Epigenetic suppression of secreted frizzled related protein 1 (SFRP1) expression in human breast cancer.
Expression of Secreted frizzled related protein 1 (SFRP1), a recently identified tumor suppressor gene encoding a WNT signaling antagonist, has been found to be frequently down-regulated in breast cancer and is associated with disease progression and poor prognosis. Here, we investigated the role of epigenetic silencing of SFRP1 in breast cancer cell lines and primary breast tumors. Through analyses by methylation-specific PCR and bisulfite sequencing, promoter methylation of SFRP1 was detected in 88% (7/8) of breast cancer cell lines, 17% (1/6) of grade 1 of ductal carcinoma in situ (DCIS), 69% (9/13) of grade 2 and 3 of DCIS, 68% (19/28) of invasive ductal carcinomas (IDC) and 33% (6/18) of lobular carcinomas but not in any (0/14) of normal mammoplasty specimens and mammary epithelial organoids examined. Real-time RT-PCR studies indicated that loss or downregulation of SFRP1 expression in tumors is frequently associated with promoter hypermethylation. In addition, breast cancer cell lines with SFRP1 promoter hypermethylation reexpressed SFRP1 mRNA after treatment with 5-azaC, implying that DNA methylation is the predominant epigenetic mechanism for SFRP1 gene silencing. These findings suggest that frequent downregulation of SFRP1 expression in breast cancer can be attributed, in large part, to aberrant promoter hypermethylation in conjunction with or without histone deacetylation. Based on the frequency of tumor-specific hypermethylation in this gene, SFRP1 could provide a valuable marker for breast cancer.
Lo
Pang-Kuo
PK
Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21231, USA.
Mehrotra
Jyoti
J
D'Costa
Anisha
A
Fackler
Mary Jo
MJ
Garrett-Mayer
Elizabeth
E
Argani
Pedram
P
Sukumar
Saraswati
S
D000107:Acetylation; D001374:Azacitidine / Q000031:analogs & derivatives / Q000494:pharmacology; D001940:Breast / Q000378:metabolism; D001943:Breast Neoplasms / Q000235:genetics*; D002460:Cell Line; D045744:Cell Line, Tumor; D019175:DNA Methylation / Q000187:drug effects; D000077209:Decitabine; D015536:Down-Regulation; D044127:Epigenesis, Genetic; D016147:Genes, Tumor Suppressor; D006657:Histones / Q000378:metabolism*; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D047908:Intracellular Signaling Peptides and Proteins; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D011506:Proteins / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D000099274:Frizzled-Related Proteins
D001374:Azacitidine; D000077209:Decitabine; D006657:Histones; D006877:Hydroxamic Acids; D047908:Intracellular Signaling Peptides and Proteins; D011506:Proteins; D000099274:Frizzled-Related Proteins; C012589:trichostatin A