Anticancer research

Association of GSTP1 methylation with aggressive phenotype in ER-positive breast cancer.

PMID 24324107


We investigated the association of glutathione S-transferase P1 (GSTP1) expression and methylation status with clinicopathological characteristics of estrogen receptor (ER)-positive breast cancers. 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. 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). GSTP1 methylation may well be associated with the pathogenesis of the biologically-aggressive phenotype in ER-positive breast cancer.