Exogenous Coenzyme Q10 Research Articles

Clinical Features, Biochemistry, Imaging, and Treatment Response in a Single-Center Cohort With Coenzyme Q 10 Biosynthesis Disorders

Clinical Features, Biochemistry, Imaging, and Treatment Response in a Single-Center Cohort With Coenzyme Q ₁₀ Biosynthesis Disorders

Coenzyme Q10 and embryonic development: a potential role in reproductive medicine

Maternal mitochondria provide energy to the embryo through oxidative phosphorylation before blastocyst implantation, where intracellular energy is mainly supplied by glycolysis. Thus, it is obvious that mitochondria play a crucial role in providing energy for embryogenesis. Coenzyme Q10 (CoQ10) is a powerful endogenous membrane-localized antioxidant that protects circulating lipoproteins from lipid peroxidation. The results of several recent clinical studies have shown that exogenous CoQ10 supplements exert antioxidant effects and may be a potential therapy to reduce oxidative stress. CoQ10 deficiency increases the risk of impaired embryonic development; however, this relationship remains unclear. Given that CoQ10 level is influenced by enzymes involved in its synthesis, it is difficult to say whether the disorders are caused by CoQ10 deficiency or directly result from defects in the target gene. It has been shown that in the absence of CoQ10, ATP synthesis decreases in parallel with increased oxidative stress in mitochondria, two biological events which affect embryonic development. The review highlights the importance of CoQ10 as an antioxidant for improving egg quality, and also emphasizes its key role in embryonic development. It is necessary to conduct further studies aimed at studying metabolic changes during embryogenesis, as well as the mechanism of CoQ10 effects.

Coenzyme Q4 is a functional substitute for coenzyme Q10 and can be targeted to the mitochondria

Coenzyme Q10 (CoQ10) is an important cofactor and antioxidant for numerous cellular processes, and its deficiency has been linked to human disorders including mitochondrial disease, heart failure, Parkinson's disease, and hypertension. Unfortunately, treatment with exogenous CoQ10 is often ineffective, likely due to its extreme hydrophobicity and high molecular weight. Here, we show that less hydrophobic CoQ species with shorter isoprenoid tails can serve as viable substitutes for CoQ10 in human cells. We demonstrate that CoQ4 can perform multiple functions of CoQ10 in CoQ-deficient cells at markedly lower treatment concentrations, motivating further investigation of CoQ4 as a supplement for CoQ10 deficiencies. In addition, we describe the synthesis and evaluation of an initial set of compounds designed to target CoQ4 selectively to mitochondria using triphenylphosphonium. Our results indicate that select versions of these compounds can successfully be delivered to mitochondria in a cell model and be cleaved to produce CoQ4, laying the groundwork for further development.

Mutations of GEMIN5 are associated with coenzyme Q10 deficiency: long-term follow-up after treatment.

GEMIN5 exerts key biological functions regulating pre-mRNAs intron removal to generate mature mRNAs. A series of patients were reported harboring mutations in GEMIN5. No treatments are currently available for this disease. We treated two of these patients with oral Coenzyme Q10 (CoQ10), which resulted in neurological improvements, although MRI abnormalities remained. Whole Exome Sequencing demonstrated compound heterozygosity at the GEMIN5 gene in both cases: Case one: p.Lys742* and p.Arg1016Cys; Case two: p.Arg1016Cys and p.Ser411Hisfs*6. Functional studies in fibroblasts revealed a decrease in CoQ10 biosynthesis compared to controls. Supplementation with exogenous CoQ10 restored it to control intracellular CoQ10 levels. Mitochondrial function was compromised, as indicated by the decrease in oxygen consumption, restored by CoQ10 supplementation. Transcriptomic analysis of GEMIN5 patients compared with controls showed general repression of genes involved in CoQ10 biosynthesis. In the rigor mortis defective flies, CoQ10 levels were decreased, and CoQ10 supplementation led to an improvement in the adult climbing assay performance, a reduction in the number of motionless flies, and partial restoration of survival. Overall, we report the association between GEMIN5 dysfunction and CoQ10 deficiency for the first time. This association opens the possibility of oral CoQ10 therapy, which is safe and has no observed side effects after long-term therapy.

