title: β-catenin is regulated by USP9x and mediates resistance to TRAIL-induced apoptosis in breast cancer.
abstract: To investigate the regulatory mechanisms of decoy receptor expression in TRAIL-resistant breast cancer MCF-7 cells, cytotoxicity and apoptosis assays were applied to examine sensitivity to TRAIL in breast cancer cells. Immunofluorescence and immunoprecipitation were used to detect the co-localization and interaction of USP9x and β-catenin. Luciferase assay was used to examine activity of the DcR1/DcR2/OPG reporter. Overexpression/silencing of β-catenin was performed to confirm β-catenin mediated transcription of the decoy receptors. Additionally, silencing of USP9x was performed to prove that USP9X stabilizes β-catenin and mediates TRAIL-resistance. It was found that USP9x interacted with β-catenin and inhibited the degradation of β-catenin through the deubiquitination of β-catenin. Luciferase reporter assays showed induction of DcR1/DcR2/OPG reporter activity observed upon co-transfection of β-catenin and Tcf-4. The overexpression/silencing of β-catenin further confirmed the role of β-catenin in the regulation of transcription of the decoy receptors. Silencing of USP9x directly evidenced that USP9x affected the protein expression level of β-catenin, the transcription level of the decoy receptors, and reversed TRAIL-resistance of MCF-7 cells. In conclusion, USP9x interacted with and stabilized β-catenin through deubiquitination to mediate transcription of the decoy receptors in breast cancer cells. Our results offer new insights into the mechanisms of resistance to TRAIL, and USP9x could potentially be a therapeutic target for TRAIL-resistant breast cancers.
authors.affiliation: Department of Radiation and Medical Oncology, Zhongnan Hospital, Wuhan University, Wuhan, Hubei 430071, P.R. China.
authors.forename: Wen
authors.initials: W
authors.lastname: Ouyang
authors.affiliation: Department of Radiation and Medical Oncology, Zhongnan Hospital, Wuhan University, Wuhan, Hubei 430071, P.R. China.
authors.forename: Shimin
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Department of Radiation and Medical Oncology, Zhongnan Hospital, Wuhan University, Wuhan, Hubei 430071, P.R. China.
authors.forename: Bo
authors.initials: B
authors.lastname: Yang
authors.affiliation: Department of Radiation and Medical Oncology, Zhongnan Hospital, Wuhan University, Wuhan, Hubei 430071, P.R. China.
authors.forename: Chunxu
authors.initials: C
authors.lastname: Yang
authors.affiliation: Department of Radiation and Medical Oncology, Zhongnan Hospital, Wuhan University, Wuhan, Hubei 430071, P.R. China.
authors.forename: Junhong
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Hubei Key Laboratory of Tumor Biological Behaviors, Zhongnan Hospital, Wuhan University, Wuhan, Hubei 430071, P.R. China.
authors.forename: Fuxiang
authors.initials: F
authors.lastname: Zhou
authors.affiliation: Department of Radiation and Medical Oncology, Zhongnan Hospital, Wuhan University, Wuhan, Hubei 430071, P.R. China.
authors.forename: Conghua
authors.initials: C
authors.lastname: Xie
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm / Q000502:physiology*; D005260:Female; D005455:Fluorescent Antibody Technique; D015972:Gene Expression Regulation, Neoplastic / Q000502:physiology; D055785:Gene Knockdown Techniques; D006801:Humans; D047468:Immunoprecipitation; D034741:RNA, Small Interfering; D011994:Recombinant Proteins / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000494:pharmacology*; D014162:Transfection; D053319:Tumor Necrosis Factor Decoy Receptors / Q000378:metabolism; D043222:Ubiquitin Thiolesterase / Q000378:metabolism*; D051176:beta Catenin / Q000378:metabolism*
chemical_list: D000970:Antineoplastic Agents; D034741:RNA, Small Interfering; D011994:Recombinant Proteins; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D053319:Tumor Necrosis Factor Decoy Receptors; C506234:USP9X protein, human; D051176:beta Catenin; D043222:Ubiquitin Thiolesterase