title: Aberrant promoter methylation and tumor suppressive activity of the DFNA5 gene in colorectal carcinoma.
abstract: To identify novel methylated gene promoters, we compared differential RNA expression profiles of colorectal cancer (CRC) cell lines with or without treatment of 5-aza-2'-deoxycytidine (5-aza-dC). Out of 1776 genes that were initially 'absent (that is, silenced)' by gene expression array analysis, we selected 163 genes that were increased after 5-aza-dC treatment in at least two of three CRC cell lines. The microarray results were confirmed by Reverse Transcription-PCR, and CpG island of the gene promoters were amplified and sequenced for examination of cancer-specific methylation. Among the genes identified, the deafness, autosomal dominant 5 gene, DFNA5, promoter was found to be methylated in primary tumor tissues with high frequency (65%, 65/100). Quantitative methylation-specific PCR of DFNA5 clearly discriminated primary CRC tissues from normal colon tissues (3%, 3/100). The mRNA expression of DFNA5 in four of five colon cancer tissues was significantly downregulated as compared to normal tissues. Moreover, forced expression of full-length DFNA5 in CRC cell lines markedly decreased the cell growth and colony-forming ability whereas knockdown of DFNA5 increased cell growth in culture. Our data implicate DFNA5 as a novel tumor suppressor gene in CRC and a valuable molecular marker for human cancer.
authors.affiliation: Department of Otolaryngology, Head and Neck Cancer Research Division, Johns Hopkins University, Baltimore, MD 21231, USA.
authors.forename: M S
authors.initials: MS
authors.lastname: Kim
authors.forename: X
authors.initials: X
authors.lastname: Chang
authors.forename: K
authors.initials: K
authors.lastname: Yamashita
authors.forename: J K
authors.initials: JK
authors.lastname: Nagpal
authors.forename: J H
authors.initials: JH
authors.lastname: Baek
authors.forename: G
authors.initials: G
authors.lastname: Wu
authors.forename: B
authors.initials: B
authors.lastname: Trink
authors.forename: E A
authors.initials: EA
authors.lastname: Ratovitski
authors.forename: M
authors.initials: M
authors.lastname: Mori
authors.forename: D
authors.initials: D
authors.lastname: Sidransky
mesh_terms: D002277:Carcinoma / Q000235:genetics*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D003110:Colonic Neoplasms / Q000378:metabolism / Q000473:pathology*; D015179:Colorectal Neoplasms / Q000235:genetics*; D019175:DNA Methylation; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D016147:Genes, Tumor Suppressor; D006801:Humans; D008954:Models, Biological; D020411:Oligonucleotide Array Sequence Analysis; D011401:Promoter Regions, Genetic; D011960:Receptors, Estrogen / Q000235:genetics* / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000094524:Gasdermins
chemical_list: D011960:Receptors, Estrogen; C111432:GSDME protein, human; D000094524:Gasdermins