Aberrant Methylation and Silencing of the BNIP3 Gene in Colorectal and Gastric Cancer

• Published in: Clinical cancer research 2005-02, Vol.11 (3), p.1021-1027
• Main Authors: MURAI, Masafumi, TOYOTA, Minoru, YANAGIHARA, Kazuyoshi, ENDO, Takao, HINODA, Yuji, TOKINO, Takashi, IMAI, Kohzoh, SUZUKI, Hiromu, SATOH, Ayumi, SASAKI, Yasushi, AKINO, Kimishige, UENO, Masako, TAKAHASHI, Fumihiko, KUSANO, Masanobu, MITA, Hiroaki
• Format: Article
• Language: English
• Subjects: Acetylation; Antineoplastic agents; Azacitidine - analogs & derivatives; Azacitidine - pharmacology; Base Sequence; Biological and medical sciences; Blotting, Western; Cell Line, Tumor; Colorectal Neoplasms - genetics; Colorectal Neoplasms - pathology; CpG Islands - genetics; DNA Methylation; DNA Modification Methylases - antagonists & inhibitors; DNA, Neoplasm - chemistry; DNA, Neoplasm - genetics; DNA, Neoplasm - metabolism; Enzyme Inhibitors - pharmacology; epigenetics; Gastroenterology. Liver. Pancreas. Abdomen; Gene Expression Regulation, Neoplastic - drug effects; Gene Silencing; Histone Deacetylases - metabolism; Histones - metabolism; Humans; hypoxia; Medical sciences; Membrane Proteins - genetics; Membrane Proteins - metabolism; Microscopy, Confocal; Microscopy, Fluorescence; Pharmacology. Drug treatments; Proto-Oncogene Proteins - genetics; Proto-Oncogene Proteins - metabolism; Reverse Transcriptase Polymerase Chain Reaction; RNA, Neoplasm - genetics; RNA, Neoplasm - metabolism; Sequence Analysis, DNA; Stomach Neoplasms - genetics; Stomach Neoplasms - pathology; Stomach. Duodenum. Small intestine. Colon. Rectum. Anus; Tumors
• ISSN: 1078-0432; 1557-3265
• DOI: 10.1158/1078-0432.1021.11.3

BNIP3 protein is a proapoptotic member of the Bcl-2 family that is expressed in hypoxic regions of tumors. To examine its role in the progression of gastrointestinal cancer, we examined the expression and DNA methylation status of BNIP3 gene in a panel of colorectal and gastric cancer cell lines. BNIP3 was not expressed in 14 of the 24 cell lines tested, and its absence was not caused by gene mutation or by altered expression of hypoxia inducible factor-1, a key transcription factor that regulates BNIP3 expression. On the other hand, methylation of the 5′ CpG island of BNIP3 was closely correlated with silencing the gene. Moreover, treating methylated cells with the methyltransferase inhibitor 5-aza-2′-deoxycytidine restored hypoxia-induced expression of BNIP3 mRNA and protein, which in turn led to cell death. Aberrant methylation of BNIP3 was also detected in 66% of primary colorectal and 49% of primary gastric cancers, but not in normal tissue samples collected from areas adjacent to the tumors. Apparently, epigenetic alteration of BNIP3 is a frequent and cancer-specific event, which suggests that inactivation of BNIP3 likely plays a key role in the progression of some gastrointestinal cancers and that it may be a useful molecular target for therapy.