The mitochondrial DNA copy number (mtDNAcn) plays a vital role in cellular energy metabolism and mitochondrial health. As mitochondria are responsible for adenosine triphosphate production through oxidative phosphorylation, maintaining an appropriate mtDNAcn level is vital for the overall cellular function. Alterations in mtDNAcn have been linked to various diseases, including neurodegenerative disorders, metabolic conditions, and cancers, making it an important biomarker for understanding the disease pathogenesis. The accurate estimation of mtDNAcn is essential for clinical applications. Quantitative polymerase chain reaction and next-generation sequencing are commonly employed techniques with distinct advantages and limitations. Clinically, mtDNAcn serves as a valuable indicator for early diagnosis, disease progression, and treatment response. For instance, in oncology, elevated mtDNAcn levels in blood samples are associated with tumor aggressiveness and can aid in monitoring treatment efficacy. In neurodegenerative diseases such as Alzheimer’s and Parkinson’s, altered mtDNAcn patterns provide insights into disease mechanisms and progression. Understanding and estimating mtDNAcn are critical for advancing diagnostic and therapeutic strategies in various medical fields. As research continues to uncover the implications of mtDNAcn alterations, its potential as a clinical biomarker is likely to expand, thereby enhancing our ability to diagnose and manage complex diseases.

• Mitochondrial DNA copy number
• Mitochondrial DNA
• Quantitative polymerase chain reaction
• Cancer
• Neurodegenerative disease
• Aging

• Aging
• Biomarkers
• Cancer
• Venous thromboembolism
• mtDNA copy number

• Humans
• Venous Thromboembolism/genetics
• Venous Thromboembolism/etiology
• Female
• Male
• DNA, Mitochondrial/genetics
• Middle Aged
• Neoplasms/genetics
• Neoplasms/complications
• Aged
• DNA Copy Number Variations
• Case-Control Studies
• Prospective Studies
• Risk Factors

• Cell proliferation
• Colon cancer
• Cyclin-dependent kinase inhibitor 1A (CDKN1A/p21)
• Mitochondria
• Mitochondrial DNA (mtDNA)
• Senescence
• Transcription factor A mitochondrial (TFAM)

• Universitätsmedizin der Johannes Gutenberg-Universität Mainz (8974)

• drug resistance
• mitochondria
• neoplasm
• oxidation-reduction

• Humans
• Mitochondria
• Neoplasms/drug therapy
• Neoplasms/metabolism
• Oxidation-Reduction

• 8-oxo-7,8-dihydro-2′-deoxyguanosine
• 8-oxodGuo
• Alu element
• Immunoprecipitation
• MT-ND5
• Oxidized DNA
• Plasma
• Quantitative polymerase chain reaction

• Humans
• 8-Hydroxy-2'-Deoxyguanosine
• Deoxyguanosine
• DNA, Mitochondrial/genetics
• Oxidation-Reduction
• Aortic Aneurysm, Abdominal/genetics

• DOC 59 Austrian Science Fund FWF

• ALU repeats
• Colorectal cancer
• biomarkers
• fcDNA
• prognosis

• Inflammation
• Metabolic syndrome
• MitoQ
• Mitochondrial DNA
• Toll-like receptor 9

• Rats
• Animals
• DNA, Mitochondrial/genetics
• DNA, Mitochondrial/metabolism
• Antioxidants/pharmacology
• Antioxidants/therapeutic use
• Metabolic Syndrome/drug therapy
• Metabolic Syndrome/metabolism
• NF-kappa B/metabolism
• Toll-Like Receptor 9/metabolism
• Cell-Free Nucleic Acids
• Hydrogen Peroxide
• Rats, Sprague-Dawley
• Inflammation/drug therapy
• Inflammation/metabolism
• Ubiquinone/pharmacology
• Ubiquinone/therapeutic use

• TFAM
• circ_0002476
• miR-1182
• non-small cell lung cancer

Mitochondria are the critical organelles involved in various cellular functions. Mitochondrial biogenesis is activated by multiple cellular mechanisms which require a synchronous regulation between mitochondrial DNA (mtDNA) and nuclear DNA (nDNA). The mitochondrial DNA copy number (mtDNA-CN) is a proxy indicator for mitochondrial activity, and its alteration reflects mitochondrial biogenesis and function. Despite the precise mechanisms that modulate the amount and composition of mtDNA, which have not been fully elucidated, mtDNA-CN is known to influence numerous cellular pathways that are associated with cancer and as well as multiple other diseases. In addition, the utility of current technology in measuring mtDNA-CN contributes to its extensive assessment of diverse traits and tumorigenesis. The present review provides an overview of mtDNA-CN variations across human cancers and an extensive summary of the existing knowledge on the regulation and machinery of mtDNA-CN. The current information on the advanced methods used for mtDNA-CN assessment is also presented.

