Mitochondrially targeted tamoxifen in patients with metastatic solid tumours: an open-label, phase I/Ib single-centre trial.

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.

Mitochondria on the move: Horizontal mitochondrial transfer in disease and health.

Mammalian genes were long thought to be constrained within somatic cells in most cell types. This concept was challenged recently when cellular organelles including mitochondria were shown to move between mammalian cells in culture via cytoplasmic bridges. Recent research in animals indicates transfer of mitochondria in cancer and during lung injury in vivo, with considerable functional consequences.

Mitochondrial Function, Fatty Acid Metabolism, and Body Composition in the Hyperbilirubinemic Gunn Rat.

Circulating bilirubin is associated with reduced adiposity in human and animal studies. A possible explanation is provided by data that demonstrates that bilirubin inhibits mitochondrial function and decreases efficient energy production. However, it remains unclear whether hyperbilirubinemic animals have similar perturbed mitochondrial function and whether this is important for regulation of energy homeostasis.

Mitocans Revisited: Mitochondrial Targeting as Efficient Anti-Cancer Therapy.

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.

Marizomib suppresses triple-negative breast cancer via proteasome and oxidative phosphorylation inhibition.

: Lacking effective targeted therapies, triple-negative breast cancer (TNBCs) is highly aggressive and metastatic disease, and remains clinically challenging breast cancer subtype to treat. Despite the survival dependency on the proteasome pathway genes, FDA-approved proteasome inhibitors induced minimal clinical response in breast cancer patients due to weak proteasome inhibition. Hence, developing effective targeted therapy using potent proteasome inhibitor is required.

Liposomal Delivery of miR-34b-5p Induced Cancer Cell Death in Thyroid Carcinoma.

This study aims to determine the functional roles of microRNA-34b-5p (miR-34b) in the suppression of anaplastic thyroid carcinoma. We used hydration-of-freeze-dried-matrix (HFDM) formulated liposomes (liposome-loaded miR-34b) for effective delivery of miR-34b to anaplastic thyroid carcinoma in vitro and in vivo. Real time polymerase chain was used to determine the level of miR-34b.

Reactivation of Dihydroorotate Dehydrogenase-Driven Pyrimidine Biosynthesis Restores Tumor Growth of Respiration-Deficient Cancer Cells.

Cancer cells without mitochondrial DNA (mtDNA) do not form tumors unless they reconstitute oxidative phosphorylation (OXPHOS) by mitochondria acquired from host stroma. To understand why functional respiration is crucial for tumorigenesis, we used time-resolved analysis of tumor formation by mtDNA-depleted cells and genetic manipulations of OXPHOS. We show that pyrimidine biosynthesis dependent on respiration-linked dihydroorotate dehydrogenase (DHODH) is required to overcome cell-cycle arrest, while mitochondrial ATP generation is dispensable for tumorigenesis.

Alternative assembly of respiratory complex II connects energy stress to metabolic checkpoints.

Cell growth and survival depend on a delicate balance between energy production and synthesis of metabolites. Here, we provide evidence that an alternative mitochondrial complex II (CII) assembly, designated as CII, serves as a checkpoint for metabolite biosynthesis under bioenergetic stress, with cells suppressing their energy utilization by modulating DNA synthesis and cell cycle progression. Depletion of CII leads to an imbalance in energy utilization and metabolite synthesis, as evidenced by recovery of the de novo pyrimidine pathway and unlocking cell cycle arrest from the S-phase.

Selective elimination of senescent cells by mitochondrial targeting is regulated by ANT2.

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.

Horizontal transfer of whole mitochondria restores tumorigenic potential in mitochondrial DNA-deficient cancer cells.

Recently, we showed that generation of tumours in syngeneic mice by cells devoid of mitochondrial (mt) DNA (ρ cells) is linked to the acquisition of the host mtDNA. However, the mechanism of mtDNA movement between cells remains unresolved. To determine whether the transfer of mtDNA involves whole mitochondria, we injected B16ρ mouse melanoma cells into syngeneic C57BL/6N mice that express red fluorescent protein in their mitochondria.

Mitochondrial Complex II: At the Crossroads.

Mitochondrial complex II (CII), also called succinate dehydrogenase (SDH), is a central purveyor of the reprogramming of metabolic and respiratory adaptation in response to various intrinsic and extrinsic stimuli and abnormalities. In this review we discuss recent findings regarding SDH biogenesis, which requires four known assembly factors, and modulation of its enzymatic activity by acetylation, succinylation, phosphorylation, and proteolysis. We further focus on the emerging role of both genetic and epigenetic aberrations leading to SDH dysfunction associated with various clinical manifestations.

