Aberrant DNA methylation of integrin alpha4: a potential novel role for metastasis of cholangiocarcinoma.
OBJECTIVE
Although the altered expression of integrin alpha4 is known to be associated with transformation or metastasis in several human cancers, the information on cholangiocarcinoma (CC) is still poor. In this study, we investigated the promoter methylation status of integrin alpha4 gene in CC.


METHODS
A total of 29 CC, 19 adjacent non-tumor-containing tissue and 15 normal liver specimens were used for identification of gene methylation status by methylation-specific polymerase chain reaction.


RESULTS
The frequency of DNA methylation was 55.17% (16 of 29) in the CC specimens (P < 0.001). Also, transcripts of the integrin alpha4 gene were decreased in all CC tissues in which there was DNA methylation of the integrin alpha4 gene. In addition, the downregulated expression of integrin alpha4 in CC cells with hypermethylation of the integrin alpha4 gene was restored by treatment with 5-aza-2'-deoxycytidine, a DNA methyltransferase inhibitor. Moreover, we found that DNA methylation of integrin alpha4 was detected in all CC tissues obtained from patients with LN metastasis (7/7). Furthermore, phosphorylation of paxillin, cell migration-related molecule, was regulated by silencing of integrin alpha4.


CONCLUSIONS
Taken together, these results suggest that loss of the integrin alpha4 gene is caused by aberrant DNA methylation of the 5'-CpG island site of the gene, and methylation of the integrin alpha4 gene can be a useful marker of metastasis of CC.
Uhm
Kyung-Ok
KO
Department of Anatomy, Institute of Human Genetics, Brain Korea 21 Biomedical Sciences, Korea University College of Medicine, 126-1, Anam-dong 5-ga, Seongbuk-gu, Seoul, 136-705, Republic of Korea.
Lee
Jung Ok
JO
Lee
Yun Mi
YM
Lee
Eun Soo
ES
Kim
Hyeon Soo
HS
Park
Sun-Hwa
SH
D000328:Adult; D000368:Aged; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D001374:Azacitidine / Q000494:pharmacology; D001483:Base Sequence; D001650:Bile Duct Neoplasms / Q000235:genetics / Q000473:pathology*; D001653:Bile Ducts, Intrahepatic; D014408:Biomarkers, Tumor / Q000235:genetics*; D045744:Cell Line, Tumor; D018281:Cholangiocarcinoma / Q000235:genetics / Q000556:secondary*; D018899:CpG Islands / Q000235:genetics; D019175:DNA Methylation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D020868:Gene Silencing; D006801:Humans; D039441:Integrin alpha4 / Q000187:drug effects / Q000235:genetics*; D019012:Integrin beta1 / Q000235:genetics; D008207:Lymphatic Metastasis; D008297:Male; D008780:Methyltransferases / Q000037:antagonists & inhibitors; D008875:Middle Aged; D008969:Molecular Sequence Data; D009361:Neoplasm Invasiveness; D051419:Paxillin / Q000378:metabolism; D010766:Phosphorylation; D034741:RNA, Small Interfering; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D014162:Transfection
D000964:Antimetabolites, Antineoplastic; D014408:Biomarkers, Tumor; D004791:Enzyme Inhibitors; D019012:Integrin beta1; D051419:Paxillin; D034741:RNA, Small Interfering; D039441:Integrin alpha4; D008780:Methyltransferases; D001374:Azacitidine