Mitochondrial defects in cancer

Mitophagy and clear cell renal cell carcinoma: insights from single-cell and spatial transcriptomics analysis

Background

Clear Cell Renal Cell Carcinoma (ccRCC) is the most common type of kidney cancer, characterized by high heterogeneity and complexity. Recent studies have identified mitochondrial defects and autophagy as key players in the development of ccRCC. This study aims to delve into the changes in mitophagic activity within ccRCC and its impact on the tumor microenvironment, revealing its role in tumor cell metabolism, development, and survival strategies.

Methods

Comprehensive analysis of ccRCC tumor tissues using single cell sequencing and spatial transcriptomics to reveal the role of mitophagy in ccRCC. Mitophagy was determined to be altered among renal clear cells by gene set scoring. Key mitophagy cell populations and key prognostic genes were identified using NMF analysis and survival analysis approaches. The role of UBB in ccRCC was also demonstrated by in vitro experiments.

Results

Compared to normal kidney tissue, various cell types within ccRCC tumor tissues exhibited significantly increased levels of mitophagy, especially renal clear cells. Key genes associated with increased mitophagy levels, such as UBC, UBA52, TOMM7, UBB, MAP1LC3B, and CSNK2B, were identified, with their high expression closely linked to poor patient prognosis. Particularly, the ubiquitination process involving the UBB gene was found to be crucial for mitophagy and its quality control.

Conclusion

This study highlights the central role of mitophagy and its regulatory factors in the development of ccRCC, revealing the significance of the UBB gene and its associated ubiquitination process in disease progression.

Beyond the membrane: Exploring non-viral methods for mitochondrial gene delivery

Mitochondrial disorders, stemming from mutations in mitochondrial DNA (mtDNA), present a significant therapeutic challenge due to their complex pathophysiology and broad spectrum of clinical manifestations. Traditional gene therapy approaches, primarily reliant on viral vectors, face obstacles such as potential immunogenicity, insertional mutagenesis, and the specificity of targeting mtDNA. This review delves into non-viral methods for mitochondrial gene delivery, emerging as a promising alternative to overcome these limitations. Focusing on lipid-based nanoparticles, polymer-based vectors, and mitochondrial-targeted peptides, the mechanisms of action, advantages, and current applications in treating mitochondrial diseases was well elucidated. Non-viral vectors offer several benefits, including reduced immunogenicity, enhanced safety profiles, and the flexibility to carry a wide range of genetic material. We examine case studies where these methods have been applied, highlighting their potential in correcting pathogenic mtDNA mutations and mitigating disease phenotypes. Despite their promise, challenges such as delivery efficiency, specificity, and long-term expression stability persist. The review underscores the need for ongoing research to refine these delivery systems carry a wide range of genetic material. We examine case studies where these methods settings. As we advance our understanding of mitochondrial biology and gene delivery technologies, non-viral methods hold the potential to revolutionize the treatment of mitochondrial disorders, offering hope for therapies that can precisely target and correct the underlying genetic defects.

Oxidative Stress in Breast Cancer: A Biochemical Map of Reactive Oxygen Species Production

This review systematizes information about the metabolic features of breast cancer directly related to oxidative stress. It has been shown those redox changes occur at all levels and affect many regulatory systems in the human body. The features of the biochemical processes occurring in breast cancer are described, ranging from nonspecific, at first glance, and strictly biochemical to hormone-induced reactions, genetic and epigenetic regulation, which allows for a broader and deeper understanding of the principles of oncogenesis, as well as maintaining the viability of cancer cells in the mammary gland. Specific pathways of the activation of oxidative stress have been studied as a response to the overproduction of stress hormones and estrogens, and specific ways to reduce its negative impact have been described. The diversity of participants that trigger redox reactions from different sides is considered more fully: glycolytic activity in breast cancer, and the nature of consumption of amino acids and metals. The role of metals in oxidative stress is discussed in detail. They can act as both co-factors and direct participants in oxidative stress, since they are either a trigger mechanism for lipid peroxidation or capable of activating signaling pathways that affect tumorigenesis. Special attention has been paid to the genetic and epigenetic regulation of breast tumors. A complex cascade of mechanisms of epigenetic regulation is explained, which made it possible to reconsider the existing opinion about the triggers and pathways for launching the oncological process, the survival of cancer cells and their ability to localize.

Ketogenic metabolic therapy in conjunction with standard treatment for glioblastoma: A case report

Glioblastoma (GBM) is the most common primary malignant brain tumour in adults. The standard of care consists of surgical resection and concurrent chemoradiation, followed by adjuvant temozolomide chemotherapy. This protocol is associated with a median survival of 12-15 months, and <5% of patients survive >3 years. Ketogenic metabolic therapy (KMT) targets cancer cell metabolism by restricting glucose availability and evoking differential stress resistance and sensitization, which may augment the standard treatments and lead to therapeutic benefit. The present study reports the case of a 64-year-old woman with isocitrate dehydrogenase (IDH)-wildtype GBM who pursued the standard treatment protocol in conjunction with an intensive, multimodal KMT program for 3 years. The KMT program consisted of a series of prolonged (7-day, fluid-only) fasts, which were specifically timed to maximize the tolerability and efficacy of the standard treatments, combined with a time-restricted ketogenic diet on all other days. During the first and second treatment years the patient sustained a glucose ketone index (GKI) of 1.65 and 2.02, respectively, which coincided with complete clinical improvement, a healthy body-mass index and a high quality of life, with no visible progressive tumour detected on imaging at the end of the second year. In the setting of the death of an immediate family member leading to increased life stress, slightly relaxed KMT adherence, and a higher GKI of 3.20, slow cancer progression occurred during the third year. The adverse effects attributed to KMT were mild. Despite the limitations of this case report, it highlights the feasibility of implementing the standard treatment protocol for GBM in conjunction with an intensive, long-term, multimodal and specifically timed KMT program, the potential therapeutic efficacy of which may depend upon achieving as low a GKI as possible.

Curcumin protects against cadmium-induced germ cell death in the testis of rats

Introduction

Cadmium (Cd) has been shown to disrupt the reproductive system. In this study, we evaluated the protective effects of Curcumin (Cur) against Cd-induced reproductive toxicity.

Methods

Exploring the role of Cur in Cd-treated rat models.

Results

The study demonstrated that Cd treatment impaired the seminiferous epithelium, leading to increased apoptosis of germ cells. Interestingly, pretreatment with Cur ameliorated the histological damage and decreased the germ cell apoptosis induced by Cd. Furthermore, after Cd exposure, B-cell lymphoma-2 expression was significantly decreased while Bax expression was increased. Pretreatment of rats with Cur protected against germ cell apoptosis by improving the expression of B-cell lymphoma-2 and reducing Bax. Additionally, Cd treatment increased reactive oxygen species, resulting in a decrease in antioxidant enzymes. However, pretreatment of rats with Cur followed by Cd administration led to a substantial decrease in reactive oxygen species levels and increased activities of antioxidant enzymes. Ultrastructural investigations revealed that damage to the mitochondrial structure was significantly ameliorated by Cur pretreatment in Cd-treated rats. Notably, Cur significantly activated the peroxisome proliferator-activated receptor gamma coactivator 1a/Sirtuins-3 signaling pathway.

Conclusions

Overall, our data suggest that Cd induces germ cell apoptosis through mitochondrial-induced oxidative stress, but Cur pretreatment offers strong protection against Cd-induced reproductive toxicity.

Pulsed Electromagnetic Fields (PEMFs) Trigger Cell Death and Senescence in Cancer Cells

The currently available anti-cancer therapies, such as gamma-radiation and chemotherapeutic agents, induce cell death and cellular senescence not only in cancer cells but also in the adjacent normal tissue. New anti-tumor approaches focus on limiting the side effects on normal cells. In this frame, the potential anti-tumor properties of Pulsed Electromagnetic Fields (PEMFs) through the irradiation of breast cancer epithelial cells (MCF-7 and MDA-MB-231) and normal fibroblasts (FF95) were investigated. PEMFs had a frequency of 8 Hz, full-square wave type and magnetic flux density of 0.011 T and were applied twice daily for 5 days. The data collected showcase that PEMF application decreases the proliferation rate and viability of breast cancer cells while having the opposite effect on normal fibroblasts. Moreover, PEMF irradiation induces cell death and cellular senescence only in breast cancer cells without any effect in the non-cancerous cells. These findings suggest PEMF irradiation as a novel, non-invasive anti-cancer strategy that, when combined with senolytic drugs, may eliminate both cancer and the remaining senescent cells, while simultaneously avoiding the side effects of the current treatments.