The Spectrum of clinical manifestations in newborns with the COQ4 mutation: case series and literature review.

Coenzyme Q10 (CoQ10) plays an important role in the electron transport chain within the human mitochondrial respiratory chain. The manifestations of this deficiency exhibit a diverse range. This study investigates the clinical manifestations of primary coenzyme Q10 deficiency in neonates with the COQ4 mutation to improve the diagnosis of the disease and the prognosis through targeted treatment. We report 4 patients with primary coenzyme Q10 deficiency by COQ4 variants in neonates. A comprehensive literature search and review for original articles and case reports with COQ4 mutation published from January 1989 to November 2023 was performed through Pubmed. We review clinical manifestations, diagnostic approaches, and treatment monitoring in these and 20 previously reported patients. Within the cohort of four cases examined, three females and one male were identified from two distinct families. Specifically, case 1 and 2 consisted of monoamniotic twins. Cases 3 and 4 were siblings. A comprehensive review of 20 cases involving neonatal-onset COQ4 mutation was conducted. Half of the cases are Chinese. There was no statistically significant difference in the mortality between Chinese (9/12, 75%) and other regions (11/12, 91.7%) (P = 0.27). The survival time for the 24 cases was 60.0 ± 98.0 days (95% confidence interval CI: 0-252.0 days). The incidence of prenatal abnormalities in preterm infants was significantly higher than that in full-term infants (66.7% vs. 16.7%, P = 0.02). Hyperlactatemia was one of the most common manifestations, accounting for 75% of cases (18/24). Twenty of the 24 cases were diagnosed by whole exome sequencing. Only 9 patients received exogenous coenzyme Q10 treatment, and all the 4 surviving patients received coenzyme Q10 supplementation. The prognosis of COQ4 mutation in the neonatal period indicates a low survival rate and an poor prognosis. This may be due to the incomplete understanding of the mechanism of how COQ4 gene defects lead to coenzyme Q10 deficiency and why CoQ10 supplementation does not respond well to treatment. To improve the diagnostic rate, in addition to genetic testing, mitochondrial functional verification should be prioritized in southern China, where the incidence is relatively high. It will facilitate more in-depth mechanistic studies.

Improving the Bioavailability and Efficacy of Coenzyme Q10 on Alzheimer's Disease Through the Arginine Based Proniosomes

Coenzyme Q10 (CoQ10) is a fat-soluble vitamin-with a benzoquinone-like structure. CoQ10 plays a role in membrane stability, energy conversion, and ATP production. It is also one of the important antioxidants in the body. The bioavailability of exogenous CoQ10 is extremely low due to its poor aqueous solubility and large molecular mass.In this study, mixed proniosomal drug delivery systems have been used to increase solubility and bioavailability of CoQ10. Arginine (semi-essential amino acid) was incorporated in the formulation composition to achieve higher efficacy by boosting nitric oxide presence, endothelial dysfunction, and cellular uptake.Proniosomes were investigated in terms of particle size, polydispersity index, zeta potential, encapsulation efficiency, and process yield, and optimization studies were carried on by utilizing STATISTICA 8.0 software considering dependent factors (carrier amount, drug amount, and surfactant ratio). Optimum proniosome formulation (particle size 187.5 ± 16.35 nm, zeta potential: -44.7 ± 12.8 mV, encapsulation efficiency 99.05±0.30%, and product yield: 90.55%) was evaluated for thermal analysis, in-vitro drug release using microcentrifuge method. In-vitro cytotoxicity studies of proniosomes were performed on intestinal Epithelial Cells (Cellartis®, ChiPSC18) and no cytotoxic effects was seen during the 72 h. Besides, anti Alzheimer effect was investigated on APPSL-GFP lentivirus-infected human neural cells (APPSL-GFP-l-HNC) and Alzheimer biomarkers (p-tau181 and p-tau217).While CoQ10’s relative bioavailability was statistically increased by proniosome compared to CoQ10 suspension (p<0.01, Grubb test). PK parameters of proniosome formulation, obtained with non-compartmental modeling, were fitting to the data (R2=0.956±0.026).The study results proved that proniosomal formulation has a high potential drug delivery system for both increasing bioavailability and anti-Alzheimer effect of CoQ10.

