OXPHOS-targeting drugs in oncology: new perspectives

Oxidative Phosphorylation Is a Metabolic Vulnerability of Endocrine Therapy-Tolerant Persister Cells in ER+ Breast Cancer

Despite adjuvant treatment with endocrine therapies, estrogen receptor-positive (ER+) breast cancers recur in a significant proportion of patients. Recurrences are attributable to clinically undetectable endocrine-tolerant persister cancer cells that retain tumor-forming potential. Therefore, strategies targeting such persister cells may prevent recurrent disease. Using CRISPR-Cas9 genome-wide knockout screening in ER+ breast cancer cells, we identified a survival mechanism involving metabolic reprogramming with reliance upon mitochondrial respiration in endocrine-tolerant persister cells. Quantitative proteomic profiling showed reduced levels of glycolytic proteins in persisters. Metabolic tracing of glucose revealed an energy-depleted state in persisters, in which oxidative phosphorylation was required to generate ATP. A phase II clinical trial was conducted to evaluate changes in mitochondrial markers in primary ER+/HER2- breast tumors induced by neoadjuvant endocrine therapy (NCT04568616). In an analysis of tumor specimens from 32 patients, tumors exhibiting residual cell proliferation after aromatase inhibitor-induced estrogen deprivation with letrozole showed increased mitochondrial content. Genetic profiling and barcode lineage tracing showed that endocrine-tolerant persistence occurred stochastically without genetic predisposition. Pharmacologic inhibition of mitochondrial complex I suppressed the tumor-forming potential of persisters in mice and synergized with the antiestrogen drug fulvestrant to induce regression of patient-derived xenografts. These findings indicate that mitochondrial metabolism is essential in endocrine-tolerant persister ER+ breast cancer cells and warrant the development of treatment strategies to leverage this vulnerability for treating breast cancer. Significance: Persister cancer cells that survive endocrine therapy exhibit increased energetic dependence upon mitochondria for survival and tumor regrowth potential, indicating that therapies targeting this metabolic dependency could help prevent disease recurrence.

Exploring the role and application of mitochondria in radiation therapy

Mitochondria are pivotal in cellular energy metabolism, the oxidative stress response and apoptosis. Recent research has focused on harnessing their functions to enhance the efficacy of radiation therapy (RT). This review focuses on the critical functions and applications of mitochondria in radiation therapy, including the targeting of mitochondrial metabolism and the modulation of mitochondria-mediated cell death and immune responses. While these strategies have demonstrated considerable potential in preclinical studies to improve radiotherapy outcomes, challenges remain, such as optimizing drug delivery systems, ensuring safety and overcoming resistance to therapy.

Metabolic crossroads: unravelling immune cell dynamics in gastrointestinal cancer drug resistance

Metabolic reprogramming within the tumor microenvironment (TME) plays a critical role in driving drug resistance in gastrointestinal cancers (GI), particularly through the pathways of fatty acid oxidation and glycolysis. Cancer cells often rewire their metabolism to sustain growth and reshape the TME, creating conditions such as nutrient depletion, hypoxia, and acidity that impair antitumor immune responses. Immune cells within the TME also undergo metabolic alterations, frequently adopting immunosuppressive phenotypes that promote tumor progression and reduce the efficacy of therapies. The competition for essential nutrients, particularly glucose, between cancer and immune cells compromises the antitumor functions of effector immune cells, such as T cells. Additionally, metabolic by-products like lactate and kynurenine further suppress immune activity and promote immunosuppressive populations, including regulatory T cells and M2 macrophages. Targeting metabolic pathways such as fatty acid oxidation and glycolysis presents new opportunities to overcome drug resistance and improve therapeutic outcomes in GI cancers. Modulating these key pathways has the potential to reinvigorate exhausted immune cells, shift immunosuppressive cells toward antitumor phenotypes, and enhance the effectiveness of immunotherapies and other treatments. Future strategies will require continued research into TME metabolism, the development of novel metabolic inhibitors, and clinical trials evaluating combination therapies. Identifying and validating metabolic biomarkers will also be crucial for patient stratification and treatment monitoring. Insights into metabolic reprogramming in GI cancers may have broader implications across multiple cancer types, offering new avenues for improving cancer treatment.