• biomarker
• cancer
• mitochondrial DNA
• mtDNA copy number alterations
• mtDNA replication

Pancreatic ductal adenocarcinoma (PDAC) is associated with poor prognosis because it is often detected at an advanced stage, and drug resistance interferes with treatment. However, the mechanism underlying drug resistance in PDAC remains unclear. Here, we investigated metabolic changes between a parental PDAC cell line and a gemcitabine (GEM)-resistant PDAC cell line. We established a GEM-resistant cell line, MIA-G, from MIA-PaCa-2 parental (MIA-P) cells using continuous therapeutic-dose GEM treatment. MIA-G cells were also more resistant to 5-fluorouracil in comparison to MIA-P cells. Metabolic flux analysis showed a higher oxygen consumption rate (OCR) in MIA-G cells than in MIA-P cells. Notably, OCR was suppressed by GEM treatment only in MIA-G cells. GEM treatment increased mitochondrial membrane potential and mitochondrial reactive oxygen species (ROS) in MIA-P cells, but not in MIA-G cells. Glutamine uptake and peroxidase levels were elevated in MIA-G cells. The antioxidants N-acetyl-L-cysteine and vitamin C increased the sensitivity to GEM in both cell lines. In MIA-G cells, the expression of the mitochondrial transcription factor A also decreased. Furthermore, rotenone reduced the sensitivity of MIA-P cells to GEM. These findings suggest that the suppression of oxidative phosphorylation contributes to GEM resistance by reducing ROS production. Our study provides a new approach for reducing GEM resistance in PDAC.

• ROS
• drug resistance
• energy metabolism
• gemcitabine
• pancreatic ductal carcinoma

• Antimetabolites, Antineoplastic/pharmacology
• Antimetabolites, Antineoplastic/therapeutic use
• Apoptosis
• Carcinoma, Pancreatic Ductal/pathology
• Cell Line, Tumor
• Cell Proliferation
• Deoxycytidine/analogs & derivatives
• Drug Resistance, Neoplasm
• Energy Metabolism
• Humans
• Pancreatic Neoplasms/pathology
• Reactive Oxygen Species/pharmacology
• Gemcitabine

We used gastric cancer cell line AGS and clinical samples to investigate the roles of mitochondrial DNA (mtDNA) alterations and mitochondrial respiratory dysfunction in gastric adenocarcinoma (GAC). A total of 131 clinical samples, including 17 normal gastric mucosa (N-GM) from overweight patients who had received sleeve gastrectomy and 57 paired non-cancerous gastric mucosae (NC-GM) and GAC from GAC patients who had undergone partial/subtotal/total gastrectomy, were recruited to examine the copy number and D310 sequences of mtDNA. The gastric cancer cell line AGS was used with knockdown (KD) mitochondrial transcription factor A (TFAM) to achieve mitochondrial dysfunction through a decrease of mtDNA copy number. Parental (PT), null-target (NT), and TFAM-KD-(A/B/C) represented the parental, control, and TFAM knocked-down AGS cells, respectively. These cells were used to compare the parameters reflecting mitochondrial biogenesis, glycolysis, and cell migration activity. The median mtDNA copy numbers of 17 N-GM, 57 NC-GM, and 57 GAC were 0.058, 0.055, and 0.045, respectively. The trend of decrease was significant (p = 0.030). In addition, GAC had a lower mean mtDNA copy number of 0.055 as compared with the paired NC-GM of 0.078 (p < 0.001). The mean mtDNA copy number ratio (mtDNA copy number of GAC/mtDNA copy number of paired NC-GM) was 0.891. A total of 35 (61.4%) GAC samples had an mtDNA copy number ratio ≤0.804 (p = 0.017) and 27 (47.4%) harbored a D310 mutation (p = 0.047), and these patients had shorter survival time and poorer prognosis. After effective knockdown of TFAM, TFAM-KD-B/C cells expressed higher levels of hexokinase II (HK-II) and v-akt murine thymoma viral oncogene homolog 1 gene (AKT)-encoded AKT, but lower levels of phosphorylated pyruvate dehydrogenase (p-PDH) than did the NT/PT AGS cells. Except for a higher level of p-PDH, the expression levels of these proteins remained unchanged in TFAM-KD-A, which had a mild knockdown of TFAM. Compared to those of NT, TFAM-KD-C had not only a lower mtDNA copy number (p = 0.050), but also lower oxygen consumption rates (OCR), including basal respiration (OCR_BR), ATP-coupled respiration (OCR_ATP), reserve capacity (OCR_RC), and proton leak (OCR_PL)(all with p = 0.050). In contrast, TFAM-KD-C expressed a higher extracellular acidification rate (ECAR)/OCR_BR ratio (p = 0.050) and a faster wound healing migration at 6, 12, and 18 h, respectively (all with p = 0.050). Beyond a threshold, the decrease in mtDNA copy number, the mtDNA D310 mutation, and mitochondrial dysfunction were involved in the carcinogenesis and progression of GACs. Activation of PDH might be considered as compensation for the mitochondrial dysfunction in response to glucose metabolic reprogramming or to adjust mitochondrial plasticity in GAC.

