Cancer is a leading cause of death worldwide. In many cases, the treatment of the disease is limited due to the metastasis of cells to distant locations of the body through the blood and lymphatic drainage. Most of the anticancer therapeutic options focus mainly on the inhibition of tumor cell growth or the induction of cell death, and do not consider the molecular basis of metastasis. The aim of this work is to provide a comprehensive review focusing on cancer metastasis and the mitogen-activated protein kinase (MAPK) pathway (ERK/JNK/P38 signaling) as a crucial modulator of this process.

Sixteen adult, 4-month-old male Wistar rats were randomly assigned to the training group (n = 8) or the control group (n = 8). We elucidated the effects of 8 weeks of endurance training on coenzyme Q (Q) content and the formation of reactive oxygen species (ROS) at the tissue level and in isolated mitochondria of the rat heart, liver and brain. We demonstrated that endurance training enhanced mitochondrial biogenesis in all tested organs, while a significant increase in the Q redox state was observed in the heart and brain, indicating an elevated level of QH₂ as an antioxidant. Moreover, endurance training increased the mQH₂ antioxidant pool in the mitochondria of the heart and liver, but not in the brain. At the tissue and isolated mitochondria level, an increase in ROS formation was only observed in the heart. ROS formation observed in the mitochondria of individual rat tissues after training may be associated with changes in the activity/amount of individual components of the oxidative phosphorylation system and its molecular organization, as well as with the size of the oxidized pool of mitochondrial Q acting as an electron carrier in the respiratory chain. Our results indicate that tissue-dependent changes induced by endurance training in the cellular and mitochondrial QH₂ pool acting as an antioxidant and in the mitochondrial Q pool serving the respiratory chain may serve important roles in energy metabolism, redox homeostasis and the level of oxidative stress.

This study examined the effects of hypoxia on coenzyme Q (Q) levels and mitochondrial function in EA. hy926 endothelial cells, shedding light on their responses to changes in oxygen levels. Chronic hypoxia during endothelial cell culture reduced Q synthesis by reducing hydroxy-methylglutaryl-CoA reductase (HMGCR) levels via hypoxia-inducible factor 1α (HIF1α), leading to severe Q deficiency. In endothelial mitochondria, hypoxia led to reorganization of the respiratory chain through upregulation of supercomplexes (I+III₂+IV), forming a complete mitochondrial Q (mQ)-mediated electron transfer pathway. Mitochondria of endothelial cells cultured under hypoxic conditions showed reduced respiratory rates and membrane potential, as well as increased production of mitochondrial reactive oxygen species (mROS) as a result of increased mQ reduction levels (mQH₂/mQtot). Anoxia/reoxygenation (A/R) in vitro caused impairment of endothelial mitochondria, manifested by reduced maximal respiration, complex III activity, membrane potential, coupling parameters, and increased mQ reduction and mROS production. Weaker A/R-induced changes compared to control mitochondria indicated better tolerance of A/R stress by the mitochondria of hypoxic cells. Moreover, in endothelial mitochondria, hypoxia-induced increases in uncoupling protein 3 (UCP3) and mitochondrial large-conductance Ca²⁺-activated potassium channel (mitoBK_Ca) levels and activities appear to have alleviated reoxygenation injury after A/R. These results not only highlight hypoxia-induced changes in mQ redox homeostasis and related mitochondrial function, but also indicate that chronic hypoxia during endothelial cell culture leads to mitochondrial adaptations that help mitochondria better withstand subsequent oxygen fluctuations.