Hypoxia studies in non‑small cell lung cancer: Pathogenesis and clinical implications (Review)

Non‑small cell lung cancer (NSCLC) is one of the most prevalent and lethal types of cancers worldwide and its high incidence and mortality rates pose a significant public health challenge. Despite significant advances in targeted therapy and immunotherapy, the overall prognosis of patients with NSCLC remains poor. Hypoxia is a critical driving factor in tumor progression, influencing the biological behavior of tumor cells through complex molecular mechanisms. The present review systematically examined the role of the hypoxic microenvironment in NSCLC, demonstrating its crucial role in promoting tumor cell growth, invasion and metastasis. Additionally, it has been previously reported that the hypoxic microenvironment enhances tumor cell resistance by activating hypoxia‑inducible factor and regulating exosome secretion. The hypoxic microenvironment also enables tumor cells to adapt to low oxygen and nutrient‑deficient conditions by enhancing metabolic reprogramming, such as through upregulating glycolysis. Further studies have shown that the hypoxic microenvironment facilitates immune escape by modulating tumor‑associated immune cells and suppressing the antitumor response of the immune system. Moreover, the hypoxic microenvironment increases tumor resistance to radiotherapy, chemotherapy and other types of targeted therapy through various pathways, significantly reducing the therapeutic efficacy of these treatments. Therefore, it could be suggested that early detection of cellular hypoxia and targeted therapy based on hypoxia may offer new therapeutic approaches for patients with NSCLC. The present review not only deepened the current understanding of the mechanisms of action and role of the hypoxic microenvironment in NSCLC but also provided a solid theoretical basis for the future development of precision treatments for patients with NSCLC.

MITOCDNB DECREASES PLATELET ACTIVATION THROUGH ITS SELECTIVE ACTION ON MITOCHONDRIAL THIOREDOXIN REDUCTASE

Platelet inhibition is a fundamental objective to prevent and treat thrombus formation. Platelet activation depends on mitochondrial function. This study aims to identify a new mitochondria-targeting compound with antiplatelet activity at safe concentrations in vitro. Cytotoxicity and viability tests were performed on human platelets from volunteer donors, together with experiments on aggregation, platelet activation, mitochondrial function, mitochondrial respiration, and thioredoxin reductase 2 (TrxR2) enzymatic activity in isolated platelet mitochondria. The compound MitoCDNB, corresponding to the molecule 5-chloro-2,4-dinitrophenylamino linked with triphenylphosphonium cation (TPP+) by a butyl chain and methanesulfonate as the counterion, was evaluated. MitoCDNB demonstrates potent, high mitochondria-selective antiplatelet effects that provide a novel approach to platelet inhibition with potentially minimized systemic risks. Here, we describe the first compound that inhibits platelet activation by decreasing TrxR2 enzymatic activity and collagen-stimulated maximal mitochondrial respiration, preventing aggregation and platelet activation. These results can be used to develop new antiplatelet drugs targeting mitochondria.

Hybrid Cell Membrane-Coated Nanoparticles for Synergizing Sonodynamic Therapy and Immunotherapy against Triple-Negative Breast Cancer

Tumor immunotherapy represents a highly promising modality for the treatment of triple-negative breast cancer (TNBC). Nevertheless, its therapeutic efficacy has been profoundly impacted by challenges such as low drug uptake, hypoxia, and immunosuppression. To address these problems, the study develops a strategy combining sonodynamic therapy (SDT) and immunotherapy using biomimetic nanoparticles coated with hybrid membranes. The nanoparticles are loaded with semiconducting polymers (PFODBT), Atovaquone (ATO), and TMP195 to enhance biocompatibility, targeting ability, and drug uptake and retention at the tumor site. In in vitro experiments, the biomimetic nanoparticles alleviate hypoxia, induce immunogenic cell death (ICD), and prompt reprogramming of tumor-associated macrophages (TAMs) from M2 type to M1 type. In in vivo experiments, the synergistic effects of enhanced SDT-mediated ICD and TAMs repolarization significantly inhibit the proliferation of primary and distant tumor in the 4T1 subcutaneous tumor model, and effectively attenuated metastasis of lung and liver. Moreover, the in vivo immune responses are further activated by improving the maturation of dendritic cells, filtration of CD8+ T cells, and depletion of regulatory T cells. This study offers a novel strategy for TNBC therapy by converting the tumor microenvironment from the "cold" into "hot" tumor through multiple synergistic therapies.

