title: Association of GSTP1 methylation with aggressive phenotype in ER-positive breast cancer.
abstract: OBJECTIVE
  We investigated the association of glutathione S-transferase P1 (GSTP1) expression and methylation status with clinicopathological characteristics of estrogen receptor (ER)-positive breast cancers.
  
  
  METHODS
  Primary ER-positive breast cancer patients (n=177, stage I-III) were retrospectively analyzed. A quantitative GSTP1 methylation assay was performed using DNA micro-dissected from formalin-fixed and paraffin-embedded (FFPE) breast surgical specimens and GSTP1 expression was examined immunohistochemically.
  
  
  RESULTS
  GSTP1 methylation index (MI) was higher for the following patient subsets: Large-size (p=0.029), high-grade (p=0.010), human epidermal growth factor receptor-2 (HER2)-positive (p=0.024) and Ki67-positive (p=0.001) patients. In addition, GSTP1 hyper-methylation was more frequently observed in the luminal-B than the luminal-A subtype (p<0.001) and there was no significant difference in GSTP1 positivity between the two subtypes (p=0.150).
  
  
  CONCLUSIONS
  GSTP1 methylation may well be associated with the pathogenesis of the biologically-aggressive phenotype in ER-positive breast cancer.
authors: Department of Breast and Endocrine Surgery, Osaka University Graduate School of Medicine, 2-2-E10 Yamada-oka, Suita, Osaka 565-0871, Japan. noguchi@onsurg.med.osaka-u.ac.jp.
authors: Tomohiro
authors: T
authors: Miyake
authors: Takahiro
authors: T
authors: Nakayama
authors: Naofumi
authors: N
authors: Kagara
authors: Noriaki
authors: N
authors: Yamamoto
authors: Yukiko
authors: Y
authors: Nakamura
authors: Yoko
authors: Y
authors: Otani
authors: Kumiko
authors: K
authors: Uji
authors: Yasuto
authors: Y
authors: Naoi
authors: Masafumi
authors: M
authors: Shimoda
authors: Naomi
authors: N
authors: Maruyama
authors: Atsushi
authors: A
authors: Shimomura
authors: Kenzo
authors: K
authors: Shimazu
authors: Seung Jin
authors: SJ
authors: Kim
authors: Shinzaburo
authors: S
authors: Noguchi
mesh_terms: D001943:Breast Neoplasms / Q000201:enzymology* / Q000378:metabolism / Q000473:pathology; D019175:DNA Methylation; D005260:Female; D051549:Glutathione S-Transferase pi / Q000235:genetics*; D006801:Humans; D010641:Phenotype; D011401:Promoter Regions, Genetic; D011960:Receptors, Estrogen / Q000378:metabolism*
chemical_list: D011960:Receptors, Estrogen; C496556:GSTP1 protein, human; D051549:Glutathione S-Transferase pi
keywords: Breast cancer; DNA methylation; ER-positive breast cancer; glutathione S-transferase P1 (GSTP1); microdissection