title: Targeting endoplasmic reticulum protein transport: a novel strategy to kill malignant B cells and overcome fludarabine resistance in CLL.
abstract: Previous studies showed that chronic lymphocytic leukemia (CLL) cells exhibit certain mitochondrial abnormalities including mtDNA mutations, increased superoxide generation, and aberrant mitochondrial biogenesis, which are associated with impaired apoptosis and reduced sensitivity to fludarabine. Here we report that CLL cells and multiple myeloma cells are highly sensitive to brefeldin A, an inhibitor of endoplasmic reticulum (ER) to Golgi protein transport currently being developed as a novel anticancer agent in a prodrug formulation. Of importance, brefeldin A effectively induced apoptosis in fludarabine-refractory CLL cells. Disruption of protein trafficking by brefeldin A caused the sequestration of the prosurvival factors APRIL and VEGF in the ER, leading to abnormal ER swelling and a decrease in VEGF secretion. Such ER stress and blockage of secretory protein traffic eventually resulted in Golgi collapse, activation of caspases, and cell death. Notably, the cellular sensitivity to this compound appeared to be independent of p53 status. Taken together, these findings suggest that malignant B cells may be highly dependent on ER-Golgi protein transport and that targeting this process may be a promising therapeutic strategy for B-cell malignancies, especially for those that respond poorly to conventional treatments.
authors.affiliation: Department of Molecular Pathology, University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Blvd, Houston, TX 77030, USA.
authors.forename: Jennifer S
authors.initials: JS
authors.lastname: Carew
authors.forename: Steffan T
authors.initials: ST
authors.lastname: Nawrocki
authors.forename: Yelena V
authors.initials: YV
authors.lastname: Krupnik
authors.forename: Kenneth
authors.initials: K
authors.lastname: Dunner
authors.forename: David J
authors.initials: DJ
authors.lastname: McConkey
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Keating
authors.forename: Peng
authors.initials: P
authors.lastname: Huang
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017209:Apoptosis / Q000187:drug effects*; D001402:B-Lymphocytes / Q000187:drug effects / Q000473:pathology*; D020126:Brefeldin A / Q000494:pharmacology; D002478:Cells, Cultured; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism*; D006056:Golgi Apparatus; D006801:Humans; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000188:drug therapy / Q000473:pathology*; D008565:Membrane Proteins / Q000378:metabolism; D008875:Middle Aged; D009101:Multiple Myeloma / Q000188:drug therapy / Q000473:pathology; D021381:Protein Transport / Q000187:drug effects; D053300:Tumor Necrosis Factor Ligand Superfamily Member 13; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism; D014740:Vidarabine / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D008565:Membrane Proteins; C114631:TNFSF13 protein, human; D053300:Tumor Necrosis Factor Ligand Superfamily Member 13; D014409:Tumor Necrosis Factor-alpha; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D020126:Brefeldin A; D014740:Vidarabine; C024352:fludarabine