Mitochondrial dynamics altered by oxidative stress in cancer

Unveiling the 4-aminoquinoline derivatives as potent agents against pancreatic ductal adenocarcinoma (PDAC) cell lines

Common antimalarials such as artemisinins, chloroquine and their derivatives also possess potent anti-inflamantory, antiviral and anticancer properties. In the search for new therapeutics to combat difficult-to-treat pancreatic carcinomas, we unveiled that 4-aminoquinoline derivatives, with significant antiplasmodial properties and a great safety profile in vivo, have remarkable anticancer activity against pancreatic ductal adenocarcinoma (PDAC) and considerable efficacy in the xenograft model in vivo. The aim of the present study was to further investigate anticancer properties of these compounds in a drug-repurposing manner. The compounds showed profound cytotoxic effects at nanomolar to low micromolar concentration in 2D cultured cells (in vitro) and in the zebrafish PDAC xenograft model (in vivo). A deeper insight into their mechanisms of cytotoxic action showed these compounds induce apoptosis while increasing reactive oxygen species levels along with autophagy inhibition. Additional investigation of the autophagy modulation proved that tested quinoline derivatives cause P62 and LC3-II accumulation in PDAC cells alongside lysosomal alkalinization. Further, in vivo toxicity studies in the zebrafish model showed low toxicity without developmental side effects of the investigated 4-aminoquinolines, while the applied compounds effectively inhibited tumor growth and prevented the metastasis of xenografted pancreatic cells. Taken together, these results highlight the 4-aminoquinolines as privileged structures that ought to be investigated further for potential application in pancreatic carcinoma treatment.

Probing the interaction of hesperidin showing antiproliferative activity in colorectal cancer cells and human hemoglobin

Hesperidin, a flavanone glycoside abundant in citrus is known to possess anti-carcinogenic properties. However, its main interaction with cancer cells and blood proteins is not well-studied yet. Here we have explored the interactions of hesperidin with human colorectal cancer cells, HCT116, and human hemoglobin (HHb) with several experimental and theoretical studies. Cellular assays showed that hesperidin interacted with colorectal cancer cells and induced membrane damage, colony formation inhibition, oxidative stress, mitochondrial dysfunction, Bax/Bcl-2, caspase-9, and caspase-3 upregulation, and cytochrome c release determined by cellular, qPCR and ELISA assays. The interaction of the hesperidin with HHb indicated the formation of a static complex mainly with the assistance of hydrogen bonds which lead to partial folding of protein determined by spectroscopy, molecular docking, and molecular dynamic studies. In conclusion, these findings show that hesperidin with potential binding affinity with a plasma protein model can also show promising anticancer activities against colorectal cancer cells.

The mitochondrial stress signaling tunes immunity from a view of systemic tumor microenvironment and ecosystem

Mitochondria play important roles in cell fate, calcium signaling, mitophagy, and the signaling through reactive oxygen species (ROS). Recently, mitochondria are considered as a signaling organelle in the cell and communicate with other organelles to constitute the mitochondrial information processing system (MIPS) that transduce input-to-output biological information. The success in immunotherapy, a concept of systemic therapy, has been proved to be dependent on paracrine interactions within the tumor microenvironment (TME) and distant organs including microbiota and immune components. We will adopt a broader view from the concept of TME to tumor micro- and macroenvironment (TM 2 E) or tumor-organ ecosystem (TOE). In this review, we will discuss the role of mitochondrial signaling by mitochondrial ROS, calcium flux, metabolites, mtDNA, vesicle transportation, and mitochondria-derived peptide in the TME and TOE, in particular immune regulation and effective cancer immunotherapy.

Effects of short-term exercise and endurance training on skeletal muscle mitochondria damage induced by particular matter, atmospherically relevant artificial PM2.5

Introduction

This study aimed to investigate the potential of short-term aerobic exercise to mitigate skeletal muscle mitochondrial damage following ambient PM2.5 exposure, and how 12 weeks of endurance training can enhance aerobic fitness to protect against such damage.

Methods

Twenty-four male C57BL/6 J mice were split into sedentary (SED, n = 12) and endurance training (ETR, n = 12) groups. The ETR group underwent 12 weeks of training (10-15 m/min, 60 min/day, 4 times/week), confirmed by an Endurance Exercise Capacity (EEC) test. Post-initial training, the SED group was further divided into SSED (SED and sedentary, n = 6) and SPE (SED and PM2.5 + Exercise, n = 6). Similarly, the ETR group was divided into EEX (ETR and Exercise, n = 6) and EPE (ETR and PM2.5 + Exercise, n = 6). These groups underwent 1 week of atmospherically relevant artificial PM2.5 exposure and treadmill running (3 times/week). Following treatments, an EEC test was conducted, and mice were sacrificed for blood and skeletal muscle extraction. Blood samples were analyzed for oxidative stress indicators, while skeletal muscles were assessed for mitochondrial oxidative metabolism, antioxidant capacity, and mitochondrial damage using western blot and transmission electron microscopy (TEM).

Results

After 12 weeks of endurance training, the EEC significantly increased (p < 0.000) in the ETR group compared to the SED group. Following a one-week comparison among the four groups with atmospherically relevant artificial PM2.5 exposure and exercise treatment post-endurance training, the EEX group showed improvements in EEC, oxidative metabolism, mitochondrial dynamics, and antioxidant functions. Conversely, these factors decreased in the EPE group compared to the EEX. Additionally, within the SPE group, exercise effects were evident in HK2, LDH, SOD2, and GPX4, while no impact of short-term exercise was observed in all other factors. TEM images revealed no evidence of mitochondrial damage in both the SED and EEX groups, while the majority of mitochondria were damaged in the SPE group. The EPE group also exhibited damaged mitochondria, although significantly less than the SPE group.

Conclusion

Atmospherically relevant artificial PM2.5 exposure can elevate oxidative stress, potentially disrupting the benefits of short-term endurance exercise and leading to mitochondrial damage. Nonetheless, increased aerobic fitness through endurance training can mitigate PM2.5-induced mitochondrial damage.

Protective Effects of Astaxanthin on Ochratoxin A-Induced Liver Injury: Effects of Endoplasmic Reticulum Stress and Mitochondrial Fission-Fusion Balance

Ochratoxin A (OTA), a common mycotoxin, can contaminate food and feed and is difficult to remove. Astaxanthin (ASTA), a natural antioxidant, can effectively protect against OTA-induced hepatotoxicity; however, its mechanism of action remains unclear. In the present study, we elucidate the protective effects of ASTA on the OTA-induced damage of the endoplasmic reticulum and mitochondria in broiler liver samples by serum biochemical analysis, antioxidant analysis, qRT-PCR, and Western blot analysis. ASTA inhibited the expressions of ahr, pxr, car, cyp1a1, cyp1a5, cyp2c18, cyp2d6, and cyp3a9 genes, and significantly alleviated OTA-induced liver oxidative damage (SOD, GSH-Px, GSH, MDA). Furthermore, it inhibited OTA-activated endoplasmic reticulum stress genes and proteins (grp94, GRP78, atf4, ATF6, perk, eif2α, ire1, CHOP). ASTA alleviated OTA-induced mitochondrial dynamic imbalance, inhibited mitochondrial division (DRP1, mff), and promoted mitochondrial fusion (OPA1, MFN1, MFN2). In conclusion, ASTA can decrease OTA-induced oxidative damage, thereby alleviating endoplasmic reticulum stress and mitochondrial dynamic imbalance.