Targeting pivotal amino acids metabolism for treatment of leukemia

Metabolic reprogramming is a crucial characteristic of cancer, allowing cancer cells to acquire metabolic properties that support their survival, immune evasion, and uncontrolled proliferation. Consequently, targeting cancer metabolism has become an essential therapeutic strategy. Abnormal amino acid metabolism is not only a key aspect of metabolic reprogramming but also plays a significant role in chemotherapy resistance and immune evasion, particularly in leukemia. Changes in amino acid metabolism in tumor cells are typically driven by a combination of signaling pathways and transcription factors. Current approaches to targeting amino acid metabolism in leukemia include inhibiting amino acid transporters, blocking amino acid biosynthesis, and depleting specific amino acids to induce apoptosis in leukemic cells. Different types of leukemic cells rely on the exogenous supply of specific amino acids, such as asparagine, glutamine, arginine, and tryptophan. Therefore, disrupting the supply of these amino acids may represent a vulnerability in leukemia. This review focuses on the pivotal role of amino acids in leukemia metabolism, their impact on leukemic stem cells, and their therapeutic potential.

Tumor energy metabolism: implications for therapeutic targets

Tumor energy metabolism plays a crucial role in the occurrence, progression, and drug resistance of tumors. The study of tumor energy metabolism has gradually become an emerging field of tumor treatment. Recent studies have shown that epigenetic regulation is closely linked to tumor energy metabolism, influencing the metabolic remodeling and biological traits of tumor cells. This review focuses on the primary pathways of tumor energy metabolism and explores therapeutic strategies to target these pathways. It covers key areas such as glycolysis, the Warburg effect, mitochondrial function, oxidative phosphorylation, and the metabolic adaptability of tumors. Additionally, this article examines the role of the epigenetic regulator SWI/SNF complex in tumor metabolism, specifically its interactions with glucose, lipids, and amino acids. Summarizing therapeutic strategies aimed at these metabolic pathways, including inhibitors of glycolysis, mitochondrial-targeted drugs, exploitation of metabolic vulnerabilities, and recent developments related to SWI/SNF complexes as potential targets. The clinical significance, challenges, and future directions of tumor metabolism research are discussed, including strategies to overcome drug resistance, the potential of combination therapy, and the application of new technologies.

Metabolic regulation of the immune system in health and diseases: mechanisms and interventions

Metabolism, including glycolysis, oxidative phosphorylation, fatty acid oxidation, and other metabolic pathways, impacts the phenotypes and functions of immune cells. The metabolic regulation of the immune system is important in the pathogenesis and progression of numerous diseases, such as cancers, autoimmune diseases and metabolic diseases. The concept of immunometabolism was introduced over a decade ago to elucidate the intricate interplay between metabolism and immunity. The definition of immunometabolism has expanded from chronic low-grade inflammation in metabolic diseases to metabolic reprogramming of immune cells in various diseases. With immunometabolism being proposed and developed, the metabolic regulation of the immune system can be gradually summarized and becomes more and more clearer. In the context of many diseases including cancer, autoimmune diseases, metabolic diseases, and many other disease, metabolic reprogramming occurs in immune cells inducing proinflammatory or anti-inflammatory effects. The phenotypic and functional changes of immune cells caused by metabolic regulation further affect and development of diseases. Based on experimental results, targeting cellular metabolism of immune cells becomes a promising therapy. In this review, we focus on immune cells to introduce their metabolic pathways and metabolic reprogramming, and summarize how these metabolic pathways affect immune effects in the context of diseases. We thoroughly explore targets and treatments based on immunometabolism in existing studies. The challenges of translating experimental results into clinical applications in the field of immunometabolism are also summarized. We believe that a better understanding of immune regulation in health and diseases will improve the management of most diseases.

