Promoter methylation of DAL-1/4.1B predicts poor prognosis in non-small cell lung cancer.
OBJECTIVE
DAL-1/4.1B is an actin-binding protein originally identified as a molecule whose expression is down-regulated in lung adenocarcinoma. We have previously shown that a lung tumor suppressor, TSLC1, associates with DAL-1, suggesting that both proteins act in the same cascade. The purpose of this study is to understand the molecular mechanisms and clinical significance of DAL-1 inactivation in lung cancer.


METHODS
We studied aberration of the DAL-1 in 103 primary non-small cell lung cancers (NSCLC) and 18 lung cancer cells. Expression and allelic and methylation status of DAL-1 was examined by reverse transcription-PCR, microsatellite analysis, and bisulfite sequencing or bisulfite single-strand conformational polymorphism, respectively.


RESULTS
Loss of DAL-1 expression was strongly correlated with promoter methylation in lung cancer cells, whereas DAL-1 expression was restored by a demethylating agent, 5-aza-2'-deoxycytidine. The DAL-1 promoter was methylated in 59 (57%) primary NSCLC tumors, 37% of which were associated with loss of heterozygosity around the DAL-1 on chromosomal region 18p11.3. In squamous cell carcinomas, DAL-1 methylation was observed in 9 of 10 tumors at stage I, whereas the incidence of methylation gradually increased in adenocarcinomas as they progressed [13 of 36 (36%), 4 of 12 (33%), 14 of 17 (82%), and 3 of 3 (100%) tumors at stages I, II, III, and IV, respectively; P = 0.0026]. Furthermore, in adenocarcinomas, disease-free survival and overall survival were significantly shorter in patients with tumors harboring the methylated DAL-1 (P = 0.0011 and P = 0.045, respectively).


CONCLUSIONS
DAL-1 methylation is involved in the development and progression of NSCLC and provides an indicator for poor prognosis.
Kikuchi
Shinji
S
Tumor Suppression and Functional Genomics Project, National Cancer Center Research Institute, Tokyo, Japan. ymurakam@gan2.ncc.go.jp
Yamada
Daisuke
D
Fukami
Takeshi
T
Masuda
Mari
M
Sakurai-Yageta
Mika
M
Williams
Yuko N
YN
Maruyama
Tomoko
T
Asamura
Hisao
H
Matsuno
Yoshihiro
Y
Onizuka
Masataka
M
Murakami
Yoshinori
Y
D000368:Aged; D002289:Carcinoma, Non-Small-Cell Lung / Q000235:genetics / Q000473:pathology*; D045744:Cell Line, Tumor; D002887:Chromosomes, Human, Pair 18 / Q000235:genetics; D018899:CpG Islands / Q000235:genetics; D019175:DNA Methylation; D004273:DNA, Neoplasm / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006801:Humans; D019656:Loss of Heterozygosity; D008175:Lung Neoplasms / Q000235:genetics / Q000473:pathology*; D008565:Membrane Proteins / Q000235:genetics*; D008840:Microfilament Proteins; D008940:Mitotic Index; D018807:Polymorphism, Single-Stranded Conformational; D011379:Prognosis; D011401:Promoter Regions, Genetic / Q000235:genetics*; D017422:Sequence Analysis, DNA; D016019:Survival Analysis; D025521:Tumor Suppressor Proteins / Q000235:genetics*
D004273:DNA, Neoplasm; C116887:EPB41L3 protein, human; D008565:Membrane Proteins; D008840:Microfilament Proteins; D025521:Tumor Suppressor Proteins