Enhanced potency of a chloro-substituted polyaromatic platinum(II) complex and its platinum(IV) prodrug against lung cancer

The present study investigates the anti-neoplastic activity of a platinum (II) complex, Pt(II)5ClSS, and its platinum (IV) di-hydroxido analogue, Pt(IV)5ClSS, against mesenchymal cells (MCs), lung (A549), melanoma (A375) and breast (MDA-MB-231) cancer cells. Both complexes exhibited up to 14-fold improved cytotoxicity compared to cisplatin. NMR was used to determine that ∼25 % of Pt(IV)5ClSS was reduced to Pt(II)5ClSS in the presence of GSH (Glutathione) after 72 h. The complex 1H NMR spectra acquired for Pt(II)5ClSS with GSH shows evidence of degradation and environmental effects (∼30 %). The prominence of the 195Pt peak at ∼ -2800 ppm suggests that a significant amount of Pt(II)5ClSS remained in the mixture. Pt(II)5ClSS and Pt(IV)5ClSS have shown exceptional selectivity to cancer cells in comparison to MCs (IC50 > 150 μM). Western blot analysis of Pt(II)5ClSS and Pt(IV)5ClSS on A549 cells revealed significant upregulation of cleaved PARP-1, BAX/Bcl2 ratio, cleaved caspase 3 and cytochrome thus suggesting apoptosis was induced through the intrinsic pathway. Flow cytometry also revealed significant cell death by apoptosis. Treatment with Pt(II)5ClSS and Pt(IV)5ClSS also showed significant amounts of free radical production while the COMET assay showed that both complexes cause minimal DNA damage. Cellular uptake results via ICP-MS suggest a time-dependent active mode of transport for both complexes with Pt(II)5ClSS being transported at a higher rate compared to Pt(IV)5ClSS. A Dose Escalation Study carried out on BALB/c mice showed that Pt(II)5ClSS and Pt(IV)5ClSS were approximately 8- folds and 12.5-folds, respectively, more tolerated than cisplatin. The present study provides evidence that both complexes may have the characteristics of an efficient and potentially safe anti-tumor drug that could support NSCLC treatment.

Cirsiliol induces autophagy and mitochondrial apoptosis through the AKT/FOXO1 axis and influences methotrexate resistance in osteosarcoma

BACKGROUND

Osteosarcoma (OS) is the most common primary malignant bone tumor in children and adolescents, with poor outcomes for patients with metastatic disease or chemotherapy resistance. Cirsiliol is a recently found flavonoid with anti-tumor effects in various tumors. However, the effects of cirsiliol in the regulation of aggressive behaviors of OS remain unknown.

METHODS

The effect of cirsiliol on the proliferation of OS cells was detected using a cell counting kit-8 (CCK-8) assay and 5-ethynyl-2'-deoxyuridine (EdU) staining, while cell apoptosis was detected using flow cytometry. Immunofluorescence was applied to visualize the expression level of the mitochondria, lysosomes and microtubule-associated protein light chain 3 (LC3). A computational molecular docking technique was used to predict the interaction between cirsiliol and the AKT protein. The impact of cirsiliol on resistance was investigated by comparing it between a methotrexate (MTX)-sensitive OS cell line, U2OS, and a MTX-resistant OS cell line, U2OS/MTX. Finally, in situ xenogeneic tumor models were used to validate the anti-tumor effect of cirsiliol in OS.

RESULTS

Cirsiliol inhibited cell proliferation and induced apoptosis in both U2OS and U2OS/MTX300 OS cells. In addition, treatment with cirsiliol resulted in G2 phase arrest in U2OS/MTX300 and U2OS cells. Cell fluorescence probe staining results showed impaired mitochondria and increased autophagy in OS cells after treatment with cirsiliol. Mechanistically, it was found that cirsiliol targeted AKT by reducing the phosphorylation of AKT, which further activated the transcriptional activity of forkhead Box O transcription factor 1 (FOXO1), ultimately affecting the function of OS cells. Moreover, in situ tumorigenesis experiments showed that cirsiliol inhibited the tumorigenesis and progression of OS in vivo.

CONCLUSIONS

Cirsiliol inhibits OS cell growth and induces cell apoptosis by reducing AKT phosphorylation and further promotes FOXO1 expression. These phenomena indicate that cirsiliol is a promising treatment option for OS.

Paraquat-induced neurogenesis abnormalities via Drp1-mediated mitochondrial fission

Neurogenesis is a fundamental process in the development and plasticity of the nervous system, and its regulation is tightly linked to mitochondrial dynamics. Imbalanced mitochondrial dynamics can result in oxidative stress, which has been implicated in various neurological disorders. Paraquat (PQ), a commonly used agricultural chemical known to be neurotoxic, induces oxidative stress that can lead to mitochondrial fragmentation. In this study, we investigated the effects of PQ on neurogenesis in primary murine neural progenitor cells (mNPCs) isolated from neonatal C57BL/6 mice. We treated the mNPCs with 0-40 μM PQ for 24 h and observed that PQ inhibited their proliferation, migration, and differentiation into neurons in a concentration-dependent manner. Moreover, PQ induced excessive mitochondrial fragmentation and upregulated the expression of Drp-1, p-Drp1, and Fis-1, while downregulating the expression of Mfn2 and Opa1. To confirm our findings, we used Mdivi-1, an inhibitor of mitochondrial fission, which reversed the adverse effects of PQ on neurogenesis, particularly differentiation into neurons and migration of mNPCs. Additionally, we found that Mito-TEMPO, a mitochondria-targeted antioxidant, ameliorated excessive mitochondrial fragmentation caused by PQ. Our study suggests that PQ exposure impairs neurogenesis by inducing excessive mitochondrial fission and abnormal mitochondrial fragmentation via oxidative stress. These findings identify mitochondrial fission as a potential therapeutic target for PQ-induced neurotoxicity. Further research is needed to elucidate the underlying mechanisms of mitochondrial dynamics and neurogenesis in the context of oxidative stress-induced neurological disorders.

Promising Strategy of mPTP Modulation in Cancer Therapy: An Emerging Progress and Future Insight

Cancer has been progressively a major global health concern. With this developing global concern, cancer determent is one of the most significant public health challenges of this era. To date, the scientific community undoubtedly highlights mitochondrial dysfunction as a hallmark of cancer cells. Permeabilization of the mitochondrial membranes has been implicated as the most considerable footprint in apoptosis-mediated cancer cell death. Under the condition of mitochondrial calcium overload, exclusively mediated by oxidative stress, an opening of a nonspecific channel with a well-defined diameter in mitochondrial membrane allows free exchange between the mitochondrial matrix and the extra mitochondrial cytosol of solutes and proteins up to 1.5 kDa. Such a channel/nonspecific pore is recognized as the mitochondrial permeability transition pore (mPTP). mPTP has been established for regulating apoptosis-mediated cancer cell death. It has been evident that mPTP is critically linked with the glycolytic enzyme hexokinase II to defend cellular death and reduce cytochrome c release. However, elevated mitochondrial Ca2+ loading, oxidative stress, and mitochondrial depolarization are critical factors leading to mPTP opening/activation. Although the exact mechanism underlying mPTP-mediated cell death remains elusive, mPTP-mediated apoptosis machinery has been considered as an important clamp and plays a critical role in the pathogenesis of several types of cancers. In this review, we focus on structure and regulation of the mPTP complex-mediated apoptosis mechanisms and follow with a comprehensive discussion addressing the development of novel mPTP-targeting drugs/molecules in cancer treatment.

HC067047 as a potent TRPV4 inhibitor repairs endotoxemia colonic injury

Colonic injury causes severe inflammation during systemic infections in patients with endotoxemia. The prevention of colonic injury could effectively reduce the progression of endotoxemia. We investigated the protective effects and detailed mechanisms of the TRPV4 inhibitor HC067047 in the treatment of colonic injury caused by endotoxemia. An LPS-induced endotoxemia colonic injury model was used to assess the in vivo effects of HC067047. Colon slices were detected by hematoxylin and eosin (HE) staining and immunofluorescence assays. Spectrophotometry was used to determine the levels of MDA, calcium, GSH, and GSSG. Alterations in oxidative stress/mitophagy/inflammatory pyroptosis-related markers were evaluated by Q-PCR and western blot assays. HC067047 reduced the body weight loss and spleen weight index of endotoxemic mice and partly recovered the normal morphology of the colonic mucous layer. As an inhibitor of the calcium permeant cation channel, HC067047 suppressed the phosphorylation of the CAMKIIɑ protein and levels of MDA and calcium, upregulated the ratio of GSH/GSSG, shortened the expression of oxidative stress-related proteins, and enhanced the expression of the anti-oxidative protein CAT in damaged colon tissues. Additionally, HC067047 maintained normal mitochondrial functions in endotoxemia colons by promoting mitochondrial fusion and biosynthesis and suppressing mitochondrial fission and the PINK/Parkin/mitophagy pathway. HC067047 potently blocked inflammatory pyroptosis and protected the colonic tight junction barrier. HC067047 restores endotoxemia colons against oxidative stress, mitophagy, inflammatory pyroptosis, and colonic barrier dysfunction. Hence, HC067047 therapy may be potentially useful in the treatment of colonic injury in endotoxemia.

