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.
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
Vasu
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Punj
Hittu
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Matta
Preet M
PM
Chaudhary
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