Abstract 506: H2O2 upregulates xCT in human breast cancer cells via NRF-2
Notice bibliographique
Résumé
Abstract Cancer cells adapt to high levels of oxidative stress in order to survive and proliferate, making the transcription factors involved in antioxidant defense regulation targets of interest. The transcription factor NF E2 Related Factor 2 (NRF-2) regulates cellular defense genes including those encoding intracellular redox-balancing proteins such as enzymes involved in glutathione metabolism. Glutathione in particular is an important intracellular antioxidant molecule. NRF-2 binds to the Antioxidant Response Element (ARE) in the promoter of its target genes. Under basal conditions, KEAP1 acts as an inhibitor that targets NRF-2 for ubiquitination. During oxidative stress, NRF-2 dissociates from KEAP1 and enters the nucleus to bind to the ARE sequence. It is hypothesized that the elevated Reactive Oxygen Species may be depleting the glutathione levels within the cancer cell. System xc- is a cysteine/glutamate antiporter that exports glutamate while importing cysteine to synthesize glutathione. In response to oxidative stress the cells increase system xc- activity in order to provide cysteine for glutathione synthesis. There is evidence that expression of xCT the specific subunit of System X is regulated by NRF-2. However this has not yet been demonstrated in human cancer cells, which is the focus of this project. Basal expression of NRF-2, Keap1 and xCT was characterized in two breast cancer cell lines (MDA MB 231 and MCF-7) compared to normal human breast epithelial 184B5 cells. Compared to 184B5 cells, Keap-1, NRF-2 and xCT were upregulated in MDA MB 231 cells, but down regulated in MCF-7 cells. MCF-7 cells were treated with H202 resulting in NRF-2 protein accumulation in the nucleus and decreased levels in the cytosol. Under the same treatment conditions, Keap-1 protein decreased in the nucleus and increased in the cytosol. With H202 treatment, xCT mRNA levels increased in MCF-7 cells. We have cloned approximately 2.6 kilobase (-2329 to +278 bp) of the human xCT promoter region from genomic DNA isolated from MDA MB 231 breast cancer cells. We found that the xCT promoter was responsive to treatment with H2O2, which increased transcriptional activity. This is consistent with results described for the mouse promoter, which is known to contain an antioxidant response element that can be bound by NRF-2 during oxidative stress. Co transfection of MDA MB 231 with the xCT promoter and an NRF-2 expression vector also increased promoter activity. This data suggests that under oxidative stress, NRF-2 is localized to the nucleus and transcriptionally upregulates xCT. This is the first study in which the regulation of xCT has been linked to oxidative stress via NRF-2 in human breast cancer cells. This work was supported by the Canadian Institutes for Health Research. Citation Format: Eric Habib, Katja Linher-Melville, Gurmit Singh. H2O2 upregulates xCT in human breast cancer cells via NRF-2. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 506. doi:10.1158/1538-7445.AM2014-506
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,005 | 0,001 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».