Experimental Oxidative Stress Breaks Down the Barrier Function of the Corneal Endothelium

Purpose: The fluid pump and barrier functions of the corneal endothelium maintain stromal deturgescence required for corneal transparency. The effect of oxidative stress, a hallmark of Fuchs endothelial corneal dystrophy (FECD), on the endothelial barrier function has been investigated. Methods: The endothelium of porcine corneas ex vivo was exposed to (1) membrane permeable oxidants (H₂O₂, 100 μM, 1 h; tert-butyl-hydroperoxide, 100 μM, 1 h), or (2) ultraviolet A (UVA) with photosensitizers for 15 min, riboflavin (50 μM) or tryptophan (Trp) (100 μM). The effects on the apical junction complex were analyzed by (1) immunostaining the perijunctional actomyosin ring (PAMR) and ZO-1 and (2) assessment of paracellular flux of fluorescein isothiocyanate (FITC)-avidin across cultured endothelial cells grown on biotinylated-gelatin film. The extent of oxidative stress was quantified by changes in intracellular reactive oxygen species (ROS) and mitochondrial membrane potential (MMP) in addition to lipid peroxidation and release of lactate dehydrogenase (LDH). Results: Both methods of oxidative stress led to the disruption of PAMR and ZO-1 concurrent with changes in ROS levels, depolarization of MMP, increased lipid peroxidation, elevated LDH release, and increased permeability of FITC-avidin. The effects of direct oxidants were opposed by SB-203580 [p38 mitogen-activating protein (MAP) kinase inhibitor; 10 μM]. The damage by UVA+photosensitizers was blocked by extracellular catalase (10,000 U/mL). Conclusions: (1) Acute oxidative stress breaks down the barrier function through destruction of PAMR in a p38 MAP kinase-dependent manner. (2) UVA+photosensitizers elicit the breakdown of PAMR via type I reactions, involving H₂O₂ release. (3) Blocking the oxidative stress prevents loss of barrier function, which could be helpful in the therapeutics of FECD.

Oxidative stress-mediated mitochondrial fission promotes hepatic stellate cell activation via stimulating oxidative phosphorylation

Previous studies have demonstrated dysregulated mitochondrial dynamics in fibrotic livers and hepatocytes. Little is currently known about how mitochondrial dynamics are involved, nor is it clear how mitochondrial dynamics participate in hepatic stellate cell (HSC) activation. In the present study, we investigated the role of mitochondrial dynamics in HSC activation and the underlying mechanisms. We verified that mitochondrial fission was enhanced in human and mouse fibrotic livers and active HSCs. Moreover, increased mitochondrial fission driven by fis1 overexpression could promote HSC activation. Inhibiting mitochondrial fission using mitochondrial fission inhibitor-1 (Mdivi-1) could inhibit activation and induce apoptosis of active HSCs, indicating that increased mitochondrial fission is essential for HSC activation. Mdivi-1 treatment also induced apoptosis in active HSCs in vivo and thus ameliorated CCl₄-induced liver fibrosis. We also found that oxidative phosphorylation (OxPhos) was increased in active HSCs, and OxPhos inhibitors inhibited activation and induced apoptosis in active HSCs. Moreover, increasing mitochondrial fission upregulated OxPhos, while inhibiting mitochondrial fission downregulated OxPhos, suggesting that mitochondrial fission stimulates OxPhos during HSC activation. Next, we found that inhibition of oxidative stress using mitoquinone mesylate (mitoQ) and Tempol inhibited mitochondrial fission and OxPhos and induced apoptosis in active HSCs, suggesting that oxidative stress contributes to excessive mitochondrial fission during HSC activation. In conclusion, our study revealed that oxidative stress contributes to enhanced mitochondrial fission, which triggers OxPhos during HSC activation. Importantly, inhibiting mitochondrial fission has huge prospects for alleviating liver fibrosis by eliminating active HSCs.

Cationic antimicrobial peptide NRC-03 induces oral squamous cell carcinoma cell apoptosis via CypD-mPTP axis-mediated mitochondrial oxidative stress

Pleurocidin-family cationic antimicrobial peptide NRC-03 exhibits potent and selective cytotoxicity towards cancer cells. However, the anticancer effect of NRC-03 in oral squamous cell carcinoma (OSCC) and the molecular mechanism of NRC-03 induced cancer cell death is still unclear. This study focused to investigate mitochondrial oxidative stress-mediated altered mitochondrial function involved in NRC-03-induced apoptosis of OSCC cells. NRC-03 entered the OSCC cells more easily than that of normal cells and bound to mitochondria as well as the nucleus, causing cell membrane blebbing, mitochondria swelling, and DNA fragmentation. NRC-03 induced high oxygen consumption, reactive oxygen species (ROS) release, mitochondrial dysfunction, and apoptosis in OSCC cells. Non-specific antioxidant N-acetyl-l-cysteine (NAC), or mitochondria-specific antioxidant mitoquinone (MitoQ) alleviated NRC-03-induced apoptosis and mitochondrial dysfunction indicated that NRC-03 exerts a cytotoxic effect in cancer cells via inducing cellular and mitochondrial oxidative stress. Moreover, the expression of cyclophilin D (CypD), the key component of mitochondrial permeability transition pore (mPTP), was upregulated in NRC-03-treated cancer cells. Blockade of CypD by siRNA-mediated depletion or pharmacological inhibitor cyclosporine A (CsA) significantly suppressed NRC-03-induced mitochondrial oxidative stress, mitochondrial dysfunction, and apoptosis. NRC-03 also activated MAPK/ERK and NF-κB pathways. Importantly, intratumoral administration of NRC-03 inhibited the growth of CAL-27 cells-derived tumors on xenografted animal models. Taken together, our study indicates that NRC-03 induces apoptosis in OSCC cells via the CypD-mPTP axis mediated mitochondrial oxidative stress.

Puzzling Out Iron Complications in Cancer Drug Resistance

Iron metabolism are frequently disrupted in cancer. Patients with cancer are prone to anemia and receive transfusions frequently; the condition which results in iron overload, contributing to serious therapeutic complications. Iron is introduced as a carcinogen that may increase tumor growth. However, investigations regarding its impact on response to chemotherapy, particularly the induction of drug resistance are still limited. Here, iron contribution to cell signaling and various molecular mechanisms underlying iron-mediated drug resistance are described. A dual role of this vital element in cancer treatment is also addressed. On one hand, the need to administer iron chelators to surmount iron overload and improve the sensitivity of tumor cells to chemotherapy is discussed. On the other hand, the necessary application of iron as a therapeutic option by iron-oxide nanoparticles or ferroptosis inducers is explained. Authors hope that this paper can help unravel the clinical complications related to iron in cancer therapy.

Oxidative phosphorylation mediated pathogenesis of Parkinson's disease and its implication via Akt signaling

Substantia Nigra Pars-compacta (SNpc), in the basal ganglion region, is a primary source of dopamine release. These dopaminergic neurons require more energy than other neurons, as they are highly arborized and redundant. Neurons meet most of their energy demand (∼90%) from mitochondria. Oxidative phosphorylation (OxPhos) is the primary pathway for energy production. Many genes involved in Parkinson's disease (PD) have been associated with OxPhos, especially complex I. Abrogation in complex I leads to reduced ATP formation in these neurons, succumbing to death by inducing apoptosis. This review discusses the interconnection between complex I-associated PD genes and specific mitochondrial metabolic factors (MMFs) of OxPhos. Interestingly, all the complex I-associated PD genes discussed here have been linked to the Akt signaling pathway; thus, neuron survival is promoted and smooth mitochondrial function is ensured. Any changes in these genes disrupt the Akt pathway, which hampers the opening of the permeability transition pore (PTP) via GSK3β dephosphorylation; promotes destabilization of OxPhos; and triggers the release of pro-apoptotic factors.

