Aberrant methylation patterns of the Rassf1a gene in rat lung adenocarcinomas induced by N-nitrosobis(2-hydroxypropyl)amine

✍ Scribed by Kyoko Shimizu; Ayumi Kato; Mayumi Shigemura; Hiromasa Fujii; Kanya Honoki; Toshifumi Tsujiuchi

• Publisher: John Wiley and Sons
• Year: 2006
• Tongue: English
• Weight: 177 KB
• Volume: 45
• Category: Article
• ISSN: 0899-1987
• DOI: 10.1002/mc.20173

✦ Synopsis

To clarify the involvement of the Rassf1a gene in lung carcinogenesis, we investigated the methylation status in the 5 0 upstream region of the RAS-association domain family 1, isoform A (Rassf1a) gene in rat lung adenocarcinomas induced by N-nitrosobis(2-hydroxypropyl)amine (BHP). Six-week-old male Wistar rats were given 2000 ppm BHP in their drinking water for 12 wk and maintained without further treatment until they were sacrificed at 25 wk. A total of 15 lung adenocarcinomas were obtained and total RNAs were extracted from each for assessment of expression of the Rassf1a gene by reverse transcription (RT)-polymerase chain reaction (PCR) analysis. To measure the methylation status of the Rassf1a gene, five adenocarcinomas with a marked reduction of the Rassf1a expression and two normal lung tissues were used for a bisulfite sequencing analysis. While the normal lung tissue was unmethylated, all five adenocarcinomas were highly methylated in the 5 0 upstream region. Genomic DNAs were also extracted from 15 adenocarcinomas, and mutation analysis of the Rassf1a was performed with PCR-single-strand conformation polymorphism (SSCP) analysis. No mutations were detected throughout exons 1-6. The present results suggest that the aberrant methylation may be involved in the inactivation of the Rassf1a gene in the development of lung adenocarcinomas induced by BHP in rats.