Silencing of tissue factor pathway inhibitor-2 gene in malignant melanomas.
To identify tumor-suppressor genes inactivated by aberrant methylation of promoter CpG islands (CGIs) in human malignant melanomas, genes upregulated by treatment of cells with a demethylating agent, 5-aza-2'-deoxycytidine (5-aza-dC), were searched for using oligonucleotide microarrays in melanoma cell lines, HMV-I, MeWo and WM-115. Seventy-nine known genes with CGIs were identified as being upregulated (>or=16-fold), and 18 of them had methylation of their putative promoter CGIs in 1 or more of 8 melanoma cell lines. Among the 18 genes, TFPI-2, which is involved in repression of the invasive potential of malignant melanomas, was further analyzed. Its expression was repressed in a melanoma cell line with its complete methylation, and was restored by 5-aza-dC treatment. It was unmethylated in cultured neonatal normal epidermal melanocyte, and was induced by ultraviolet B. In surgical melanoma specimens, TFPI-2 methylation was detected in 5 of 17 metastatic site specimens (29%), while it was not detected in 20 primary site specimens (0%) (p=0.009). By immunohistochemistry, the 5 specimens with promoter methylation lacked immunoreactivity for TFPI-2. The results showed that TFPI-2 is silenced in human malignant melanomas by methylation of its promoter CGI and suggested that its silencing is involved in melanoma metastasis.
Nobeyama
Yoshimasa
Y
Carcinogenesis Division, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo, Japan.
Okochi-Takada
Eriko
E
Furuta
Junichi
J
Miyagi
Yohei
Y
Kikuchi
Kanako
K
Yamamoto
Akifumi
A
Nakanishi
Yukihiro
Y
Nakagawa
Hidemi
H
Ushijima
Toshikazu
T
D001374:Azacitidine / Q000031:analogs & derivatives / Q000494:pharmacology; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D018899:CpG Islands; D019175:DNA Methylation / Q000187:drug effects; D000077209:Decitabine; D005786:Gene Expression Regulation / Q000528:radiation effects; D020868:Gene Silencing; D006023:Glycoproteins / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D008545:Melanoma / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D009362:Neoplasm Metastasis; D020411:Oligonucleotide Array Sequence Analysis; D011401:Promoter Regions, Genetic / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014466:Ultraviolet Rays
D006023:Glycoproteins; C021240:tissue-factor-pathway inhibitor 2; D000077209:Decitabine; D001374:Azacitidine