Endocrine persistence in ER+ breast cancer is accompanied by metabolic vulnerability in oxidative phosphorylation

Despite adjuvant treatment with endocrine therapies, estrogen receptor-positive (ER+) breast cancers recur in a significant proportion of patients. Recurrences are attributable to clinically undetectable endocrine-tolerant persister cancer cells that retain tumor-forming potential. Therefore, strategies targeting such persister cells may prevent recurrent disease. Using CRISPR-Cas9 genome-wide knockout screening in ER+ breast cancer cells, we identified a survival mechanism involving metabolic reprogramming with reliance upon mitochondrial respiration in endocrine-tolerant persister cells. Quantitative proteomic profiling showed reduced levels of glycolytic proteins in persisters. Metabolic tracing of glucose revealed an energy-depleted state in persisters where oxidative phosphorylation was required to generate ATP. A phase II clinical trial was conducted to evaluate changes in mitochondrial markers in primary ER+/HER2-breast tumors induced by neoadjuvant endocrine therapy ( NCT04568616 ). In an analysis of tumor specimens from 32 patients, tumors exhibiting residual cell proliferation after aromatase inhibitor-induced estrogen deprivation with letrozole showed increased mitochondrial content. Genetic profiling and barcode lineage tracing showed that endocrine-tolerant persistence occurred stochastically without genetic predisposition. Mice bearing cell line- and patient-derived xenografts were used to measure the anti-tumor effects of mitochondrial complex I inhibition in the context of endocrine therapy. Pharmacological inhibition of complex I suppressed the tumor-forming potential of persisters and synergized with the anti-estrogen fulvestrant to induce regression of patient-derived xenografts. These findings indicate that mitochondrial metabolism is essential in endocrine-tolerant persister ER+ breast cancer cells and warrant the development of treatment strategies to leverage this vulnerability in the context of endocrine-sensitive disease.

Statement of Significance

Endocrine-tolerant persister cancer cells that survive endocrine therapy can cause recurrent disease. Persister cells exhibit increased energetic dependence upon mitochondria for survival and tumor re-growth potential.

Synthesis, Characterization, In Vitro Anticancer Evaluation, ADMET Properties, and Molecular Docking of Novel 5-Sulfanyl Substituted (Thiazol-4-yl)-Phosphonium Salts

Seven TPP+ new 5-sulfanyl substituted (thiazol-4-yl) phosphonium salts functionalized with different substituents were designed, synthesized, and studied against the NCI-60 human cancer cell lines. Compounds 1-4 show the total average parameters GI50=0.7-2.7 μM, TGI=7.0-14.6 μM, and LC50=25.2-41.8 μM, and compounds 5-7 show GI50=0.3-0.5 μM, TGI=1.3-3.1 μM, and LC50=3.6-4.0 μM. The most active compound 7 demonstrated the best anticancer results against leukemia (K-562, GI50=0.141 μM; RPMI-8226, GI50=0.143 μM), ovarian cancer (NCI/ADR-RES, GI50=0.142 μM), breast cancer (HS578T, GI50=0.175 μM; MDA-MB-468, GI50=0.101 μM), melanoma (SK-MEL-5, GI50=0.155 μM), and colon cancer (COLO 205, GI50=0.163 μM). All compounds showed low cytotoxicity against the leukemia subpanel (LC50>100 μM). The SAR analysis reveals the critical role of the substitutes at the thiazole C2 and C5 positions. Adding the phenyl, p-tolyl, or 4-chlorophenyl group to the C2 position in compounds 5-7 increases anticancer effectiveness. According to the NCI COMPARE analysis, compounds 2-3 showed a very high (r=0.92, 0.81) correlation with morpholino-doxorubicin. Molecular docking-analyzing the antitumor mechanism of compounds 1-4 action demonstrated that the DNA chain is a probable biotarget. The ADMET analysis acknowledges the favorable prognosis using compounds as potential anticancer agents.

