D018797:Cell Cycle Proteins; D050762:Cyclin-Dependent Kinase Inhibitor p15; D019941:Cyclin-Dependent Kinase Inhibitor p16; D017931:DNA Primers; D064550:Death-Associated Protein Kinases; D051549:Glutathione S-Transferase pi; D005982:Glutathione Transferase; D015801:Helminth Proteins; D007527:Isoenzymes; D009124:Muscle Proteins; D009363:Neoplasm Proteins; D019853:O(6)-Methylguanine-DNA Methyltransferase; D018168:Receptors, Retinoic Acid; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; C493966:CDKN2B protein, human; C411762:RASSF1 protein, human; C118619:calponin homolog protein, Schistosoma japonicum; D000096985:Calponins; C082925:retinoic acid receptor beta; C496556:GSTP1 protein, human