Type 2 diabetes mellitus represents a major health problem with increasing prevalence worldwide. Limited efficacy of current therapies has prompted a search for novel therapeutic options. Here we show that treatment of pre-diabetic mice with mitochondrially targeted tamoxifen, a potential anti-cancer agent with senolytic activity, improves glucose tolerance and reduces body weight with most pronounced reduction of visceral adipose tissue due to reduced food intake, suppressed adipogenesis and elimination of senescent cells. Glucose-lowering effect of mitochondrially targeted tamoxifen is linked to improvement of type 2 diabetes mellitus-related hormones profile and is accompanied by reduced lipid accumulation in liver. Lower senescent cell burden in various tissues, as well as its inhibitory effect on pre-adipocyte differentiation, results in lower level of circulating inflammatory mediators that typically enhance metabolic dysfunction. Targeting senescence with mitochodrially targeted tamoxifen thus represents an approach to the treatment of type 2 diabetes mellitus and its related comorbidities, promising a complex impact on senescence-related pathologies in aging population of patients with type 2 diabetes mellitus with potential translation into the clinic.

• MeSH
• diabetes mellitus 2. typu * komplikace   farmakoterapie   MeSH
• experimentální diabetes mellitus * komplikace   farmakoterapie   MeSH
• glukosa metabolismus   MeSH
• lidé MeSH
• myši MeSH
• obezita komplikace   farmakoterapie   metabolismus   MeSH
• senioři MeSH
• tamoxifen farmakologie   terapeutické užití   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• senioři MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• glukosa MeSH
• tamoxifen MeSH

BACKGROUND: Mitochondria present an emerging target for cancer treatment. We have investigated the effect of mitochondrially targeted tamoxifen (MitoTam), a first-in-class anti-cancer agent, in patients with solid metastatic tumours. METHODS: MitoTam was tested in an open-label, single-centre (Department of Oncology, General Faculty Hospital, Charles University, Czech Republic), phase I/Ib trial in metastatic patients with various malignancies and terminated oncological therapies. In total, 75 patients were enrolled between May 23, 2018 and July 22, 2020. Phase I evaluated escalating doses of MitoTam in two therapeutic regimens using the 3 + 3 design to establish drug safety and maximum tolerated dose (MTD). In phase Ib, three dosing regimens were applied over 8 and 6 weeks to evaluate long-term toxicity of MitoTam as the primary objective and its anti-cancer effect as a secondary objective. This trial was registered with the European Medicines Agency under EudraCT 2017-004441-25. FINDINGS: In total, 37 patients were enrolled into phase I and 38 into phase Ib. In phase I, the initial application of MitoTam via peripheral vein indicated high risk of thrombophlebitis, which was avoided by central vein administration. The highest dose with acceptable side effects was 5.0 mg/kg. The prevailing adverse effects (AEs) in phase I were neutropenia (30%), anaemia (30%) and fever/hyperthermia (30%), and in phase Ib fever/hyperthermia (58%) together with anaemia (26%) and neutropenia (16%). Serious AEs were mostly related to thromboembolic (TE) complications that affected 5% and 13% of patients in phase I and Ib, respectively. The only statistically significant AE related to MitoTam treatment was anaemia in phase Ib (p = 0.004). Of the tested regimens weekly dosing with 3.0 mg/kg for 6 weeks afforded the best safety profile with almost all being grade 1 (G1) AEs. Altogether, five fatalities occurred during the study, two of them meeting criteria for Suspected Unexpected Serious Adverse Events Reporting (SUSAR) (G4 thrombocytopenia and G5 stroke). MitoTam showed benefit evaluated as clinical benefit rate (CBR) in 37% patients with the largest effect in renal cell carcinoma (RCC) where four out of six patients reached disease stabilisation (SD), one reached partial response (PR) so that in total, five out of six (83%) patients showed CBR. INTERPRETATION: In this study, the MTD was established as 5.0 mg/kg and the recommended dose of MitoTam as 3.0 mg/kg given once per week via central vein with recommended preventive anti-coagulation therapy. The prevailing toxicity included haematological AEs, hyperthermia/fever and TE complications. One fatal stroke and non-fatal G4 thrombocytopenia were recorded. MitoTam showed high efficacy against RCC. FUNDING: Smart Brain Ltd. TRANSLATION: For the Czech translation of the abstract see Supplementary Materials section.

