title: Contribution of the orphan nuclear receptor Nur77 to the apoptotic action of IGFBP-3.
abstract: Tumor suppression by insulin-like growth factor-binding protein-3 (IGFBP-3) has been demonstrated to occur via insulin-like growth factor-dependent and -independent mechanisms in vitro and in vivo. We have recently described IGFBP-3-induced mitochondrial translocation of the nuclear receptors RXRalpha/Nur77 in the induction of prostate cancer (CaP) cell apoptosis. Herein, we demonstrate that IGFBP-3 and Nur77 associate in the cytoplasmic compartment in 22RV1 CaP cells. Nur77 is a major component of IGFBP-3-induced apoptosis as shown by utilizing mouse embryonic fibroblasts (MEFs) derived from Nur77 wild-type and knockout (KO) mice. However, dose-response experiments revealed that a small component of IGFBP-3-induced apoptosis is Nur77 independent. Reintroduction of Nur77 into Nur77 KO MEFs restores full responsiveness to IGFBP-3. IGFBP-3 induces phosphorylation of Jun N-terminal kinase and inhibition of Akt phosphorylation and activity, which have been associated with Nur77 translocation. Finally, IGFBP-3 administration to CaP xenografts on SCID mice induced apoptosis and translocated Nur77 out of the nucleus. Taken together, our results verify an important role for the orphan nuclear receptor Nur77 in the apoptotic actions of IGFBP-3.
authors: Division of Pediatric Endocrinology, Mattel Children's Hospital at University of California at Los Angeles, David Geffen School of Medicine, 10833 Le Conte Avenue, MDCC 22-315, Los Angeles, CA 90095, USA. kukwhalee@mednet.ucla.edu
authors: Kuk-Wha
authors: KW
authors: Lee
authors: Laura J
authors: LJ
authors: Cobb
authors: Vladislava
authors: V
authors: Paharkova-Vatchkova
authors: Bingrong
authors: B
authors: Liu
authors: Jeffrey
authors: J
authors: Milbrandt
authors: Pinchas
authors: P
authors: Cohen
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D045744:Cell Line, Tumor; D004268:DNA-Binding Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D005347:Fibroblasts / Q000166:cytology / Q000201:enzymology / Q000378:metabolism; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3; D018969:Insulin-Like Growth Factor Binding Proteins / Q000378:metabolism / Q000502:physiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D016513:Mice, SCID; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1; D011471:Prostatic Neoplasms / Q000378:metabolism / Q000473:pathology; D011485:Protein Binding / Q000502:physiology; D021381:Protein Transport / Q000502:physiology; D018160:Receptors, Cytoplasmic and Nuclear / Q000172:deficiency / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D011987:Receptors, Steroid / Q000172:deficiency / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D013347:Subcellular Fractions / Q000378:metabolism; D014157:Transcription Factors / Q000172:deficiency / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
chemical_list: D004268:DNA-Binding Proteins; C515497:IGFBP3 protein, human; D018972:Insulin-Like Growth Factor Binding Protein 3; D018969:Insulin-Like Growth Factor Binding Proteins; C539821:NR4A1 protein, human; C539818:Nr4a1 protein, mouse; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1; D018160:Receptors, Cytoplasmic and Nuclear; D011987:Receptors, Steroid; D014157:Transcription Factors