A Mitochondria-Targeting SIRT3 Inhibitor with Activity against Diffuse Large B Cell Lymphoma

Diffuse large B-cell lymphomas (DLBCLs) are heterogeneous cancers that still require better and less toxic treatments. SIRT3, a member of the sirtuin family of NAD+-dependent protein deacylase, is critical for DLBCL growth and survival. A mitochondria-targeted SIRT3 small-molecule inhibitor, YC8-02, exhibits promising activity against DLBCL. However, YC8-02 has several limitations including poor solubility. Here, we report our medicinal chemistry efforts that led to an improved mitochondria-targeted SIRT3 inhibitor, SJ-106C, achieved by using a triethylammonium group, which helps to increase both solubility and SIRT3 inhibition potency. SJ-106C, while still inhibiting SIRT1 and SIRT2, is enriched in the mitochondria to help with SIRT3 inhibition. It is more active against DLBCL than other solid tumor cells and effectively inhibits DLBCL xenograft tumor growth. The findings provide useful insights for the development of SIRT3 inhibitors and mitochondrial targeting agents and further support the notion that SIRT3 is a promising druggable target for DLBCL.

Mitochondrial dysfunction in sepsis: mechanisms and therapeutic perspectives

Sepsis is a severe medical condition characterized by a systemic inflammatory response, often culminating in multiple organ dysfunction and high mortality rates. In recent years, there has been a growing recognition of the pivotal role played by mitochondrial damage in driving the progression of sepsis. Various factors contribute to mitochondrial impairment during sepsis, encompassing mechanisms such as reactive nitrogen/oxygen species generation, mitophagy inhibition, mitochondrial dynamics change, and mitochondrial membrane permeabilization. Damaged mitochondria actively participate in shaping the inflammatory milieu by triggering key signaling pathways, including those mediated by Toll-like receptors, NOD-like receptors, and cyclic GMP-AMP synthase. Consequently, there has been a surge of interest in developing therapeutic strategies targeting mitochondria to mitigate septic pathogenesis. This review aims to delve into the intricate mechanisms underpinning mitochondrial dysfunction during sepsis and its significant impact on immune dysregulation. Moreover, we spotlight promising mitochondria-targeted interventions that have demonstrated therapeutic efficacy in preclinical sepsis models.

Discovery of NFκB2-Coordinated Dual Regulation of Mitochondrial and Nuclear Genomes Leads to an Effective Therapy for Acute Myeloid Leukemia

Acute myeloid leukemia (AML) has a poor survival rate for both pediatric and adult patients due to its frequent relapse. To elucidate the bioenergetic principle underlying AML relapse, we investigated the transcriptional regulation of mitochondrial-nuclear dual genomes responsible for metabolic plasticity in treatment-resistant blasts. Both the gain and loss of function results demonstrated that NFκB2, a noncanonical transcription factor (TF) of the NFκB (nuclear factor kappa-light-chain-enhancer of activated B cells) family, can control the expression of TFAM (mitochondrial transcription factor A), which is known to be essential for metabolic biogenesis. Furthermore, genetic tracking and promoter assays revealed that NFκB2 is in the mitochondria and can bind the specific "TTGGGGGGTG" region of the regulatory D-loop domain to activate the light-strand promoter (LSP) and heavy-strand promoter 1 (HSP1), promoters of the mitochondrial genome. Based on our discovery of NFκB2's novel function of regulating mitochondrial-nuclear dual genomes, we explored a novel triplet therapy including inhibitors of NFκB2, tyrosine kinase, and mitochondrial ATP synthase that effectively eliminated primary AML blasts with mutations of the FMS-related receptor tyrosine kinase 3 (FLT3) and displayed minimum toxicity to control cells ex vivo. As such, effective treatments for AML must include strong inhibitory actions on the dual genomes mediating metabolic plasticity to improve leukemia prognosis.

