Tamoxifen and its metabolites induce mitochondrial membrane depolarization and caspase‐3 activation in equine neutrophils

Albornoz, Alejandro; Morales, Natalia; Uberti, Benjamín; Henríquez, Claudio; Burgos, Rafael A.; Alarcón, Pablo; Morán, Gabriel

doi:10.1002/vms3.316

Cited by 3 publications

(4 citation statements)

References 23 publications

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“…Additionally, they indicate that the inhibition of membrane estrogen receptors (GPR30) was able to reverse TAM-induced autophagy, but not its effect on cell viability, speculating that these off-target mechanisms of TAM could be associated with its inhibitory effect on PCK or directly on the mitochondria. Something similar was described by our group on equine neutrophils since this drug is also capable of inducing a marked loss of mitochondrial membrane potential at similar concentrations, which was associated with caspase-3 activation and cell apoptosis ( 49 ). The same occurs in the case of PS translocation, demonstrating a significant increase in the case of neutrophils incubated with TAM at a concentration of 2 μM ( 21 ).…”

Section: Discussionsupporting

confidence: 70%

Effects of tamoxifen on the immune response phenotype in equine peripheral blood mononuclear cells

Rodríguez,

Quiroga,

Cortés

et al. 2024

Front. Vet. Sci.

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Tamoxifen (TAM) is widely utilized in the prevention and treatment of human breast cancer and has demonstrated the potential to modulate the immune response. It has been proposed as a therapeutic tool for immune-mediated diseases. TAM has been investigated as a possible treatment for asthma-like conditions in horses, revealing specific impacts on the innate immune system. While the effects of TAM on equine neutrophils are well-documented, its influence on lymphocytes and the modulation of the immune response polarization remains unclear. This in vitro study employed peripheral blood mononuclear cells (PBMC) from healthy horses, exposing them to varying concentrations of the TAM and assessing the expression of genes involved in the polarization of the immune response (TBX21, IFNG, GATA3, IL4, IL10, FOXP3, and CTLA4) in PBMC stimulated or not with PMA/ionomycin. Additionally, the effect of TAM over the proportion of regulatory T cells (Treg) was also assessed. TAM did not significantly affect the expression of these genes and Treg at low concentrations. However, at the highest concentration, there was an impact on the expression of GATA3, IL4, IL10, and CTLA4 genes. These alterations in genes associated with a Th2 and regulatory response coincided with a noteworthy increase in drug-associated cytotoxicity but only at concentrations far beyond those achieved in pharmacological therapy. These findings suggest that the effects of TAM, as described in preclinical studies on asthmatic horses, may not be attributed to the modification of the adaptive response.

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Section: Discussionsupporting

confidence: 70%

Effects of tamoxifen on the immune response phenotype in equine peripheral blood mononuclear cells

Rodríguez,

Quiroga,

Cortés

et al. 2024

Front. Vet. Sci.

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“…In particular, mitochondrial membrane potential (∆ ψ m ) depolarization appears to be an early mitochondrial event leading to cell death [ 60 ]. Correspondingly, many weak base drugs are known to depolarize the mitochondrial membrane potential [ 61 , 62 ] and our findings clearly showed that the weak base drug-induced efflux of Fe 2+ from endolysosomes caused mitochondrial depolarization as well as cell death.…”

Section: Discussionsupporting

confidence: 68%

Weak base drug-induced endolysosome iron dyshomeostasis controls the generation of reactive oxygen species, mitochondrial depolarization, and cytotoxicity