• SNP
• dog
• mammary gland tumours
• mtDNA genome
• mutations

• TMAO
• biomarkers
• cardiovascular disease
• hypertension
• mitochondrial DNA
• sex

• Mitochondria
• Mitochondrial DNA copy number
• Polychlorinated biphenyls
• Rat
• TCDD

• Animals
• DNA Copy Number Variations/drug effects
• DNA, Mitochondrial/drug effects
• Dose-Response Relationship, Drug
• Female
• Liver/drug effects
• Liver/pathology
• Lung/drug effects
• Lung/pathology
• Oxidative Stress/drug effects
• Polychlorinated Biphenyls/administration & dosage
• Polychlorinated Biphenyls/toxicity
• Polychlorinated Dibenzodioxins/administration & dosage
• Polychlorinated Dibenzodioxins/toxicity
• Rats
• Rats, Sprague-Dawley

• ZIA BC011476 Intramural NIH HHS

Most of the genetic information has been lost or transferred to the nucleus during the evolution of mitochondria. Nevertheless, mitochondria have retained their own genome that is essential for oxidative phosphorylation (OXPHOS). In mammals, a gene‐dense circular mitochondrial DNA (mtDNA) of about 16.5 kb encodes 13 proteins, which constitute only 1% of the mitochondrial proteome. Mammalian mtDNA is present in thousands of copies per cell and mutations often affect only a fraction of them. Most pathogenic human mtDNA mutations are recessive and only cause OXPHOS defects if present above a certain critical threshold. However, emerging evidence strongly suggests that the proportion of mutated mtDNA copies is not the only determinant of disease but that also the absolute copy number matters. In this review, we critically discuss current knowledge of the role of mtDNA copy number regulation in various types of human diseases, including mitochondrial disorders, neurodegenerative disorders and cancer, and during ageing. We also provide an overview of new exciting therapeutic strategies to directly manipulate mtDNA to restore OXPHOS in mitochondrial diseases.

• Alzheimer’s disease
• Parkinson’s disease
• TFAM
• ageing
• cancer
• mitochondria
• mitochondrial diseases
• mtDNA
• mtDNA copy number
• neurodegenerative disorders

• Alzheimer’s disease
• China
• folate metabolites
• mitochondrial function
• peripheral blood cells

• Amerindian haplogroup
• Clinical features
• Polymorphisms
• mtDNA copy number

• 8-Hydroxy-2′-Deoxyguanosine
• DNA mitochondrial
• Female
• Humans
• Metformin
• Polycystic ovary syndrome
• Testosterone

• Adolescent
• Adult
• Body Mass Index
• DNA Copy Number Variations/drug effects
• DNA, Mitochondrial/analysis
• DNA, Mitochondrial/drug effects
• DNA, Mitochondrial/genetics
• Female
• Humans
• Hypoglycemic Agents/therapeutic use
• Insulin Resistance/physiology
• Longitudinal Studies
• Metformin/therapeutic use
• Polycystic Ovary Syndrome/drug therapy
• Polycystic Ovary Syndrome/genetics
• Polycystic Ovary Syndrome/pathology
• Young Adult

• Ministry of Science and Technology, Taiwan

Although human papillomavirus (HPV) infection has been regarded as the cause of cervical cancer in over 99% of cases, only a small fraction of HPV-infected women develop this malignancy. Emerging evidence suggests that alterations of mitochondrial DNA copy number (mtCN) may contribute to carcinogenesis. However, the relationship between mtCN and cervical cancer remains undetermined.

The current study included 591 cervical cancer cases and 373 cancer-free controls, all of whom were infected with high-risk HPV. Relative mtCN in cervical cancer exfoliated cells was measured by qRT-PCR assays, and logistic regression analysis was performed to compute odds ratios (ORs) and 95% confidence intervals (CIs). Interaction between mtCN and HPV types was assessed by using the Wald test in logistic regression models.

HPV16, 18, 52, and 58 were the most common types in both case and control groups. Median mtCN in cases was significantly higher than that in controls (1.63 vs. 1.23, P = 0.03). After adjustment for age and HPV types, the highest quartile of mtCN was associated with increased odds of having cervical cancer (OR = 1.77, 95% CI = 1.19, 2.62; P < 0.01), as compared to the lowest quartile. A dose-response effect of mtCN on cervical cancer was also observed (P_trend < 0.001). The interaction between mtCN and HPV types was statistically nonsignificant.

In women who test HPV positive, the increase of mtCN in cervical exfoliated cells is associated with cervical cancer. This suggests a potential role of mtCN in cervical carcinogenesis.