Modulatory effect of exogenous Coenzyme Q10 on redox and inflammatory biomarkers during aging in rats.

An impaired redox homeostasis is an important hallmark of biological aging. Coenzyme Q10 is an endogenous lipophilic antioxidant that decreases with age and has been linked to oxidative stress. The purpose of this study was to evaluate the effect of CoQ10 supplementation on redox homeostasis and levels of inflammatory cytokines in young and old rats. Male Wistar rats (young and old) were randomly divided into four groups (n = 6). Group I: young control, Group II: young rats treated with CoQ10, Group III: old control, Group IV: old rats treated with CoQ10. CoQ10 (20mg/kg) was administered daily to Group II and IV via oral gavage. After 28days of treatment, rats were sacrificed and biomarkers of oxidative stress and inflammatory cytokines were evaluated. Results demonstrated a significant (p ≤ 0.05) increase in malondialdehyde, protein carbonyl oxidation, advanced oxidation protein products, inflammatory cytokines: CRP, IL-6, TNF-α, and a decline in levels of superoxide dismutase, catalase, reduced glutathione, ferric reducing antioxidant potential in plasma and plasma membrane redox system in old rats when compared to young rats. After treatment with CoQ10 significant decrease in the level of MDA, PCO, AOPP, CRP, IL-6, and TNF-α was observed. Also, significant up-regulation of SOD, CAT, GSH, FRAP, and PMRS was observed. The results show that supplementing rats with CoQ10 aids in the maintenance of redox equilibrium with replenishment of antioxidant reserves and down-regulation of inflammatory biomarkers. Thus CoQ10 supplementation could be a potential anti-aging therapy.

Assessing Cellular Uptake of Exogenous Coenzyme Q10 into Human Skin Cells by X-ray Fluorescence Imaging.

X-ray fluorescence (XRF) imaging is a highly sensitive non-invasive imaging method for detection of small element quantities in objects, from human-sized scales down to single-cell organelles, using various X-ray beam sizes. Our aim was to investigate the cellular uptake and distribution of Q10, a highly conserved coenzyme with antioxidant and bioenergetic properties. Q10 was labeled with iodine (I2-Q10) and individual primary human skin cells were scanned with nano-focused beams. Distribution of I2-Q10 molecules taken up inside the screened individual skin cells was measured, with a clear correlation between individual Q10 uptake and cell size. Experiments revealed that labeling Q10 with iodine causes no artificial side effects as a result of the labeling procedure itself, and thus is a perfect means of investigating bioavailability and distribution of Q10 in cells. In summary, individual cellular Q10 uptake was demonstrated by XRF, opening the path towards Q10 multi-scale tracking for biodistribution studies.

Using a neonatal rat model to explore the therapeutic potential of coenzyme Q10 in prematurity under hyperoxia.