Fluorescence and Photoacoustic Spectroscopy-Based Assessment of Mitochondrial Dysfunction in Oral Cancer Together with Machine Learning: A Pilot Study

The current study reports an integrated approach of machine learning and tryptophan fluorescence and photoacoustic spectral properties to assess the mitochondrial status under oral pathological conditions. The mitochondria in the study were isolated from oral cancer tissues and adjacent normal counterparts, and the corresponding fluorescence and photoacoustic spectra of tryptophan were recorded at 281 nm pulsed laser excitations. A set of features were selected from the pre-processed spectra and were used to classify the data using support vector machine (SVM) learning in the MATLAB platform. SVM analysis demonstrated clear differentiation between mitochondria isolated from normal and cancer tissues for fluorescence (sensitivity, 86.6%; specificity, 90%) and photoacoustic (sensitivity, 86.6%; specificity, 96.6%) measurements. Further investigation into the influence of change in protein conformation on the nature of tryptophan spectral properties was evaluated by 8-anilino-1-naphthalene sulfonic acid (ANS) fluorescence assay. The impact of protein structural changes on the mitochondrial functions was also estimated by mitochondrial membrane potential (MMP), reactive oxygen species (ROS), and cytochrome c oxidase (COX) assays, suggesting an altered mitochondrial function. The findings indicate that tryptophan fluorescence and photoacoustic spectral properties together with machine learning algorithms may delineate the mitochondrial functional status in vitro, indicating its translational potential.

Mitochondria-Shaping Proteins and Chemotherapy

The emergence, in recent decades, of an entirely new area of “Mitochondrial dynamics”, which consists principally of fission and fusion, reflects the recognition that mitochondria play a significant role in human tumorigenesis and response to therapeutics. Proteins that determine mitochondrial dynamics are referred to as “shaping proteins”. Marked heterogeneity has been observed in the response of tumor cells to chemotherapy, which is associated with imbalances in mitochondrial dynamics and function leading to adaptive and acquired resistance to chemotherapeutic agents. Therefore, targeting mitochondria-shaping proteins may prove to be a promising approach to treat chemotherapy resistant cancers. In this review, we summarize the alterations of mitochondrial dynamics in chemotherapeutic processing and the antitumor mechanisms by which chemotherapy drugs synergize with mitochondria-shaping proteins. These might shed light on new biomarkers for better prediction of cancer chemosensitivity and contribute to the exploitation of potent therapeutic strategies for the clinical treatment of cancers.

Mitochondrial Redox Metabolism: The Epicenter of Metabolism during Cancer Progression

Mitochondrial redox metabolism is the central component in the cellular metabolic landscape, where anabolic and catabolic pathways are reprogrammed to maintain optimum redox homeostasis. During different stages of cancer, the mitochondrial redox status plays an active role in navigating cancer cells’ progression and regulating metabolic adaptation according to the constraints of each stage. Mitochondrial reactive oxygen species (ROS) accumulation induces malignant transformation. Once vigorous cell proliferation renders the core of the solid tumor hypoxic, the mitochondrial electron transport chain mediates ROS signaling for bringing about cellular adaptation to hypoxia. Highly aggressive cells are selected in this process, which are capable of progressing through the enhanced oxidative stress encountered during different stages of metastasis for distant colonization. Mitochondrial oxidative metabolism is suppressed to lower ROS generation, and the overall cellular metabolism is reprogrammed to maintain the optimum NADPH level in the mitochondria required for redox homeostasis. After reaching the distant organ, the intrinsic metabolic limitations of that organ dictate the success of colonization and flexibility of the mitochondrial metabolism of cancer cells plays a pivotal role in their adaptation to the new environment.

Mitochondrial dynamics regulators: implications for therapeutic intervention in cancer

Regardless of the recent advances in therapeutic developments, cancer is still among the primary causes of death globally, indicating the need for alternative therapeutic strategies. Mitochondria, a dynamic organelle, continuously undergo the fusion and fission processes to meet cell requirements. The balanced fission and fusion processes, referred to as mitochondrial dynamics, coordinate mitochondrial shape, size, number, energy metabolism, cell cycle, mitophagy, and apoptosis. An imbalance between these opposing events alters mitochondWangrial dynamics, affects the overall mitochondrial shape, and deregulates mitochondrial function. Emerging evidence indicates that alteration of mitochondrial dynamics contributes to various aspects of tumorigenesis and cancer progression. Therefore, targeting the mitochondrial dynamics regulator could be a potential therapeutic approach for cancer treatment. This review will address the role of imbalanced mitochondrial dynamics in mitochondrial dysfunction during cancer progression. We will outline the clinical significance of mitochondrial dynamics regulators in various cancer types with recent updates in cancer stemness and chemoresistance and its therapeutic potential and clinical utility as a predictive biomarker.

Transferrin-conjugated liposomes loaded with carnosic acid inhibit liver cancer growth by inducing mitochondria-mediated apoptosis

Our previous studies have proven that carnosic acid (CA) induces apoptosis of liver cancer cells. However, the poor chemical properties of CA limit its in vivo anti-cancer effects. In this study, CA was loaded into liposomes (LP-CA), and LP-CA was further conjugated with transferrin (Tf-LP-CA) to overcome the shortcomings of poor solubility and absorption at the lesion site. In HepG2 and SMMC-7721 cells, compared with CA and LP-CA, more Tf-LP-CA was absorbed by liver cancer cells, which induced higher levels of apoptosis and reduced the mitochondrial membrane potential more effectively. In HepG2- and SMMC-7721-xenotransplanted mice, Tf-LP-CA inhibited tumor growth with no cytotoxicity to the liver, spleen, or kidney. Furthermore, compared with CA and LP-CA, Tf-LP-CA targeted the tumor site more effectively, enhanced the expressions of cleaved poly(ADP-ribose) polymerase, and Caspase-3 and -9, and regulated the expression levels of B-cell lymphoma 2 (Bcl2) family members in the tumor tissues. Tf-LP-CA was taken up by tumor cells and targeted at tumor tissues, ensuring the precise delivery of CA, which further promoted mitochondria-mediated intrinsic apoptosis in the liver cancer cells. These results provide evidence for the clinical application of the Tf-LP-based CA drug delivery system for liver cancer.

The Effects of P53 in the Globular Heads of the C1q Receptor in Gastric Carcinoma Cell Apoptosis Are Exerted via a Mitochondrial-Dependent Pathway

The globular heads of the C1q receptor (gC1qR), located in the B cell cytoplasm, perform important roles in many cellular processes. A recent studies reported a major role of mitochondrial apoptosis in several cancers, but there has been no report on gastric carcinoma (GC). In this study, the mechanism by which cell apoptosis is induced by gC1qR in GC was explored. Western blot showed that gC1qR and P53 protein levels were lower in GC tissues than in normal tissues. Cytotoxicity was dynamically increased in gC1qR-overexpressing GC cells compared to the control. CCK8 assay indicated that overexpression of gC1qR induced GC cell apoptosis, increased reactive oxygen species (ROS) production, decreased the mitochondrial transmembrane potential and promoted mitochondrial apoptosis. Moreover, the P53 level increased in response to gC1qR. The viability, migration, and mitochondrial transmembrane potential of GC cells increased in association with decreased levels of ROS and mitochondrial apoptosis in the P53-silenced group. Collectively, our findings indicate that apoptosis of GC cells is enhanced when gC1qR overexpression is induced by P53-mediated mitochondrial apoptosis.

PHLDA1 Modulates the Endoplasmic Reticulum Stress Response and is required for Resistance to Oxidative Stress-induced Cell Death in Human Ovarian Cancer Cells

Objective: Pleckstrin homology-like domain family A member 1 (PHLDA1) has been implicated in the regulation of apoptosis in a variety of normal cell types and cancers. However, its precise pathophysiological functions remain unclear. Here, we examined the expression of PHLDA1 in human ovarian cancer (OvCa), the most lethal gynecologic malignancy, and investigated its functions in vitro.