Little is known about the effects of statins, which are cholesterol-lowering drugs, on the bioenergetic functions of mitochondria in the brain. This study aimed to elucidate the direct effects of atorvastatin and simvastatin on the bioenergetics of isolated rat brain mitochondria by measuring the statin-induced changes in respiratory chain activity, ATP synthesis efficiency, and the production of reactive oxygen species (ROS). Our results in isolated brain mitochondria are the first to demonstrate that atorvastatin and simvastatin dose-dependently significantly inhibit the activity of the mitochondrial respiratory chain, resulting in a decreased respiratory rate, a decreased membrane potential, and increased ROS formation. Moreover, the tested statins reduced mitochondrial coupling parameters, the ADP/O ratio, the respiratory control ratio, and thus, the oxidative phosphorylation efficiency in brain mitochondria. Among the oxidative phosphorylation complexes, statin-induced mitochondrial impairment concerned complex I, complex III, and ATP synthase activity. The calcium-containing atorvastatin had a significantly more substantial effect on isolated brain mitochondria than simvastatin. The higher inhibitory effect of atorvastatin was dependent on calcium ions, which may lead to the disruption of calcium homeostasis in mitochondria. These findings suggest that while statins are effective in their primary role as cholesterol-lowering agents, their use may impair mitochondrial function, which may have consequences for brain health, particularly when mitochondrial energy efficiency is critical.

Nitrogen-containing bisphosphonates (N-BPs) are commonly used drugs in the treatment of bone diseases due to their potent inhibition of the mevalonate pathway, leading to disrupted protein prenylation and reduced osteoclast activity. Although N-BPs are effective in reducing bone resorption, increasing evidence indicates their side effects on various non-skeletal cells. The aim of this review is to synthesize the current knowledge on the cellular and molecular effects of N-BPs outside the skeletal system, with particular emphasis on their impact on mitochondrial function and energy metabolism. At the cellular level, N-BPs may reduce viability, modulate inflammatory responses, trigger apoptosis, disrupt cytoskeletal organization, and influence signaling and energy metabolism. N-BPs may also impair the prenylation of proteins essential for mitochondrial dynamics and quality control, and may disrupt Ca²⁺ homeostasis. As we have shown in endothelial cells, by inhibiting the mevalonate pathway, N-BPs may lead to a reduction in key components of the mitochondrial respiratory chain, such as coenzyme Q (CoQ) and a-heme. These effects can contribute to impaired mitochondrial respiratory function, increased oxidative stress, and mitochondria-dependent apoptosis, affecting cellular energy metabolism and viability. These findings underscore the multifaceted impact of N-BPs beyond bone, emphasizing the importance of mitochondrial health and energy metabolism in understanding their broader biological effects and potential adverse outcomes.

Statins are commonly used cholesterol-lowering drugs, but their effects on astrocyte oxidative metabolism are poorly understood. To investigate this, rat astrocytes were exposed to 200 nM atorvastatin or simvastatin for 6 days and then assessed for changes in coenzyme Q (CoQ) homeostasis, mitochondrial function, and energy metabolism. Both statins comparably decreased cellular CoQ9 and CoQ10 levels (~35%), with greater losses of their reduced antioxidant forms (60–75%). Lower intracellular and mitochondrial levels of reactive oxygen species (ROS) were accompanied by the upregulation of nuclear factor erythroid 2-related factor 2 (NRF2)-dependent antioxidant pathways (superoxide dismutase 1 and glutathione reductase) and metabolic stress response factors, including hypoxia-inducible factor 1-alpha (HIF1α) and brain-derived neurotrophic factor (BDNF). Both statins promoted glycolytic reprogramming, mitochondrial fission, and biogenesis while impairing oxidative phosphorylation, as evidenced by reduced ATP-linked respiration, increased proton leak, and lower ATP levels. These findings suggest that statin-treated astrocytes adapt by prioritizing redox homeostasis over ATP production. CoQ10 supplementation increased cellular CoQ10 levels and restored ATP levels without further decreasing ROS, suggesting that its primary benefit is bioenergetic support, not additional antioxidant protection. Overall, statin-induced CoQ deficiency induces adaptive metabolic remodeling of astrocytes, while CoQ10 supplementation may help maintain energy metabolism under these conditions.