Therapeutic Approaches of Dual-targeted Nanomedicines for Tumor Multidrug Resistance

Currently, the main cause of cancer chemotherapy failure is multi-drug resistance (MDR), which involves a variety of complex mechanisms. Compared with traditional small-molecule chemotherapy, targeted nanomedicines offer promising alternative strategies as an emerging form of therapy, especially active targeted nanomedicines. However, although single-targeted nanomedicines have made some progress in tumor therapy, the complexity of tumor microenvironment and tumor heterogeneity limits their efficacy. Dual-targeted nanomedicines can simultaneously target two tumor-specific factors that cause tumor MDR, which have the potential in overcoming tumor MDR superior to single-targeted nanomedicines by further enhancing cell uptake and cytotoxicity in new forms, as well as the effectiveness of tumor-targeted delivery. This review discusses tumor MDR mechanisms and the latest achievements applied to dual-targeted nanomedicines in tumor MDR.

Mitochondrial Proteins as Metabolic Biomarkers and Sites for Therapeutic Intervention in Primary and Metastatic Cancers

Accelerated aerobic glycolysis is one of the main metabolic alterations in cancer, associated with malignancy and tumor growth. Although glycolysis is one of the most studied properties of tumor cells, recent studies demonstrate that oxidative phosphorylation (OxPhos) is the main ATP provider for the growth and development of cancer. In this last regard, the levels of mRNA and protein of OxPhos enzymes and transporters (including glutaminolysis, acetate and ketone bodies catabolism, free fatty acid β-oxidation, Krebs Cycle, respiratory chain, phosphorylating system- ATP synthase, ATP/ADP translocator, Pi carrier) are altered in tumors and cancer cells in comparison to healthy tissues and organs, and non-cancer cells. Both energy metabolism pathways are tightly regulated by transcriptional factors, oncogenes, and tumor-suppressor genes, all of which dictate their protein levels depending on the micro-environmental conditions and the type of cancer cell, favoring cancer cell adaptation and growth. In the present review paper, variation in the mRNA and protein levels as well as in the enzyme/ transporter activities of the OxPhos machinery is analyzed. An integral omics approach to mitochondrial energy metabolism pathways may allow for identifying their use as suitable, reliable biomarkers for early detection of cancer development and metastasis, and for envisioned novel, alternative therapies.

Metabolic reprogramming and its clinical implication for liver cancer

Cancer cells often encounter hypoxic and hypo-nutrient conditions, which force them to make adaptive changes to meet their high demands for energy and various biomaterials for biomass synthesis. As a result, enhanced catabolism (breakdown of macromolecules for energy production) and anabolism (macromolecule synthesis from bio-precursors) are induced in cancer. This phenomenon is called "metabolic reprogramming," a cancer hallmark contributing to cancer development, metastasis, and drug resistance. HCC and cholangiocarcinoma (CCA) are 2 different liver cancers with high intertumoral heterogeneity in terms of etiologies, mutational landscapes, transcriptomes, and histological representations. In agreement, metabolism in HCC or CCA is remarkably heterogeneous, although changes in the glycolytic pathways and an increase in the generation of lactate (the Warburg effect) have been frequently detected in those tumors. For example, HCC tumors with activated β-catenin are addicted to fatty acid catabolism, whereas HCC tumors derived from fatty liver avoid using fatty acids. In this review, we describe common metabolic alterations in HCC and CCA as well as metabolic features unique for their subsets. We discuss metabolism of NAFLD as well, because NAFLD will likely become a leading etiology of liver cancer in the coming years due to the obesity epidemic in the Western world. Furthermore, we outline the clinical implication of liver cancer metabolism and highlight the computation and systems biology approaches, such as genome-wide metabolic models, as a valuable tool allowing us to identify therapeutic targets and develop personalized treatments for liver cancer patients.

Metabolic factors associated with the prognosis of oligometastatic patients treated with stereotactic body radiotherapy

Over the past two decades, it has been established that cancer patients with oligometastases, i.e., only a few detectable metastases confined to one or a few organs, may benefit from an aggressive local treatment approach such as the application of high-precision stereotactic body radiotherapy (SBRT). Specifically, some studies have indicated that achieving long-term local tumor control of oligometastases is associated with prolonged overall survival. This motivates investigations into which factors may modify the dose-response relationship of SBRT by making metastases more or less radioresistant. One such factor relates to the uptake of the positron emission tomography tracer 2-deoxy-2-[18F]fluoro-D-glucose (FDG) which reflects the extent of tumor cell glycolysis or the Warburg effect, respectively. Here we review the biological mechanisms how the Warburg effect drives tumor cell radioresistance and metastasis and draw connections to clinical studies reporting associations between high FDG uptake and worse clinical outcomes after SBRT for oligometastases. We further review the evidence for distinct metabolic phenotypes of metastases preferentially seeding to specific organs and their possible translation into distinct radioresistance. Finally, evidence that obesity and hyperglycemia also affect outcomes after SBRT will be presented. While delivered dose is the main determinant of a high local tumor control probability, there might be clinical scenarios when metabolic targeting could make the difference between achieving local control or not, for example when doses have to be compromised in order to spare neighboring high-risk organs, or when tumors are expected to be highly therapy-resistant due to heavy pretreatment such as chemotherapy and/or radiotherapy.

Mitochondrial DNA-targeted therapy: A novel approach to combat cancer

Mitochondrial DNA (mtDNA) encodes proteins and RNAs that are essential for mitochondrial function and cellular homeostasis, and participates in important processes of cellular bioenergetics and metabolism. Alterations in mtDNA are associated with various diseases, especially cancers, and are considered as biomarkers for some types of tumors. Moreover, mtDNA alterations have been found to affect the proliferation, progression and metastasis of cancer cells, as well as their interactions with the immune system and the tumor microenvironment (TME). The important role of mtDNA in cancer development makes it a significant target for cancer treatment. In recent years, many novel therapeutic methods targeting mtDNA have emerged. In this study, we first discussed how cancerogenesis is triggered by mtDNA mutations, including alterations in gene copy number, aberrant gene expression and epigenetic modifications. Then, we described in detail the mechanisms underlying the interactions between mtDNA and the extramitochondrial environment, which are crucial for understanding the efficacy and safety of mtDNA-targeted therapy. Next, we provided a comprehensive overview of the recent progress in cancer therapy strategies that target mtDNA. We classified them into two categories based on their mechanisms of action: indirect and direct targeting strategies. Indirect targeting strategies aimed to induce mtDNA damage and dysfunction by modulating pathways that are involved in mtDNA stability and integrity, while direct targeting strategies utilized molecules that can selectively bind to or cleave mtDNA to achieve the therapeutic efficacy. This study highlights the importance of mtDNA-targeted therapy in cancer treatment, and will provide insights for future research and development of targeted drugs and therapeutic strategies.

Role of mitochondrial alterations in human cancer progression and cancer immunity

Dysregulating cellular metabolism is one of the emerging cancer hallmarks. Mitochondria are essential organelles responsible for numerous physiologic processes, such as energy production, cellular metabolism, apoptosis, and calcium and redox homeostasis. Although the "Warburg effect," in which cancer cells prefer aerobic glycolysis even under normal oxygen circumstances, was proposed a century ago, how mitochondrial dysfunction contributes to cancer progression is still unclear. This review discusses recent progress in the alterations of mitochondrial DNA (mtDNA) and mitochondrial dynamics in cancer malignant progression. Moreover, we integrate the possible regulatory mechanism of mitochondrial dysfunction-mediated mitochondrial retrograde signaling pathways, including mitochondrion-derived molecules (reactive oxygen species, calcium, oncometabolites, and mtDNA) and mitochondrial stress response pathways (mitochondrial unfolded protein response and integrated stress response) in cancer progression and provide the possible therapeutic targets. Furthermore, we discuss recent findings on the role of mitochondria in the immune regulatory function of immune cells and reveal the impact of the tumor microenvironment and metabolism remodeling on cancer immunity. Targeting the mitochondria and metabolism might improve cancer immunotherapy. These findings suggest that targeting mitochondrial retrograde signaling in cancer malignancy and modulating metabolism and mitochondria in cancer immunity might be promising treatment strategies for cancer patients and provide precise and personalized medicine against cancer.