Exploring the mystery of tumor metabolism: Warburg effect and mitochondrial metabolism fighting side by side

The metabolic reconfiguration of tumor cells constitutes a pivotal aspect of tumor proliferation and advancement. This study delves into two primary facets of tumor metabolism: the Warburg effect and mitochondrial metabolism, elucidating their contributions to tumor dominance. The Warburg effect facilitates efficient energy acquisition by tumor cells through aerobic glycolysis and lactic acid fermentation, offering metabolic advantages conducive to growth and proliferation. Simultaneously, mitochondrial metabolism, serving as the linchpin of sustained tumor vitality, orchestrates the tricarboxylic acid cycle and electron transport chain, furnishing a steadfast and dependable wellspring of biosynthesis for tumor cells. Regarding targeted therapy, this discourse examines extant strategies targeting tumor glycolysis and mitochondrial metabolism, underscoring their potential efficacy in modulating tumor metabolism while envisaging future research trajectories and treatment paradigms in the realm of tumor metabolism. By means of a thorough exploration of tumor metabolism, this study aspires to furnish crucial insights into the regulation of tumor metabolic processes, thereby furnishing valuable guidance for the development of novel therapeutic modalities. This comprehensive deliberation is poised to catalyze advancements in tumor metabolism research and offer novel perspectives and pathways for the formulation of cancer treatment strategies in the times ahead.

Identification of TEFM as a potential therapeutic target for LUAD treatment

BACKGROUND

Molecularly targeted therapies have recently become a hotspot in the treatment of LUAD, with ongoing efforts to identify new effective targets due to individual variability. Among these potential targets, the mitochondrial transcription elongation factor (TEFM) stands out as a crucial molecule involved in mitochondrial synthetic transcriptional processing. Dysregulation of TEFM has been implicated in the development of various diseases; however, its specific role in LUAD remains unclear.

METHODS

We conducted a comprehensive analysis of TEFM expression in LUAD, leveraging data from the TCGA database. Subsequently, we validated these findings using clinical specimens obtained from the First Affiliated Hospital of Soochow University, employing western blotting and qRT-PCR techniques. Further experimental validation was performed through the transfection of cells with TEFM overexpression, knockdown, and knockout lentiviruses. The effects of TEFM on LUAD were evaluated both in vitro and in vivo using a range of assays, including CCK-8, colony formation, EdU incorporation, Transwell migration, Tunel assay, flow cytometry, JC-1 staining, and xenograft tumour models.

RESULTS

Our investigation uncovered that TEFM exhibited elevated expression levels in LUAD and exhibited co-localization with mitochondria. Overexpression of TEFM facilitated malignant processes in LUAD cells, whereas its silencing notably curbed these behaviors and induced mitochondrial depolarization, along with ROS production, culminating in apoptosis. Moreover, the absence of TEFM substantially influenced the expression of mitochondrial transcripts and respiratory chain complexes. Results from nude mouse xenograft tumors further validated that inhibiting TEFM expression markedly hindered tumor growth.

CONCLUSION

TEFM promotes LUAD malignant progression through the EMT pathway and determines apoptosis by affecting the expression of mitochondrial transcripts and respiratory chain complexes, providing a new therapeutic direction for LUAD-targeted therapy.

Decoding mitochondria's role in immunity and cancer therapy

The functions of mitochondria, including energy production and biomolecule synthesis, have been known for a long time. Given the rising incidence of cancer, the role of mitochondria in cancer has become increasingly popular. Activated by components released by mitochondria, various pathways interact with each other to induce immune responses to protect organisms from attack. However, mitochondria play dual roles in the progression of cancer. Abnormalities in proteins, which are the elementary structures of mitochondria, are closely linked with oncogenesis. Both the aberrant accumulation of intermediates and mutations in enzymes result in the generation and progression of cancer. Therefore, targeting mitochondria to treat cancer may be a new strategy. Several drugs aimed at inhibiting mutated enzymes and accumulated intermediates have been tested clinically. Here, we discuss the current understanding of mitochondria in cancer and the interactions between mitochondrial functions, immune responses, and oncogenesis. Furthermore, we discuss mitochondria as hopeful targets for cancer therapy, providing insights into the progression of future therapeutic strategies.

