title: Activation and suppression of the TRAIL death-receptor pathway in chemotherapy sensitive and resistant follicular lymphoma cells.
abstract: Aberrant expression of the apoptosis inhibitor bcl-2 provides a survival advantage throughout oncogenesis and can facilitate chemotherapeutic resistance in a variety of human cancers. Follicular lymphoma (FL) for example, is characterized by the chromosomal translocation t(14;18), which results in bcl-2 overexpression and initiates lymphomagenesis. Although FL cells possess ample amounts of bcl-2, they respond remarkably well to standard first-round chemotherapy. However, the vast majority of patients relapses and becomes progressively resistant to therapy. We obtained cell lines derived from chemosensitive and chemoresistant FL patients, that are characterized by the chromosomal translocation t(14;18) and expression of bcl-2, to investigate how chemotherapeutic drugs can circumvent bcl-2 anti-apoptotic function and to identify alterations in those pathways that may facilitate resistance to DNA damaging drugs. In chemosensitive FL cells, we found that DNA damaging drugs promote apoptosis through p53-dependent upregulation of the TRAIL-DR5 receptor, resulting in activation of caspase-8 and downstream executioner caspases, thereby evading bcl-2 mediated suppression of apoptosis. Examination of drug resistant FL cell lines revealed that at least two defects in this pathway can contribute to chemotherapeutic resistance: 1. p53 gene mutations that disable the transcriptional response to DNA damaging drugs, including expression of the TRAIL-DR5 receptor, and 2. transcriptional repression of the cell-death executioner enzyme caspase-3.
authors: Genomics Institute of the Novartis Research Foundation (GNF), San Diego, California 92121, USA.
authors: Klaus W
authors: KW
authors: Wagner
authors: Fred
authors: F
authors: King
authors: Ken
authors: K
authors: Nomoto
authors: Deborah A
authors: DA
authors: Knee
authors: Garret
authors: G
authors: Hampton
authors: Marc
authors: M
authors: Nasoff
authors: Quinn L
authors: QL
authors: Deveraux
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism*; D004249:DNA Damage; D019008:Drug Resistance, Neoplasm; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005047:Etoposide / Q000494:pharmacology; D006801:Humans; D008024:Ligands; D008224:Lymphoma, Follicular / Q000378:metabolism / Q000473:pathology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism*; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D016159:Tumor Suppressor Protein p53 / Q000502:physiology*
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D061945:Caspase Inhibitors; D004791:Enzyme Inhibitors; D008024:Ligands; D019253:Proto-Oncogene Proteins c-bcl-2; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor; C505639:TNFRSF10B protein, human; D016159:Tumor Suppressor Protein p53; D005047:Etoposide; D020169:Caspases