UBXN2A enhances CHIP-mediated proteasomal degradation of oncoprotein mortalin-2 in cancer cells.
Mol Oncol
; 12(10): 1753-1777, 2018 10.
Article
em En
| MEDLINE
| ID: mdl-30107089
ABSTRACT
Overexpression of oncoproteins is a major cause of treatment failure using current chemotherapeutic drugs. Drug-induced degradation of oncoproteins is feasible and can improve clinical outcomes in diverse types of cancers. Mortalin-2 (mot-2) is a dominant oncoprotein in several tumors, including colorectal cancer (CRC). In addition to inactivating the p53 tumor suppressor protein, mot-2 enhances tumor cell invasion and migration. Thus, mot-2 is considered a potential therapeutic target in several cancer types. The current study investigated the biological role of a ubiquitin-like protein called UBXN2A in the regulation of mot-2 turnover. An orthogonal ubiquitin transfer technology followed by immunoprecipitation, in vitro ubiquitination, and Magnetic Beads TUBE2 pull-down experiments revealed that UBXN2A promotes carboxyl terminus of the HSP70-interacting protein (CHIP)-dependent ubiquitination of mot-2. We subsequently showed that UBXN2A increases proteasomal degradation of mot-2. A subcellular compartmentalization experiment revealed that induced UBXN2A decreases the level of mot-2 and its chaperone partner, HSP60. Pharmacological upregulation of UBXN2A using a small molecule, veratridine (VTD), decreases the level of mot-2 in cancer cells. Consistent with the in vitro results, UBXN2A+/- mice exhibited selective elevation of mot-2 in colon tissues. An in vitro Anti-K48 TUBE isolation approach showed that recombinant UBXN2A enhances proteasomal degradation of mot-2 in mouse colon tissues. Finally, we observed enhanced association of CHIP with the UBXN2A-mot-2 complex in tumors in an azoxymethane/dextran sulfate sodium-induced mouse CRC model. The existence of a multiprotein complex containing UBXN2A, CHIP, and mot-2 suggests a synergistic tumor suppressor activity of UBXN2A and CHIP in mot-2-enriched tumors. This finding validates the UBXN2A-CHIP axis as a novel and potential therapeutic target in CRC.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Ubiquitinas
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Proteínas de Choque Térmico HSP70
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Proteínas Mitocondriais
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Ubiquitina
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Ubiquitina-Proteína Ligases
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Complexo de Endopeptidases do Proteassoma
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Proteólise
Tipo de estudo:
Prognostic_studies
Limite:
Animals
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Female
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Humans
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Male
Idioma:
En
Ano de publicação:
2018
Tipo de documento:
Article