Materials and Methods: The expression of PHLDA1 was detected by reverse-transcription quantitative PCR (RT-qPCR), immunohistochemical analysis, or western blotting, silencing of PHLDA was achieved by shRNA, cell proliferation was detected by MTT assay, apoptosis was detected by flow cytometric analysis, PHLDA1 transcriptional activity was detected by dual luciferase reporter assay.

Results: PHLDA1 mRNA levels were significantly higher in serous OvCa specimens compared with normal ovarian tissue, confirmed by immunohistochemical staining of PHLDA1 protein, which also indicated the expression was predominantly cytoplasmic. Bioinformatics analysis of publicly available datasets indicated that PHLDA1 expression in clinical specimens was significantly associated with disease stage, progression-free survival, and overall survival. In human OvCa cell lines, shRNA-mediated silencing of PHLDA1 expression enhanced apoptosis after exposure to oxidative stress- and endoplasmic reticulum stress-inducing agents. PHLDA1 silencing increased not the expression of anti-apoptotic or autophagy-related proteins, but the expression of ER stress response-associated proteins.

Conclusion: PHLDA1 modulates the susceptibility of human OvCa cells to apoptosis via the endoplasmic reticulum stress response pathway.

Drp-1-Dependent Mitochondrial Fragmentation Contributes to Cobalt Chloride-Induced Toxicity in Caenorhabditis elegans

Excess cobalt may lead to metallosis, characterized by sensorineural hearing loss, visual, and cognitive impairment, and peripheral neuropathy. In the present study, we sought to address the molecular mechanisms of cobalt-induced neurotoxicity, using Caenorhabditis elegans as an experimental model. Exposure to cobalt chloride for 2 h significantly decreased the survival rate and lifespan in nematodes. Cobalt chloride exposure led to increased oxidative stress and upregulation of glutathione S-transferase 4. Consistently, its upstream regulator skn-1, a mammalian homolog of the nuclear factor erythroid 2-related factor 2, was activated. Among the mRNAs examined by quantitative real-time polymerase chain reactions, apoptotic activator egl-1, proapoptotic gene ced-9, autophagic (bec-1 and lgg-1), and mitochondrial fission regulator drp-1 were significantly upregulated upon cobalt exposure, concomitant with mitochondrial fragmentation, as determined by confocal microscopy. Moreover, drp-1 inhibition suppressed the cobalt chloride-induced reactive oxygen species generation, growth defects, and reduced mitochondrial fragmentation. Our novel findings suggest that the acute toxicity of cobalt is mediated by mitochondrial fragmentation and drp-1 upregulation.

IκBα targeting promotes oxidative stress-dependent cell death

BACKGROUND

Oxidative stress is a hallmark of many cancers. The increment in reactive oxygen species (ROS), resulting from an increased mitochondrial respiration, is the major cause of oxidative stress. Cell fate is known to be intricately linked to the amount of ROS produced. The direct generation of ROS is also one of the mechanisms exploited by common anticancer therapies, such as chemotherapy.

METHODS

We assessed the role of NFKBIA with various approaches, including in silico analyses, RNA-silencing and xenotransplantation. Western blot analyses, immunohistochemistry and RT-qPCR were used to detect the expression of specific proteins and genes. Immunoprecipitation and pull-down experiments were used to evaluate protein-protein interactions.

RESULTS

Here, by using an in silico approach, following the identification of NFKBIA (the gene encoding IκBα) amplification in various cancers, we described an inverse correlation between IκBα, oxidative metabolism, and ROS production in lung cancer. Furthermore, we showed that novel IκBα targeting compounds combined with cisplatin treatment promote an increase in ROS beyond the tolerated threshold, thus causing death by oxytosis.

CONCLUSIONS

NFKBIA amplification and IκBα overexpression identify a unique cancer subtype associated with specific expression profile and metabolic signatures. Through p65-NFKB regulation, IκBα overexpression favors metabolic rewiring of cancer cells and distinct susceptibility to cisplatin. Lastly, we have developed a novel approach to disrupt IκBα/p65 interaction, restoring p65-mediated apoptotic responses to cisplatin due to mitochondria deregulation and ROS-production.

Mitochondrial Dynamics, ROS, and Cell Signaling: A Blended Overview

Mitochondria are key intracellular organelles involved not only in the metabolic state of the cell, but also in several cellular functions, such as proliferation, Calcium signaling, and lipid trafficking. Indeed, these organelles are characterized by continuous events of fission and fusion which contribute to the dynamic plasticity of their network, also strongly influenced by mitochondrial contacts with other subcellular organelles. Nevertheless, mitochondria release a major amount of reactive oxygen species (ROS) inside eukaryotic cells, which are reported to mediate a plethora of both physiological and pathological cellular functions, such as growth and proliferation, regulation of autophagy, apoptosis, and metastasis. Therefore, targeting mitochondrial ROS could be a promising strategy to overcome and hinder the development of diseases such as cancer, where malignant cells, possessing a higher amount of ROS with respect to healthy ones, could be specifically targeted by therapeutic treatments. In this review, we collected the ultimate findings on the blended interplay among mitochondrial shaping, mitochondrial ROS, and several signaling pathways, in order to contribute to the dissection of intracellular molecular mechanisms involved in the pathophysiology of eukaryotic cells, possibly improving future therapeutic approaches.

Beyond Pseudo-natural Products: Sequential Ugi/Pictet-Spengler Reactions Leading to Steroidal Pyrazinoisoquinolines That Trigger Caspase-Independent Death in HepG2 Cells

In this work, we describe how stereochemically complex polycyclic compounds can be generated by applying a synthetic sequence comprising an intramolecular Ugi reaction followed by a Pictet-Spengler cyclization on steroid-derived scaffolds. The resulting compounds, which combine a fragment derived from a natural product and a scaffold not found in nature. are both structurally distinct and globally similar to natural products at the same time, and interrogate an alternative region of the chemical space. One of the new compounds showed significant antiproliferative activity on HepG2 cells through a caspase-independent cell-death mechanism, an appealing feature when new antitumor compounds are searched.

NIK promotes metabolic adaptation of glioblastoma cells to bioenergetic stress

Cancers, including glioblastoma multiforme (GBM), undergo coordinated reprogramming of metabolic pathways that control glycolysis and oxidative phosphorylation (OXPHOS) to promote tumor growth in diverse tumor microenvironments. Adaptation to limited nutrient availability in the microenvironment is associated with remodeling of mitochondrial morphology and bioenergetic capacity. We recently demonstrated that NF-κB-inducing kinase (NIK) regulates mitochondrial morphology to promote GBM cell invasion. Here, we show that NIK is recruited to the outer membrane of dividing mitochondria with the master fission regulator, Dynamin-related protein1 (DRP1). Moreover, glucose deprivation-mediated metabolic shift to OXPHOS increases fission and mitochondrial localization of both NIK and DRP1. NIK deficiency results in decreased mitochondrial respiration, ATP production, and spare respiratory capacity (SRC), a critical measure of mitochondrial fitness. Although IκB kinase α and β (IKKα/β) and NIK are required for OXPHOS in high glucose media, only NIK is required to increase SRC under glucose deprivation. Consistent with an IKK-independent role for NIK in regulating metabolism, we show that NIK phosphorylates DRP1-S616 in vitro and in vivo. Notably, a constitutively active DRP1-S616E mutant rescues oxidative metabolism, invasiveness, and tumorigenic potential in NIK-/- cells without inducing IKK. Thus, we establish that NIK is critical for bioenergetic stress responses to promote GBM cell pathogenesis independently of IKK. Our data suggest that targeting NIK may be used to exploit metabolic vulnerabilities and improve therapeutic strategies for GBM.

