PML mediates IFN-alpha-induced apoptosis in myeloma by regulating TRAIL induction.
Interferon (IFN) induces expression of proapoptotic genes and has been used in the clinical treatment of multiple myeloma. The promyelocytic leukemia (PML) gene is an IFN-induced target that encodes a tumor suppressor protein. PML protein is typically localized within discrete speckled nuclear structures termed PML nuclear bodies (NBs). Multiple myeloma cells demonstrate differential responses to IFN treatment, the mechanism of which is largely unknown. Herein, we show that growth inhibition effects of IFN-alpha in myeloma cells correlate with PML NBs and tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) induction, whereas known IFN targets including signal transducer and activator of transcription-1 (STAT1), STAT3, p38, and Daxx cannot account for these differential responses. RNAi silencing of PML blocks IFN-alpha-induced apoptosis in myeloma cells and correspondingly down-regulates TRAIL expression. Similarly, stable expression of a dominant negative TRAIL receptor DR5 partially blocks IFN-induced cell death. These results demonstrate that PML and TRAIL play important roles in IFN-induced apoptosis and identify TRAIL as a novel downstream transcriptional target of PML. Identification of PML and PML NBs as effectors of IFN responses provides insights into mechanisms by which tumor cells exhibit resistance to this class of agents and may prove useful in assessing treatment regimens.
Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
Chun
C
Crowder
Øyvind
Ø
Dahle
R Eric
RE
Davis
Odd S
OS
Gabrielsen
Stuart
S
Rudikoff
D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D006801:Humans; D016898:Interferon-alpha / Q000494:pharmacology*; D015473:Leukemia, Promyelocytic, Acute; D008562:Membrane Glycoproteins / Q000502:physiology*; D009101:Multiple Myeloma; D009363:Neoplasm Proteins / Q000235:genetics / Q000502:physiology*; D009687:Nuclear Proteins / Q000235:genetics / Q000502:physiology*; D000071156:Promyelocytic Leukemia Protein; D034741:RNA, Small Interfering / Q000235:genetics; D053221:TNF-Related Apoptosis-Inducing Ligand; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology*; D025521:Tumor Suppressor Proteins
D051017:Apoptosis Regulatory Proteins; D016898:Interferon-alpha; D008562:Membrane Glycoproteins; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D000071156:Promyelocytic Leukemia Protein; D034741:RNA, Small Interfering; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D014157:Transcription Factors; D014409:Tumor Necrosis Factor-alpha; D025521:Tumor Suppressor Proteins; C070576:PML protein, human