• Klíčová slova
• Cancer, Mitochondrially targeted tamoxifen, Phase I/Ib clinical trial, Renal cell carcinoma,
• Publikační typ
• časopisecké články MeSH

Mitochondrially targeted anticancer drugs (mitocans) that disrupt the energy-producing systems of cancer are emerging as new potential therapeutics. Mitochondrially targeted tamoxifen (MitoTam), an inhibitor of mitochondrial respiration respiratory complex I, is a first-in-class mitocan that was tested in the phase I/Ib MitoTam-01 trial of patients with metastatic cancer. MitoTam exhibited a manageable safety profile and efficacy; among 37% (14/38) of responders, the efficacy was greatest in patients with metastatic renal cell carcinoma (RCC) with a clinical benefit rate of 83% (5/6) of patients. This can be explained by the preferential accumulation of MitoTam in the kidney tissue in preclinical studies. Here we report the mechanism of action and safety profile of MitoTam in a case series of RCC patients. All six patients were males with a median age of 69 years, who had previously received at least three lines of palliative systemic therapy and suffered progressive disease before starting MitoTam. We recorded stable disease in four, partial response in one, and progressive disease (PD) in one patient. The histological subtype matched clear cell RCC (ccRCC) in the five responders and claro-cellular carcinoma with sarcomatoid features in the non-responder. The number of circulating tumor cells (CTCs) was evaluated longitudinally to monitor disease dynamics. Beside the decreased number of CTCs after MitoTam administration, we observed a significant decrease of the mitochondrial network mass in enriched CTCs. Two patients had long-term clinical responses to MitoTam, of 50 and 36 weeks. Both patients discontinued treatment due to adverse events, not PD. Two patients who completed the trial in November 2019 and May 2020 are still alive without subsequent anticancer therapy. The toxicity of MitoTam increased with the dosage but was manageable. The efficacy of MitoTam in pretreated ccRCC patients is linked to the novel mechanism of action of this first-in-class mitochondrially targeted drug.

• Klíčová slova
• MitoTam, case series, efficacy, mechanism of action, mitocans, mitochondria, mitochondrially targeted tamoxifen, phase I/Ib trial, renal cell carcinoma, safety,
• Publikační typ
• časopisecké články MeSH
• kazuistiky MeSH

Tamoxifen resistance remains a clinical obstacle in the treatment of hormone sensitive breast cancer. It has been reported that tamoxifen is able to target respiratory complex I within mitochondria. Therefore, we established two tamoxifen-resistant cell lines, MCF7 Tam5R and T47D Tam5R resistant to 5 μM tamoxifen and investigated whether tamoxifen-resistant cells exhibit mitochondrial changes which could help them survive the treatment. The function of mitochondria in this experimental model was evaluated in detail by studying i) the composition and activity of mitochondrial respiratory complexes; ii) respiration and glycolytic status; iii) mitochondrial distribution, dynamics and reactive oxygen species production. We show that Tam5R cells exhibit a significant decrease in mitochondrial respiration, low abundance of assembled mitochondrial respiratory supercomplexes, a more fragmented mitochondrial network connected with DRP1 Ser637 phosphorylation, higher glycolysis and sensitivity to 2-deoxyglucose. Tam5R cells also produce significantly higher levels of mitochondrial superoxide but at the same time increase their antioxidant defense (CAT, SOD2) through upregulation of SIRT3 and show phosphorylation of AMPK at Ser 485/491. Importantly, MCF7 ρ0 cells lacking functional mitochondria exhibit a markedly higher resistance to tamoxifen, supporting the role of mitochondria in tamoxifen resistance. We propose that reduced mitochondrial function and higher level of reactive oxygen species within mitochondria in concert with metabolic adaptations contribute to the phenotype of tamoxifen resistance.

