title: Combined effect of tumor necrosis factor-related apoptosis-inducing ligand and ionizing radiation in breast cancer therapy.
abstract: Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a potent endogenous activator of the cell death pathway and functions by activating the cell surface death receptors 4 and 5 (DR4 and DR5). TRAIL is nontoxic in vivo and preferentially kills neoplastically transformed cells over normal cells by an undefined mechanism. Radiotherapy is a common treatment for breast cancer as well as many other cancers. Here we demonstrate that ionizing radiation can sensitize breast carcinoma cells to TRAIL-induced apoptosis. This synergistic effect is p53-dependent and may be the result of radiation-induced up-regulation of the TRAIL-receptor DR5. Importantly, TRAIL and ionizing radiation have a synergistic effect in the regression of established breast cancer xenografts. Changes in tumor cellularity and extracellular space were monitored in vivo by diffusion-weighted magnetic resonance imaging (diffusion MRI), a noninvasive technique to produce quantitative images of the apparent mobility of water within a tissue. Increased water mobility was observed in combined TRAIL- and radiation-treated tumors but not in tumors treated with TRAIL or radiation alone. Histological analysis confirmed the loss of cellularity and increased numbers of apoptotic cells in TRAIL- and radiation-treated tumors. Taken together, our results provide support for combining radiation with TRAIL to improve tumor eradication and suggest that efficacy of apoptosis-inducing cancer therapies may be monitored noninvasively, using diffusion MRI.
authors.affiliation: Center for Molecular Imaging, Department of Pathology, University of Michigan Medical School, 1301 Catherine Road, MSI Room 4237, Ann Arbor, MI 48109-0602, USA.
authors.forename: A M
authors.initials: AM
authors.lastname: Chinnaiyan
authors.forename: U
authors.initials: U
authors.lastname: Prasad
authors.forename: S
authors.initials: S
authors.lastname: Shankar
authors.forename: D A
authors.initials: DA
authors.lastname: Hamstra
authors.forename: M
authors.initials: M
authors.lastname: Shanaiah
authors.forename: T L
authors.initials: TL
authors.lastname: Chenevert
authors.forename: B D
authors.initials: BD
authors.lastname: Ross
authors.forename: A
authors.initials: A
authors.lastname: Rehemtulla
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D051017:Apoptosis Regulatory Proteins; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000532:radiotherapy*; D002455:Cell Division / Q000187:drug effects / Q000528:radiation effects; D053938:DNA Fragmentation / Q000187:drug effects / Q000528:radiation effects; D005260:Female; D006801:Humans; D020287:In Situ Nick-End Labeling; D008279:Magnetic Resonance Imaging; D008562:Membrane Glycoproteins / Q000235:genetics / Q000627:therapeutic use*; D051379:Mice; D008815:Mice, Inbred Strains; D009368:Neoplasm Transplantation; D011839:Radiation, Ionizing; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism; D011994:Recombinant Proteins; D053221:TNF-Related Apoptosis-Inducing Ligand; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000627:therapeutic use*
chemical_list: D051017:Apoptosis Regulatory Proteins; D008562:Membrane Glycoproteins; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor; D011994:Recombinant Proteins; D053221:TNF-Related Apoptosis-Inducing Ligand; C505639:TNFRSF10B protein, human; C505653:TNFSF10 protein, human; C505640:Tnfrsf10b protein, mouse; C505654:Tnfsf10 protein, mouse; D014409:Tumor Necrosis Factor-alpha