Human neuroblastoma cells with MYCN amplification are selectively resistant to oxidative stress by transcriptionally up‐regulating glutamate cysteine ligase

Abstract

Neuroblastoma is a sympathetic nervous system tumour whose degree of malignancy, prognosis and therapy resistance has been associated with the amplification of MYCN oncogene. However, the molecular pathway responsible for such resistance is unknown. To contribute addressing this issue, in this study, we have compared the vulnerability of four human neuroblastoma cell lines differentially amplifying MYCN, namely SK-N-BE-2 and IMR-32 (MYCN-amplified cells) and SH-SY5Y and SK-N-SH (MCYN-non-amplified cells), to H 2 O 2 -mediated apoptotic death. We found that the high resistance of the MYCN-amplified neuroblastoma cells against oxidative damage can be accounted for by their greater expression of both the mRNA and protein of the catalytic subunit of glutamate-cysteine ligase (GCL cat ), the ratelimiting step in GSH biosynthesis. Furthermore, we found that MYCN directly binds to an E-box containing GCL cat promoter and that over-expression of MYCN in MYCN-non-amplified cells stimulated GCL cat expression and provided resistance to oxidative damage; whereas knock down of MYCN in MYCNamplified cells decreased GCL cat expression and sensitized them to oxidative damage. Finally, GCL cat knock down enhanced the vulnerability of MYCN-amplified cells to oxidative damage. These results demonstrate that regulation of GCL cat by MYCN accounts for the survival of neuroblastoma cells against oxidative damage, and suggest that GCL should be considered a potential therapeutic target for the treatment of MYCN-amplified neuroblastoma.

PKCδ Sensitizes Neuroblastoma Cells to L-Buthionine-Sulfoximine and Etoposide Inducing Reactive Oxygen Species Overproduction and DNA Damage

“…In recent literature, it has been reported that human NB cells with MYCN amplification are selectively resistant to oxidative stress by transcriptionally up-regulating glutamate cysteine ligase [31]. These findings could explain, in part, the major vulnerability of MYCN-amplified NB cells following treatment with BSO, an irreversible inhibitor of GSH biosynthesis.…”

The dietary flavonoid isoliquiritigenin is a potent cytotoxin for human neuroblastoma cells

“…We first carried out a dose-response experiment on the effects of ISLQ treatment on cell viability in SK-N-BE(2) cultures. This cell line is MYCN-amplified [36] and therefore a suitable model of aggressive NB, given that MYCN amplification is the main prognostic marker of poor survival in NB [5]. Treatment with ISLQ at concentrations of 5 μM or greater resulted in a dose-dependent decrease (P<0.01) in cell viability in SK-N-BE(2), as measured by MTT assays ( Figure 1A).…”

Targeting Glutamine Induces Apoptosis: A Cancer Therapy Approach

“…In addition, MYC probably binds to the promoter elements of glutamine transporters, which is associated with enhanced levels of glutamine transporters, e.g., SLC7A5 (solute carrier family 7 member 5, LAT1) and ASCT2 ( Figure 1 ) [ 30 , 31 ]. N-MYC overexpression stimulates mRNA and protein expression of the catalytic subunit of GCL (glutamate-cysteine ligase), and causes rate-limiting step in GSH biosynthesis, which increases GSH level and provides resistance to oxidative damage [ 33 ]. Therefore, targeting MYC can provide a therapeutic window for cancers that have MYC amplification.…”