• Klíčová slova
• Breast cancer, Mitochondria, Mitochondrial fragmentation, Reactive oxygen species, Tamoxifen resistance,
• MeSH
• antitumorózní látky hormonální farmakologie   MeSH
• apoptóza MeSH
• buněčný cyklus MeSH
• chemorezistence * MeSH
• fenotyp MeSH
• glykolýza * MeSH
• lidé MeSH
• mitochondrie metabolismus   patologie   MeSH
• myši nahé MeSH
• myši MeSH
• nádorové buňky kultivované MeSH
• nádory prsu farmakoterapie   metabolismus   patologie   MeSH
• pohyb buněk MeSH
• proliferace buněk MeSH
• reaktivní formy kyslíku metabolismus   MeSH
• respirační komplex I metabolismus   MeSH
• superoxidy metabolismus   MeSH
• tamoxifen farmakologie   MeSH
• xenogenní modely - testy antitumorózní 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
• antitumorózní látky hormonální MeSH
• reaktivní formy kyslíku MeSH
• respirační komplex I MeSH
• superoxidy MeSH
• tamoxifen MeSH

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
• antitumorózní látky chemie   farmakologie   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
• 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
• antitumorózní látky MeSH
• biologické markery MeSH
• elektronový transportní řetězec MeSH
• reaktivní formy kyslíku MeSH
• receptor erbB-2 MeSH
• respirační komplex I MeSH
• tamoxifen MeSH

Cellular senescence is a form of cell cycle arrest that limits the proliferative potential of cells, including tumour cells. However, inability of immune cells to subsequently eliminate senescent cells from the organism may lead to tissue damage, inflammation, enhanced carcinogenesis and development of age-related diseases. We found that the anticancer agent mitochondria-targeted tamoxifen (MitoTam), unlike conventional anticancer agents, kills cancer cells without inducing senescence in vitro and in vivo. Surprisingly, it also selectively eliminates both malignant and non-cancerous senescent cells. In naturally aged mice treated with MitoTam for 4 weeks, we observed a significant decrease of senescence markers in all tested organs compared to non-treated animals. Mechanistically, we found that the susceptibility of senescent cells to MitoTam is linked to a very low expression level of adenine nucleotide translocase-2 (ANT2), inherent to the senescent phenotype. Restoration of ANT2 in senescent cells resulted in resistance to MitoTam, while its downregulation in non-senescent cells promoted their MitoTam-triggered elimination. Our study documents a novel, translationally intriguing role for an anticancer agent targeting mitochondria, that may result in a new strategy for the treatment of age-related diseases and senescence-associated pathologies.

• MeSH
• antitumorózní látky hormonální farmakologie   MeSH
• apoptóza účinky léků   genetika   MeSH
• genový knockdown MeSH
• lidé MeSH
• MFC-7 buňky MeSH
• mitochondrie účinky léků   metabolismus   MeSH
• myši inbrední NOD MeSH
• myši SCID MeSH
• myši transgenní MeSH
• myši MeSH
• proliferace buněk účinky léků   MeSH
• stárnutí buněk účinky léků   MeSH
• tamoxifen farmakologie   MeSH
• transfekce MeSH
• translokátor adeninových nukleotidů 2 genetika   metabolismus   MeSH
• viabilita buněk účinky léků   genetika   MeSH
• xenogenní modely - testy antitumorózní aktivity MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• antitumorózní látky hormonální MeSH
• tamoxifen MeSH
• translokátor adeninových nukleotidů 2 MeSH