• Case-control study
• Cervical cancer
• Human papillomavirus
• Mitochondrial DNA copy number
• Mitochondrion

• Biochemistry
• Biological sciences
• Cancer research
• Hydrogen peroxide
• Lung cancer markers
• Mitochondria
• Molecular biology
• Oncology
• Reactive oxygen species
• mtDNA damage

• predictive markers
• cancer genetics

• Antineoplastic Agents/pharmacology
• Apoptosis/drug effects
• Apoptosis/genetics
• Carcinoma, Squamous Cell/genetics
• Carcinoma, Squamous Cell/metabolism
• Carcinoma, Squamous Cell/pathology
• Cell Line, Tumor
• Cell Proliferation/drug effects
• Cell Proliferation/genetics
• Cell Survival/drug effects
• Cell Survival/genetics
• Cisplatin/pharmacology
• DNA, Mitochondrial/drug effects
• DNA, Mitochondrial/genetics
• DNA, Mitochondrial/metabolism
• Drug Resistance, Neoplasm/drug effects
• Drug Resistance, Neoplasm/genetics
• Gene Expression Profiling/methods
• Gene Expression Regulation, Neoplastic/drug effects
• Humans
• Mitochondria/drug effects
• Mitochondria/genetics
• Mitochondria/metabolism
• Mouth Neoplasms/genetics
• Mouth Neoplasms/metabolism
• Mouth Neoplasms/pathology
• Neoplastic Stem Cells/drug effects
• Neoplastic Stem Cells/metabolism

• Universiti Kebangsaan Malaysia (National University of Malaysia)
• Majlis Kanser Nasional (National Cancer Council Malaysia)

Little is known about whether mitochondria 8-hydroxy-2′-deoxyguanosine (8-OHdG), a biomarker of mitochondrial DNA (mtDNA) oxidative damage, contributes to the development of coronary artery disease (CAD) in diabetic patients. Here, we explored the associations of mtDNA 8-OHdG in leukocytes with obstructive CAD, coronary stenosis severity, cardiovascular biomarkers, and 1-year adverse outcomes after coronary revascularization in patients with type 2 diabetes mellitus (T2DM).

In a total of 1920 consecutive patients with T2DM who underwent coronary angiography due to symptoms of angina or angina equivalents, the presence of obstructive CAD, the number of diseased vessels with ≥ 50% stenosis, and modified Gensini score were cross-sectionally evaluated; the level of mtDNA 8-OHdG was quantified by quantitative PCR. Then, 701 of 1920 diabetic patients who further received coronary revascularization completed 1-year prospective follow-up to document major adverse cardiovascular and cerebral events (MACCEs). In vitro experiments were also performed to observe the effects of mtDNA oxidative damage in high glucose-cultured human umbilical vein endothelial cells (HUVECs).

Cross-sectionally, greater mtDNA 8-OHdG was associated with increased odds of obstructive CAD (odds ratio [OR] 1.38, 95% CI confidence interval 1.24–1.52), higher degree of coronary stenosis (number of diseased vessels: OR 1.29, 95% CI 1.19–1.41; modified Gensini scores: OR 1.28, 95% CI 1.18–1.39), and higher levels of C-reactive protein (β 0.18, 95% CI 0.06–0.31) after adjusting for confounders. Sensitivity analyses using propensity score matching yielded similar results. Stratification by smoking status showed that the association between mtDNA 8-OHdG and obstructive CAD was most evident in current smokers (P_interation < 0.01). Prospectively, the adjusted hazards ratio per 1-SD increase in mtDNA 8-OHdG was 1.59 (95% CI 1.33–1.90) for predicting 1-year MACCEs after revascularization. In HUVECs, exposure to antimycin A, an inducer for mtDNA oxidative damage, led to adverse alterations in markers of mitochondrial and endothelia function.

Greater mtDNA 8-OHdG in leukocytes may serve as an independent risk factor for CAD in patients with T2DM.

• Clinical outcomes after revascularization
• Coronary artery disease
• Mitochondrial 8-OHdG
• Type 2 diabetes mellitus

• cancer
• mitochondrial DNA
• mutation
• oxidative stress
• predictor

Metabolism and mitochondrial biology have gained a prominent role as determinants of stem cell fate and function. In the context of regenerative medicine, innovative parameters predictive of therapeutic efficacy could be drawn from the association of metabolic or mitochondrial parameters to different degrees of stemness and differentiation potentials. Herein, this possibility was addressed in human mesenchymal stromal/stem cells (hMSC) previously shown to differ in lifespan and telomere length. First, these hMSC were shown to possess significantly distinct proliferation rate, senescence status and differentiation capacity. More potential hMSC were associated to higher mitochondrial (mt) DNA copy number and lower mtDNA methylation. In addition, they showed higher expression levels of oxidative phosphorylation subunits. Consistently, they exhibited higher coupled oxygen consumption rate and lower transcription of glycolysis-related genes, glucose consumption and lactate production. All these data pointed at oxidative phosphorylation-based central metabolism as a feature of higher stemness-associated hMSC phenotypes. Consistently, reduction of mitochondrial activity by complex I and III inhibitors in higher stemness-associated hMSC triggered senescence. Finally, functionally higher stemness-associated hMSC showed metabolic plasticity when challenged by glucose or glutamine shortage, which mimic bioenergetics switches that hMSC must undergo after transplantation or during self-renewal and differentiation. Altogether, these results hint at metabolic and mitochondrial parameters that could be implemented to identify stem cells endowed with superior growth and differentiation potential.

