Isolation of the human anionic glutathione S-transferase cDNA and the relation of its gene expression to estrogen-receptor content in primary breast cancer.

Abstract

The development of multdrug iresisance in MCF7 human breast cancer cells is acted with ovexpression of P-glycoprotein, changes in activities of several deo don enzymes, and loss of hornmoe senivity and etg receptors (ERs). We In vitro exposure of cancer cells to certain cytotoxins not only leads to resistance of the cells to the selecting agent but can also lead to broad crossresistance to structurally dissimilar cytotoxins (1-7). This phenomenon of multidrug resistance has been associated with decreased intracellular drug accumulation (2-4) and with overexpression of a 130-to 180-kDa membrane-associated glycoprotein (P-glycoprotein) (3,(5)(6)(7) (14,(23)(24)(25). Among these phase II enzymes is the anionic isozyme of glutathione S-transferase (GST; RX:glutathione R-transferase, EC 2.5.1.18), an isozyme found in placenta and usually present only in low levels in human liver. Another phenotypic change associated with the development of multidrug resistance in MCF7 cells is the loss of hormonal sensitivity and the development of resstae to antiestrogens (26). This transformation from estrogenresponsive, wild-type (WI) MCF7 to estrogn-unresponsive Adr' MCF7 is associated with the loss of estren receptors (ERs).Since the increase in anionic GST is one of the marked changes in both AdrR MCF7 cells and rat hyperplastic nodules, we have cloned the cDNA encoding GSThr, the human anionic GST, and used it as a probe to examine the expression of this enzyme in human tumors. In this study we sought to determine whether the regulation of this drug-metabolizing enzyme was related to hormone-receptor regulation.MATERALS AND METHODS Cell Cuture. WT MCF7 and AdrR MCF7 cells were grown in improved minimum essential medium (IMEM) containing 5% (vol/vol) fetal bovine serum (GIBCO) as described (20). AdrR MCF7 cells were grown in medium containing 10 jm doxorubicin. When used in specific studies, Adr' MCF7 cells were grown in drug-free medium for 2-4 weeks.Abbreviations: WT MCF7, wild-type, drug-sensitive MCF7 human breast cancer cell line; AdrR MCF7, multidrug-resistant MCF7 cells initially selected for resistance to doxorubicin (former generic name, adriamycin); GST, glutathione S-transferase; GSTvr, human anionic isozyme ofGST; ER, estrogen receptor; PR, progesterone receptor.

Comparative evaluation by semiquantitative reverse transcriptase polymerase chain reaction of MDR1, MRP and GSTp gene expression in breast carcinomas

“…Our results concerning GSTp mRNA levels are in accordance with those published by Moscow et al (1988). However, as reported by Shea et al (1990) and Peters et al (1993), we did not find any relationship between GSTp expression and hormone receptor status.…”

“…However, as reported by Shea et al (1990) and Peters et al (1993), we did not find any relationship between GSTp expression and hormone receptor status. Such a result is at variance with previous reports (Moscow et al, 1988;Gilbert et al, 1993). In addition, we also showed that diploid tumours exhibited higher GSTp mRNA levels than aneuploid tumours.…”

“…In addition, we also showed that diploid tumours exhibited higher GSTp mRNA levels than aneuploid tumours. Although GSTp has not been unambiguously directly involved in MDR (Moscow et al, 1988;Tew, 1994 andcited in Morrow et al, 1993), its value as a prognostic marker has to be appraised. Indeed, an increased GSTp expression has been suggested to be predictive of early recurrence and death in nodenegative breast cancer (Gilbert et al, 1993;Silverstini et al, 1997), particularly when not treated by adjuvant radiotherapy (Silverstini et al, 1997).…”

Variation of hormonal receptor, pS2, c-erbB-2 and GSTπ contents in breast carcinomas under tamoxifen: a study of 74 cases

“…A significant increase in GSTi expression was observed following tamoxifen treatment. GSTx gene is highly expressed in ER-negative breast cancer cell lines (Morrow et al, 1992) and tumours (Howie et al, 1989;Moscow et al, 1988;Gilbert et al, 1993). Comparing ER-and ER' cell lines, Morrow et al (1992) showed that endogenous GSTi gene transcription rates are similar in both cell lines but the stability of endogeneous GSTi mRNA is extraordinarily higher in ER-negative cells.…”

Molecular Cloning, Characterization, and Expression in Escherichia coli of Full-length cDNAs of Three Human Glutathione S-Transferase Pi Gene Variants

“…To date, the nucleotide sequences of the complete human GST Pi cDNA and GST Pi gene reported from different laboratories (23)(24)(25)(26) have been identical, leading to the notion that only one human GST Pi gene exists (5). The isolation of two different GST Pi proteins from human placenta (27), however, strongly indicates that genetic polymorphism may exist in the human GST Pi gene locus.…”