Hyperoxia, is often used in preterm supportive care, leading to high oxygen exposure in neonates. Coenzyme Q10 (CoQ10) is a free radical scavenger that has been studied in older children but never be investigated for its role in preterm care. We hypothesize that the administration of exogenous CoQ10 would raise serum concentrations of CoQ10 and mitigate the adverse effects of hyperoxia on the organs by reducing oxygen-free radicals and inflammation. The aim of this study was to evaluate the effects of oxidative stress, inflammatory response, and survival in neonatal rats after CoQ10 treatment. Neonatal rats delivered from four pregnant Wistar rats were randomly divided into four groups: (a) control, (b) CoQ10, (c) hyperoxia (O2 group), and (d) treatment (CoQ10 + O2 ) groups. The dose of CoQ10 injected was 30 mg/kg. The CoQ9, CoQ10, cytokines, oxidative stress, and antioxidant enzyme activity were measured. Tissue samples were histologically examined and mortality was monitored for 16 days. The level of CoQ9 significantly increased in the liver, kidney, and plasma, while the level of CoQ10 significantly increased in most organ tissues in the CoQ10 + O2 group. Additionally, CoQ10 decrease oxidative stress in the liver, increase antioxidant enzyme activity in the heart, kidney, and brain, and reverse an inclined level of hematopoietic growth factors. However, CoQ10 had no effect on inflammation, organ damage, or mortality. Therefore, the use of CoQ10 in potential adjuvant therapy for neonatal hyperoxia requires further research.

Coenzyme Q10 in Male Infertility

Currently the male factor is frequently encountered in the infertility problem. Basically, the factors that cause sperm dysfunction and male infertility are environmental, physiological and genetic. Excessive amount of reactive oxygen species and other oxidant radicals have been associated with male infertility. In addition, although semen analysis parameters appear normal in idiopathic male infertility, it is suggested that the possible cause of infertility is oxidative stress. Antioxidants in foods that are protective against oxidative stress increase the success of assisted reproductive techniques by protecting spermatozoa from free oxygen radicals, preventing DNA breaks caused by free oxygen radicals, and supporting the sperm maturation process. Coenzyme Q10 (CoQ10), which is found in every cell and has the ability to dissolve in oil, is a vitamin-like compound that acts as a coenzyme in key enzymatic reactions in energy production in the cell. Endogenous CoQ10, is significantly associated with sperm count and motility and is shown as one of the most important antioxidants in seminal plasma. Exogenous CoQ10 administration can be explained by its positive effects on sperm motility, its effectiveness in mitochondria and its antioxidant effects. In this review, articles investigating the effect of oxidative stress on infertility and the role of CoQ10, a natural antioxidant vitamin in the treatment of infertility, were presented. As a result, the positive effects of using CoQ10 as a supportive treatment in male infertility have been shown in studies. However, more comprehensive, long-term and pregnancy-related studies are needed.

CoQ10 Deficient Endothelial Cell Culture Model for the Investigation of CoQ10 Blood-Brain Barrier Transport.

Primary coenzyme Q10 (CoQ10) deficiency is unique among mitochondrial respiratory chain disorders in that it is potentially treatable if high-dose CoQ10 supplements are given in the early stages of the disease. While supplements improve peripheral abnormalities, neurological symptoms are only partially or temporarily ameliorated. The reasons for this refractory response to CoQ10 supplementation are unclear, however, a contributory factor may be the poor transfer of CoQ10 across the blood–brain barrier (BBB). The aim of this study was to investigate mechanisms of CoQ10 transport across the BBB, using normal and pathophysiological (CoQ10 deficient) cell culture models. The study identifies lipoprotein-associated CoQ10 transcytosis in both directions across the in vitro BBB. Uptake via SR-B1 (Scavenger Receptor) and RAGE (Receptor for Advanced Glycation Endproducts), is matched by efflux via LDLR (Low Density Lipoprotein Receptor) transporters, resulting in no “net” transport across the BBB. In the CoQ10 deficient model, BBB tight junctions were disrupted and CoQ10 “net” transport to the brain side increased. The addition of anti-oxidants did not improve CoQ10 uptake to the brain side. This study is the first to generate in vitro BBB endothelial cell models of CoQ10 deficiency, and the first to identify lipoprotein-associated uptake and efflux mechanisms regulating CoQ10 distribution across the BBB. The results imply that the uptake of exogenous CoQ10 into the brain might be improved by the administration of LDLR inhibitors, or by interventions to stimulate luminal activity of SR-B1 transporters.