• Extracellular vesicles
• melanoma
• membrane proteins
• mitochondria

• Adverse birth outcome
• Endocrine disruption
• Mitochondrial DNA
• Oxidative stress
• PM(2.5) (particulate matter ≤2.5 µm in aerodynamic diameter)
• Prenatal exposure

• Air Pollutants/toxicity
• Air Pollution, Indoor/adverse effects
• Female
• Humans
• Infant, Low Birth Weight
• Infant, Newborn
• Male
• Maternal Exposure/adverse effects
• Particulate Matter/toxicity
• Pregnancy
• Pregnancy Outcome
• Premature Birth/chemically induced
• Reproduction/drug effects

Alterations of mitochondrial DNA (mtDNA) have been identified in several types of solid tumor. However, to the best of our knowledge, the clinical significance of plasma mtDNA content in lung cancer remains unknown. Thus, the current study explored the diagnostic and prognostic value of plasma mtDNA quantification in patients with lung cancer. Plasma mtDNA copy numbers of patients with lung cancer (n=128) and healthy individuals (n=107) were quantified by quantitative polymerase chain reaction. Plasma mtDNA copy numbers in patients and healthy controls were 0.89×10⁴ and 1.37×10⁴ copies/µl, respectively (P<0.0001). Furthermore, lower plasma mtDNA content was associated with tumor size, lymph node metastases, distant metastases and serum carcinoembryonic antigen levels (P<0.05), but was not associated with pathological type, age, sex or main driver gene mutation status (P>0.05). Plasma mtDNA facilitated the detection of lung cancer at a threshold of 1.19×10⁴ copies/µl with a sensitivity of 71.1% and specificity of 70.1%, as determined by receiver operating characteristic curve analysis. Advanced stage (III and IV) patients with a lower mtDNA copy number (cutoff: 1.02×10⁴ copies/µl) tended to exhibit poorer prognosis (P<0.05). These results indicated that plasma mtDNA content is a promising and complementary candidate with tissue mtDNA for diagnosis and prognostic prediction for lung cancer.

• diagnosis
• lung cancer
• mitochondrial DNA
• prognosis
• quantitative polymerase chain reaction

• 8-Hydroxyl-2′-deoxyguanosine (8-OHdG)
• Acute appendicitis
• Immune response
• Mitochondrial DNA copy number

• DNA methylation
• cancer biomarkers
• cancer epigenetics

• Epidermal Growth Factor Receptor
• breast cancer
• gene amplification
• genomic instability
• mitochondrial DNA

Colorectal cancer is one of the leading causes of cancer death worldwide. According to global genomic status, colorectal cancer can be classified into two main types: microsatellite-stable and microsatellite-instable tumors. Moreover, the two subtypes also exhibit different responses to chemotherapeutic agents through distinctive molecular mechanisms. Recently, mitochondrial DNA depletion has been shown to induce apoptotic resistance in microsatellite-instable colorectal cancer. However, the effects of altered mitochondrial DNA copy number on the progression of microsatellite-stable colorectal cancer, which accounts for the majority of colorectal cancer, remain unclear. In this study, we systematically investigated the functional role of altered mitochondrial DNA copy number in the survival and metastasis of microsatellite-stable colorectal cancer cells. Moreover, the underlying molecular mechanisms were also explored. Our results demonstrated that increased mitochondrial DNA copy number by forced mitochondrial transcription factor A expression significantly facilitated cell proliferation and inhibited apoptosis of microsatellite-stable colorectal cancer cells both in vitro and in vivo. Moreover, we demonstrated that increased mitochondrial DNA copy number enhanced the metastasis of microsatellite-stable colorectal cancer cells. Mechanistically, the survival advantage conferred by increased mitochondrial DNA copy number was caused in large part by elevated mitochondrial oxidative phosphorylation. Furthermore, treatment with oligomycin significantly suppressed the survival and metastasis of microsatellite-stable colorectal cancer cells with increased mitochondrial DNA copy number. Our study provides evidence supporting a possible tumor-promoting role for mitochondrial DNA and uncovers the underlying mechanism, which suggests a potential novel therapeutic target for microsatellite-stable colorectal cancer.

