X-linked ectodermal dysplasia receptor is downregulated in breast cancer via promoter methylation.
OBJECTIVE
The X-linked ectodermal dysplasia receptor (XEDAR) is a novel receptor of the tumor necrosis factor receptor family that binds to ectodysplasin-A2 (EDA-A2) and induces cell death. The purpose of this study was to determine the tumor-suppressive potential of XEDAR in the development of breast cancer.


METHODS
We analyzed the expression of XEDAR in breast cancer cell lines and tumor samples using quantitative real-time PCR analysis and immunoblotting. We analyzed the human XEDAR gene promoter for the presence of any CpG island and examined its methylation status using methylation-specific real-time PCR. We examined the effect of 5-aza-2'-deoxycytidine on the expression of XEDAR and sensitivity to EDA-A2-induced apoptosis in breast cancer cell lines.


RESULTS
Expression of XEDAR, but not EDA-A2, was downregulated in most tumorigenic breast cancer cell lines and tumor samples. Loss of XEDAR expression correlated with the hypermethylation of its promoter. Ectopic expression of XEDAR in MDA-MB-231 cells resulted in significant induction of apoptosis and reduction in colony formation. Treatment with 5-aza-2'-deoxycytidine restored XEDAR expression in breast cancer cell lines with methylated XEDAR promoter and sensitized them to EDA-A2-induced cell death.


CONCLUSIONS
Our results suggest that XEDAR expression is downregulated in most breast cancers via promoter methylation, which may contribute to accelerated tumor development by blocking EDA-A2-induced cell death. XEDAR may represent a novel breast tumor suppressor gene, and restoration of its expression by treatment with DNA demethylating agents may represent an attractive approach for the treatment of breast cancer.
Punj
Vasu
V
Department of Medicine, Division of Hematology-Oncology, Hillman Cancer Center, University of Pittsburgh Cancer Institute, University of Pittsburgh, Pittsburgh, Pennsylvania 15213-1863, USA. punjv@upmc.edu
Matta
Hittu
H
Chaudhary
Preet M
PM
D024506:5' Flanking Region; D001374:Azacitidine / Q000494:pharmacology; D001943:Breast Neoplasms / Q000235:genetics*; D045744:Cell Line, Tumor; D019175:DNA Methylation; D015536:Down-Regulation; D053331:Ectodysplasins / Q000235:genetics; D005260:Female; D006801:Humans; D011401:Promoter Regions, Genetic; D053340:Xedar Receptor / Q000235:genetics*
C506018:EDA protein, human; C506011:EDA2R protein, human; D053331:Ectodysplasins; D053340:Xedar Receptor; D001374:Azacitidine