title: Hypermethylated 14-3-3-sigma and ESR1 gene promoters in serum as candidate biomarkers for the diagnosis and treatment efficacy of breast cancer metastasis.
abstract: BACKGROUND
  Numerous hypermethylated genes have been reported in breast cancer, and the silencing of these genes plays an important role in carcinogenesis, tumor progression and diagnosis. These hypermethylated promoters are very rarely found in normal breast. It has been suggested that aberrant hypermethylation may be useful as a biomarker, with implications for breast cancer etiology, diagnosis, and management. The relationship between primary neoplasm and metastasis remains largely unknown. There has been no comprehensive comparative study on the clinical usefulness of tumor-associated methylated DNA biomarkers in primary breast carcinoma and metastatic breast carcinoma. The objective of the present study was to investigate the association between clinical extension of breast cancer and methylation status of estrogen receptor1 (ESR1) and stratifin (14-3-3-sigma) gene promoters in disease-free and metastatic breast cancer patients.
  
  
  METHODS
  We studied two cohorts of patients: 77 patients treated for breast cancer with no signs of disease, and 34 patients with metastatic breast cancer. DNA was obtained from serum samples, and promoter methylation status was determined by using DNA bisulfite modification and quantitative methylation-specific PCR.
  
  
  RESULTS
  Serum levels of methylated gene promoter 14-3-3-sigma significantly differed between Control and Metastatic Breast Cancer groups (P < 0.001), and between Disease-Free and Metastatic Breast Cancer groups (P < 0.001). The ratio of the 14-3-3-sigma level before the first chemotherapy cycle to the level just before administration of the second chemotherapy cycle was defined as the Biomarker Response Ratio [BRR]. We calculated BRR values for the "continuous decline" and "rise-and-fall" groups. Subsequent ROC analysis showed a sensitivity of 75% (95% CI: 47.6 - 86.7) and a specificity of 66.7% (95% CI: 41.0 - 86.7) to discriminate between the groups for a cut-off level of BRR = 2.39. The area under the ROC curve (Z = 0.804 +/- 0.074) indicates that this test is a good approach to post-treatment prognosis.
  
  
  CONCLUSIONS
  The relationship of 14-3-3-sigma with breast cancer metastasis and progression found in this study suggests a possible application of 14-3-3-sigma as a biomarker to screen for metastasis and to follow up patients treated for metastatic breast cancer, monitoring their disease status and treatment response.
authors.affiliation: Radiation Oncology, Hospital Virgen de Nieves, Granada, Spain.
authors.forename: Mercedes
authors.initials: M
authors.lastname: Zurita
authors.forename: Pedro C
authors.initials: PC
authors.lastname: Lara
authors.forename: Rosario
authors.initials: R
authors.lastname: del Moral
authors.forename: Blanca
authors.initials: B
authors.lastname: Torres
authors.forename: José Luis
authors.initials: JL
authors.lastname: Linares-Fernández
authors.forename: Sandra Ríos
authors.initials: SR
authors.lastname: Arrabal
authors.forename: Joaquina
authors.initials: J
authors.lastname: Martínez-Galán
authors.forename: Francisco Javier
authors.initials: FJ
authors.lastname: Oliver
authors.forename: José Mariano
authors.initials: JM
authors.lastname: Ruiz de Almodóvar
mesh_terms: D048948:14-3-3 Proteins; D014408:Biomarkers, Tumor / Q000235:genetics*; D001943:Breast Neoplasms / Q000175:diagnosis / Q000235:genetics* / Q000473:pathology / Q000628:therapy*; D002277:Carcinoma / Q000175:diagnosis / Q000235:genetics* / Q000556:secondary / Q000628:therapy*; D017024:Chemotherapy, Adjuvant; D015331:Cohort Studies; D019175:DNA Methylation; D004273:DNA, Neoplasm / Q000097:blood*; D018572:Disease-Free Survival; D047628:Estrogen Receptor alpha / Q000235:genetics*; D005092:Exonucleases / Q000235:genetics*; D005095:Exoribonucleases; D005260:Female; D006801:Humans; D009363:Neoplasm Proteins / Q000235:genetics*; D009367:Neoplasm Staging; D016133:Polymerase Chain Reaction; D011237:Predictive Value of Tests; D011401:Promoter Regions, Genetic; D013030:Spain; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D048948:14-3-3 Proteins; D014408:Biomarkers, Tumor; D004273:DNA, Neoplasm; C506487:ESR1 protein, human; D047628:Estrogen Receptor alpha; D009363:Neoplasm Proteins; D005092:Exonucleases; D005095:Exoribonucleases; C413442:SFN protein, human