An increase in mitochondrial DNA (mtDNA) in microsatellite stable colorectal cancer (MSSCRC) cells stimulates cell proliferation and prevents cell death. MtDNA copy number is regulated by mitochondrial transcription factor A and both increases and decreases in mtDNA levels have been associated with different types of cancer. A study led by Qichao Huang and Xianli He at the Fourth Military Medical University, China, investigated the effects of altering mtDNA levels in MSSCRC cells on tumor progression in mice. They found that high levels of mtDNA promoted MSSCRC cell survival and metastasis by stimulating mitochondrial oxidative phosphorylation and energy production. Conversely, mtDNA depletion or treatment with the mitochondrial toxin oligomycin reduced the survival and metastasis of MSSCRC cells. These findings suggest that reducing mtDNA copy number could be a useful therapeutic strategy for MSSCRC.

Changes in mitochondrial DNA (mtDNA) content is a useful clinical biomarker for various diseases, however results are controversial as several analytical factors can affect measurement of mtDNA. MtDNA is often quantified by taking ratio between a target mitochondrial gene and a reference nuclear gene (mtDNA/nDNA) using quantitative real time PCR often on two separate experiments. It measures relative levels by using external calibrator which may not be comparable across laboratories. We have developed and optimized a droplet digital PCR (ddPCR) based method for quantification of absolute copy number of both mtDNA and nDNA gene in whole blood. Finally, the role of mtDNA in suspected cancer patients referred to a cancer diagnostic center was investigated.

Analytical factors which can result in false quantification of mtDNA have been optimized and both target and reference have been quantified simultaneously with intra- and inter-assay coefficient variances as 3.1% and 4.2% respectively. Quantification of mtDNA show that compared to controls, solid tumors (but not hematologic malignancies) and other diseases had significantly lower copy number of mtDNA. Higher mtDNA (highest quartile) was associated with a significantly lower risk of both solid tumors and other diseases, independent of age and sex. Receiver operating curve demonstrated that mtDNA levels could differentiate controls from patients with solid tumors and other diseases.

Quantification of mtDNA by a well optimized ddPCR method showed that its depletion may be a hallmark of general illness and can be used to stratify healthy individuals from patients diagnosed with cancer and other chronic diseases.

• Biomarker
• Cancer
• Droplet digital PCR
• Mitochondrial DNA
• Nuclear DNA
• ddPCR
• mtDNA

Therapies targeting epigenetic changes for cancer treatment are in Phase I/II trials; however, all of these target only nuclear DNA. Emerging evidence suggests presence of methylation marks on mitochondrial DNA (mtDNA); but their contribution in cancer is unidentified. Expression of genes encoded on mtDNA are altered in cancer cells, along with increased glycolytic flux. Such glycolytic flux and elevated reactive oxygen species is supported by increased antioxidant; glutathione. MicroRNA-34a can translocate to mitochondria, mediate downstream apoptotic effects of tumor suppressor P53, and inhibit the antioxidant response element Nrf-2, resulting in depleted glutathione levels. Based on such strong rationale, we encapsulated microRNA-34a in our well-established Hyaluronic-Acid nanoparticles and delivered to cisplatin-sensitive and cisplatin-resistant A549-lung adenocarcinoma cells. Successful delivery and uptake in cells resulted in altered ATP levels, decreased glycolytic flux, Nrf-2 and glutathione levels, ultimately resulting in caspase-3 activation and apoptosis. Most important were the concurrent underlying molecular changes in epigenetic status of D-loop on the mtDNA and transcription of mtDNA-encoded genes. Although preliminary, we provide a novel therapeutic approach in form of altered mitochondrial bioenergetics and redox status of cancer cells with underlying changes in epigenetic status of mtDNA that can subsequently results in induction of cancer cell apoptosis.

• Cancer metabolism
• Krebs cycle
• Mitochondria
• Mutations
• Oncometabolites
• TCA cycle

• Animals
• Citric Acid Cycle/physiology
• Humans
• Hypoxia-Inducible Factor 1/metabolism
• Mutation
• NF-E2-Related Factor 2/metabolism
• Neoplasms/genetics
• Neoplasms/metabolism
• Neoplasms/pathology
• Reactive Oxygen Species/metabolism

• HIV
• HIV/HCV coinfection
• mtDNA 8-oxo-dG
• oxidative stress
• zinc

• 8-Hydroxy-2'-Deoxyguanosine
• Adult
• Cohort Studies
• Deficiency Diseases/blood
• Deficiency Diseases/metabolism
• Deoxyguanosine/analogs & derivatives
• Deoxyguanosine/metabolism
• Female
• Florida/epidemiology
• HIV Infections/blood
• HIV Infections/complications
• Hepatitis C/blood
• Hepatitis C/complications
• Humans
• Liver Cirrhosis/etiology
• Male
• Mitochondria/drug effects
• Mitochondria/physiology
• Oxidative Stress/physiology
• Zinc/blood

