Comparative analysis of biological effects of selective activator of the glucocorticoid receptor CPDA on different subtypes of breast cancer cell lines

Glucocorticoids (GCs) are often used as an adjuvant therapy to reduce the adverse effects of chemotherapy in breast cancer patients. Moreover, GCs can display pro-proliferative or anti-proliferative effects on BC cells depending on their molecular subtype. In addition, long-term use of GCs can induce drug resistance and tumor progression. The biological activity of GCs is mediated by glucocorticoid receptor (GR) via either transrepression or transactivation. The anti-inflammatory effects of GCs are thought to be due to transrepression, while side effects, drug resistance and tumor progression/metastasis are associated with transactivation. We have previously demonstrated that Compound A, a selective GR agonist (SEGRA), has a GR-dependent antitumor effect on blood cancer cells in vitro, not triggering the GR transactivation. This study was focused on the analysis of the CpdA activity in BC models in vitro. We demonstrated the antiproliferative effect of CpdA on BC cells and its ability to induce transrepression of GR-depended genes such as CCND1-3, COX-2, iNOS without the induction of transactivation. A comparative analysis showed that CpdA was an effective and safe alternative to dexamethasone in adjuvant chemotherapy for breast cancer.