Aberrant promoter methylation in human DAB2 interactive protein (hDAB2IP) gene in breast cancer.
OBJECTIVE
Human DOC-2/DAB2 interactive protein (hDAB2IP) gene is a novel member of the Ras GTPase-activating family and has been demonstrated to be a tumor suppressor gene inactivated by methylation in prostate cancer. We analyzed methylation and expression status of hDAB2IP in breast cancer.


METHODS
The promoter region of hDAB2IP was divided into two regions (m2a and m2b) following our previous report on prostate cancer, and methylation status was determined in breast cancer cell lines with bisulfited DNA sequencing. Expression was semiquantified with real-time reverse transcription-PCR to find that aberrant methylation showed the inverse relationship with expression. On the basis of sequence data, we developed methylation-specific PCR for m2a and m2b regions and applied to samples.


RESULTS
Aberrant methylation was detected in 11 of 25 breast cancer cell lines (44%) and 15 of 39 primary tumors (38%) at the m2a region and in 12 of 25 cell lines (48%) and 13 of 39 tumors (33%) at the m2b region. In addition, gene expression was restored in methylated cell lines with 5-aza-2'-deoxycytidine, confirming that methylation caused gene down-regulation. We also examined the relationship between hDAB2IP methylation and clinicopathologic features in primary tumors and found that methylation in the m2b region was associated with progressive nodal status of tumors.


CONCLUSIONS
We developed methylation-specific PCR for hDAB2IP and examined its methylation status in breast cancer. Our results demonstrate that hDAB2IP methylation frequently is present in breast cancer and plays a key role in hDAB2IP inactivation, suggesting the relationship between hDAB2IP methylation and lymph node metastasis of breast cancer.
Dote
Hideaki
H
Department of Cancer, Graduate School of Medicine and Dentistry, Okayama University, Okayama, Japan.
Toyooka
Shinichi
S
Tsukuda
Kazunori
K
Yano
Masaaki
M
Ouchida
Mamoru
M
Doihara
Hiroyoshi
H
Suzuki
Makoto
M
Chen
Hong
H
Hsieh
Jer-Tsong
JT
Gazdar
Adi F
AF
Shimizu
Nobuyoshi
N
D020121:5' Untranslated Regions / Q000235:genetics; D000328:Adult; D000368:Aged; D001483:Base Sequence; D001943:Breast Neoplasms / Q000235:genetics* / Q000473:pathology; D045744:Cell Line, Tumor; D002869:Chromosome Aberrations; D019175:DNA Methylation; D017931:DNA Primers; D004273:DNA, Neoplasm / Q000235:genetics*; D005260:Female; D006801:Humans; D008875:Middle Aged; D011401:Promoter Regions, Genetic / Q000235:genetics*; D020703:ras GTPase-Activating Proteins / Q000235:genetics*
D020121:5' Untranslated Regions; C462952:DAB2IP protein, human; D017931:DNA Primers; D004273:DNA, Neoplasm; D020703:ras GTPase-Activating Proteins