• R01 DA023405 NIDA NIH HHS
• U01 DA040381 NIDA NIH HHS
• U01 MD017423 NIMHD NIH HHS
• R01 AA018011 NIAAA NIH HHS

• Cancer
• Mitochondria
• OXPHOS
• ROS
• Warburg effect
• mtDNA

Mitochondrial dysfunction is associated with pathogenic mitochondrial (mt)DNA mutations. The majority of mtDNA point mutations have a heteroplasmic status, which is defined as the coexistence of wild-type and mutated DNA within a cell or tissue. Previous findings demonstrated that certain mtDNA heteroplasmic mutations contribute to widely spread chronic diseases, including cancer, and alterations in the heteroplasmy level are associated with the clinical phenotype and severity of cancer. In the present study, the proportions of mutant mtDNA 10398G were assessed using amplification-refractory mutation system-quantitative polymerase chain reaction (PCR) assay in 129 non-small cell lung cancer (NSCLC) tissue samples. Wild-type and mutant sequences were separately amplified using allele-specific primers and, subsequently, the PCR products containing the mtDNA 10398 site were ligated into vectors to construct a standard plasmid DNA construct. The association between mtDNA A10398G and the prognosis of patients was analyzed by survival analysis and Cox proportional hazards model. For the patient cohort, the median follow-up time and overall survival time were 20.6 and 26.3 months, respectively. The ratios of mutant heteroplasmy ranged between 0.31 and 97.04%. Patients with a high degree of mutant mtDNA 10398G had a significantly longer overall survival time compared with those with a low degree of mutant mtDNA 10398G (28.7 vs. 22.5 months, respectively; P<0.05). In addition, multivariate analysis demonstrated that epidermal growth factor receptor mutation status, tumor stage and the possession of a low degree of mutant 10398G were the three most independent prognostic factors. In conclusion, the present study suggests that, among NSCLC patients, there are large shifts in mutant mtDNA 10398G heteroplasmy and a low degree of mutant mtDNA 10398G heteroplasmy may be a marker of poor prognosis in patients with NSCLC.

• heteroplasmy
• mitochondrial DNA 10398
• mutation
• non-small cell lung cancer
• prognosis

• Cardiorespiratory diseases (CRD)
• Coagulation
• EV-encapsulated microRNAs (EVmiRNAs)
• Extracellular vesicles (EVs)
• Inflammation
• Particulate air pollution (PM)
• Type 2 diabetes (T2D)
• microRNAs

We investigated the role of mitochondrial DNA (mtDNA) copy number alteration in human renal cell carcinoma (RCC). The mtDNA copy numbers of paired cancer and non-cancer parts from five resected RCC kidneys after radical nephrectomy were determined by quantitative polymerase chain reaction (Q-PCR). An RCC cell line, 786-O, was infected by lentiviral particles to knock down mitochondrial transcriptional factor A (TFAM). Null target (NT) and TFAM-knockdown (TFAM-KD) represented the control and knockdown 786-O clones, respectively. Protein or mRNA expression levels of TFAM; mtDNA-encoded NADH dehydrogenase subunit 1 (ND1), ND6 and cytochrome c oxidase subunit 2 (COX-2); nuclear DNA (nDNA)-encoded succinate dehydrogenase subunit A (SDHA); v-akt murine thymoma viral oncogene homolog 1 gene (AKT)-encoded AKT and v-myc myelocytomatosis viral oncogene homolog gene (c-MYC)-encoded MYC; glycolytic enzymes including hexokinase II (HK-II), glucose 6-phosphate isomerase (GPI), phosphofructokinase (PFK), and lactate dehydrogenase subunit A (LDHA); and hypoxia-inducible factors the HIF-1α and HIF-2α, pyruvate dehydrogenase kinase 1 (PDK1), and pyruvate dehydrogenase E1 component α subunit (PDHA1) were analyzed by Western blot or Q-PCR. Bioenergetic parameters of cellular metabolism, basal mitochondrial oxygen consumption rate (mOCR_B) and basal extracellular acidification rate (ECAR_B), were measured by a Seahorse XF^e-24 analyzer. Cell invasiveness was evaluated by a trans-well migration assay and vimentin expression. Doxorubicin was used as a chemotherapeutic agent. The results showed a decrease of mtDNA copy numbers in resected RCC tissues (p = 0.043). The TFAM-KD clone expressed lower mtDNA copy number (p = 0.034), lower mRNA levels of TFAM (p = 0.008), ND1 (p = 0.007), and ND6 (p = 0.017), and lower protein levels of TFAM and COX-2 than did the NT clone. By contrast, the protein levels of HIF-2α, HK-II, PFK, LDHA, AKT, MYC and vimentin; trans-well migration activity (p = 0.007); and drug resistance to doxorubicin (p = 0.008) of the TFAM-KD clone were significantly higher than those of the NT clone. Bioenergetically, the TFAM-KD clone expressed lower mOCR_B (p = 0.009) but higher ECAR_B (p = 0.037) than did the NT clone. We conclude that a reduction of mtDNA copy number and decrease of respiratory function of mitochondria in RCC might be compensated for by an increase of enzymes and factors that are involved in the upregulation of glycolysis to confer RCC more invasive and a drug-resistant phenotype in vitro.