Mitochondrial Targeting of Metformin Enhances Its Activity against Pancreatic Cancer.

Pancreatic cancer is one of the hardest-to-treat types of neoplastic diseases. Metformin, a widely prescribed drug against type 2 diabetes mellitus, is being trialed as an agent against pancreatic cancer, although its efficacy is low. With the idea of delivering metformin to its molecular target, the mitochondrial complex I (CI), we tagged the agent with the mitochondrial vector, triphenylphosphonium group.

The Assembly Factor SDHAF2 Is Dispensable for Flavination of the Catalytic Subunit of Mitochondrial Complex II in Breast Cancer Cells.

Mitochondrial complex II or succinate dehydrogenase (SDH) is at the crossroads of oxidative phosphorylation and the tricarboxylic acid cycle. It has been shown that Sdh5 (SDHAF2/SDH5 in mammals) is required for flavination of the subunit Sdh1 (SDHA in human cells) in yeast. Here we demonstrate that in human breast cancer cells, SDHAF2/SDH5 is dispensable for SDHA flavination.

Selective Disruption of Respiratory Supercomplexes as a New Strategy to Suppress Her2 Breast Cancer.

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 Her2 disease.

Results: We demonstrate that Her2 cells and tumors have increased assembly of respiratory supercomplexes (SCs) and increased complex I-driven respiration in vitro and in vivo.

Correction: Characterisation of Mesothelioma-Initiating Cells and Their Susceptibility to Anti-Cancer Agents.

[This corrects the article DOI: 10.1371/journal.pone.

MicroRNA-126 induces autophagy by altering cell metabolism in malignant mesothelioma.

Autophagy favors both cell survival and cancer suppression, and increasing evidence reveals that microRNAs (MIRs) regulate autophagy. Previously we reported that MIR126 is downregulated in malignant mesothelioma (MM). Therefore, we investigated the role of MIR126 in the regulation of cell metabolism and autophagy in MM models.

Mitochondria: An intriguing target for killing tumour-initiating cells.

Tumour-initiating cells (TICs) play a pivotal role in cancer initiation, metastasis and recurrence, as well as in resistance to therapy. Therefore, development of drugs targeting TICs has become a focus of contemporary research. Mitochondria have emerged as a promising target of anti-cancer therapies due to their specific role in cancer metabolism and modulation of apoptotic pathways.

Combined circulating epigenetic markers to improve mesothelin performance in the diagnosis of malignant mesothelioma.

Objectives: Malignant mesothelioma (MM) is a highly aggressive tumor with poor prognosis. A major challenge is the development and application of early and highly reliable diagnostic marker(s). Serum biomarkers, such as 'soluble mesothelin-related proteins' (SMRPs), is the most studied and frequently used in MM.

Mitochondrial DNA in Tumor Initiation, Progression, and Metastasis: Role of Horizontal mtDNA Transfer.

Mitochondrial DNA (mtDNA), encoding 13 out of more than 1,000 proteins of the mitochondrial proteome, is of paramount importance for the bioenergetic machinery of oxidative phosphorylation that is required for tumor initiation, propagation, and metastasis. In stark contrast to the widely held view that mitochondria and mtDNA are retained and propagated within somatic cells of higher organisms, recent in vitro and in vivo evidence demonstrates that mitochondria move between mammalian cells. This is particularly evident in cancer where defective mitochondrial respiration can be restored and tumor-forming ability regained by mitochondrial acquisition.

Selenium supplementation induces mitochondrial biogenesis in trophoblasts.

Introduction: Placental oxidative stress has been implicated in pregnancy complications and previous work has shown that selenium can protect trophoblast mitochondria from oxidative stress. This report examines mitochondrial function and content in trophoblasts supplemented with selenium.

Methods: Swan-71, JEG-3 and BeWo cells and placental tissue were incubated with sodium selenite or selenomethionine.

Mitochondrially targeted vitamin E succinate efficiently kills breast tumour-initiating cells in a complex II-dependent manner.

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.

Characterisation of mesothelioma-initiating cells and their susceptibility to anti-cancer agents.

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.

Evaluation of respiration of mitochondria in cancer cells exposed to mitochondria-targeted agents.

Respiration is one of the major functions of mitochondria, whereby these vital organelles use oxygen to produce energy. Many agents that may be of potential clinical relevance act by targeting mitochondria, where they may suppress mitochondrial respiration. It is therefore important to evaluate this process and understand how this is modulated by small molecules.