BACKGROUND AND PURPOSE: Radiotherapy (RT) is an integral treatment part for patients with head and neck squamous cell carcinoma (HNSCC), but radioresistance remains a major issue. Here, we use MitoTam, a mitochondrially targeted analogue of tamoxifen, which we aim to stimulate ferroptotic cell death with, and sensitize radioresistant cells to RT. MATERIALS AND METHODS: We assessed viability, reactive oxygen species (ROS) production, disruption of mitochondrial membrane potential, and lipid peroxidation in radiosensitive (UT-SCC-40) and radioresistant (UT-SCC-5) HNSCC cells following MitoTam treatment. To assess ferroptosis specificity, we used the ferroptosis inhibitor ferrostatin-1 (fer-1). Also, total antioxidant capacity and sensitivity to tert-butyl hydroperoxide were evaluated to assess ROS-responses. 53BP1 staining was used to assess radiosensitivity after MitoTam treatment. RESULTS: Our data revealed increased ROS, cell death, disruption of mitochondrial membrane potential, and lipid peroxidation following MitoTam treatment in both cell lines. Adverse effects of MitoTam on cell death, membrane potential and lipid peroxidation were prevented by fer-1, indicating induction of ferroptosis. Radioresistant HNSCC cells were less sensitive to the effects of MitoTam due to intrinsic higher antioxidant capacity. MitoTam treatment prior to RT led to superadditive residual DNA damage expressed by 53BP1 foci compared to RT or MitoTam alone. CONCLUSION: MitoTam induced ferroptosis in HNSCC cells, which could be used to overcome the elevated antioxidant capacity of radioresistant cells and sensitize such cells to RT. Treatment with MitoTam followed by RT could therefore present a promising effective therapy of radioresistant cancers. STATEMENT OF SIGNIFICANCE: Radiotherapy is applied in the treatment of a majority of cancer patients. Radioresistance due to elevated antioxidant levels can be overcome by promoting ferroptotic cell death combining ROS-inducing drug MitoTam with radiotherapy.

• Klíčová slova
• Antioxidants, Ferroptosis, Head and neck cancer, MitoTam, ROS, Radioresistance, Radiosensitivity, Radiosensitization,
• MeSH
• dlaždicobuněčné karcinomy hlavy a krku radioterapie   farmakoterapie   patologie   MeSH
• ferroptóza * účinky léků   MeSH
• lidé MeSH
• membránový potenciál mitochondrií účinky léků   MeSH
• nádorové buněčné linie MeSH
• nádory hlavy a krku * radioterapie   patologie   farmakoterapie   MeSH
• peroxidace lipidů * účinky léků   MeSH
• reaktivní formy kyslíku * metabolismus   MeSH
• spinocelulární karcinom radioterapie   patologie   farmakoterapie   MeSH
• tamoxifen farmakologie   MeSH
• tolerance záření * účinky léků   MeSH
• viabilita buněk účinky léků   účinky záření   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• reaktivní formy kyslíku * MeSH
• tamoxifen MeSH

Mitochondria are essential cellular organelles, controlling multiple signalling pathways critical for cell survival and cell death. Increasing evidence suggests that mitochondrial metabolism and functions are indispensable in tumorigenesis and cancer progression, rendering mitochondria and mitochondrial functions as plausible targets for anti-cancer therapeutics. In this review, we summarised the major strategies of selective targeting of mitochondria and their functions to combat cancer, including targeting mitochondrial metabolism, the electron transport chain and tricarboxylic acid cycle, mitochondrial redox signalling pathways, and ROS homeostasis. We highlight that delivering anti-cancer drugs into mitochondria exhibits enormous potential for future cancer therapeutic strategies, with a great advantage of potentially overcoming drug resistance. Mitocans, exemplified by mitochondrially targeted vitamin E succinate and tamoxifen (MitoTam), selectively target cancer cell mitochondria and efficiently kill multiple types of cancer cells by disrupting mitochondrial function, with MitoTam currently undergoing a clinical trial.

