FOXO1 Is a Key Mediator of Glucocorticoid-Induced Expression of Tristetraprolin in MDA-MB-231 Breast Cancer Cells

• Published in: International journal of molecular sciences 2022-11, Vol.23 (22), p.13673
• Main Authors: Jeon, Do Yong, Jeong, So Yeon, Lee, Ju Won, Kim, Jeonghwan, Kim, Jee Hyun, Chu, Hun Su, Jeong, Won Jin, Lee, Byung Ju, Ahn, Byungyong, Kim, Junil, Choi, Seong Hee, Park, Jeong Woo
• Format: Article
• Language: English
• Subjects: 1-Phosphatidylinositol 3-kinase; AKT protein; Apoptosis; betamethasone; Breast cancer; cancer cells; Cytokines; Dexamethasone; Enantiomers; Forkhead protein; FOXO1; FOXO1 protein; Gene expression; Glucocorticoids; Glucocorticoids - pharmacology; Homeostasis; Ligands; Neoplasms; NF-κB protein; p53 Protein; Phosphatidylinositol 3-Kinases; Proteins; Receptors, Glucocorticoid - genetics; Signal transduction; Steroids; Transcription factors; Transcriptomes; tristetraprolin; Tristetraprolin - genetics; Tumor suppressor genes; Tumorigenesis
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms232213673

The mRNA destabilizing factor tristetraprolin (TTP) functions as a tumor suppressor by down-regulating cancer-associated genes. expression is significantly reduced in various cancers, which contributes to cancer processes. Enforced expression of impairs tumorigenesis and abolishes maintenance of the malignant state, emphasizing the need to identify a inducer in cancer cells. To search for novel candidate agents for inducing TTP in cancer cells, we screened a library containing 1019 natural compounds using MCF-7 breast cancer cells transfected with a reporter vector containing the promoter upstream of the luciferase gene. We identified one molecule, of which the enantiomers are betamethasone 21-phosphate (BTM-21-P) and dexamethasone 21-phosphate (BTM-21-P), as a potent inducer of in cancer cells. We confirmed that BTM-21-P, DXM-21-P, and dexamethasone (DXM) induced the expression of in MDA-MB-231 cells in a glucocorticoid receptor (GR)-dependent manner. To identify potential pathways linking BTM-21-P and DXM-21-P to induction, we performed an RNA sequencing-based transcriptome analysis of MDA-MB-231 cells at 3 h after treatment with these compounds. A heat map analysis of FPKM expression showed a similar expression pattern between cells treated with the two compounds. The KEGG pathway analysis results revealed that the upregulated DEGs were strongly associated with several pathways, including the Hippo signaling pathway, PI3K-Akt signaling pathway, FOXO signaling pathway, NF-κB signaling pathway, and p53 signaling pathway. Inhibition of the FOXO pathway using a FOXO1 inhibitor blocked the effects of BTM-21-P and DXM-21-P on the induction of in MDA-MB-231 cells. We found that DXM enhanced the binding of FOXO1 to the promoter in a GR-dependent manner. In conclusion, we identified a natural compound of which the enantiomers are DXM-21-P and BTM-21-P as a potent inducer of in breast cancer cells. We also present new insights into the role of FOXO1 in the DXM-21-P- and BTM-21-P-induced expression of in cancer cells.