Blockade of 6-phosphogluconate dehydrogenase generates CD8+ effector T cells with enhanced anti-tumor function

Although T cell expansion depends on glycolysis, T effector cell differentiation requires signaling via the production of reactive oxygen species (ROS). Because the pentose phosphate pathway (PPP) regulates ROS by generating nicotinamide adenine dinucleotide phosphate (NADPH), we examined how PPP blockade affects T cell differentiation and function. Here, we show that genetic ablation or pharmacologic inhibition of the PPP enzyme 6-phosphogluconate dehydrogenase (6PGD) in the oxidative PPP results in the generation of superior CD8+ T effector cells. These cells have gene signatures and immunogenic markers of effector phenotype and show potent anti-tumor functions both in vitro and in vivo. In these cells, metabolic reprogramming occurs along with increased mitochondrial ROS and activated antioxidation machinery to balance ROS production against oxidative damage. Our findings reveal a role of 6PGD as a checkpoint for T cell effector differentiation/survival and evidence for 6PGD as an attractive metabolic target to improve tumor immunotherapy.

Icariin-induced inhibition of SIRT6/NF-κB triggers redox mediated apoptosis and enhances anti-tumor immunity in triple-negative breast cancer

Abnormal activation of the nuclear factor-kappa B (NF-κB) signaling pathway is closely implicated in triple-negative breast cancer growth, metastasis, and tumor immune escape. In this study, the anti-cancer effects of icariin, a natural flavonol glycoside, toward breast cancer cells and the underlying mechanisms were investigated. This investigation showed that icariin selectively inhibited proliferation and triggered apoptosis in breast cancer cells in a concentration- and time-dependent manner, but exhibited little cytotoxicity in normal breast cells. Moreover, icariin induced cell apoptosis via a mitochondria-mediated pathway, as indicated by the upregulated ratio of Bax/Bcl-2 and reactive oxygen species induction. Importantly, icariin impaired the activation of the NF-κB/EMT pathway, as evidenced by upregulation of SIRT6, resulting in inhibition of migration and invasion of breast cancer cells. Additionally, oss-128167, an inhibitor of SIRT6, dramatically attenuated anti-migration and anti-invasion effects of icariin. Transcriptomic analysis verified that impairment of NF-κB led to the selective function of icariin in breast cancer cells. Notably, icariin exhibited a significant tumor growth inhibition and anti-pulmonary metastasis effect in a tumor mouse model of MDA-MB-231 and 4T1 cells by regulating the tumor immunosuppressive microenvironment. Together, these results showed that icariin could effectively trigger apoptosis and inhibit the migration of breast cancer cells via the SIRT6/NF-κB signaling pathway, suggesting that icariin might serve as a potential candidate drug for the treatment of breast cancer.

Endothelial dysfunction in neuroprogressive disorders-causes and suggested treatments

BACKGROUND

Potential routes whereby systemic inflammation, oxidative stress and mitochondrial dysfunction may drive the development of endothelial dysfunction and atherosclerosis, even in an environment of low cholesterol, are examined.

MAIN TEXT

Key molecular players involved in the regulation of endothelial cell function are described, including PECAM-1, VE-cadherin, VEGFRs, SFK, Rho GEF TRIO, RAC-1, ITAM, SHP-2, MAPK/ERK, STAT-3, NF-κB, PI3K/AKT, eNOS, nitric oxide, miRNAs, KLF-4 and KLF-2. The key roles of platelet activation, xanthene oxidase and myeloperoxidase in the genesis of endothelial cell dysfunction and activation are detailed. The following roles of circulating reactive oxygen species (ROS), reactive nitrogen species and pro-inflammatory cytokines in the development of endothelial cell dysfunction are then described: paracrine signalling by circulating hydrogen peroxide, inhibition of eNOS and increased levels of mitochondrial ROS, including compromised mitochondrial dynamics, loss of calcium ion homeostasis and inactivation of SIRT-1-mediated signalling pathways. Next, loss of cellular redox homeostasis is considered, including further aspects of the roles of hydrogen peroxide signalling, the pathological consequences of elevated NF-κB, compromised S-nitrosylation and the development of hypernitrosylation and increased transcription of atherogenic miRNAs. These molecular aspects are then applied to neuroprogressive disorders by considering the following potential generators of endothelial dysfunction and activation in major depressive disorder, bipolar disorder and schizophrenia: NF-κB; platelet activation; atherogenic miRs; myeloperoxidase; xanthene oxidase and uric acid; and inflammation, oxidative stress, nitrosative stress and mitochondrial dysfunction.

CONCLUSIONS

Finally, on the basis of the above molecular mechanisms, details are given of potential treatment options for mitigating endothelial cell dysfunction and activation in neuroprogressive disorders.

Mitochondrial pathways in human health and aging

Mitochondria are eukaryotic organelles known best for their roles in energy production and metabolism. While often thought of as simply the 'powerhouse of the cell,' these organelles participate in a variety of critical cellular processes including reactive oxygen species (ROS) production, regulation of programmed cell death, modulation of inter- and intracellular nutrient signaling pathways, and maintenance of cellular proteostasis. Disrupted mitochondrial function is a hallmark of eukaryotic aging, and mitochondrial dysfunction has been reported to play a role in many aging-related diseases. While mitochondria are major players in human diseases, significant questions remain regarding their precise mechanistic role. In this review, we detail mechanisms by which mitochondrial dysfunction participate in disease and aging based on findings from model organisms and human genetics studies.

Reactive oxygen species-sensitive nanophotosensitizers of aminophenyl boronic acid pinacol ester conjugated chitosan-g-methoxy poly(ethylene glycol) copolymer for photodynamic treatment of cancer

The aim of this study is to prepare reactive oxygen species (ROS)-sensitive nanophotosensitizers for targeted delivery of chlorin e6 (Ce6) and photodynamic tumor therapy. For this purpose, thiodipropionic acid (TDPA) was conjugated with phenyl boronic acid pinacol ester (PBAP) (TDPA-PBAP conjugates) and then the TDPA-PBAP conjugates were attached to the chitosan backbone of chitosan-g-methoxy poly(ethylene glycol) (ChitoPEG) copolymer (ChitoPEG-PBAP). Ce6-incorporated ChitoPEG-PBAP nanophotosensitizers have an ROS-sensitive manner in vitro. The size of ChitoPEG-PBAP nanoparticles increased or disintegrated in a responsive manner against H₂O₂ concentration. The Ce6 release rate from ChitoPEG-PBAP nanophotosensitizers also increased by adding H₂O₂. These results indicated that nanophotosensitizers have sensitivity against ROS and showed triggered Ce6 release behavior. ChitoPEG-PBAP nanophotosensitizers can be more efficiently internalized into cancer cells compared to Ce6 alone and then produce ROS in a more efficient manner. Furthermore, ChitoPEG-PBAP nanophotosensitizers suppressed the viability of cancer cells in vitro and tumor growth in vivo with higher efficacy compared to Ce6 alone. Furthermore, ChitoPEG-PBAP nanophotosensitizers were efficiently delivered to irradiated tumor tissues, indicating that ChitoPEG-PBAP nanophotosensitizers can be delivered to the tumor with ROS-sensitive manner. We suggest that a ChitoPEG-PBAP nanophotosensitizer is a promising candidate for photodynamic therapy of cancers.

Luteolin enhances TRAIL sensitivity in non-small cell lung cancer cells through increasing DR5 expression and Drp1-mediated mitochondrial fission

Cancer cells exhibit extreme sensitivity to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) over normal cells, highlighting TRAIL's potential as a novel and effective cancer drug. However, the therapeutic effect of TRAIL is limited due to drug resistance. In the present study, we sought to investigate the potential effects of luteolin as a TRAIL sensitizer in non-small cell lung cancer (NSCLC) cells. A549 and H1975 cells had low sensitivity or were resistant to TRAIL. Luteolin alone or in combination with TRAIL decreased cell viability and increased apoptosis. Furthermore, luteolin alone or in combination with TRAIL enhanced death receptor 5 (DR5) expression and dynamin-related protein 1 (Drp1)-dependent mitochondrial fission. However, the synergistic effect of luteolin on cell viability and apoptosis was reversed by DR5 and Drp1 inhibition, suggesting that DR5 upregulation and mitochondrial dynamics may be essential for luteolin as a sensitizer of TRAIL-based therapy in NSCLC. Moreover, luteolin treatment alone or in combination with TRAIL increased the phosphorylation of c-Jun N-terminal kinase (JNK), while SP600125 (the JNK inhibitor) significantly abolished the synergistic effect on DR5 expression and Drp1 translocation, indicating that JNK signaling activation was greatly associated with the synergistic effect exerted by luteolin in NSCLC cells. Therefore, TRAIL combined with luteolin could be as an effective chemotherapeutic strategy for NSCLC.