• Klíčová slova
• anti-cancer strategy, drug delivery, mitocans, mitochondrial targeting,
• MeSH
• antitumorózní látky farmakologie   terapeutické užití   MeSH
• chemorezistence účinky léků   MeSH
• cílená molekulární terapie MeSH
• citrátový cyklus účinky léků   MeSH
• elektronový transportní řetězec účinky léků   metabolismus   MeSH
• klinické zkoušky jako téma MeSH
• lidé MeSH
• mitochondrie účinky léků   metabolismus   MeSH
• nádory farmakoterapie   metabolismus   MeSH
• oxidace-redukce účinky léků   MeSH
• progrese nemoci MeSH
• regulace genové exprese u nádorů účinky léků   MeSH
• signální transdukce účinky léků   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• antitumorózní látky MeSH
• elektronový transportní řetězec MeSH

Estrogen receptor alpha (ER) is a key biomarker for breast cancer, and the presence or absence of ER in breast and other hormone-dependent cancers decides treatment regimens and patient prognosis. ER is activated after ligand binding - typically by steroid. 2682 steroid compounds were used in a molecular docking study to identify novel ligands for ER and to predict compounds that may show anticancer activity. The effect of the most promising compounds was determined by a novel luciferase reporter assay. Two compounds, 7 and 12, showing ER inhibitory activity comparable to clinical inhibitors such as tamoxifen or fulvestrant were selected. We propose that the inhibitory effect of compounds 7 and 12 on ER is related to the presence of a double bond in their D-ring, which may protect against ER activation by reducing the electron density of the keto group, or may undergo metabolism leading to an active compound. Western blotting revealed that compound 12 decreased the level of ER in the breast cancer cell line MCF7, which was associated with reduced expression of both isoforms of the progesterone receptor, a well-known downstream target of ER. However, compound 12 has a different mechanism of action from fulvestrant. Furthermore, we found that compound 12 interferes with mitochondrial functions, probably by disrupting the electron transport chain, leading to induction of the intrinsic apoptotic pathway even in ER-negative breast cancer cells. In conclusion, the combination of computational and experimental methods shown here represents a rapid approach to determine the activity of compounds towards ER. Our data will not only contribute to research focused on the regulation of ER activity but may also be useful for the further development of novel steroid receptor-targeted drugs applicable in clinical practice.

• Klíčová slova
• Apoptosis, Docking of steroid library, Estrogen receptor alpha, Luciferase assay, Mitochondrial membrane potential,
• MeSH
• alfa receptor estrogenů genetika   metabolismus   MeSH
• estradiol farmakologie   terapeutické užití   MeSH
• estron * farmakologie   MeSH
• fulvestrant farmakologie   terapeutické užití   MeSH
• lidé MeSH
• nádorové buněčné linie MeSH
• nádory prsu * farmakoterapie   metabolismus   MeSH
• receptory pro estrogeny metabolismus   MeSH
• simulace molekulového dockingu MeSH
• tamoxifen farmakologie   MeSH
• Check Tag
• lidé MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• alfa receptor estrogenů MeSH
• estradiol MeSH
• estron * MeSH
• fulvestrant MeSH
• receptory pro estrogeny MeSH
• tamoxifen MeSH

Aging, characterized by accumulation of senescent cells, is a driving factor of various age-related diseases. These conditions pose significant health risks globally due to their increasing prevalence and serious complications. Reduction of senescent cells therefore represents a promising strategy promoting healthy aging. Here we demonstrate that targeting tamoxifen to mitochondria via triphenyl and tricyclohexyl phosphine selectively eliminates senescent cells. Our findings show a complex effect of mitochondrially targeted tamoxifen on mitochondrial function and integrity of senescent cells, including inhibition of oxidative phosphorylation and activity of respiratory complex IV. These changes result in activation of ferroptosis as the major mode of cell death, which results in rejuvenation of tissues. Targeting mitochondria of senescent cells represents a general senolytic strategy and may extend the healthspan and improve the quality of life in aging populations.

• Publikační typ
• časopisecké články MeSH