Hypermethylation of the retinoic acid receptor-beta(2) gene in head and neck carcinogenesis.

Abstract

PURPOSE:

Retinoic acid receptor-beta(2) (RAR-beta(2)) expression is suppressed in oral premalignant lesions and head and neck squamous cell carcinomas (HNSCCs). This study was conducted to determine whether RAR-beta(2) gene expression in such lesions can be silenced by promoter methylation.

EXPERIMENTAL DESIGN:

RAR-beta(2) methylation was analyzed in DNA samples from 22 pairs of primary HNSCC and adjacent normal epithelium, 124 samples of oral leukoplakia, and 18 HNSCC cell lines using methylation-specific PCR. RAR-beta(2) promoter was methylated in 67, 56, and 53% of HNSCC tumors, HNSCC cell lines, and microdissected oral leukoplakia specimens, respectively. RAR-beta(2) hypermethylation was confirmed by sodium bisulfite-PCR combined with restriction enzyme digestion analysis and by random cloning and sequencing of bisulfite-treated DNA isolates.

RESULTS:

Significantly higher RAR-beta(2) hypermethylation levels were found in tumor tissue compared with adjacent normal tissue (P = 0.002). RAR-beta(2) methylation in the cell lines was correlated with loss of RAR-beta(2) expression (P = 0.013) and inversely related to the presence of mutated p53 (P = 0.025). The demethylating agent 5-aza-2'-deoxycytidine (5-aza-CdR) restored RAR-beta(2) inducibility by all-trans-retinoic acid (ATRA) in some of the cell lines, which posses a methylated RAR-beta(2) promoter. In some cell lines, this effect was associated with increased growth inhibition after combined treatment with 5-aza-CdR and ATRA.

CONCLUSIONS:

RAR-beta(2) silencing by methylation is an early event in head and neck carcinogenesis; 5-Aza-CdR can restore RAR-beta(2) inducibility by ATRA in most cell lines, and the combination of 5-aza-CdR and ATRA is more effective in growth inhibition than single agents.

• Authors: Emile M Youssef, Dafna Lotan, Jean-Pierre Issa, Kenichi Wakasa, You-Hong Fan, Li Mao, Khaled Hassan, Lei Feng, J Jack Lee, Scott M Lippman, Waun K Hong, Reuben Lotan
• Journal: Clinical cancer research : an official journal of the American Association for Cancer Research (Clin Cancer Res) Vol. 10 Issue 5 Pg. 1733-42 (Mar 01 2004) ISSN: 1078-0432 [Print] United States
• PMID: 15014026 (Publication Type: Journal Article, Research Support, U.S. Gov't, Non-P.H.S., Research Support, U.S. Gov't, P.H.S.)

Chemical References

• DNA Primers
• DNA, Neoplasm
• Receptors, Retinoic Acid
• retinoic acid receptor beta
• Tretinoin

Topics

• Adult
• Aged
• Aged, 80 and over
• Base Sequence
• Carcinoma, Squamous Cell (genetics, pathology)
• Cell Division
• Cell Line, Tumor
• Cloning, Molecular
• DNA Methylation
• DNA Primers
• DNA, Neoplasm (genetics)
• Female
• Gene Silencing
• Head and Neck Neoplasms (genetics, pathology)
• Humans
• Leukoplakia, Oral (genetics, pathology)
• Male
• Middle Aged
• Molecular Sequence Data
• Mouth Neoplasms (genetics, pathology)
• Polymerase Chain Reaction
• Precancerous Conditions (genetics, pathology)
• Promoter Regions, Genetic (genetics)
• Receptors, Retinoic Acid (drug effects, genetics)
• Tretinoin (pharmacology)