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Effects of Paclitaxel on Glucocorticoid‐induced apoptosis of Human Leukemic CEM Cells
Author(s) -
Aranas Ivymarie,
Medh Rheem
Publication year - 2018
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2018.32.1_supplement.664.13
Subject(s) - apoptosis , downregulation and upregulation , paclitaxel , cell culture , ectopic expression , glucocorticoid , glucocorticoid receptor , cancer research , transcription factor , biology , microbiology and biotechnology , chemistry , gene , immunology , cancer , biochemistry , genetics
Glucocorticoids (GCs) are steroid hormones widely used in anti‐leukemia therapy as they can induce apoptosis through certain gene‐regulatory pathways that affect pro‐ and anti‐apoptotic genes. In cell culture models of human acute lymphoblastic leukemia (ALL), the synthetic GC, Dexamethasone (Dex), has been shown to induce expression of pro‐apoptotic genes including E4BP4 (a transcription factor that upregulates pro‐apoptotic BIM), and regulators of apoptosis such as FOXO3 and BIRC3, in correlation with apoptosis. Paclitaxel (Ptx), a taxol derived anti‐proliferative alkaloid, induces apoptosis via a distinct but overlapping transcriptional response, and is often used in combination with Dex as an anti‐leukemic agent. In this study we are investigating the effect of Ptx alone, and in combination with Dex, on apoptosis and regulation of key pro‐ and anti‐apoptotic genes, in an effort to understand the molecular implications of combined treatment with Dex and Ptx. The CCRF‐CEM cell lines CEM‐C7‐14 and CEM‐C1‐15 were previously found to be sensitive and resistant, respectively, to Dex. Sensitivity to Dex was restored in CEM‐C1‐15 cells upon ectopic expression of mouse E4BP4 (line CEM‐C1‐15mE#3). We are testing the hypothesis that E4BP4 and BIM play a central role in regulating apoptosis triggered by Ptx as well, and that combined treatment synergistically triggers apoptosis via a greater magnitude of upregulation, in addition to activating a broader spectrum of pro‐apoptotic pathways. All three CEM cell lines were treated with 1 mM Dex and 1mM Ptx either alone or in combination for 24–96h. All three cell lines were sensitive to Ptx, but CEM‐C1‐15mE#3 was least susceptible. Apoptosis was confirmed by staining cells with Annexin V‐FITC followed by epifluorescence microscopy. Reverse transcription and end‐point PCR followed by ImageJ analysis was employed to evaluate relative gene expression in response to each treatment. Our data suggest that Ptx upregulated FOXO3 , BIRC3 , and BIM , but down‐regulated E4BP4 in the CEM‐C7‐14 cells, suggesting that Dex and Ptx have distinct effects on E4BP4 regulation but may share common downstream pathways for apoptosis via BIM upregulation. Support or Funding Information NIH SC3 grant, #GM081099, and a Building Infrastructure Leading to Diversity (BUILD) grant from the NIH, #5RL5MD009603 This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .