title: Proteasome inhibition increases recruitment of IκB kinase β (IKKβ), S536P-p65, and transcription factor EGR1 to interleukin-8 (IL-8) promoter, resulting in increased IL-8 production in ovarian cancer cells.
abstract: Proinflammatory and pro-angiogenic chemokine interleukin-8 (IL-8, CXCL8) contributes to ovarian cancer progression through its induction of tumor cell proliferation, survival, angiogenesis, and metastasis. Proteasome inhibition by bortezomib, which has been used as a frontline therapy in multiple myeloma, has shown only limited effectiveness in ovarian cancer and other solid tumors. However, the responsible mechanisms remain elusive. Here, we show that proteasome inhibition dramatically increases the IL-8 expression and release in ovarian cancer cells. The responsible mechanism involves an increased nuclear accumulation of IκB kinase β (IKKβ) and an increased recruitment of the nuclear IKKβ, p65-phosphorylated at Ser-536, and the transcription factor early growth response-1 (EGR-1) to the endogenous IL-8 promoter. Coimmunoprecipitation studies identified the nuclear EGR-1 associated with IKKβ and with p65, with preferential binding to S536P-p65. Both IKKβ activity and EGR-1 expression are required for the increased IL-8 expression induced by proteasome inhibition in ovarian cancer cells. Interestingly, in multiple myeloma cells the IL-8 release is not increased by bortezomib. Together, these data indicate that the increased IL-8 release may represent one of the underlying mechanisms responsible for the decreased effectiveness of proteasome inhibition in ovarian cancer treatment and identify IKKβ and EGR-1 as potential new targets in ovarian cancer combination therapies.
authors: From the Department of Biological Sciences and.
authors: Bipradeb
authors: B
authors: Singha
authors: Himavanth Reddy
authors: HR
authors: Gatla
authors: Subrata
authors: S
authors: Manna
authors: Tzu-Pei
authors: TP
authors: Chang
authors: Shannon
authors: S
authors: Sanacora
authors: Vladimir
authors: V
authors: Poltoratsky
authors: Ales
authors: A
authors: Vancura
authors: Ivana
authors: I
authors: Vancurova
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D001897:Boronic Acids / Q000494:pharmacology; D000069286:Bortezomib; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D018932:Chemokine CCL2 / Q000235:genetics / Q000378:metabolism; D054365:Chemokine CXCL5 / Q000235:genetics / Q000378:metabolism; D051766:Early Growth Response Protein 1 / Q000378:metabolism*; D005260:Female; D015973:Gene Expression Regulation, Leukemic / Q000187:drug effects / Q000276:immunology; D006801:Humans; D051550:I-kappa B Kinase / Q000378:metabolism*; D016209:Interleukin-8 / Q000235:genetics* / Q000378:metabolism; D009101:Multiple Myeloma / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D010051:Ovarian Neoplasms / Q000276:immunology* / Q000378:metabolism* / Q000473:pathology; D011401:Promoter Regions, Genetic / Q000187:drug effects / Q000276:immunology / Q000528:radiation effects; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D061988:Proteasome Inhibitors / Q000494:pharmacology; D011719:Pyrazines / Q000494:pharmacology; D051996:Transcription Factor RelA / Q000378:metabolism*
chemical_list: D000970:Antineoplastic Agents; D001897:Boronic Acids; C111835:CCL2 protein, human; C486263:CXCL5 protein, human; C508606:CXCL8 protein, human; D018932:Chemokine CCL2; D054365:Chemokine CXCL5; C497325:EGR1 protein, human; D051766:Early Growth Response Protein 1; D016209:Interleukin-8; D061988:Proteasome Inhibitors; D011719:Pyrazines; D051996:Transcription Factor RelA; D000069286:Bortezomib; D051550:I-kappa B Kinase; C496560:IKBKB protein, human; D046988:Proteasome Endopeptidase Complex
keywords: Chemokines; Chromatin Immunoprecipitation (ChIP); Egr-1; Immunology; Interleukin-8; NF-κB (NF-KB); Ovarian Cancer; Proteasome; Transcription Regulation