EvIPqPCR, Target Circulating Tumorous Extracellular Vesicles for Detection of Pancreatic Cancer

Pancreatic cancer patients predominantly present with advanced disease at diagnosis, contributing to its high mortality. A noninvasive, fast screening method to detect this disease is an unmet need. Tumor-derived extracellular vesicles (tdEVs) bearing information from parental cells have emerged as a promising cancer diagnostic biomarker. However, most tdEV-based assays have impractical sample volumes and time-consuming, complex, and costly techniques. To overcome these limitations, we developed a novel diagnostic method for pancreatic cancer screening. Our approach utilizes the mitochondrial DNA to nuclear DNA ratio of EVs as a collective cell-specific characteristic. We introduce EvIPqPCR, a fast method that combines immunoprecipitation (IP) and qPCR quantification to detect tumor-derived EVs directly from serum. Importantly, our method employs DNA isolation-free and duplexing probes for qPCR, saving at least 3 h. This technique has the potential to serve as a translational assay for cancer screening with a weak correlation to prognosis biomarkers and sufficient discriminatory power among healthy controls, pancreatitis, and pancreatic cancer cases.

The Interplay between Dysregulated Metabolism and Epigenetics in Cancer

Cellular metabolism (or energetics) and epigenetics are tightly coupled cellular processes. It is arguable that of all the described cancer hallmarks, dysregulated cellular energetics and epigenetics are the most tightly coregulated. Cellular metabolic states regulate and drive epigenetic changes while also being capable of influencing, if not driving, epigenetic reprogramming. Conversely, epigenetic changes can drive altered and compensatory metabolic states. Cancer cells meticulously modify and control each of these two linked cellular processes in order to maintain their tumorigenic potential and capacity. This review aims to explore the interplay between these two processes and discuss how each affects the other, driving and enhancing tumorigenic states in certain contexts.

Methods to Evaluate Changes in Mitochondrial Structure and Function in Cancer

Mitochondria are regulators of key cellular processes, including energy production and redox homeostasis. Mitochondrial dysfunction is associated with various human diseases, including cancer. Importantly, both structural and functional changes can alter mitochondrial function. Morphologic and quantifiable changes in mitochondria can affect their function and contribute to disease. Structural mitochondrial changes include alterations in cristae morphology, mitochondrial DNA integrity and quantity, and dynamics, such as fission and fusion. Functional parameters related to mitochondrial biology include the production of reactive oxygen species, bioenergetic capacity, calcium retention, and membrane potential. Although these parameters can occur independently of one another, changes in mitochondrial structure and function are often interrelated. Thus, evaluating changes in both mitochondrial structure and function is crucial to understanding the molecular events involved in disease onset and progression. This review focuses on the relationship between alterations in mitochondrial structure and function and cancer, with a particular emphasis on gynecologic malignancies. Selecting methods with tractable parameters may be critical to identifying and targeting mitochondria-related therapeutic options. Methods to measure changes in mitochondrial structure and function, with the associated benefits and limitations, are summarized.

The Role of Genetic Mutations in Mitochondrial-Driven Cancer Growth in Selected Tumors: Breast and Gynecological Malignancies

There is an increasing understanding of the molecular and cytogenetic background of various tumors that helps us better conceptualize the pathogenesis of specific diseases. Additionally, in many cases, these molecular and cytogenetic alterations have diagnostic, prognostic, and/or therapeutic applications that are heavily used in clinical practice. Given that there is always room for improvement in cancer treatments and in cancer patient management, it is important to discover new therapeutic targets for affected individuals. In this review, we discuss mitochondrial changes in breast and gynecological (endometrial and ovarian) cancers. In addition, we review how the frequently altered genes in these diseases (BRCA1/2, HER2, PTEN, PIK3CA, CTNNB1, RAS, CTNNB1, FGFR, TP53, ARID1A, and TERT) affect the mitochondria, highlighting the possible associated individual therapeutic targets. With this approach, drugs targeting mitochondrial glucose or fatty acid metabolism, reactive oxygen species production, mitochondrial biogenesis, mtDNA transcription, mitophagy, or cell death pathways could provide further tailored treatment.

Comprehensive analysis reveals signal and molecular mechanism of mitochondrial energy metabolism pathway in pancreatic cancer

Pancreatic cancer (PAAD) is one of the most malignant tumors with the worst prognosis. The abnormalities in the mitochondrial energy metabolism pathway are intimately correlated with the occurrence and progression of cancer. For the diagnosis and treatment of pancreatic cancer, abnormal genes in the mitochondrial energy metabolism system may offer new targets and biomarkers. In this study, we compared the dysregulated mitochondrial energy metabolism-associated pathways in PAAD based on pancreatic cancer samples in the Cancer Genome Atlas (TCGA) database and normal pancreas samples from the Genotype Tissue Expression project (GTEx) database. Then identified 32 core genes of mitochondrial energy metabolism pathway-related genes (MMRG) were based on the gene set enrichment analysis (GSEA). We found most of these genes were altered among different clinical characteristic groups, and showed significant prognostic value and association with immune infiltration, suggesting critical roles of MMRG involve tumor genesis of PAAD. Therefore, we constructed a four-gene (LDHA, ALDH3B1, ALDH3A1, and ADH6) prognostic biomarker after eliminating redundant factors, and confirming its efficiency and independence. Further analysis indicated the potential therapeutic compounds based on the mitochondrial energy metabolism-associated prognostic biomarker. All of the above analyses dissected the critical role of mitochondrial energy metabolism signaling in pancreatic cancer and gave a better understanding of the clinical intervention of PAAD.

Associations of mitochondrial DNA copy number with incident risks of gastrointestinal cancers: A prospective case-cohort study

Epidemiological investigations implied that mitochondrial DNA copy number (mtDNAcn) variations could trigger predisposition to multiple cancers, but evidence regarding gastrointestinal cancers (GICs) was still uncertain. We conducted a case-cohort study within the prospective Dongfeng-Tongji cohort, including incident cases of colorectal cancer (CRC, n = 278), gastric cancer (GC, n = 138), and esophageal cancer (EC, n = 72) as well as a random subcohort (n = 1173), who were followed up from baseline to the end of 2018. We determined baseline blood mtDNAcn and associations of mtDNAcn with the GICs risks were estimated by using weighted Cox proportional hazards models. Significant U-shaped associations were observed between mtDNAcn and GICs risks. Compared to subjects within the second quartile (Q2) mtDNAcn subgroup, those within the 1st (Q1), 3rd (Q3), and 4th (Q4) quartile subgroups showed increased risks of CRC (hazard ratio [HR] [95% confidence interval, CI] = 2.27 [1.47-3.52], 1.65 [1.04-2.62], and 2.81 [1.85-4.28], respectively) and total GICs (HR [95%CI] = 1.84 [1.30-2.60], 1.47 [1.03-2.10], and 2.51 [1.82-3.47], respectively], and those within Q4 subgroup presented elevated GC and EC risks (HR [95% CI] = 2.16 [1.31-3.54] and 2.38 [1.13-5.02], respectively). Similar associations of mtDNAcn with CRC and total GICs risks remained in stratified analyzes by age, gender, smoking, and drinking status. This prospective case-cohort study showed U-shaped associations between mtDNAcn and GICs risks, but further research works are needed to uncover underlying biological mechanisms.

