AIMS: Expression of the HER2 oncogene in breast cancer is associated with resistance to treatment, and Her2 may regulate bioenergetics. Therefore, we investigated whether disruption of the electron transport chain (ETC) is a viable strategy to eliminate Her2high disease. RESULTS: We demonstrate that Her2high cells and tumors have increased assembly of respiratory supercomplexes (SCs) and increased complex I-driven respiration in vitro and in vivo. They are also highly sensitive to MitoTam, a novel mitochondrial-targeted derivative of tamoxifen. Unlike tamoxifen, MitoTam efficiently suppresses experimental Her2high tumors without systemic toxicity. Mechanistically, MitoTam inhibits complex I-driven respiration and disrupts respiratory SCs in Her2high background in vitro and in vivo, leading to elevated reactive oxygen species production and cell death. Intriguingly, higher sensitivity of Her2high cells to MitoTam is dependent on the mitochondrial fraction of Her2. INNOVATION: Oncogenes such as HER2 can restructure ETC, creating a previously unrecognized therapeutic vulnerability exploitable by SC-disrupting agents such as MitoTam. CONCLUSION: We propose that the ETC is a suitable therapeutic target in Her2high disease. Antioxid. Redox Signal. 26, 84-103.

• Klíčová slova
• HER2, breast cancer, mitochondria, mitochondrially targeted tamoxifen, respirasome,
• MeSH
• biologické markery MeSH
• buněčná smrt účinky léků   MeSH
• buněčné dýchání účinky léků   MeSH
• cílená molekulární terapie MeSH
• elektronový transportní řetězec antagonisté a inhibitory   chemie   metabolismus   MeSH
• inhibiční koncentrace 50 MeSH
• lidé MeSH
• membránový potenciál mitochondrií účinky léků   MeSH
• mitochondrie účinky léků   metabolismus   MeSH
• molekulární konformace MeSH
• molekulární modely MeSH
• nádorové buněčné linie MeSH
• nádory prsu farmakoterapie   metabolismus   patologie   MeSH
• protinádorové látky chemie   farmakologie   MeSH
• reaktivní formy kyslíku metabolismus   MeSH
• receptor erbB-2 antagonisté a inhibitory   metabolismus   MeSH
• respirační komplex I antagonisté a inhibitory   chemie   metabolismus   MeSH
• tamoxifen farmakologie   MeSH
• vazba proteinů MeSH
• Check Tag
• lidé MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• biologické markery MeSH
• elektronový transportní řetězec MeSH
• protinádorové látky MeSH
• reaktivní formy kyslíku MeSH
• receptor erbB-2 MeSH
• respirační komplex I MeSH
• tamoxifen MeSH

BACKGROUND: Accumulating evidence suggests that breast cancer involves tumour-initiating cells (TICs), which play a role in initiation, metastasis, therapeutic resistance and relapse of the disease. Emerging drugs that target TICs are becoming a focus of contemporary research. Mitocans, a group of compounds that induce apoptosis of cancer cells by destabilising their mitochondria, are showing their potential in killing TICs. In this project, we investigated mitochondrially targeted vitamin E succinate (MitoVES), a recently developed mitocan, for its in vitro and in vivo efficacy against TICs. METHODS: The mammosphere model of breast TICs was established by culturing murine NeuTL and human MCF7 cells as spheres. This model was verified by stem cell marker expression, tumour initiation capacity and chemotherapeutic resistance. Cell susceptibility to MitoVES was assessed and the cell death pathway investigated. In vivo efficacy was studied by grafting NeuTL TICs to form syngeneic tumours. RESULTS: Mammospheres derived from NeuTL and MCF7 breast cancer cells were enriched in the level of stemness, and the sphere cells featured altered mitochondrial function. Sphere cultures were resistant to several established anti-cancer agents while they were susceptible to MitoVES. Killing of mammospheres was suppressed when the mitochondrial complex II, the molecular target of MitoVES, was knocked down. Importantly, MitoVES inhibited progression of syngeneic HER2(high) tumours derived from breast TICs by inducing apoptosis in tumour cells. CONCLUSIONS: These results demonstrate that using mammospheres, a plausible model for studying TICs, drugs that target mitochondria efficiently kill breast tumour-initiating cells.

• MeSH
• apoptóza účinky léků   MeSH
• buněčné sféroidy MeSH
• chemorezistence MeSH
• lidé MeSH
• MFC-7 buňky MeSH
• mitochondrie účinky léků   metabolismus   MeSH
• modely nemocí na zvířatech MeSH
• myši transgenní MeSH
• myši MeSH
• nádorové buněčné linie MeSH
• nádorové buňky kultivované MeSH
• nádorové kmenové buňky účinky léků   metabolismus   MeSH
• nádory prsu farmakoterapie   metabolismus   patologie   MeSH
• protinádorové látky farmakologie   MeSH
• respirační komplex II metabolismus   MeSH
• tokoferoly farmakologie   MeSH
• tumor burden účinky léků   MeSH
• viabilita buněk účinky léků   MeSH
• xenogenní modely - testy protinádorové aktivity MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• protinádorové látky MeSH
• respirační komplex II MeSH
• tokoferoly MeSH

Malignant mesothelioma (MM) is an aggressive type of tumour causing high mortality. One reason for this paradigm may be the existence of a subpopulation of tumour-initiating cells (TICs) that endow MM with drug resistance and recurrence. The objective of this study was to identify and characterise a TIC subpopulation in MM cells, using spheroid cultures, mesospheres, as a model of MM TICs. Mesospheres, typified by the stemness markers CD24, ABCG2 and OCT4, initiated tumours in immunodeficient mice more efficiently than adherent cells. CD24 knock-down cells lost the sphere-forming capacity and featured lower tumorigenicity. Upon serial transplantation, mesospheres were gradually more efficiently tumrigenic with increased level of stem cell markers. We also show that mesospheres feature mitochondrial and metabolic properties similar to those of normal and cancer stem cells. Finally, we show that mesothelioma-initiating cells are highly susceptible to mitochondrially targeted vitamin E succinate. This study documents that mesospheres can be used as a plausible model of mesothelioma-initiating cells and that they can be utilised in the search for efficient agents against MM.

• MeSH
• antigen CD24 metabolismus   MeSH
• buněčná adheze účinky léků   MeSH
• buněčné sféroidy účinky léků   patologie   MeSH
• fenotyp MeSH
• genový knockdown MeSH
• inhibiční koncentrace 50 MeSH
• invazivní růst nádoru MeSH
• lidé MeSH
• maligní mezoteliom MeSH
• mezoteliom metabolismus   patologie   MeSH
• mitochondrie účinky léků   metabolismus   MeSH
• myši nahé MeSH
• nádorové biomarkery metabolismus   MeSH
• nádorové buněčné linie MeSH
• nádorové kmenové buňky účinky léků   metabolismus   patologie   MeSH
• nádory plic metabolismus   patologie   MeSH
• progrese nemoci MeSH
• proliferace buněk účinky léků   MeSH
• protinádorové látky farmakologie   MeSH
• tokoferoly farmakologie   MeSH
• transplantace nádorů MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• antigen CD24 MeSH
• nádorové biomarkery MeSH
• protinádorové látky MeSH
• tokoferoly MeSH