• Warburg effect
• invasiveness
• mitochondrial DNA copy number
• mitochondrial biogenesis
• renal cell carcinoma

Caveolin-1 (CAV-1) participates in regulating vesicular transport, signal transduction, tumor progression, and cholesterol homeostasis. In the present study, we tested the hypothesis that CAV-1 improves dyslipidemia, inhibits cyclophilin A (CypA)- mediated ROS production, prevents mitochondrial compensatory action and attenuates oxidative stress responses in cholesterol-induced hypercholesterolemia. To determine the role of CAV-1 in mediating oxidative and antioxidative as well as cholesterol homeostasis, hypercholesterolemic rabbits were intravenously administered antenapedia-CAV-1 (AP-CAV-1) peptide for 2 wk. AP-CAV-1 enhanced CAV-1 expression by ˃15%, inhibited CypA expression by ˃50% (P < 0.05) and significantly improved dyslipidemia, thus reducing neutral lipid peroxidation. Moreover, CAV-1 attenuated hypercholesterolemia-induced changes in mitochondrial morphology and biogenesis and preserved mitochondrial respiratory function. In addition, CAV-1 protected against hypercholesterol-induced oxidative stress responses by reducing the degree of oxidative damage and enhancing the expression of antioxidant enzymes. CAV-1 treatment significantly suppressed apoptotic cell death, as evidenced by the reduction in the number of terminal deoxynucleotidyl transferase dUTP nick end-labeling-positive cells. We concluded that CAV-1 plays a critical role in inhibiting CypA-mediated ROS production, improving dyslipidemia, maintaining mitochondrial function, and suppressing oxidative stress responses that are vital for cell survival in hypercholesterol-affected renal organs.

• Animals
• Antioxidants/metabolism
• Apoptosis/drug effects
• Caveolin 1/genetics
• Caveolin 1/metabolism
• Caveolin 1/pharmacology
• Cholesterol/adverse effects
• Cyclophilin A/antagonists & inhibitors
• Cyclophilin A/genetics
• Cyclophilin A/metabolism
• Disease Models, Animal
• Electron Transport/drug effects
• Gene Expression Regulation
• Humans
• Hypercholesterolemia/chemically induced
• Hypercholesterolemia/drug therapy
• Hypercholesterolemia/metabolism
• Hypercholesterolemia/pathology
• Kidney/drug effects
• Kidney/metabolism
• Kidney/pathology
• Lipid Peroxidation/drug effects
• Male
• Mitochondria/drug effects
• Mitochondria/metabolism
• Oxidative Stress
• Peptides/chemical synthesis
• Peptides/pharmacology
• Rabbits
• Reactive Oxygen Species/antagonists & inhibitors
• Reactive Oxygen Species/metabolism
• Signal Transduction

• Changhua Christian Hospital

• mitochondrial DNA copy numbers
• mitochondrial mutation
• mitochondrial transcription factor A
• peroxisome proliferator-activated receptor gamma coactivator-1 alpha
• squamous cell carcinoma

• 8-ohdg
• foetal development
• mitochondrial function
• oxidative damage
• particulate matter

• Adult
• Air Pollutants/toxicity
• Cohort Studies
• DNA, Mitochondrial/blood
• Environmental Exposure/statistics & numerical data
• Female
• Fetal Blood/drug effects
• Fetal Blood/metabolism
• Humans
• Infant, Newborn
• Maternal Exposure/statistics & numerical data
• Particulate Matter/toxicity
• Placenta/drug effects
• Placenta/metabolism
• Pregnancy
• Young Adult

• EU Programme “Ideas”
• EU Program “Ideas”
• Flemish Scientific Fund (FWO)

• Mitochondria
• Neuronal death
• c-Fos

• 4977bp common deletion
• Breast cancer
• MnSOD
• Oxidative stress
• mtDNA mutations

• Adult
• Aged
• Base Sequence
• Breast Neoplasms/genetics
• Breast Neoplasms/metabolism
• Breast Neoplasms/pathology
• DNA, Mitochondrial/genetics
• DNA, Mitochondrial/metabolism
• Female
• Humans
• Middle Aged
• Mitochondria/genetics
• Mitochondria/metabolism
• Mitochondria/pathology
• Oxidative Stress/genetics
• Reactive Oxygen Species/metabolism
• Sequence Deletion

• R01 GM109434 NIGMS NIH HHS
• UL1 TR001120 NCATS NIH HHS