Title: Cyclooxygenase-2 independent effects of cyclooxygenase-2 inhibitors on oxidative stress and intracellular glutathione content in normal and malignant human B-cells.
Authors: Ryan, Elizabeth P; Bushnell, Timothy P; Friedman, Alan E; Rahman, Irfan; Phipps, Richard P
Published In Cancer Immunol Immunother, (2008 Mar)
Abstract: We recently reported that inhibition of Cyclooxygenase-2 (Cox-2) reduced human B-CLL proliferation and survival. Herein, we investigated the mechanisms whereby small molecule Cox-2 selective inhibitors, SC-58125 (a Celebrex analog) and CAY10404 blunt survival of human B-cell lymphomas and chronic lymphocytic leukemia B-cells. SC-58125 and OSU03012 (a Celebrex analog that lacks Cox-2 inhibitory activity) both decreased intracellular glutathione (GSH) content in malignant human B-cells, as well as in Cox-2 deficient mouse B-cells. This new finding supports Cox-2 independent effects of SC-58125. Interestingly, SC-58125 also significantly increased B-cell reactive oxygen species (ROS) production, suggesting that ROS are a pathway that reduces malignant cell survival. Addition of GSH ethyl ester protected B lymphomas from the increased mitochondrial membrane permeability and reduced survival induced by SC-58125. Moreover, the SC-58125-mediated GSH depletion resulted in elevated steady-state levels of the glutamate cysteine ligase catalytic subunit mRNA and protein. These new findings of increased ROS and diminished GSH levels following SC-58125 exposure support novel mechanisms whereby a Cox-2 selective inhibitor reduces malignant B-cell survival. These observations also support the concept that certain Cox-2 selective inhibitors may have therapeutic value in combination with other drugs to kill malignant B lineage cells.
PubMed ID: 17668203
MeSH Terms: Animals; B-Lymphocytes/drug effects*; B-Lymphocytes/metabolism; Catalytic Domain/drug effects; Catalytic Domain/genetics; Cell Proliferation/drug effects; Cell Survival/drug effects; Cells, Cultured; Cyclooxygenase 2 Inhibitors/pharmacology*; Cyclooxygenase 2/deficiency; Cyclooxygenase 2/drug effects*; Cyclooxygenase 2/metabolism; Dose-Response Relationship, Drug; Glutamate-Cysteine Ligase/drug effects; Glutamate-Cysteine Ligase/genetics; Glutathione/analogs & derivatives; Glutathione/antagonists & inhibitors; Glutathione/metabolism*; Glutathione/pharmacology; Humans; Isoxazoles/pharmacology; Leukemia, Lymphocytic, Chronic, B-Cell/drug therapy*; Leukemia, Lymphocytic, Chronic, B-Cell/metabolism; Lymphoma, B-Cell/drug therapy*; Lymphoma, B-Cell/metabolism; Mice; Mice, Knockout; Oxidative Stress/drug effects*; Pyrazoles/pharmacology; RNA, Messenger/drug effects; RNA, Messenger/genetics; Reactive Oxygen Species/metabolism; Reverse Transcriptase Polymerase Chain Reaction/methods; Sulfonamides/pharmacology; Sulfones/pharmacology