Baicalin, a Potent Inhibitor of NF-κB Signaling Pathway, Enhances Chemosensitivity of Breast Cancer Cells to Docetaxel and Inhibits Tumor Growth and Metastasis Both In Vitro and In Vivo

Objective

The aim of this study is to investigate the anti-cancer activity and sensibilization of baicalin (BA) against breast cancer (BC) cells.

Methods

The anti-proliferation of BA in BC cell lines was evaluated by MTT and colony formation assays. Apoptotic induction of BA was measured by flow cytometry. Wound-healing and transwell assays were exploited to assess migrated and invasive inhibition of BA. Western-blot and immunofluorescence were used to study mechanisms of anti-migration and sensibilization of BA. Anti-tumor and anti-metastasis effects of BA were evaluated in subcutaneous and pulmonary metastasis mouse model of BC cells.

Results

BA significantly suppressed proliferation and induced apoptosis of BC cells in a concentration- and time-dependent manner. Additionally, BA induced cell apoptosis via the mitochondria-mediated pathway, as evidenced by cellular induction of reactive oxygen species and upregulated expression of the Bax/Bcl-2 ratio. The overall expression and nuclear translocation of NF-κB signaling pathway in BC cells were dramatically inhibited by treatment with BA. BA significantly suppressed abilities of migration and invasion in BC cells. Notably, BA sensitized BC cells to docetaxel (DXL) by suppressing the expression of survivin/Bcl-2. BA also retarded tumor growth and triggered apoptosis of tumor cells in a tumor mouse model of 4T1 cells. Furthermore, pulmonary metastasis of BC cells was distinctly suppressed by BA in a tumor mouse model of 4T1 cells.

Conclusion

BA effectively triggered apoptosis, inhibited metastasis, and enhanced chemosensitivity of BC, implying that BA might serve as a promising agent for the treatment of BC.

Peroxiredoxin 5 deficiency exacerbates iron overload-induced neuronal death via ER-mediated mitochondrial fission in mouse hippocampus

Iron is an essential element for cellular functions, including those of neuronal cells. However, an imbalance of iron homeostasis, such as iron overload, has been observed in several neurodegenerative diseases, including Alzheimer’s disease and Parkinson’s disease. Iron overload causes neuronal toxicity through mitochondrial fission, dysregulation of Ca²⁺, ER-stress, and ROS production. Nevertheless, the precise mechanisms between iron-induced oxidative stress and iron toxicity related to mitochondria and endoplasmic reticulum (ER) in vivo are not fully understood. Here, we demonstrate the role of peroxiredoxin 5 (Prx5) in iron overload-induced neurotoxicity using Prx5-deficient mice. Iron concentrations and ROS levels in mice fed a high iron diet were significantly higher in Prx5^−/− mice than wildtype (WT) mice. Prx5 deficiency also exacerbated ER-stress and ER-mediated mitochondrial fission via Ca²⁺/calcineurin-mediated dephosphorylation of Drp1 at Serine 637. Moreover, immunoreactive levels of cleaved caspase3 in the CA3 region of the hippocampus were higher in iron-loaded Prx5^−/− mice than WT mice. Furthermore, treatment with N-acetyl-cysteine, a reactive oxygen species (ROS) scavenger, attenuated iron overload-induced hippocampal damage by inhibiting ROS production, ER-stress, and mitochondrial fission in iron-loaded Prx5^−/− mice. Therefore, we suggest that iron overload-induced oxidative stress and ER-mediated mitochondrial fission may be essential for understanding iron-mediated neuronal cell death in the hippocampus and that Prx5 may be useful as a novel therapeutic target in the treatment of iron overload-mediated diseases and neurodegenerative diseases.

Antioxidant Properties and Redox-Modulating Activity of Chitosan and Its Derivatives: Biomaterials with Application in Cancer Therapy

Many studies have shown that mitochondrial metabolism has a fundamental role in induction of carcinogenesis due to the influence of increased levels of reactive oxygen species (ROS) generation in all steps of oncogene transformation and cancer progression. It is widely accepted that the anticancer effect of conventional anticancer drugs is due to induction of oxidative stress and elevated intracellular levels of ROS, which alter the redox homeostasis of cancer cells. On the other hand, the harmful side effects of conventional anticancer chemotherapeutics are also due to increased production of ROS and disruption of redox homeostasis of normal cells and tissues. Therefore, there is a growing interest toward the development of natural antioxidant compounds from various sources, which could impact the redox state of cancer and normal cells by different pathways and could prevent damage from oxidant-mediated reactions. It is known that chitosan exhibits versatile biological properties, including biodegradability, biocompatibility, and a less toxic nature. Because of its antioxidant, antibacterial, anticancer, anti-inflammatory, and immunostimulatory activities, the biopolymer has been used in a wide variety of pharmaceutical, biomedical, food industry, health, and agricultural applications and has been classified as a new physiologically bioactive material.

Mitochondrial Dysfunction at the Center of Cancer Therapy

Significance: Mitochondria undergo constant morphological changes through fusion, fission, and mitophagy. As the key organelle in cells, mitochondria are responsible for numerous essential cellular functions such as metabolism, regulation of calcium (Ca²⁺), generation of reactive oxygen species, and initiation of apoptosis. Unsurprisingly, mitochondrial dysfunctions underlie many pathologies including cancer. Recent Advances: Currently, the gold standard for cancer treatment is chemotherapy, radiation, and surgery. However, the efficacy of these treatments varies across different cancer cells. It has been suggested that mitochondria may be at the center of these diverse responses. In the past decade, significant advances have been made in understanding distinct types of mitochondrial dysfunctions in cancer. Through investigations of underlying mechanisms, more effective treatment options are developed. Critical Issues: We summarize various mitochondria dysfunctions in cancer progression that have led to the development of therapeutic options. Current mitochondrial-targeted therapies and challenges are discussed. Future Directions: To address the "root" of cancer, utilization of mitochondrial-targeted therapy to target cancer stem cells may be valuable. Investigation of other areas such as mitochondrial trafficking may offer new insights into cancer therapy. Moreover, common antibiotics could be explored as mitocans, and synthetic lethality screens can be utilized to overcome the plasticity of cancer cells.

NF-κB and mitochondria cross paths in cancer: mitochondrial metabolism and beyond

NF-κB plays a pivotal role in oncogenesis. This transcription factor is best known for promoting cancer cell survival and tumour-driving inflammation. However, several lines of evidence support a crucial role for NF-κB in governing energy homeostasis and mediating cancer metabolic reprogramming. Mitochondria are central players in many metabolic processes altered in cancer. Beyond their bioenergetic activity, several facets of mitochondria biology, including mitochondrial dynamics and oxidative stress, promote and sustain malignant transformation. Recent reports revealed an intimate connection between NF-κB pathway and the oncogenic mitochondrial functions. NF-κB can impact mitochondrial respiration and mitochondrial dynamics, and, reciprocally, mitochondria can sense stress signals and convert them into cell biological responses leading to NF-κB activation. In this review we discuss their emerging reciprocal regulation and the significance of this interplay for anticancer therapy.

Prognostic significance of IMMT expression in surgically-resected lung adenocarcinoma

BACKGROUND

Mitochondrial dysfunction contributes to many types of human disorders and cancer progression. Inner membrane mitochondrial protein (IMMT) plays an important role in the maintenance of mitochondrial structure and function. The aims of this study were to examine IMMT expression in lung adenocarcinoma and evaluate its correlation with clinicopathological parameters and patient prognosis.

