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RelB-activated GPX4 inhibits ferroptosis and confers tamoxifen resistance in breast cancer.

ABSTRACT: Tamoxifen (TAM) resistance remains a major obstacle in the treatment of advanced breast cancer (BCa). In addition to the competitive inhibition of the estrogen receptor (ER) signaling pathway, damping of mitochondrial function by increasing reactive oxygen species (ROS) is critical for enhancing TAM pharmacodynamics. Here, we showed that RelB contributes to TAM resistance by inhibiting TAM-provoked ferroptosis. TAM-induced ROS level promoted ferroptosis in TAM-sensitive cells, but the effect was alleviated in TAM-resistant cells with high constitutive levels of RelB. Mechanistically, RelB inhibited ferroptosis by transcriptional upregulating glutathione peroxidase 4 (GPX4). Consequently, elevating RelB and GPX4 in sensitive cells increased TAM resistance, and conversely, depriving RelB and GPX4 in resistant cells decreased TAM resistance. Furthermore, suppression of RelB transcriptional activation resensitized TAM-resistant cells by enhancing ferroptosis in vitro and in vivo. The inactivation of GPX4 in TAM-resistant cells consistently resensitized TAM by increasing ferroptosis-mediated cell death. Together, this study uncovered that inhibition of ferroptosis contributes to TAM resistance of BCa via RelB-upregulated GPX4.

SUBMITTER: Xu Z

PROVIDER: S-EPMC10641764 | biostudies-literature | 2023 Dec

REPOSITORIES: biostudies-literature

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RelB-activated GPX4 inhibits ferroptosis and confers tamoxifen resistance in breast cancer.

Xu Zhi Z Wang Xiumei X Sun Wenbo W Xu Fan F Kou Hengyuan H Hu Weizi W Zhang Yanyan Y Jiang Qin Q Tang Jinhai J Xu Yong Y

Redox biology 20231104

Tamoxifen (TAM) resistance remains a major obstacle in the treatment of advanced breast cancer (BCa). In addition to the competitive inhibition of the estrogen receptor (ER) signaling pathway, damping of mitochondrial function by increasing reactive oxygen species (ROS) is critical for enhancing TAM pharmacodynamics. Here, we showed that RelB contributes to TAM resistance by inhibiting TAM-provoked ferroptosis. TAM-induced ROS level promoted ferroptosis in TAM-sensitive cells, but the effect was ...[more]

PMID: 37944384

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Project description:The identification of clinically important molecular mechanisms driving endocrine resistance is a priority in estrogen receptor-positive (ER+) breast cancer. Although both genomic and non-genomic cross-talk between the ER and growth factor receptors such as human epidermal growth factor receptor 2 (HER2) has frequently been associated with both experimental and clinical endocrine therapy resistance, combined targeting of ER and HER2 has failed to improve overall survival in endocrine non-responsive disease. Herein, we questioned the role of fatty acid synthase (FASN), a lipogenic enzyme linked to HER2-driven breast cancer aggressiveness, in the development and maintenance of hormone-independent growth and resistance to anti-estrogens in ER/HER2-positive (ER+/HER2+) breast cancer. The stimulatory effects of estradiol on FASN gene promoter activity and protein expression were blunted by anti-estrogens in endocrine-responsive breast cancer cells. Conversely, an AKT/MAPK-related constitutive hyperactivation of FASN gene promoter activity was unaltered in response to estradiol in non-endocrine responsive ER+/HER2+ breast cancer cells, and could be further enhanced by tamoxifen. Pharmacological blockade with structurally and mechanistically unrelated FASN inhibitors fully impeded the strong stimulatory activity of tamoxifen on the soft-agar colony forming capacity-an in vitro metric of tumorigenicity-of ER+/HER2+ breast cancer cells. In vivo treatment with a FASN inhibitor completely prevented the agonistic tumor-promoting activity of tamoxifen and fully restored its estrogen antagonist properties against ER/HER2-positive xenograft tumors in mice. Functional cancer proteomic data from The Cancer Proteome Atlas (TCPA) revealed that the ER+/HER2+ subtype was the highest FASN protein expressor compared to basal-like, HER2-enriched, and ER+/HER2-negative breast cancer groups. FASN is a biological determinant of HER2-driven endocrine resistance in ER+ breast cancer. Next-generation, clinical-grade FASN inhibitors may be therapeutically relevant to countering resistance to tamoxifen in FASN-overexpressing ER+/HER2+ breast carcinomas.