Bioavailability of Coenzyme Q10: An Overview of the Absorption Process and Subsequent Metabolism

A lack of understanding of the processes determining the absorption and subsequent metabolism of coenzyme Q10 (CoQ10) has resulted in some manufacturers’ making incorrect claims regarding the bioavailability of their CoQ10 supplements, with potential consequences for the use of such products in clinical trials. The purpose of the present review article is, therefore, to describe the various stages of exogenous CoQ10 metabolism, from its first ingestion, stomach transit, absorption from the small intestine into the lymphatic system, transport in blood, and access into cells. In particular, the importance of CoQ10 crystal dispersion in the initial formulation is emphasised, the absence of which reduces bioavailability by 75%. In addition, evidence comparing the relative bioavailability and efficacy of ubiquinone and ubiquinol forms of CoQ10 has been reviewed.

Coenzyme Q10: Clinical Applications in Cardiovascular Diseases

Coenzyme Q10 (CoQ10) is a ubiquitous factor present in cell membranes and mitochondria, both in its reduced (ubiquinol) and oxidized (ubiquinone) forms. Its levels are high in organs with high metabolism such as the heart, kidneys, and liver because it acts as an energy transfer molecule but could be reduced by aging, genetic factors, drugs (e.g., statins), cardiovascular (CV) diseases, degenerative muscle disorders, and neurodegenerative diseases. As CoQ10 is endowed with significant antioxidant and anti-inflammatory features, useful to prevent free radical-induced damage and inflammatory signaling pathway activation, its depletion results in exacerbation of inflammatory processes. Therefore, exogenous CoQ10 supplementation might be useful as an adjuvant in the treatment of cardiovascular diseases such as heart failure, atrial fibrillation, and myocardial infarction and in associated risk factors such as hypertension, insulin resistance, dyslipidemias, and obesity. This review aims to summarize the current evidences on the use of CoQ10 supplementation as a therapeutic approach in cardiovascular diseases through the analysis of its clinical impact on patients’ health and quality of life. A substantial reduction of inflammatory and oxidative stress markers has been observed in several randomized clinical trials (RCTs) focused on several of the abovementioned diseases, even if more RCTs, involving a larger number of patients, will be necessary to strengthen these interesting findings.

Supplementation with exogenous coenzyme Q10 to media for in vitro maturation and embryo culture fails to promote the developmental competence of porcine embryos.

The coenzyme Q10 (CoQ10) is a potent antioxidant with critical protection role against cell oxidative stress, caused by the mitochondrial dysfunction. This study evaluated the effects of CoQ10 supplementation to in vitro maturation (IVM) or embryo culture media on the maturation, fertilization and subsequent embryonic development of pig oocytes and embryos. Maturation (Experiment 1) or embryo culture (Experiment 2) media were supplemented with 0 (control), 10, 25, 50 and 100μM CoQ10. The addition of 10-50μM CoQ10 to the IVM medium did not affect the percentage of MII oocytes nor the fertilization or the parameters of subsequent embryonic development. Exogenous CoQ10 in the culture medium neither did affect the development to the 2-4-cell stage nor rates of blastocyst formation. Moreover, the highest concentration of CoQ10 (100μM) in the maturation medium negatively affected blastocyst rates. In conclusion, exogenous CoQ10 supplementation of maturation or embryo culture media failed to improve the outcomes of our in vitro embryo production system and its use as an exogenous antioxidant should not be encouraged.

Extracellular coenzyme Q10 (CoQ10) is reduced to ubiquinol-10 by intact Hep G2 cells independent of intracellular CoQ10 reduction