DPEP Inhibits Cancer Cell Glucose Uptake, Glycolysis and Survival by Upregulating Tumor Suppressor TXNIP

We have designed cell-penetrating peptides that target the leucine zipper transcription factors ATF5, CEBPB and CEBPD and that promote apoptotic death of a wide range of cancer cell types, but not normal cells, in vitro and in vivo. Though such peptides have the potential for clinical application, their mechanisms of action are not fully understood. Here, we show that one such peptide, Dpep, compromises glucose uptake and glycolysis in a cell context-dependent manner (in about two-thirds of cancer lines assessed). These actions are dependent on induction of tumor suppressor TXNIP (thioredoxin-interacting protein) mRNA and protein. Knockdown studies show that TXNIP significantly contributes to apoptotic death in those cancer cells in which it is induced by Dpep. The metabolic actions of Dpep on glycolysis led us to explore combinations of Dpep with clinically approved drugs metformin and atovaquone that inhibit oxidative phosphorylation and that are in trials for cancer treatment. Dpep showed additive to synergistic activities in all lines tested. In summary, we find that Dpep induces TXNIP in a cell context-dependent manner that in turn suppresses glucose uptake and glycolysis and contributes to apoptotic death of a range of cancer cells.

Studies on Autophagy and Apoptosis of Fibrosarcoma HT-1080 Cells Mediated by Chalcone with Indole Moiety

This study demonstrated the anticancer efficacy of chalcones with indole moiety (MIPP, MOMIPP) in fibrosarcoma cells for the first time. The results showed that MIPP and MOMIPP reduced the viability of HT-1080 cells in a concentration-dependent manner. MOMIPP was more active than MIPP in HT-1080 cells, showing lower IC50 values (3.67 vs. 29.90 μM). Both compounds at a concentration of 1 μM induced apoptosis in HT-1080 cells, causing death strictly related to caspase activation, as cell viability was restored when the caspase inhibitor Z-VAD was added. Reactive oxygen species production was approximately 3-fold higher than in control cells, and cotreatment with the inhibitor of mitochondrial ATPase oligomycin diminished this effect. Such effects were also reflected in mitochondrial dysfunction, including decreased membrane potential. Interestingly, the compounds that were studied caused massive vacuolization in HT-1080 cells. Immunocytochemical staining and TEM analysis showed that HT-1080 cells exhibited increased expression of the LC3-II protein and the presence of autophagosomes with a double membrane, respectively. Both compounds induced apoptosis, highlighting a promising link between autophagy and apoptosis. This connection could be a new target for therapeutic strategies to overcome chemoresistance, which is a significant cause of treatment failure and tumour recurrence in fibrosarcoma following traditional chemotherapy.

The troglitazone derivative EP13 disrupts energy metabolism through respiratory chain complex I inhibition in breast cancer cells and potentiates the antiproliferative effect of glycolysis inhibitors

BACKGROUND

The metabolism of cancer cells generally differs from that of normal cells. Indeed, most cancer cells have a high rate of glycolysis, even at normal oxygen concentrations. These metabolic properties can potentially be exploited for therapeutic intervention. In this context, we have developed troglitazone derivatives to treat hormone-sensitive and triple-negative breast cancers, which currently lack therapeutic targets, have an aggressive phenotype, and often have a worse prognosis than other subtypes. Here, we studied the metabolic impact of the EP13 compound, a desulfured derivative of Δ2-troglitazone that we synthetized and is more potent than its parent compounds.

METHODS

EP13 was tested on two triple-negative breast cancer cell lines, MDA-MB-231 and Hs578T, and on the luminal cell line MCF-7. The oxygen consumption rate (OCR) of the treated cell lines, Hs578T mammospheres and isolated mitochondria was measured using the XFe24 Seahorse analyser. ROS production was quantified using the MitoSOX fluorescent probe. Glycolytic activity was evaluated through measurement of the extracellular acidification rate (ECAR), glucose consumption and lactate production in extracellular medium. The synergistic effect of EP13 with glycolysis inhibitors (oxamate and 2-deoxyglucose) on cell cytotoxicity was established using the Chou-Talalay method.

RESULTS

After exposure to EP13, we observed a decrease in the mitochondrial oxygen consumption rate in MCF7, MDA-MB-231 and Hs578T cells. EP13 also modified the maximal OCR of Hs578T spheroids. EP13 reduced the OCR through inhibition of respiratory chain complex I. After 24 h, ATP levels in EP13-treated cells were not altered compared with those in untreated cells, suggesting compensation by glycolysis activity, as shown by the increase in ECAR, the glucose consumption and lactate production. Finally, we performed co-treatments with EP13 and glycolysis inhibitors (oxamate and 2-DG) and observed that EP13 potentiated their cytotoxic effects.

