{'fraction_non_alphanumeric': 0.031972265023112484, 'fraction_numerical': 0.018875192604006163, 'mean_word_length': 5.658974358974359, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Gene Regulatory Pathways that Modulate Response to Dexamethasone and Daunorubicin in Breast Cancer Cell Lines

Glucocorticoids (GCs) such as Dexamethasone (Dex) are anti‐cancer agents that induce apoptosis (programmed cell death) and counter side effects of chemotherapy through regulation of pro‐ and anti‐apoptotic genes such as E4BP4, FOXO3A, BIM and BIRC3. Anthracyclines, such as Daunorubicin (Dauno), are effective anti‐cancer agents for leukemias, breast cancer and ovarian cancer. Although several regimens combine both classes of chemotherapy agents, Dex has been reported to promote rather than retard breast cancer cell proliferation, and counter the pro‐apoptotic effects of other chemotherapeutic agents. E4BP4, a transcriptional regulator, is upregulated by GCs and is known to mediate Dex‐evoked apoptosis in leukemia cells, but has been reported to promote cell survival in other models of cancer, including breast cancer. The phosphorylation state of E4BP4 and its crosstalk with the FOXO3A and AKT pathways modulate its pro‐survival or pro‐apoptosis functions. We hypothesize that Dex‐evoked upregulation of E4BP4 and its subsequent modulation of proliferative signals may contribute to pro‐survival effects of Dex in breast cancer. In the present study we are investigating the response of breast cancer cell lines MCF‐7 (estrogen receptor positive) and MDA‐MB‐468 (triple negative) to Dex and Dauno (single agent and in combination) with respect to cell viability, apoptosis and regulation of pro‐ and anti‐apoptotic genes including E4BP4, FOXO3A, BIM and BIRC3. MTT cell viability assays determined that MDA‐MB‐468 and MCF‐7 cells are resistant to 1 μM Dex, with viable cells being about 92% and 140% compared to untreated controls, respectively. However, MDA‐MB‐468 cells were sensitive to 1 μM Dauno and in combination with 1 μM Dauno and 10 μM Dex with viability at 54% and 58% compared to control, respectively. To confirm that cell death occurs via apoptosis, cells are stained with Annexin V‐FITC followed by epifluorescence microscopy to detect apoptotic cells. Evaluation of Dex and Dauno‐mediated regulation of gene expression was done via reverse‐transcriptase and end‐point PCR analysis, followed by ImageJ quantitation, or by RT‐qPCR analysis. Our data suggest that Dauno upregulates while Dex downregulates E4BP4 in MDA‐MB‐468 cells. Combined treatment significantly enhances FOXO3 upregulation compared to either single agent, in correlation with increased cell death. Our data suggest that Dex and Dauno may cooperatively promote apoptosis in MDA‐MB‐468 cells.