Coenzyme Q10 (CoQ10) is an essential factor in the mitochondrial respiratory chain and is closely associated with ATP production in humans. It is known that orally administered CoQ10 in humans is rapidly reduced, and most is detected as a reduced form, ubiquinol-10 (CoQ10H2), in serum. However, the mechanism of exogenous CoQ10 reduction in vivo is unclear. Therefore, in order to clarify how CoQ10 is reduced to CoQ10H2, we conducted a study using human liver cancer cell line Hep G2 cells, which show strong intracellular CoQ10-reducing activity. When intact cells were incubated with CoQ10, the exogenously added CoQ10 was incorporated into the cells, time-, concentration-, and temperature-dependently, and 50–80% of that was detected as CoQ10H2. On the other hand, a part of the extracellular CoQ10 was also detected as CoQ10H2, and the amount was greater than that of the intracellular CoQ10H2. Furthermore, the CoQ10-loaded cells did not leak the intracellular CoQ10H2 (or CoQ10) to the outside of the cells, and modulation of the extracellular CoQ10H2 amount had little effect on the intracellular CoQ10 or CoQ10H2 contents, suggesting the existence of an individual mechanism of CoQ10 reduction inside and outside the cells. Moreover, intact cells could reduce CoQ10 in low-density lipoprotein to CoQ10H2. Therefore, we concluded that a novel CoQ10-reducing mechanism may exist in the plasma membrane, probably the outer surface, of Hep G2 cells, and it may work to reduce extracellular CoQ10 and/or maintain extracellular CoQ10H2.

Long-term follow-up results of patients with ADCK4 mutations who have been diagnosed in the asymptomatic period: effects of early initiation of CoQ10 supplementation.

Atmaca M, Gülhan B, Atayar E, Karabay Bayazıt A, Candan C, Arıcı M, Topaloğlu R, Özaltın F. Long-term follow-up results of patients with ADCK4 mutations who have been diagnosed in the asymptomatic period: effects of early initiation of CoQ10 supplementation. Turk J Pediatr 2019; 61: 657-663. ADCK4-related glomerulopathy is a recently recognized clinical entity associated with insidious onset in young children and a high potential to progress to chronic kidney disease in adolescents. Early initiation of exogenous coenzyme Q10 (CoQ10) supplementation in the asymptomatic period could be protective on renal functions. In the present study, we aimed to investigate long-term follow-up of patients that we have diagnosed during the asymptomatic period and in whom we started CoQ10 treatment. We analyzed long-term effects of CoQ10 on proteinuria and estimated glomerular filtration rate (eGFR) in this patient population. A total of 8 patients (4 female, 4 male) from 6 different families were included. The mean age at diagnosis and at last visit were 16.8±11.2 years and 20.7±11.7 years, respectively. None of the patients had extrarenal system involvement. At the time of initiation of treatment; median eGFR was 107.8 ml/min/1.73 m2, median proteinuria was 1008 mg/m2/day. After a median follow-up period of 25.3±5.8 months, median proteinuria decreased to 318.5 mg/m2/day (p=0.03) and median eGFR remained stable at 99.6 ml/min/1.73 m2 (p=0.21). Coenzyme Q10 treatment is effective for reducing proteinuria and seems to be renoprotective.

Beneficial effect of coenzyme Q10 injection on nitric oxide -related dilation of the rat aorta

This study examined whether coenzyme Q10 can improve nitric oxide (NO)-dependent vasodilatation in the rat aorta after pre-incubation or intravenous administration. In initial experiments, intact isolated aortic rings were incubated with coenzyme Q10 or L-arginine. In further experiments, coenzyme Q10 was administered intravenously in anesthetized rats, then in 2h aorta was isolated. In both cases, after preliminary preparation the isolated aortic rings were tested for acetylcholine-induced NO-dependent relaxation. Acetylcholine elicited concentration-dependent relaxation of phenylephine precontracted aortic rings. Relaxant responses to acetylcholine were markedly potentiated after pre-incubation with coenzyme Q10 or L-arginine. The maximum relaxant responses (%) were significantly increased from 64.1±5.3 (control) to 89.8±3.0 and 83.6±3.0 (coenzyme Q10 and L-arginine, respectively). pD2 (-lgEC50) value in control study was 5.81±0.28, after pretreatment with coenzyme Q10 or L-arginine were 7.59±0.16 and 7.26±0.32, respectively. There was no difference between coenzyme Q10 and L-arginine groups. After intravenous administration, the relaxant responses to acetylcholine were significantly increased in coenzyme Q10-treated group (94.2±2.0) compared with controls (68.1±4.4). pD2 values were also different between control and treatment groups (5.79±0.29 vs. 8.14±0.65, respectively).Thus, coenzyme Q10 improved NO-mediated vasodilation in rat aorta in magnitude close to the effects of L-arginine - substrate for eNOS. Our data first show that exogenous coenzyme Q10 through intravenous administration is able to improve rapidly NO-dependent vasodilation in rat aorta, likely due to accumulation of coenzyme Q10 in the vessel wall. Improvement of endothelial function can contribute, at least in part, to beneficial effects of coenzyme Q10 in cardiovascular diseases associated with endothelial dysfunction.

