Tsujiuchi Toshifumi, Masaoka Tomomi, Sugata Eriko, Onishi Mariko, Fujii Hiromasa, Shimizu Kyoko, Honoki Kanya
Laboratory of Cancer Biology and Bioinformatics, Department of Life Science, Faculty of Science and Engineering, Kinki University, 3-4-1, Kowakae, Higashiosaka, Osaka, Japan.
Mol Carcinog. 2007 Oct;46(10):819-23. doi: 10.1002/mc.20316.
DAL-1 (differentially expressed in adenocarcinoma of the lung) is an actin-binding protein that has been shown to suppress growth in lung cancer cells. Recently, inactivation of the gene encoding DAL-1 due to hypermethylation has been found in several human malignancies, including lung cancers. To assess the involvement of the Dal-1 gene in rat lung carcinogenesis, we investigated the expression of Dal1 and its methylation status in rat lung adenocarcinomas induced by N-nitrosobis(2-hydroxypropyl)amine (BHP). Six-week old male Wistar rats (n = 11) were given 2,000 ppm BHP in their drinking water for 12 wk and maintained without further treatment until they were sacrificed at 25 wk. Total RNA was extracted from 11 lung adenocarcinomas, one from each BHP treated rat, and Dal-1 gene expression was analyzed using real-time quantitative reverse transcription-polymerase chain reaction. Dal-1 expression was significantly reduced in the lung adenocarcinomas compared with three normal lung tissues (P < 0.05). For methylation analysis, bisulfite sequencing was performed using normal lung tissue and tissue from 4 tumors, all of which showed reduced expression of Dal-1. The 5' upstream region was highly methylated in all four adenocarcinomas, whereas this region was unmethylated in normal lung tissue. These results suggest that aberrant methylation of the Dal-1 gene might be involved in the development of lung adenocarcinomas induced in rats by BHP.
DAL-1（在肺腺癌中差异表达）是一种肌动蛋白结合蛋白，已被证明可抑制肺癌细胞的生长。最近，在包括肺癌在内的几种人类恶性肿瘤中发现，由于高甲基化导致编码DAL-1的基因失活。为了评估Dal-1基因在大鼠肺癌发生中的作用，我们研究了N-亚硝基双（2-羟丙基）胺（BHP）诱导的大鼠肺腺癌中Dal1的表达及其甲基化状态。六周龄雄性Wistar大鼠（n = 11）饮用含2000 ppm BHP的水12周，之后不再接受进一步处理，直至25周时处死。从11个肺腺癌中提取总RNA，每个BHP处理的大鼠各取一个，使用实时定量逆转录-聚合酶链反应分析Dal-1基因表达。与三个正常肺组织相比，肺腺癌中Dal-1表达显著降低（P < 0.05）。为进行甲基化分析，使用正常肺组织和4个肿瘤组织进行亚硫酸氢盐测序，所有这些组织均显示Dal-1表达降低。在所有四个腺癌中，5'上游区域高度甲基化，而在正常肺组织中该区域未甲基化。这些结果表明，Dal-1基因的异常甲基化可能参与了BHP诱导的大鼠肺腺癌的发生。
