title: CpG hypomethylation of MDR1 gene in tumor and serum of invasive ductal breast carcinoma patients.
abstract: OBJECTIVE
  Multidrug resistance 1 (MDR1) gene encodes P-glycoprotein (P-gp), a transmembrane calcium-dependent efflux pump, implicated in drug resistance. In this prospective study, methylation status of MDR1 promoter and its correlation with clinicopathological parameters were evaluated in tumor and serum of breast cancer patients.
  
  
  METHODS
  Methylation-specific PCR was carried out to investigate the promoter methylation status of MDR1 in tumor and serum of 100 patients with invasive ductal carcinomas of breast (IDCs). The effect of promoter methylation on protein expression was evaluated by immunohistochemistry.
  
  
  RESULTS
  MDR1 was hypomethylated in 47% tumors and 44% paired sera of IDC patients and correlated significantly with increased tumor size and advanced tumor stage. Promoter hypomethylation of MDR1 in serum DNA showed 98% specificity and 50% sensitivity.
  
  
  CONCLUSIONS
  Hypomethylation of MDR1 promoter in IDCs accounted for P-gp overexpression and aggressive biologic behavior in a subset of patients. Detection of these epigenetic changes in circulating DNA may not only enhance insight into the biological behavior of the primary tumor of an individual but may also provide valuable information regarding prognosis that can be readily monitored throughout the disease course.
authors.affiliation: Department of Biochemistry, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110029, India.
authors.forename: Gayatri
authors.initials: G
authors.lastname: Sharma
authors.forename: Sameer
authors.initials: S
authors.lastname: Mirza
authors.forename: Rajinder
authors.initials: R
authors.lastname: Parshad
authors.forename: Anurag
authors.initials: A
authors.lastname: Srivastava
authors.forename: Siddartha
authors.initials: S
authors.lastname: Datta Gupta
authors.forename: Pranav
authors.initials: P
authors.lastname: Pandya
authors.forename: Ranju
authors.initials: R
authors.lastname: Ralhan
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics* / Q000378:metabolism; D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000097:blood* / Q000235:genetics* / Q000473:pathology; D018270:Carcinoma, Ductal, Breast / Q000097:blood* / Q000235:genetics* / Q000473:pathology; D018899:CpG Islands / Q000235:genetics*; D019175:DNA Methylation / Q000235:genetics*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D016019:Survival Analysis; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: C513055:ABCB1 protein, human; D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1