Epigenetic Changes of CXCR4 and Its Ligand CXCL12 as Prognostic Factors for Sporadic Breast Cancer
Chemokines and their receptors are involved in the development and cancer progression. The chemokine CXCL12 interacts with its receptor, CXCR4, to promote cellular adhesion, survival, proliferation and migration. The CXCR4 gene is upregulated in several types of cancers, including skin, lung, pancre...
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| Published in: | PloS one Vol. 6; no. 12; p. e29461 |
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| Main Authors: | , , , , , , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
United States
Public Library of Science
29.12.2011
Public Library of Science (PLoS) |
| Subjects: | |
| ISSN: | 1932-6203, 1932-6203 |
| Online Access: | Get full text |
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| Summary: | Chemokines and their receptors are involved in the development and cancer progression. The chemokine CXCL12 interacts with its receptor, CXCR4, to promote cellular adhesion, survival, proliferation and migration. The CXCR4 gene is upregulated in several types of cancers, including skin, lung, pancreas, brain and breast tumors. In pancreatic cancer and melanoma, CXCR4 expression is regulated by DNA methylation within its promoter region. In this study we examined the role of cytosine methylation in the regulation of CXCR4 expression in breast cancer cell lines and also correlated the methylation pattern with the clinicopathological aspects of sixty-nine primary breast tumors from a cohort of Brazilian women. RT-PCR showed that the PMC-42, MCF7 and MDA-MB-436 breast tumor cell lines expressed high levels of CXCR4. Conversely, the MDA-MB-435 cell line only expressed CXCR4 after treatment with 5-Aza-CdR, which suggests that CXCR4 expression is regulated by DNA methylation. To confirm this hypothesis, a 184 bp fragment of the CXCR4 gene promoter region was cloned after sodium bisulfite DNA treatment. Sequencing data showed that cell lines that expressed CXCR4 had only 15% of methylated CpG dinucleotides, while the cell line that not have CXCR4 expression, had a high density of methylation (91%). Loss of DNA methylation in the CXCR4 promoter was detected in 67% of the breast cancer analyzed. The absence of CXCR4 methylation was associated with the tumor stage, size, histological grade, lymph node status, ESR1 methylation and CXCL12 methylation, metastasis and patient death. Kaplan-Meier curves demonstrated that patients with an unmethylated CXCR4 promoter had a poorer overall survival and disease-free survival. Furthermore, patients with both CXCL12 methylation and unmethylated CXCR4 had a shorter overall survival and disease-free survival. These findings suggest that the DNA methylation status of both CXCR4 and CXCL12 genes could be used as a biomarker for prognosis in breast cancer. |
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| Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 14 content type line 23 Carried out the experimental data acquisition, performed data analyses and interpretation and drafted the manuscript: EASR. Sequencing data collection: MG. Biostatistician in the study: KB. Processed cell cultures and DNA extractions: GGS. Provided patient material and clinicopathological data and critically revised the manuscript: EMSFR IJC. Critically revised the manuscript and suggested experiments: AAC. Experimental design, critically revised the manuscript and gave partial financial support: FFC. Designed and coordinated the study, supplied administrative support and critically revised the manuscript: GK. Performed the experiments: EASR MG GGS GK. Analyzed the data: EASR KB FFC GK. Contributed reagents/materials/analysis tools: IJC EMSFR AAC. Wrote the paper: EASR FFC GK. All authors read and approved the final manuscript. |
| ISSN: | 1932-6203 1932-6203 |
| DOI: | 10.1371/journal.pone.0029461 |