Phosphofructokinase Platelet Overexpression Accelerated Colorectal Cancer Cell Growth and Motility

Background: Glycolysis is a glucose metabolism pathway that generates the high-energy compound adenosine triphosphate, which supports cancer cell growth. Phosphofructokinase platelet (PFKP) plays a crucial role in glycolysis regulation and is involved in human cancer progression. However, the biological function of PFKP remains unclear in colorectal cancer (CRC). Methods: We analyzed the expression levels of PFKF in colon cancer cells and clinical samples using real-time PCR and western blot techniques. To determine the clinical significance of PFKP expression in colorectal cancer (CRC), we analyzed public databases. In addition, we conducted in vitro assays to investigate the effects of PFKP on cell growth, cell cycle, and motility. Results: An analysis by the Cancer Genome Atlas database revealed that PFKP was significantly overexpressed in CRC. We examined the levels of PFKP mRNA and protein, revealing that PFKP expression was significantly increased in CRC. The results of the univariate Cox regression analysis showed that high PFKP expression was linked to worse disease-specific survival (DSS) and overall survival (OS) [DSS: crude hazard ratio (CHR) = 1.84, 95% confidence interval (CI): 1.01-3.36, p = 0.047; OS: CHR=1.91, 95% CI: 1.06-3.43, p = 0.031]. Multivariate Cox regression analysis revealed that high PFKP expression was an independent prognostic biomarker for the DSS and OS of patients with CRC (DSS: adjusted HR = 2.07, 95% CI: 1.13-3.79, p = 0.018; AHR = 2.34, 95% CI: 1.29-4.25, p = 0.005). PFKP knockdown reduced the proliferation, colony formation, and invasion of CRC cells. In addition, the knockdown induced cell cycle arrest at the G0/G1 phase by impairing cell cycle-related protein expression. Conclusion: Overexpression of PFKP contributes to the growth and invasion of CRC by regulating cell cycle progression. PFKP expression can serve as a valuable molecular biomarker for cancer prognosis and a potential therapeutic target for treating CRC.

Melatonin and MitoEbselen-2 Are Radioprotective Agents to Mitochondria

Mitochondria are responsible for controlling cell death during the early stages of radiation exposure, but their perturbations are associated with late effects of radiation-related carcinogenesis. Therefore, it is important to protect mitochondria to mitigate the harmful effects of radiation throughout life. The glutathione peroxidase (GPx) enzyme is essential for the maintenance of mitochondrial-derived reactive oxygen species (ROS) levels. However, radiation inactivates the GPx, resulting in metabolic oxidative stress and prolonged cell injury in irradiated normal human fibroblasts. Here, we used the GPx activator N-acetyl-5-methoxy-tryptamine (melatonin) and a mitochondria-targeted mimic of GPx MitoEbselen-2 to stimulate the GPx. A commercial GPx activity assay kit was used to measure the GPx activity. ROS levels were determined by using some ROS indicators. Protein expression associated with the response of mitochondria to radiation was assessed using immunostaining. Concurrent pre-administration or post-administration of melatonin or MitoEbselen-2 with radiation maintained GPx activity and ROS levels and suppressed mitochondrial radiation responses associated with cellular damage and radiation-related carcinogenesis. In conclusion, melatonin and MitoEbselen-2 prevented radiation-induced mitochondrial injury and metabolic oxidative stress by targeting mitochondria. These drugs have the potential to protect against acute radiation injury and late effects of carcinogenesis in a variety of radiation scenarios assuming pre-administration or post-administration.

Androgen receptor signaling-mitochondrial DNA-oxidative phosphorylation: A critical triangle in early prostate cancer

Mitochondria are more than just the cellular powerhouse. They also play key roles in vital functions such as apoptosis, metabolism regulation, and other intracellular interactions. The mitochondrial DNA (mtDNA) encodes for 12 subunits of the oxidative phosphorylation (OXPHOS) system. Depletion of mtDNA in androgen-dependent prostate cancer (PCa) cell lines renders them androgen-independent and more aggressive. Paradoxically, pharmaceutical inhibition of OXPHOS is lethal for subsets of PCa cells, whereas others become dependent on androgen receptor (AR) signaling for survival. Given that the AR-mitochondria interaction is critical for early PCa, it is crucial to understand the details of this interaction. Technical hurdles have made mitochondria traditionally difficult to study, with many techniques used for isolation masking the properties of given individual mitochondria. Although the isolation of mitochondria enables us to study OXPHOS, we miss the context in which mitochondria interact with the rest of the cell. Both AR signaling and mtDNA affect apoptosis, metabolism regulation, cellular calcium storage and homeostasis, intracellular calcium signaling, and redox homeostasis. In this review, we will attempt to understand how the crosstalk between AR-mtDNA-OXPHOS is responsible for "life or death" decisions inside the cells. Our aim is to point toward potential vulnerabilities that can lead to the discovery of novel therapeutic targets.

Oxidative Stress and Antioxidants-A Critical Review on In Vitro Antioxidant Assays

Antioxidants have been widely studied in the fields of biology, medicine, food, and nutrition sciences. There has been extensive work on developing assays for foods and biological systems. The scientific communities have well-accepted the effectiveness of endogenous antioxidants generated in the body. However, the health efficacy and the possible action of exogenous dietary antioxidants are still questionable. This may be attributed to several factors, including a lack of basic understanding of the interaction of exogenous antioxidants in the body, the lack of agreement of the different antioxidant assays, and the lack of specificity of the assays, which leads to an inability to relate specific dietary antioxidants to health outcomes. Hence, there is significant doubt regarding the relationship between dietary antioxidants to human health. In this review, we documented the variations in the current methodologies, their mechanisms, and the highly varying values for six common food substrates (fruits, vegetables, processed foods, grains, legumes, milk, and dairy-related products). Finally, we discuss the strengths and weaknesses of the antioxidant assays and examine the challenges in correlating the antioxidant activity of foods to human health.

The Association of Ketolytic Enzymes Gene Expression Levels with Mitochondrial Activity and Content in Oral Squamous Cell Carcinoma

Background: Recent studies have pointed to the anti-tumour effects of a ketogenic diet (KD) in cancer. It is believed that patients with low ketolytic Enzymes gene expression levels are more sensitive and may respond better to the KD therapy. However, the ketolytic Enzymes gene expression levels and their association with mitochondrial activity and content in oral squamous cell carcinoma (OSCC) is not yet obvious. Therefore, the aim of this study was to explore the potential use of ketolytic enzymes as biomarkers for mitochondrial activity and content. Materials and Methods: Here we aimed to compare the mRNA expression levels of ketolytic enzymes (ACAT1, BDH1, BDH2 and OXCT1) between tumour and adjacent pre-tumor tissues of 16 OSCC patients. Additionally, we examined the association of the mitochondrial ketolytic enzymes, including ACAT1, OXCT1, and BDH1 gene expression with mitochondrial activity and content. Results: Our findings did not show any significant difference in ketolytic gene expression levels between tumour and pre-tumor tissues of OSCC patients. ACAT1 and BDH1 mRNA expression levels were significantly correlated with the mRNA level of ND2 in tumour of OSCC patients. The mRNA levels of ACAT1, BDH1 and BDH2 were not correlated with the mRNA expression of 16srRNA. Conclusion: Our data suggest that mRNA gene expression levels of BDH1 and ACAT1 correlate with the mitochondrial activity in tumour of OSCC patients. BDH2 mRNA level significantly anti-correlate with tumour grade. We offer clues on the potential of ACAT1 as a biomarker of mitochondrial activity, but future studies are needed to establish this concept.

Mitochondrial Control Region Variants Related to Breast Cancer

Breast cancer has an important incidence in the worldwide female population. Although alterations in the mitochondrial genome probably play an important role in carcinogenesis, the actual evidence is ambiguous and inconclusive. Our purpose was to explore differences in mitochondrial sequences of cases with breast cancer compared with control samples from different origins. We identified 124 mtDNA sequences associated with breast cancer cases, of which 86 were complete and 38 were partial sequences. Of these 86 complete sequences, 52 belonged to patients with a confirmed diagnosis of breast cancer, and 34 sequences were obtained from healthy mammary tissue of the same patients used as controls. From the mtDNA analysis, two polymorphisms with significant statistical differences were found: m.310del (rs869289246) in 34.6% (27/78) of breast cancer cases and 61.7% (21/34) in the controls; and m.315dup (rs369786048) in 60.2% (47/78) of breast cancer cases and 38.2% (13/34) in the controls. In addition, the variant m.16519T>C (rs3937033) was found in 59% of the control sequences and 52% of the breast cancer sequences with a significant statistical difference. Polymorphic changes are evolutionarily related to the haplogroup H of Indo-European and Euro-Asiatic origins; however, they were found in all non-European breast cancers.