CONCLUSION

This study demonstrates that EP13 inhibits OXPHOS in breast cancer cells and potentiates the effect of glycolysis inhibitors.

Ursolic acid loaded tri-block copolymer nanoparticles based on triphenylphosphine for mitochondria-targeted cancer therapy

A novel biodegradable amphiphilic triblock copolymer, polyphosphate, polyethylene glycol, and polylactic acid (PAEEP-PEG-PLLA), was synthesized by twice ring-opening polymerization and triphenylphosphine (TPP) was grafted onto the block copolymer to synthesize a carrier material TPP-PAEEP-PEG-PLLA, which was identified by1H-nuclear magnetic resonance (1H-NMR) spectroscopy. The TPP-PAEEP-PEG-PLLA nanoparticles encapsulated with ursolic acid (UA) were prepared by the emulsion-solvent evaporation method and characterized by dynamic light scattering. The mitochondrial targeting ability of fluorescently labeled nanoparticles was evaluated by laser confocal microscopy. The average particle size and surface charge of the UA -loaded nanoparticle solution were 180.07 ± 1.67 nm and +15.57 ± 1.33 mV, respectively. The biocompatibility of nanoparticles was briefly evaluated by erythrocyte hemolysis assay.In vitrocell proliferation assay and scratch migration assay were performed to compare the difference in anti-tumor effect between UA and UA nanoparticles. The results showed that TPP-modified triblock copolymers had good mitochondrial targeting and improved the low bioavailability of UA, and UA nanoparticles exhibited more pronounced anti-tumor capabilities. In summary, the results suggested that our UA nanoparticles were a promising drug-targeted delivery system for the treatment of tumors.

Ovarian cancer cells regulate their mitochondrial content and high mitochondrial content is associated with a poor prognosis

Most cancer patients ultimately die from the consequences of distant metastases. As metastasis formation consumes energy mitochondria play an important role during this process as they are the most important cellular organelle to synthesise the energy rich substrate ATP, which provides the necessary energy to enable distant metastasis formation. However, mitochondria are also important for the execution of apoptosis, a process which limits metastasis formation. We therefore wanted to investigate the mitochondrial content in ovarian cancer cells and link its presence to the patient's prognosis in order to analyse which of the two opposing functions of mitochondria dominates during the malignant progression of ovarian cancer. Monoclonal antibodies directed against different mitochondrial specific proteins, namely heat shock proteins 60 (HSP60), fumarase and succinic dehydrogenase, were used in immunohistochemistry in preliminary experiments to identify the antibody most suited to detect mitochondria in ovarian cancer cells in clinical tissue samples. The clearest staining pattern, which even delineated individual mitochondria, was seen with the anti-HSP60 antibody, which was used for the subsequent clinical study staining primary ovarian cancers (n = 155), borderline tumours (n = 24) and recurrent ovarian cancers (n = 26). The staining results were semi-quantitatively scored into three groups according to their mitochondrial content: low (n = 26), intermediate (n = 50) and high (n = 84). Survival analysis showed that high mitochondrial content correlated with a statistically significant overall reduced survival rate In addition to the clinical tissue samples, mitochondrial content was analysed in ovarian cancer cells grown in vitro (cell lines: OVCAR8, SKOV3, OVCAR3 and COV644) and in vivo in severe combined immunodeficiency (SCID) mice.In in vivo grown SKOV3 and OVCAR8 cells, the number of mitochondria positive cells was markedly down-regulated compared to the in vitro grown cells indicating that mitochondrial number is subject to regulatory processes. As high mitochondrial content is associated with a poor prognosis, the provision of high energy substrates by the mitochondria seems to be more important for metastasis formation than the inhibition of apoptotic cell death, which is also mediated by mitochondria. In vivo and in vitro grown human ovarian cancer cells showed that the mitochondrial content is highly adaptable to the growth condition of the cancer cells.