Project description:BackgroundDiffuse large B-cell lymphoma (DLBCL) is predominant subtype of non-Hodgkin lymphoma and can be effectively treated. Nevertheless, a subset of patients experiences refractory or relapsed disease, highlighting the need for new therapeutic strategies.MethodsDepmap database based on CRISPR/Cas9 knock out analysis was employed to identify the essential gene SH3GL1, which encodes endophilin A2, as crucial for the proliferation and survival of DLBCL cells. Immunohistochemistry (IHC) staining was performed on the 126 paraffin-embedded clinical DLBCL samples to investigate the association between SH3GL1 expression levels and the prognosis. To investigate the specific mechanism modulated by SH3GL1 in the progression of DLBCL, an integrative approach was employed. This approach combined high-throughput sequencing technologies, such as Deep-DIA and LC-MS, with functional validation techniques, including CRISPR/Cas9 gene editing, xenograft models, and molecular pathway analyses.ResultsOur study found that high expression levels of SH3GL1 correlate with poor prognosis in a cohort of 126 newly diagnosed DLBCL patients, underscoring its significance in disease progression. Mechanistically, we found that SH3GL1 deficiency triggers ferritin heavy chain 1 (FTH1)-mediated ferroptosis, specifically ferritinophagy-induced ferroptosis, in DLBCL cells. Additionally, high expression of SH3GL1 suppresses doxorubicin-induced ferroptosis. Cancer cells' resistance to conventional therapies is associated with increased sensitivity to ferroptosis.ConclusionsThese findings emphasise SH3GL1 as a promising prognostic biomarker and a potential therapeutic target in DLBCL, offering new avenues for treatment strategies aimed at overcoming drug resistance and improving patients' outcomes.Key pointsElevated SH3GL1 expression in DLBCL patients was associated with a negative prognosis. SH3GL1 plays a crucial role in promoting DLBCL cell survival through the regulation of FTH1-mediated ferroptosis and doxorubicin resistance.

Project description:Gankyrin is found in high levels in triple-negative breast cancer (TNBC) and has been established to form a complex with the E3 ubiquitin ligase MDM2 and p53, resulting in the degradation of p53 in hepatocarcinoma cells. Therefore, this study sought to determine whether gankyrin could inhibit ferroptosis through this mechanism in TNBC cells. The expression of gankyrin was investigated in relation to the prognosis of TNBC using bioinformatics. Co-immunoprecipitation and GST pull-down assays were then conducted to determine the presence of a gankyrin and MDM2 complex. RT-qPCR and immunoblotting were used to examine molecules related to ferroptosis, such as gankyrin, p53, MDM2, SLC7A11, and GPX4. Additionally, cell death was evaluated using flow cytometry detection of 7-AAD and a lactate dehydrogenase release assay, as well as lipid peroxide C11-BODIPY. Results showed that the expression of gankyrin is significantly higher in TNBC tissues and cell lines, and is associated with a poor prognosis for patients. Subsequent studies revealed that inhibiting gankyrin activity triggered ferroptosis in TNBC cells. Additionally, silencing gankyrin caused an increase in the expression of the p53 protein, without altering its mRNA expression. Co-immunoprecipitation and GST pull-down experiments indicated that gankyrin and MDM2 form a complex. In mouse embryonic fibroblasts lacking both MDM2 and p53, this gankyrin/MDM2 complex was observed to ubiquitinate p53, thus raising the expression of molecules inhibited by ferroptosis, such as SLC7A11 and GPX4. Furthermore, silencing gankyrin in TNBC cells disrupted the formation of the gankyrin/MDM2 complex, hindered the degradation of p53, increased SLC7A11 expression, impeded cysteine uptake, and decreased GPX4 production. Our findings suggest that TNBC cells are able to prevent cell ferroptosis through the gankyrin/p53/SLC7A11/GPX4 signaling pathway, indicating that gankyrin may be a useful biomarker for predicting TNBC prognosis or a potential therapeutic target.

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RelB-activated GPX4 inhibits ferroptosis and confers tamoxifen resistance in breast cancer.

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RelB-activated GPX4 inhibits ferroptosis and confers tamoxifen resistance in breast cancer.

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