Mitochondrial mutations and mitoepigenetics: Focus on regulation of oxidative stress-induced responses in breast cancers

Epigenetic regulation of mitochondrial DNA (mtDNA) is an emerging and fast-developing field of research. Compared to regulation of nucler DNA, mechanisms of mtDNA epigenetic regulation (mitoepigenetics) remain less investigated. However, mitochondrial signaling directs various vital intracellular processes including aerobic respiration, apoptosis, cell proliferation and survival, nucleic acid synthesis, and oxidative stress. The later process and associated mismanagement of reactive oxygen species (ROS) cascade were associated with cancer progression. It has been demonstrated that cancer cells contain ROS/oxidative stress-mediated defects in mtDNA repair system and mitochondrial nucleoid protection. Furthermore, mtDNA is vulnerable to damage caused by somatic mutations, resulting in the dysfunction of the mitochondrial respiratory chain and energy production, which fosters further generation of ROS and promotes oncogenicity. Mitochondrial proteins are encoded by the collective mitochondrial genome that comprises both nuclear and mitochondrial genomes coupled by crosstalk. Recent reports determined the defects in the collective mitochondrial genome that are conducive to breast cancer initiation and progression. Mutational damage to mtDNA, as well as its overproliferation and deletions, were reported to alter the nuclear epigenetic landscape. Unbalanced mitoepigenetics and adverse regulation of oxidative phosphorylation (OXPHOS) can efficiently facilitate cancer cell survival. Accordingly, several mitochondria-targeting therapeutic agents (biguanides, OXPHOS inhibitors, vitamin-E analogues, and antibiotic bedaquiline) were suggested for future clinical trials in breast cancer patients. However, crosstalk mechanisms between altered mitoepigenetics and cancer-associated mtDNA mutations remain largely unclear. Hence, mtDNA mutations and epigenetic modifications could be considered as potential molecular markers for early diagnosis and targeted therapy of breast cancer. This review discusses the role of mitoepigenetic regulation in cancer cells and potential employment of mtDNA modifications as novel anti-cancer targets.

Nuclear respiratory factor 1 promotes the growth of liver hepatocellular carcinoma cells via E2F1 transcriptional activation

Background

Recent studies have shown that functional mitochondria are essential for cancer cells. Nuclear respiratory factor 1 (NRF1) is a transcription factor that activates mitochondrial biogenesis and the expression of the respiratory chain, but little is known about its role and underlying mechanism in liver hepatocellular carcinoma (LIHC).

Methods

NRF1 expression was analyzed via public databases and 24 paired LIHC samples. Clinical-pathological information and follow-up data were collected from 165 patients with LIHC or online datasets. Furthermore, cellular proliferation and the cell cycle were analyzed by MTT, Clone-forming assay and flow cytometric analyses. NRF1 target genes were analyzed by Chromatin immunoprecipitation sequencing (ChIP-Seq). PCR and WB analysis was performed to detect the expression of related genes. ChIP and luciferase activity assays were used to identify NRF1 binding sites.

Results

Our results showed that NRF1 expression was upregulated in LIHC compared to normal tissues. NRF1 expression was associated with tumour size and poor prognosis in patients. Knockdown of NRF1 repressed cell proliferation and overexpression of NRF1 accelerated the G₁/S phase transition. Additionally, data from ChIP-seq pointed out that some NRF1 target genes are involved in the cell cycle. Our findings indicated that NRF1 directly binds to the E2F1 promoter as a transcription factor and regulates its gene expression.

Conclusion

Therefore, this study revealed that NRF1 promotes cancer cell growth via the indirect transcriptional activation of E2F1 and is a potential biomarker in LIHC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12876-022-02260-7.

Crosstalk Between ROS and Autophagy in Tumorigenesis: Understanding the Multifaceted Paradox

Cancer formation is a highly regulated and complex process, largely dependent on its microenvironment. This complexity highlights the need for developing novel target-based therapies depending on cancer phenotype and genotype. Autophagy, a catabolic process, removes damaged and defective cellular materials through lysosomes. It is activated in response to stress conditions such as nutrient deprivation, hypoxia, and oxidative stress. Oxidative stress is induced by excess reactive oxygen species (ROS) that are multifaceted molecules that drive several pathophysiological conditions, including cancer. Moreover, autophagy also plays a dual role, initially inhibiting tumor formation but promoting tumor progression during advanced stages. Mounting evidence has suggested an intricate crosstalk between autophagy and ROS where they can either suppress cancer formation or promote disease etiology. This review highlights the regulatory roles of autophagy and ROS from tumor induction to metastasis. We also discuss the therapeutic strategies that have been devised so far to combat cancer. Based on the review, we finally present some gap areas that could be targeted and may provide a basis for cancer suppression.

Multipotent Poly(Tertiary Amine-Oxide) Micelles for Efficient Cancer Drug Delivery

The cancer drug delivery process involves a series of biological barriers, which require the nanomedicine to exhibit different, even opposite properties for high therapeutic efficacy. The prevailing design philosophy, i.e., integrating these properties within one nanomedicine via on-demand property transitions such as PEGylation/dePEGylation, complicates nanomedicines' composition and thus impedes clinical translation. Here, polyzwitterionic micelles of poly(tertiary amine-oxide)-block-poly(ε-caprolactone) (PTAO-PCL) amphiphiles that enable all the required functions are presented. The zwitterionic nature and unique cell membrane affinity confer the PTAO micelles long blood circulation, efficient tumor accumulation and penetration, and fast cellular internalization. The mitochondrial targeting capability allows drug delivery into the mitochondria to induce mitochondrial dysfunction and overcome tumor multidrug resistance. As a result, the PTAO/drug micelles exhibit potent anticancer efficacy. This simple yet multipotent carrier system holds great promise as a generic platform for potential clinical translation.

Bone mineral: A trojan horse for bone cancers efficient mitochondria targeted delivery and tumor eradication with nano hydroxyapatite containing doxorubicin

Efficient systemic pharmacological treatment of solid tumors is hampered by inadequate tumor concentration of cytostatics necessitating development of smart local drug delivery systems. To overcome this, we demonstrate that doxorubicin (DOX), a cornerstone drug used for osteosarcoma treatment, shows reversible accretion to hydroxyapatite (HA) of both nano (nHA) and micro (mHA) size. nHA particles functionalized with DOX get engulfed in the lysosome of osteosarcoma cells where the acidic microenvironment causes a disruption of the binding between DOX and HA. The released DOX then accumulates in the mitochondria causing cell starvation, reduced migration and apoptosis. The HA+DOX delivery system was also tested in-vivo on osteosarcoma bearing mice. Locally delivered DOX via the HA particles had a stronger tumor eradication effect compared to the controls as seen by PET-CT and immunohistochemical staining of proliferation and apoptosis markers. These results indicate that in addition to systemic chemotherapy, an adjuvant nHA could be used as a carrier for intracellular delivery of DOX for prevention of tumor recurrence after surgical resection in an osteosarcoma. Furthermore, we demonstrate that nHA particles are pivotal in this approach but a combination of nHA with mHA could increase the safety associated with particulate nanomaterials while maintaining similar therapeutic potential.