Effect of Coenzyme Q10 Supplementation on Markers of Oxidative Stress in Streptozotocin Induced Diabetic Rats

Suppressive effect of Ginkgo biloba extract (EGb 761) on topsin induced ovarian toxicity and oxidative stress in albino ratsSaber A. Sakr,Hoda A. Mahran, Asmaa M. Abdel-Maksoud

Coenzyme Q10supplementation in infertile men with low-grade varicocele: an open, uncontrolled pilot study

Many conditions associated with male infertility are inducers of oxidative stress, including varicocele. Antioxidants, such as coenzyme Q10, may be useful in this case. To evaluate the antioxidant capacity of seminal plasma of infertile men with varicocele before and after an oral supplementation with coenzyme Q10 , 38 patients were recruited from a pilot clinical trial. A standard semen analysis was also performed at baseline and 3 months after an oral supplementation with exogenous coenzyme Q10 100 mg per die. Seminal plasma antioxidant capacity was measured using a spectroscopic method. Coenzyme Q10 therapy improved semen parameters and antioxidant status. This study highlights the importance of oxidative stress in the pathogenesis of male infertility, namely in varicocele, and strengthens the possibility of the usefulness of the antioxidant therapy.

Lack of Effect of Coenzyme Q10 on Doxorubicin Cytotoxicity in Breast Cancer Cell Cultures

BACKGROUND/HYPOTHESES: Doxorubicin is a standard adjuvant therapy for early-stage breast cancer, and it significantly improves disease-free and overall survival. However, 3% to 20% of breast cancer patients develop chronic cardiomyopathic changes and congestive heart failure because of doxorubicin therapy. Doxorubicin-induced cardiotoxicity is thought to be due to the increased generation of reactive oxygen species within cardiac myocyte mitochondria. Coenzyme Q10 (CoQ10) is a lipid-soluble antioxidant that may protect against mitochondrial reactive oxygen species and thus prevent doxorubicin-induced cardiotoxicity. Despite the potential benefits of CoQ10 in preventing cardiotoxicity, it is not known if CoQ10 diminishes the antineoplastic effects of doxorubicin therapy. In vitro cell culture experiments. Breast cancer cell lines (MDA-MB-468 and BT549) were tested for their ability to uptake exogenous CoQ10 using high-performance liquid chromatography. Breast cancer cell lines were then treated with doxorubicin and a range of CoQ10 concentrations to determine the effect of CoQ10 on doxorubicin's cytotoxicity. This study demonstrated that intracellular and mitochondrial CoQ10 concentrations increased substantially as higher exogenous concentrations were administered to breast cancer cells. CoQ10 had no effect on the ability of doxorubicin to induce apoptosis or inhibit growth or colony formation in both the cell lines tested when applied over a wide dose range, which encompassed typical basal plasma levels and plasma levels above those typically achieved by supplemented patients. The clinical testing of CoQ10 as a supplement to prevent doxorubicin-induced cardiotoxicity requires confidence that it does not decrease the efficacy of chemotherapy. These results support the hypothesis that CoQ10 does not alter the antineoplastic properties of doxorubicin. Further in vivo studies, as well as combination chemotherapy studies, would be reassuring before a large-scale clinical testing of CoQ10 as a cardioprotective drug.