A pilot study of pi-class glutathione S-transferase expression in breast cancer: correlation with estrogen receptor expression and prognosis in node-negative breast cancer.

Abstract

PURPOSE AND METHODSPrevious studies have indicated that RNA levels for pi-class glutathione S-transferase (GST pi), a phase II, drug-metabolizing enzyme, were inversely related to estrogen receptor (ER) and progesterone receptor (PR) levels in human breast tumors. Because GST pi also is expressed in normal breast epithelium, an immunohistochemical assay that uses affinity-purified polyclonal antibodies to GST pi was developed to examine the possible relationship between GST pi expression in breast cancer cells and hormone receptor expression, as well as prognosis, in patients with primary breast cancer.RESULTSA strong inverse correlation between GST pi expression and ER (two-sided P [P2] = .002) and PR status (P2 = .023) was found in our study of 189 patients with primary breast cancer. GST pi expression was not related to tumor size, nodal metastasis, nuclear grade, histology, or age of the patient. In node-negative breast cancer (n = 72), increased GST pi expression was associated with decreased disease...