Genetic interactions of mitochondrial sirtuins in brain tumorigenesis

Purpose: The present study was designed to understand the role of expression variations of mitochondrial imported sirtuins in brain tumorigenesis. The expression levels of mitochondrial imported sirtuins were further analyzed for biomarker potential. Methods: Samples from 200 brain tumors and 200 healthy control tissues were used for expression analysis using qPCR and for DNA damage using LORD-Q analysis. Results: Significant deregulation of SIRT3 (p = 0.002), SIRT4 (p = 0.03) and SIRT5 (p = 0.006) was observed in brain tumors versus controls. Co-expression analysis showed a significant correlation between the mitochondrial imported sirtuins versus apoptotic genes. LORD-Q analysis showed a significantly increased frequency of lesions/10 kb of mitochondrial imported sirtuins (p < 0.0001) in brain tumor tissue versus controls. Conclusion: The present study showed a correlation between variations of mitochondrial imported sirtuins and increased brain tumor risk.

Research progress on the pharmacological effects of berberine targeting mitochondria

Berberine is a natural active ingredient extracted from the rhizome of Rhizoma Coptidis, which interacts with multiple intracellular targets and exhibits a wide range of pharmacological activities. Previous studies have preliminarily confirmed that the regulation of mitochondrial activity is related to various pharmacological actions of berberine, such as regulating blood sugar and lipid and inhibiting tumor progression. However, the mechanism of berberine's regulation of mitochondrial activity remains to be further studied. This paper summarizes the molecular mechanism of the mitochondrial quality control system and briefly reviews the targets of berberine in regulating mitochondrial activity. It is proposed that berberine mainly regulates glycolipid metabolism by regulating mitochondrial respiratory chain function, promotes tumor cell apoptosis by regulating mitochondrial apoptosis pathway, and protects cardiac function by promoting mitophagy to alleviate mitochondrial dysfunction. It reveals the mechanism of berberine's pharmacological effects from the perspective of mitochondria and provides a scientific basis for the application of berberine in the clinical treatment of diseases.

β-Sheet Richness of the Circulating Tumor-Derived Extracellular Vesicles for Noninvasive Pancreatic Cancer Screening

Tumor-derived extracellular vesicles (EVs) are under intensive study for their potential as noninvasive diagnosis biomarkers. Most EV-based cancer diagnostic assays trace supernumerary of a single cancer-associated marker or marker signatures. These types of biomarker assays are either subtype-specific or vulnerable to be masked by high background signals. In this study, we introduce using the β-sheet richness (BR) of the tumor-derived EVs as an effective way to discriminate EVs originating from malignant and nonmalignant cells, where EV contents are evaluated as a collective attribute rather than single factors. Circular dichroism, Fourier transform infrared spectroscopy, fluorescence staining assays, and a de novo workflow combining proteomics, bioinformatics, and protein folding simulations were employed to validate the collective attribute at both cellular and EV levels. Based on the BR of the tumorous EVs, we integrated immunoprecipitation and fluorescence labeling targeting the circulating tumor-derived EVs in serum and developed the process into a clinical assay, named EvIPThT. The assay can distinguish patients with and without malignant disease in a pilot cohort, with weak correlations to prognosis biomarkers, suggesting the potential for a cancer screening panel with existing prognostic biomarkers to improve overall performance.

Somatic mitochondrial DNA mutations in different grades of glioma

Aim: Mitochondrial DNA (mtDNA) alterations play an important role in the multistep processes of cancer development. Gliomas are among the most diagnosed brain cancer. The relationship between mtDNA alterations and different grades of gliomas are still elusive. This study aimed to elucidate the profile of somatic mtDNA mutations in different grades of gliomas and correlate it with clinical phenotype. Materials & methods: Forty histopathologically confirmed glioma tissue samples and their matched blood were collected and subjected for mtDNA sequencing. Results & conclusion: About 75% of the gliomas harbored at least one somatic mutation in the mtDNA gene, and 45% of these mutations were pathogenic. Mutations were scattered across the mtDNA genome, and the commonest nonsynonymous mutations were located at complex I and IV of the mitochondrial respiratory chain. These findings may have implication for future research to determine the mitochondrial energetics and its downstream metabolomics on gliomas.

Mitochondria-Targeted Nanocarriers Promote Highly Efficient Cancer Therapy: A Review

Mitochondria are the primary organelles which can produce adenosine triphosphate (ATP). They play vital roles in maintaining normal functions. They also regulated apoptotic pathways of cancer cells. Given that, designing therapeutic agents that precisely target mitochondria is of great importance for cancer treatment. Nanocarriers can combine the mitochondria with other therapeutic modalities in cancer treatment, thus showing great potential to cancer therapy in the past few years. Herein, we summarized lipophilic cation- and peptide-based nanosystems for mitochondria targeting. This review described how mitochondria-targeted nanocarriers promoted highly efficient cancer treatment in photodynamic therapy (PDT), chemotherapy, combined immunotherapy, and sonodynamic therapy (SDT). We further discussed mitochondria-targeted nanocarriers’ major challenges and future prospects in clinical cancer treatment.

Let-7a induces metabolic reprogramming in breast cancer cells via targeting mitochondrial encoded ND4

BACKGROUND AND OBJECTIVES

MicroRNA (miRNA) that translocate from the nucleus to mitochondria are referred to as mitochondrial microRNA (mitomiR). Albeit mitomiRs have been shown to modulate gene expression, their functional impact within mitochondria is unknown. The main objective of this study is to investigate whether the mitochondrial genome is regulated by miR present inside the mitochondria.

METHODS AND RESULTS

Here, we report mitomiR let-7a regulates mitochondrial transcription in breast cancer cells and reprogram the metabolism accordingly. These effects were mediated through the interaction of let-7a with mtDNA, as studied by RNA pull-down assays, altering the activity of Complex I in a cell line-specific manner. Our study, for the first time, identifies the role of mitomiR (let-7a) in regulating the mitochondrial genome by transcriptional repression and its contribution to regulating mitochondrial metabolism of breast cancer cells.

CONCLUSION

These findings uncover a novel mechanism by which mitomiR regulates mitochondrial transcription.

Mitochondrial complex II and V activity is enhanced in pediatric acute myeloid leukemia

BACKGROUND

Mitochondrial bioenergetic alterations are commonly observed metabolic adaptation in malignancies including acute myeloid leukemia (AML). Mitochondrial DNA alterations are well known in pediatric AML with possible prognostic significance; however, mitochondrial complex activity and its impact on disease outcome have not been previously explored. The aim of this study was to evaluate the mitochondrial complex II and complex V activity and its prognostic significance in pediatric AML patients.

METHODS

Consecutive 82 de novo pediatric (≤18 years) patients with AML were included in the study along with age and sex matched controls. Bone marrow mononuclear cells were isolated from baseline bone marrow samples from all patients and controls. DNA, RNA and proteins were extracted and relative expression of mitochondrial biogenesis genes TFAM, POLG, POLRMT were estimated along with mitochondrial DNA copy number. The mitochondrial complex II and V enzymes were immunocaptured and their activity was measured by substrate specific absorbance change by kinetic ELISA. The mitochondrial complex II and V activity was compared with controls and their association with clinico-pathological features and survival outcome were analysed. Complex activity was also correlated with relative expression of biogenesis genes.

RESULTS

The activity of mitochondrial complex II and V were found to be significantly enhanced (P = 0.010 and P = 0.0013 respectively) in pediatric AML patients compared to controls. The activity of mitochondrial complex II and V showed significant positive correlation with relative gene expression of mitochondrial biogenesis genes TFAM (P = 0.001 and P = 0.016 respectively) and POLG (P = 0.005 and P = 0.006 respectively). Neither of the two complex activities showed any significant association with baseline disease demographics or any clinico-pathological feature. Furthermore, the complex II and V activity did not show any impact on event free survival (P = 0.25 and P = 0.24 respectively) and overall survival (P = 0.14 and P = 0.17 respectively) in our cohort.

CONCLUSION

The activity of both mitochondrial complex II and V are significantly elevated in bone marrow mononuclear cells of children with AML compared to controls. The enhanced activity may be related to upregulation of mitochondrial biogenesis genes TFAM and POLG. The enhanced activity of either of the complexes did not impact disease biology or survival outcomes in pediatric AML.

