Glycation of glutamate cysteine ligase by 2-deoxy-d-ribose and its potential impact on chemoresistance in glioblastoma.
Neurochem Res
; 38(9): 1838-49, 2013 Sep.
Article
em En
| MEDLINE
| ID: mdl-23743623
ABSTRACT
The antioxidant glutathione (GSH) plays a critical role in maintaining intracellular redox homeostasis but in tumors the GSH biosynthetic pathway is often dysregulated, contributing to tumor resistance to radiation and chemotherapy. Glutamate-cysteine ligase (GCL) catalyzes the first and rate-limiting reaction in GSH synthesis, and enzyme function is controlled by GSH feedback inhibition or by transcriptional upregulation of the catalytic (GCLC) and modifier (GCLM) subunits. However, it has recently been reported that the activity of GCLC and the formation of GCL can be modified by reactive aldehyde products derived from lipid peroxidation. Due to the susceptibility of GCLC to posttranslational modifications by reactive aldehydes, we examined the potential for 2-deoxy-D-ribose (2dDR) to glycate GCLC and regulate enzyme activity and GCL formation. 2dDR was found to directly modify both GCLC and GCLM in vitro, resulting in a significant inhibition of GCLC and GCL enzyme activity without altering substrate affinity or feedback inhibition. 2dDR-mediated glycation also inhibited GCL subunit heterodimerization and formation of the GCL holoenzyme complex while not causing dissociation of pre-formed holoenzyme. This PTM could be of particular importance in glioblastoma (GBM) where intratumoral necrosis provides an abundance of thymidine, which can be metabolized by thymidine phosphorylase (TP) to form 2dDR. TP is expressed at high levels in human GBM tumors and shRNA knockdown of TP in U87 GBM cells results in a significant increase in cellular GCL enzymatic activity.
Texto completo:
1
Bases de dados:
MEDLINE
Assunto principal:
Neoplasias Encefálicas
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Glioblastoma
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Resistencia a Medicamentos Antineoplásicos
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Desoxirribose
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Glutamato-Cisteína Ligase
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Glucose
Limite:
Humans
Idioma:
En
Revista:
Neurochem Res
Ano de publicação:
2013
Tipo de documento:
Article
País de afiliação:
Estados Unidos