title: Mitochondrial DNA levels in blood and tissue samples from breast cancer patients of different stages.
abstract: OBJECTIVE
  Alterations in mitochondrial DNA (mtDNA) have been implicated in carcinogenesis and tumor progression. We here evaluated the diagnostic and prognostic potential of mtDNA as a biomarker for breast cancer.
  
  
  METHODS
  Using multiplex real-time polymerase chain reaction, nuclear DNA (nDNA) and mtDNA levels in serum, buffy coat, tumor, and tumor-adjacent tissue samples from 50 breast cancer patients were determined and assessed for associations with clinicopathological features. To evaluate mtDNA as a biomarker for distinguishing between the four sample types, we created receiver operating characteristic (ROC) curves.
  
  
  RESULTS
  The mtDNA levels in buffy coat were significantly lower than in other sample types. Relative to tumor-adjacent tissue, reduced levels of mtDNA were identified in buffy coat and tumor tissue but not in serum. According to ROC curve analysis, mtDNA levels could be used to distinguish between buffy coat and tumor-adjacent tissue samples with good sensitivity (77%) and specificity (83%). Moreover, mtDNA levels in serum and tumor tissue were positively associated with cancer TMN stage.
  
  
  CONCLUSIONS
  The mtDNA levels in blood samples may represent a promising, non-invasive biomarker in breast cancer patients. Additional, large-scale validation studies are required to establish the potential use of mtDNA levels in the early diagnosis and monitoring of breast cancer.
authors.affiliation: Department of Oncology Surgery, First Affiliated Hospital, Xi'an Jiaotong University, Xi'an, China E-mail : cchen898@nwu.edu.cn, jintianbo@gmail.com.
authors.forename: Peng
authors.initials: P
authors.lastname: Xia
authors.forename: Hui-Juan
authors.initials: HJ
authors.lastname: Wang
authors.forename: Ting-Ting
authors.initials: TT
authors.lastname: Geng
authors.forename: Xiao-Jie
authors.initials: XJ
authors.lastname: Xun
authors.forename: Wen-Jing
authors.initials: WJ
authors.lastname: Zhou
authors.forename: Tian-Bo
authors.initials: TB
authors.lastname: Jin
authors.forename: Chao
authors.initials: C
authors.lastname: Chen
mesh_terms: D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000097:blood* / Q000235:genetics; D001943:Breast Neoplasms / Q000097:blood* / Q000235:genetics / Q000473:pathology; D004272:DNA, Mitochondrial / Q000097:blood*; D005260:Female; D018628:Gene Dosage; D006801:Humans; D008297:Male; D008875:Middle Aged; D008928:Mitochondria / Q000235:genetics; D009367:Neoplasm Staging; D011379:Prognosis; D012372:ROC Curve; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D014408:Biomarkers, Tumor; D004272:DNA, Mitochondrial