Engineering Mitochondriotropic Carbon Dots for Targeting Cancer Cells

Aiming to understand and enhance the capacity of carbon dots (CDs) to transport through cell membranes and target subcellular organelles—in particular, mitochondria—a series of nitrogen-doped CDs were prepared by the one-step microwave-assisted pyrolysis of citric acid and ethylenediamine. Following optimization of the reaction conditions for maximum fluorescence, functionalization at various degrees with alkylated triphenylphosphonium functional groups of two different alkyl chain lengths afforded a series of functionalized CDs that exhibited either lysosome or mitochondria subcellular localization. Further functionalization with rhodamine B enabled enhanced fluorescence imaging capabilities in the visible spectrum and allowed the use of low quantities of CDs in relevant experiments. It was thus possible, by the appropriate selection of the alkyl chain length and degree of functionalization, to attain successful mitochondrial targeting, while preserving non-toxicity and biocompatibility. In vitro cell experiments performed on normal as well as cancer cell lines proved their non-cytotoxic character and imaging potential, even at very low concentrations, by fluorescence microscopy. Precise targeting of mitochondria is feasible with carefully designed CDs that, furthermore, are specifically internalized in cells and cell mitochondria of high transmembrane potential and thus exhibit selective uptake in malignant cells compared to normal cells.

Probing the Hidden Role of Mitochondrial DNA Damage and Dysfunction in the Etiology of Aristolochic Acid Nephropathy

Aristolochic acid nephropathy (AAN) is a unique type of progressive renal interstitial fibrotic disease caused by prolonged exposure to aristolochic acids (AAs) through AA-containing herbal medicines or AA-tainted food. Despite decades of research and affecting millions of people around the world, the pathophysiology of AAN remains incompletely understood. In this study, we tested the potential causative role of mitochondrial dysfunction in AAN development. Our findings revealed AA exposure induces an exposure concentration and duration dependent lowering of adenosine triphosphate in both cultured human kidney and liver cells, highlighting an AA exposure effect on mitochondrial energy production in the kidney and liver, which both are highly metabolically active and energy-demanding organs. Analysis with liquid chromatography-tandem mass spectrometry coupled with stable isotope dilution method detected high levels of mutagenic 8-oxo-2'-deoxyguanosine and 7-(deoxyadenosine-N⁶-yl)-aristolactam adduct on mitochondrial DNA isolated from AA-treated cells, unmasking a potentially important causative, but previously unknown role of mitochondrial DNA mutation in the pathophysiology of AAN development.

Characterization of G4 DNA formation in mitochondrial DNA and their potential role in mitochondrial genome instability

Mitochondria possess their own genome which can be replicated independently of nuclear DNA. Mitochondria being the powerhouse of the cell produce reactive oxygen species, due to which the mitochondrial genome is frequently exposed to oxidative damage. Previous studies have demonstrated an association of mitochondrial deletions to aging and human disorders. Many of these deletions were present adjacent to non-B DNA structures. Thus, we investigate noncanonical structures associated with instability in mitochondrial genome. In silico studies revealed the presence of > 100 G-quadruplex motifs (of which 5 have the potential to form 3-plate G4 DNA), 23 inverted repeats, and 3 mirror repeats in the mitochondrial DNA (mtDNA). Further analysis revealed that among the deletion breakpoints from patients with mitochondrial disorders, majority are located at G4 DNA motifs. Interestingly, ~ 50% of the deletions were at base-pair positions 8271-8281, ~ 35% were due to deletion at 12362-12384, and ~ 12% due to deletion at 15516-15545. Formation of 3-plate G-quadruplex DNA structures at mitochondrial fragile regions was characterized using electromobility shift assay, circular dichroism (CD), and Taq polymerase stop assay. All 5 regions could fold into both intramolecular and intermolecular G-quadruplex structures in a KCl-dependent manner. G4 DNA formation was in parallel orientation, which was abolished in the presence of LiCl. The formation of G4 DNA affected both replication and transcription. Finally, immunolocalization of BG4 with MitoTracker confirmed the formation of G-quadruplex in mitochondrial genome. Thus, we characterize the formation of 5 different G-quadruplex structures in human mitochondrial region, which may contribute toward formation of mitochondrial deletions.

Dual-Targeting Polymeric Nanocarriers to Deliver ROS-Responsive Prodrugs and Combat Multidrug Resistance of Cancer Cells

Targeting delivery of anticancer drugs that can interact with DNA into mitochondria of cancer cells has been demonstrated to be an effective method to combat drug resistance. In this report, a cancer cell and mitochondria dual-targeting drug delivery system (DT-NP) is presented based on nanoparticles self-assembled from amphiphilic block copolymers with pH-responsive release of cinnamaldehyde (CA), which is used to encapsulate reactive oxygen species (ROS)-activable prodrug, phenylboronic pinacol ester-caged doxorubicin (BDOX). The surfaces of nanoparticles are conjugated by cancer cell-targeting folic acid (FA) and mitochondria-targeting triphenyl phosphonium (TPP) for dual targeting delivery. After incubation of DT-NP with multidrug-resistant breast cancer cells MCF-7/ADR, CA release under acidic conditions in endosomes from DT-NP can effectively induce intracellular oxidative stress improvement, especially in mitochondria. After targeting drug delivery into mitochondria, high level of ROS in mitochondria can in situ activate BDOX to interact with mitochondrial DNA and induce cell apoptosis. DT-NP displays a remarkably higher cancer cell killing effect on MCF-7/ADR as compared with DOX. Accordingly, DT-NP shows great potentials toward multidrug-resistant cancers as dual-targeting drug delivery systems with intracellular oxidative stress improvement and ROS-responsive prodrug activation in mitochondria.

Transmission electron microscopy of the liver mitochondria of N-Nitrosodibutylamine-treated mice

N-Nitrosodibutylamine (DBN) has been found in a wide variety of products because of the nitrosation of amines present in these products. An extensive series of synthesis and carcinogenicity studies of various compounds related to DBN and its metabolites have revealed that they have markedly different carcinogenic effects. The role of mitochondria in disease has been found to be expanded beyond the respiratory chain, as defects in additional mitochondrial functions and behaviors have been linked to cancer, metabolic disorders, and many neurodegenerative diseases, such as Alzheimer's, Parkinson's, and Huntington's disease (Nunnari & Suomalainen (2012) Cell, 148, 1145-1159). The sample preparation was performed using the protocol standardized by Sophisticated Analytical Instrumentation Facility (SAIF) laboratory in NEHU. The prepared sample was then mounted and observed under the transmission electron microscope model JEM-100 CC II. The micrographs obtained from transmission electron microscopy (TEM) at various magnifications 2,000, 5,000, and 12,000× from DBN-treated mice showed significant changes. Mitochondria showed variability in number, size, and shape. This significant alteration in the morphology and population of liver mitochondria observed in DBN-treated animals in comparison to that of the age-matched normal control mice provide a unique potential for the use of mitochondria as markers for the early detection for the treatment of liver cancer.

The role of mitochondrial oxidative stress and the tumor microenvironment in radiation-related cancer

The health risks associated with low-dose radiation, which are a major concern after the Fukushima Daiichi nuclear power plant accident (the Fukushima accident), have been extensively investigated, and the cancer risks from low-dose radiation exposure (below ~ 100 mSv) are thought to be negligible. According to World Health Organization and the United Nations Scientific Committee on the Effects of Atomic Radiation reports, the level of radiation exposure from the Fukushima accident is limited, estimating no significant increased risk from the accident. Radiation-induced cell injury is mainly caused by oxidative damage to biomolecules, including DNA, lipids and proteins. Radiation stimulates metabolic activation within the mitochondria to provide energy for the DNA damage response. Mitochondrial respiratory chain complexes I and III are the most important intracellular source of reactive oxygen species (ROS) during oxidative phosphorylation in eukaryotic cells. Manganese superoxide dismutase and glutathione are key players in redox control within cells. However, perturbation of the antioxidant response leads to chronic oxidative stress in irradiated cells. Excess ROS of mitochondrial origin is reported in cancer-associated fibroblast and promotes carcinogenesis. The aim of this review paper is to discuss critical roles of mitochondria in radiation-related cancer by introducing our recent studies. In particular, elevated mitochondrial ROS in stromal fibroblasts potentiate transforming growth factor-beta (TGF-β) signaling, which triggers smooth muscle actin (α-SMA) expression to stimulate myofibroblast differentiation. Radiation-induced myofibroblasts promote tumor growth by enhancing angiogenesis. Thus, radiation affects both malignant cancer cells and neighboring stromal cells through secretion of soluble factors.

