Estrogen receptor–negative (ER⁻) breast cancers have limited treatment options and are associated with earlier relapses. Because glucocorticoid receptor (GR) signaling initiates antiapoptotic pathways in ER⁻ breast cancer cells, we hypothesized that activation of these pathways might be associated with poor prognosis in ER⁻ disease. Here we report findings from a genome-wide study of GR transcriptional targets in a premalignant ER⁻ cell line model of early breast cancer (MCF10A-Myc) and in primary early-stage ER⁻ human tumors. Chromatin immunoprecipitation with massively parallel sequencing (ChIP-seq) coupled to time-course expression profiling led us to identify epithelial-to-mesenchymal transition (EMT) pathways as an important aspect associated with GR activation. We validated these findings by carrying out a meta-analysis of primary breast tumor gene expression from 1,378 early-stage breast cancer patients with long-term clinical follow-up, confirming that high levels of GR expression significantly correlated with shorter relapse-free survival in ER⁻ patients who were treated or untreated with adjuvant chemotherapy. Notably, in ER⁺ breast cancer patients, high levels of GR expression in tumors were significantly associated with better outcome relative to low levels of GR expression. Gene expression analysis revealed that ER⁻ tumors expressing high GR levels exhibited differential activation of EMT, cell adhesion, and inflammation pathways. Our findings suggest a direct transcriptional role for GR in determining the outcome of poor-prognosis ER⁻ breast cancers. Cancer Res; 71(20); 6360–70. ©2011 AACR.

Until recently, the study of nuclear receptor (NR) function in breast cancer biology has been largely limited to estrogen and progesterone receptors. The development of reliable gene expression arrays, real-time quantitative RT-PCR, and immunohistochemical techniques for studying NR superfamily members in primary human breast cancers has now revealed the presence and potential importance of several additional NRs in the biology of breast cancer. These include receptors for steroid hormones (including androgens and corticosteroids), fat-soluble vitamins A and D, fatty acids, and xenobiotic lipids derived from diet. It is now clear that after NR activation, both genomic and nongenomic NR pathways can coordinately activate growth factor signaling pathways. Advances in our understanding of both NR functional networks and epithelial cell growth factor signaling pathways have revealed a frequent interplay between NR and epithelial cell growth factor family signaling that is clinically relevant to breast cancer. Understanding how growth factor receptors and their downstream kinases are activated by NRs (and vice-versa) is a central goal for maximizing treatment opportunities in breast cancer. In addition to the estrogen receptor, it is predicted that modulating the activity of other NRs will soon provide novel prevention and treatment approaches for breast cancer patients.

Clinical studies have revealed that social support improves the outcome of cancer patients, whereas epidemiologic studies suggest that social isolation increases the risk of death associated with several chronic diseases. However, the precise molecular consequences of an unfavorable social environment have not been defined. To do so, robust, reproducible preclinical models are needed to study the mechanisms whereby an adverse environment affects gene expression and cancer biology. Because random assignment of inbred laboratory mice to well-defined social environments allows accurate and repeated measurements of behavioral and endocrine parameters, transgenic mice provide a preclinical framework with which to begin to determine gene-environment mechanisms. In this study, we found that female C3(1)/SV40 T-antigen mice deprived of social interaction from weaning exhibited increased expression of genes encoding key metabolic pathway enzymes in the premalignant mammary gland. Chronic social isolation was associated with up-regulated lipid synthesis and glycolytic pathway gene expression—both pathways are known to contribute to increased breast cancer growth. Consistent with the expression of metabolic genes in premalignant mammary tissue, isolated mice subsequently developed a significantly larger mammary gland tumors burden compared with group-housed mice. Endocrine evaluation confirmed that isolated mice developed a heightened corticosterone stress response compared with group-housed mice. Together, these transdisciplinary studies show for the first time that an adverse social environment is associated with altered mammary gland gene expression and tumor growth. Moreover, the identification of specific alterations in metabolic pathways gene expression favoring tumor growth suggests potential molecular biomarkers and/or targets (e.g., fatty acid synthesis) for preventive intervention in breast cancer.

The glucocorticoid receptor has a context-dependent role in breast and prostate cancers and may serve as a therapeutic target.

Purpose: To prevent chemotherapy-related side effects, synthetic glucocorticoids, for example, dexamethasone, are routinely administered to patients with ovarian cancer. However, preclinical data implicate glucocorticoids in suppressing chemotherapy-mediated apoptosis in epithelial tumors. The anti-apoptotic mechanisms underlying this increased survival have been shown to require up-regulation of prosurvival genes, including serum and glucocorticoid-regulated kinase 1 (SGK1) and map kinase phosphatase 1 (MKP1)/dual specificity phosphatase 1 (DUSP1). Despite abundant preclinical data, there are no correlative studies in patients. We therefore evaluated anti-apoptotic gene expression in tumor samples from patients randomized to dexamethasone or normal saline. Experimental Design: Eighteen patients were randomized before exploratory laparotomy for suspected ovarian cancer. Dexamethasone or normal saline was administered i.v. following anesthesia. Ovarian and omental tumor samples were collected intra-operatively before and after infusion. Samples were analyzed for histology and glucocorticoid receptor expression by immunohistochemistry. SGK1 and MKP1/DUSP1 mRNA levels were determined using quantitative real-time PCR. Results: Ten patients were evaluable. At 30 min postinfusion, tumor samples from five patients receiving dexamethasone revealed an average SGK1 mRNA induction of 6.1-fold (SEM, ±2.6) compared with only 1.5-fold (SEM, ±0.4) in tumor samples from five patients receiving normal saline (P = 0.028). Average MKP1/DUSP1 mRNA expression was increased by 8.2-fold (SEM, ±2.9) following dexamethasone versus 1.1-fold (SEM, ±0.4) following normal saline (P = 0.009). All samples expressed glucocorticoid receptor. Conclusion: Glucocorticoid administration to patients is associated with rapid up-regulation of SGK1 and MKP1 expression in ovarian tumors. This finding supports the hypothesis that pharmacologic doses of glucocorticoids may decrease chemotherapy effectiveness in ovarian cancer patients through increased anti-apoptotic gene expression.