Frequent loss of Brm expression in gastric cancer correlates with histologic features and differentiation state.
The mammalian SWI/SNF chromatin remodeling complex, an essential epigenetic regulator, contains either a single Brm or BRG1 molecule as its catalytic subunit. We observed frequent loss of Brm expression but not of BRG1 in human gastric cancer cell lines. Treatment with histone deacetylase inhibitor rescued Brm expression, indicating epigenetic regulation of this gene, and an RNA interference-based colony formation assay revealed antioncogenic properties of Brm. Brm immunostaining of 89 primary gastric cancers showed an obvious reduction in 60 cases (67%) and a severe decrease in 37 cases (42%). Loss of Brm is frequent in the major gastric cancer types (well- or moderately-differentiated tubular adenocarcinoma and poorly-differentiated adenocarcinoma) and positively correlates with the undifferentiated state. Among the minor gastric cancer types, Brm expression persists in signet-ring cell carcinoma and mucinous adenocarcinoma, but a marked decrease is observed in papillary adenocarcinoma. Intestinal metaplasia never shows decreased expression, indicating that Brm is a valid marker of gastric oncogenesis. In contrast, BRG1 is retained in most cases; a concomitant loss of BRG1 and Brm is rare in gastric cancer, contrary to other malignancies. We further show that Brm is required for villin expression, a definitive marker of intestinal metaplasia and differentiation. Via regulating such genes important for gut differentiation, Brm should play significant roles in determining the histologic features of gastric malignancy.
Yamamichi
Nobutake
N
Division of Host-Parasite Interaction, Department of Microbiology and Immunology, Institute of Medical Science, University of Tokyo, Tokyo, Japan.
Inada
Ken-ichi
K
Ichinose
Masao
M
Yamamichi-Nishina
Mitsue
M
Mizutani
Taketoshi
T
Watanabe
Hirotaka
H
Shiogama
Kazuya
K
Fujishiro
Mitsuhiro
M
Okazaki
Takuya
T
Yahagi
Naohisa
N
Haraguchi
Takeshi
T
Fujita
Shuji
S
Tsutsumi
Yutaka
Y
Omata
Masao
M
Iba
Hideo
H
D000230:Adenocarcinoma / Q000378:metabolism*; D002454:Cell Differentiation; D045744:Cell Line, Tumor; D015179:Colorectal Neoplasms / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D044127:Epigenesis, Genetic; D005753:Gastric Mucosa / Q000378:metabolism; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D056572:Histone Deacetylase Inhibitors; D006801:Humans; D008840:Microfilament Proteins / Q000096:biosynthesis*; D008954:Models, Biological; D013274:Stomach Neoplasms / Q000378:metabolism*; D014157:Transcription Factors / Q000096:biosynthesis* / Q000235:genetics*
D004791:Enzyme Inhibitors; D056572:Histone Deacetylase Inhibitors; D008840:Microfilament Proteins; C084011:SMARCA2 protein, human; D014157:Transcription Factors; C026615:villin