Dye-free spectrophotometric measurement of nucleic acid-to-protein ratio for cell-selective extracellular vesicle discrimination

Extracellular vesicles (EVs) can represent a novel source of disease biomarkers, and are under intensive study for their clinical potential. Most EV-based cancer diagnostic studies have focused on establishing EV assays that detect increased expression of a single cancer-associated marker or marker signatures based on multiplex detection of these biomarkers. EV biomarker readouts can be obscured by high background signal leading to false positives, and may markedly differ between analyses due to variation in sample purity during EV isolation. This can obstruct the comparisons among studies and lead to conflicting conclusions. This work reports that the nucleic acid to protein UV absorption ratio of an EV is a cell-specific EV characteristic. This EV collective attribute can be measured at low-cost to discriminate EVs derived from malignant and non-malignant cells rather than employing single markers that may be cancer- or subtype-specific. Our work also highlighted the application for accessing purity in EV preparations irrelevant to EV yield. It can be employed to distinguish from patients with and without malignant disease upon analysis of EVs isolated from their serum samples.

Mitochondrial genome stability in human: understanding the role of DNA repair pathways

Mitochondria are semiautonomous organelles in eukaryotic cells and possess their own genome that replicates independently. Mitochondria play a major role in oxidative phosphorylation due to which its genome is frequently exposed to oxidative stress. Factors including ionizing radiation, radiomimetic drugs and replication fork stalling can also result in different types of mutations in mitochondrial DNA (mtDNA) leading to genome fragility. Mitochondria from myopathies, dystonia, cancer patient samples show frequent mtDNA mutations such as point mutations, insertions and large-scale deletions that could account for mitochondria-associated disease pathogenesis. The mechanism by which such mutations arise following exposure to various DNA-damaging agents is not well understood. One of the well-studied repair pathways in mitochondria is base excision repair. Other repair pathways such as mismatch repair, homologous recombination and microhomology-mediated end joining have also been reported. Interestingly, nucleotide excision repair and classical nonhomologous DNA end joining are not detected in mitochondria. In this review, we summarize the potential causes of mitochondrial genome fragility, their implications as well as various DNA repair pathways that operate in mitochondria.

Mechanism and application of metformin in kidney diseases: An update

Metformin is an oral antihyperglycemic drug widely used to treat type 2 diabetes mellitus (T2DM), acting via indirect activation of 5' Adenosine monophosphate-activated Protein Kinase (AMPK). Beyond the anti-diabetic effect, accumulative pieces of evidence have revealed that metformin also everts a beneficial effect in diverse kidney diseases. In various acute kidney diseases (AKI) animal models, metformin protects renal tubular cells from inflammation, apoptosis, reactive oxygen stress (ROS), endoplasmic reticulum (ER) stress, epithelial-mesenchymal transition (EMT) via AMPK activation. In diabetic kidney disease (DKD), metformin also alleviates podocyte loss, mesangial cells apoptosis, and tubular cells senescence through AMPK-mediated signaling pathways. Besides, metformin inhibits cystic fibrosis transmembrane conductance regulator (CFTR)-mediated fluids secretion and the mammalian target of rapamycin (mTOR)-involved cyst formation negatively regulated by AMPK in autosomal dominant polycystic kidney disease (APDKD). Furthermore, metformin also contributes to the alleviation of urolithiasis and renal cell carcinoma (RCC). As the common pathway for chronic kidney disease (CKD) progressing towards end-stage renal disease (ESRD), renal fibrosis is ameliorated by metformin, to a great extent dependent on AMPK activation. However, clinical data are not always consistent with preclinical data, some clinical investigations showed the unmeaningful even detrimental effect of metformin on T2DM patients with kidney diseases. Most importantly, metformin-associated lactic acidosis (MALA) is a vital issue restricting the application of metformin. Thus, we conclude the application of metformin in kidney diseases and uncover the underlying molecular mechanisms in this review.

Mitochondrial impairments in aetiopathology of multifactorial diseases: common origin but individual outcomes in context of 3P medicine

Mitochondrial injury plays a key role in the aetiopathology of multifactorial diseases exhibiting a "vicious circle" characteristic for pathomechanisms of the mitochondrial and multi-organ damage frequently developed in a reciprocal manner. Although the origin of the damage is common (uncontrolled ROS release, diminished energy production and extensive oxidative stress to life-important biomolecules such as mtDNA and chrDNA), individual outcomes differ significantly representing a spectrum of associated pathologies including but not restricted to neurodegeneration, cardiovascular diseases and cancers. Contextually, the role of predictive, preventive and personalised (PPPM/3P) medicine is to introduce predictive analytical approaches which allow for distinguishing between individual outcomes under circumstance of mitochondrial impairments followed by cost-effective targeted prevention and personalisation of medical services. Current article considers innovative concepts and analytical instruments to advance management of mitochondriopathies and associated pathologies.

The Role of Mitochondria in the Chemoresistance of Pancreatic Cancer Cells

The first-line chemotherapies for patients with unresectable pancreatic cancer (PC) are 5-fluorouracil (5-FU) and gemcitabine therapy. However, due to chemoresistance the prognosis of patients with PC has not been significantly improved. Mitochondria are essential organelles in eukaryotes that evolved from aerobic bacteria. In recent years, many studies have shown that mitochondria play important roles in tumorigenesis and may act as chemotherapeutic targets in PC. In addition, according to recent studies, mitochondria may play important roles in the chemoresistance of PC by affecting apoptosis, metabolism, mtDNA metabolism, and mitochondrial dynamics. Interfering with some of these factors in mitochondria may improve the sensitivity of PC cells to chemotherapeutic agents, such as gemcitabine, making mitochondria promising targets for overcoming chemoresistance in PC.

Synthesis, Anticancer, and Antibacterial Activity of Betulinic and Betulonic Acid C-28-Triphenylphosphonium Conjugates with Variable Alkyl Linker Length

BACKGROUND

Conjugation of triterpenoids such as betulinic acid 1 with the Triphenylphosphonium (TPP) group is a powerful approach to generating medicinal compounds. Their development proposes structure optimization in respect of availability and activity towards target cells and organelles. Selection of 1 or its precursor betulonic acid 2 and the optimal linker is of particular importance for drug candidate identification among the TPP-triterpenoid conjugates.

OBJECTIVE

In this study, new C-28-TPP conjugated derivatives of 1 and 2 with the alkyl/alkoxyalkyl linkers of variable length were synthesized and compared regarding their anticancer, antibacterial, and mitochondriatargeted effects.

METHODS

The TPP conjugates of 1 and 2 [6a-f, 7a-f] were synthesized by the reaction of halogenalkyl esters [3a-f, 4a-f, 5] with triphenylphosphine in acetonitrile upon heating. Cytotoxicity (MTT assay), antibacterial activity (microdilution assay), and mitochondrial effects (flow cytofluorometry) were studied.

RESULTS

Conjugation with the TPP group greatly increased the cytotoxicity of the triterpenoids up to 30 times. The conjugates were up to 10-17 times more active against MCF-7 (IC50 = 0.17μM, 72h, 6c) and PC-3 (IC50 = 0.14μM, 72h, 6a) cancer cells than for human skin fibroblasts. The enhanced antibacterial (bactericidal) activity of the TPP-triterpenoid conjugates with MIC for Gram-positive bacteria as low as 2μM (6a, 7a) was for the first time revealed. The conjugates were found to effectively inhibit fluorescence of 2′,7′-dichlorofluorescin probe in the cytosol upon oxidation, decrease transmembrane potential, and increase superoxide radical level in mitochondria.

CONCLUSION

Relationships between the effects and structure of the TPP-triterpenoid conjugates were evaluated and discussed. Based on the results, 6a can be selected for further preclinical investigation as a potential anticancer compound.