Halcrow,

Quansah,

Kumar

et al. 2024

NeuroImmune Pharmacology and Therapeutics

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Objectives Approximately 75 % of marketed drugs have the physicochemical property of being weak bases. Weak-base drugs with relatively high pKa values enter acidic organelles including endosomes and lysosomes (endolysosomes), reside in and de-acidify endolysosomes, and induce cytotoxicity. Divalent cations within endolysosomes, including iron, are released upon endolysosome de-acidification. Endolysosomes are “master regulators of iron homeostasis”, and neurodegeneration is linked to ferrous iron (Fe2+)-induced reactive oxygen species (ROS) generation via Fenton chemistry. Because endolysosome de-acidification-induced lysosome-stress responses release endolysosome Fe2+, it was crucial to determine the mechanisms by which a functionally and structurally diverse group of weak base drugs including atropine, azithromycin, fluoxetine, metoprolol, and tamoxifen influence endolysosomes and cause cell death. Methods Using U87MG astrocytoma and SH-SY5Y neuroblastoma cells, we conducted concentration-response relationships for 5 weak-base drugs to determine EC50 values. From these curves, we chose pharmacologically and therapeutically relevant concentrations to determine if weak-base drugs induced lysosome-stress responses by de-acidifying endolysosomes, releasing endolysosome Fe2+ in sufficient levels to increase cytosolic and mitochondria Fe2+ and ROS levels and cell death. Results Atropine (anticholinergic), azithromycin (antibiotic), fluoxetine (antidepressant), metoprolol (beta-adrenergic), and tamoxifen (anti-estrogen) at pharmacologically and therapeutically relevant concentrations (1) de-acidified endolysosomes, (2) decreased Fe2+ levels in endolysosomes, (3) increased Fe2+ and ROS levels in cytosol and mitochondria, (4) induced mitochondrial membrane potential depolarization, and (5) increased cell death; effects prevented by the endocytosed iron-chelator deferoxamine. Conclusions Weak-base pharmaceuticals induce lysosome-stress responses that may affect their safety profiles; a better understanding of weak-base drugs on Fe2+ interorganellar signaling may improve pharmacotherapeutics.

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“…Thus, the source of ROS that triggers NETs by TX should come from the mitochondria. Likewise, Albornoz et al (15) showed that tamoxifen, N-desmethyltamoxifen and endoxifen depolarize the mitochondrial membrane and activate caspase-3 in healthy equine neutrophils in vitro. These results suggest that TX has the capacity to produce alterations in mitochondria, probably by stimulating the release of mtROS.…”

Section: Discussionmentioning

confidence: 97%

“…Tamoxifen (TX), a selective estrogen receptor modulator which belongs to the triphenylethyllenes group of molecules, is used as a treatment in all stages of estrogen-positive human breast cancer. It has potent anti-inflammatory effects: we have described an early pro-apoptotic effect of tamoxifen in granulocytic cells, both in vitro with peripheral blood and BALF (13), and in vivo (14); in addition, we showed that tamoxifen and its metabolites can activate the intrinsic apoptotic pathway in equine neutrophils (15). Our laboratory group has also shown that tamoxifen has an inhibitory action on respiratory burst, chemotaxis and chemokinesis of equine neutrophils in a dose-dependent manner (16,17), and that tamoxifen induces efferocytosis by macrophages and modulates immune function through an estrogen-independent mechanism (18,19).…”

Section: Introductionmentioning

confidence: 88%

Tamoxifen triggers the in vitro release of neutrophil extracellular traps in healthy horses

et al. 2023

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Neutrophils display an array of biological functions including the formation of neutrophil extracellular traps (NETs), web-like structures specialized in trapping, neutralizing, killing and preventing microbial dissemination within the host. However, NETs contribute to a number of inflammatory pathologies, including severe equine asthma. Tamoxifen (TX) is a selective estrogen receptor modulator which belongs to the triphenylethyllenes group of molecules, and which is used as a treatment in all stages of estrogen-positive human breast cancer. Our previous results suggest that tamoxifen can modulate neutrophil functionality and promote resolution of inflammation; this would partly explain the clinical beneficial effect of this drug in horses with airway inflammation. Enhanced NETs production has been reported with tamoxifen use in humans, but minimal data exists regarding the drug's effect on NETs in horses. The aim of this study is to assess the in vitro effect of TX on NETs formation from peripheral blood of healthy horses. Five clinically healthy mixed-breed adult horses were enrolled in the study. For this, cellular free DNA quantification, immunofluorescence for the visualization of NETs, assessment of different types of NETs, and detection of mitochondrial superoxide. TX induced NETs formation at a concentration of 10 uM. Our results show that only two types of NETs were induced by TX: 95% spread NETs (sprNETs) and 5% aggregated NETs (aggNETs). Furthermore, induction of these NETs could be influenced by mitochondrial ROS. Future research should involve an In vivo study of horses with severe asthma and TX treatment, to evaluate BALF neutrophil NET formation. In conclusion, this in vitro study suggests that the resolution of inflammation by TX in horses with airway inflammation is due to inhibition of other neutrophilic functions but not to NET formation.

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Tamoxifen and its metabolites induce mitochondrial membrane depolarization and caspase‐3 activation in equine neutrophils

Cited by 3 publications

References 23 publications

Effects of tamoxifen on the immune response phenotype in equine peripheral blood mononuclear cells

Effects of tamoxifen on the immune response phenotype in equine peripheral blood mononuclear cells

Weak base drug-induced endolysosome iron dyshomeostasis controls the generation of reactive oxygen species, mitochondrial depolarization, and cytotoxicity

Tamoxifen triggers the in vitro release of neutrophil extracellular traps in healthy horses

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