Promoter hypermethylation of high-in-normal 1 gene in primary nasopharyngeal carcinoma.
OBJECTIVE
The methylation of high-in-normal-1 (HIN-1) gene promoter in undifferentiated nasopharyngeal carcinoma (NPC) is studied.


METHODS
The methylation status of HIN-1 in NPC cell lines, primary NPC, paired nasopharyngeal swabs, paired throat-rinsing fluid, and paired peripheral blood was assessed by methylation-specific PCR assay. The relationship between HIN-1 promoter methylation and transcription in NPC cell lines was evaluated by reverse transcription-PCR and demethylation agent treatment (5-aza-2-deoxycytidine).


RESULTS
Hypermethylated promoter was observed in five of five (100%) NPC cell lines and not found in three normal nasopharyngeal outgrowths, two tonsil epithelial cell cultures, and two skin fibroblast cultures. Reverse transcription-PCR assay indicated that HIN-1 transcription was significantly down-regulated in the NPC cell line with promoter methylation. Treatment with demethylation agent, 5-aza-2-deoxycytidine, restored HIN-1 transcription in the NPC cell line. Methylated HIN-1 promoter was found in 36 of 47 (77%) primary NPC tumors and not found in the normal nasopharyngeal biopsies. Methylated HIN-1 promoter was detected in 12 of 26 (46%) nasopharyngeal swabs, 5 of 26 (19%) throat-rinsing fluids, 2 of 11 (18%) plasmas, and 5 of 11 (46%) buffy coats of peripheral blood of the NPC patients but was not detectable in all normal controls.


CONCLUSIONS
HIN-1 promoter hypermethylation is common in NPC. Methylated promoter DNA in nasopharyngeal swab, throat-rinsing fluid, and peripheral blood might be potentially useful as tumor marker for screening of NPC.
Wong
Thian Sze
TS
Department of Surgery, The University of Hong Kong, Hong Kong, SAR China.
Kwong
Dora Lai-Wen
DL
Sham
Jonathan Shun-Tong
JS
Tsao
Sai Wah
SW
Wei
William Ignace
WI
Kwong
Yok Lam
YL
Yuen
Anthony Po-Wing
AP
D000328:Adult; D000368:Aged; D002277:Carcinoma / Q000097:blood / Q000175:diagnosis / Q000235:genetics*; D002454:Cell Differentiation; D016207:Cytokines / Q000097:blood / Q000235:genetics* / Q000378:metabolism; D019175:DNA Methylation; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009303:Nasopharyngeal Neoplasms / Q000097:blood / Q000175:diagnosis / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D025521:Tumor Suppressor Proteins / Q000097:blood / Q000235:genetics* / Q000378:metabolism
D016207:Cytokines; C434732:SCGB3A1 protein, human; D025521:Tumor Suppressor Proteins