METHODS

IMMT expression was immunohistochemically studied in 176 consecutive lung adenocarcinoma resection tissues, and its correlations with clinicopathological parameters were evaluated. Kaplan-Meier survival analysis and Cox-proportional hazards models were used to estimate the effect of IMMT expression on survival.

RESULTS

High-IMMT expression was detected in 84 of 176 (47.7%) lung adenocarcinomas. Levels were significantly correlated with advanced disease stage (stage II and III; P = 0.024), larger tumor size (>3 cm; P = 0.002), intratumoral vascular invasion (P < 0.001), and poorer adenocarcinoma patient prognosis (P = 0.002). Based on 176 patients with adenocarcinoma, multivariate analysis revealed that IMMT expression was an independent predictor of poorer survival (HR, 1.99; 95% confidence interval [CI], 1.06-3.74; P = 0.031). Further, treating A549 cells derived from lung adenocarcinoma, with IMMT siRNA resulted in significantly decreased proliferation.

CONCLUSION

Here, we first demonstrated that high-IMMT expression is related to some clinicopathological parameters, and that its expression is an independent prognostic predictor of poorer survival in patients with lung adenocarcinoma; further studies are required to clarify the biological function of IMMT in lung adenocarcinoma. However, results suggest that this protein could be a novel prognostic indicator and therapeutic target.

A Unique Morphological Phenotype in Chemoresistant Triple-Negative Breast Cancer Reveals Metabolic Reprogramming and PLIN4 Expression as a Molecular Vulnerability

The major obstacle in successfully treating triple-negative breast cancer (TNBC) is resistance to cytotoxic chemotherapy, the mainstay of treatment in this disease. Previous preclinical models of chemoresistance in TNBC have suffered from a lack of clinical relevance. Using a single high dose chemotherapy treatment, we developed a novel MDA-MB-436 cell-based model of chemoresistance characterized by a unique and complex morphologic phenotype, which consists of polyploid giant cancer cells giving rise to neuron-like mononuclear daughter cells filled with smaller but functional mitochondria and numerous lipid droplets. This resistant phenotype is associated with metabolic reprogramming with a shift to a greater dependence on fatty acids and oxidative phosphorylation. We validated both the molecular and histologic features of this model in a clinical cohort of primary chemoresistant TNBCs and identified several metabolic vulnerabilities including a dependence on PLIN4, a perilipin coating the observed lipid droplets, expressed both in the TNBC-resistant cells and clinical chemoresistant tumors treated with neoadjuvant doxorubicin-based chemotherapy. These findings thus reveal a novel mechanism of chemotherapy resistance that has therapeutic implications in the treatment of drug-resistant cancer. IMPLICATIONS: These findings underlie the importance of a novel morphologic-metabolic phenotype associated with chemotherapy resistance in TNBC, and bring to light novel therapeutic targets resulting from vulnerabilities in this phenotype, including the expression of PLIN4 essential for stabilizing lipid droplets in resistant cells.

tiRNAs: A novel class of small noncoding RNAs that helps cells respond to stressors and plays roles in cancer progression

tRNA-derived stress-induced RNAs (tiRNAs), important components of tRNA-derived fragments, are gaining popularity for their functions as small noncoding RNAs involved in cancer progression. Under cellular stress, tiRNAs are generated when mature tRNA is specifically cleaved by angiogenin and suggested to act as transducers or effectors involved in cellular stress responses. tiRNAs facilitate cells to respond to stresses mainly via reprogramming translation, inhibiting apoptosis, degrading mRNA, and generating stress granules. This review introduces the cellular biogenesis, molecular mechanisms, and biological roles of tiRNAs in stress response and disease regulation. A better understanding of their roles in regulating cancer may provide novel biomarkers or therapeutic targets for diagnosis and treatment.

Exploiting Mitochondrial Vulnerabilities to Trigger Apoptosis Selectively in Cancer Cells

The transformation of normal cells to the cancerous stage involves multiple genetic changes or mutations leading to hyperproliferation, resistance to apoptosis, and evasion of the host immune system. However, to accomplish hyperproliferation, cancer cells undergo profound metabolic reprogramming including oxidative glycolysis and acidification of the cytoplasm, leading to hyperpolarization of the mitochondrial membrane. The majority of drug development research in the past has focused on targeting DNA replication, repair, and tubulin polymerization to induce apoptosis in cancer cells. Unfortunately, these are not cancer-selective targets. Recently, researchers have started focusing on metabolic, mitochondrial, and oxidative stress vulnerabilities of cancer cells that can be exploited as selective targets for inducing cancer cell death. Indeed, the hyperpolarization of mitochondrial membranes in cancer cells can lead to selective importing of mitocans that can induce apoptotic effects. Herein, we will discuss recent mitochondrial-selective anticancer compounds (mitocans) that have shown selective toxicity against cancer cells. Increased oxidative stress has also been shown to be very effective in selectively inducing cell death in cancer cells. This oxidative stress could lead to mitochondrial dysfunction, which in turn will produce more reactive oxygen species (ROS). This creates a vicious cycle of mitochondrial dysfunction and ROS production, irreversibly leading to cell suicide. We will also explore the possibility of combining these compounds to sensitize cancer cells to the conventional anticancer agents. Mitocans in combination with selective oxidative-stress producing agents could be very effective anticancer treatments with minimal effect on healthy cells.

NEO212 induces mitochondrial apoptosis and impairs autophagy flux in ovarian cancer

Background

Temozolomide-perillyl alcohol conjugate (NEO212), a novel temozolomide (TMZ) analog, was previously reported to exert its anti-cancer effect in non-small cell lung cancer (NSCLC), and human nasopharyngeal carcinoma (NPC), etc.. In the current study, we intend to illuminate the potential anticancer property and the underly mechanisms of NEO212 in ovarian cancer cells.

Methods

The cytotoxicity of NEO212 was detected by MTT, colony formation analysis and xenograft model. The proteins involved in cell proliferation, DNA damage, autophagy and lysosomal function were detected by western blots; mitochondria, lysosome and autophagosome were visualized by TEM and/or immunofluorescence; Apoptosis, cell cycle analysis and mitochondrial transmembrane potential were detected by flow cytometry. TFEB translocation was detected by immunofluorescence and western blot.

Results

NEO212 has the potential anticancer property in ovarian cancer cells, as evidence from cell proliferation inhibition, G₂/M arrest, DNA damage, xenograft, mitochondrial dysfunction and apoptosis. Importantly, we observed that although it induced significant accumulation of autophagosomes, NEO212 quenched GFP-LC3 degradation, down-regulated a series of lysosome related gene expression and blocked the autophagic flux, which significantly facilitated it induced apoptosis and was largely because it inhibited the nuclear translocation of transcription factor EB (EB).

Conclusions

NEO212 inhibited TFEB translocation, and impaired the lysosomal function, implying NEO212 might avoid from autophagy mediated chemo-resistance, thus proposing NEO212 as a potential therapeutic candidate for ovarian cancer.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1249-1) contains supplementary material, which is available to authorized users.

Effects of Long-Term Citrate Treatment in the PC3 Prostate Cancer Cell Line

Acute administration of a high level of extracellular citrate displays an anti-proliferative effect on both in vitro and in vivo models. However, the long-term effect of citrate treatment has not been investigated yet. Here, we address this question in PC3 cells, a prostate-cancer-derived cell line. Acute administration of high levels of extracellular citrate impaired cell adhesion and inhibited the proliferation of PC3 cells, but surviving cells adapted to grow in the chronic presence of 20 mM citrate. Citrate-resistant PC3 cells are significantly less glycolytic than control cells. Moreover, they overexpress short-form, citrate-insensitive phosphofructokinase 1 (PFK1) together with full-length PFK1. In addition, they show traits of mesenchymal-epithelial transition: an increase in E-cadherin and a decrease in vimentin. In comparison with PC3 cells, citrate-resistant cells display morphological changes that involve both microtubule and microfilament organization. This was accompanied by changes in homeostasis and the organization of intracellular organelles. Thus, the mitochondrial network appears fragmented, the Golgi complex is scattered, and the lysosomal compartment is enlarged. Interestingly, citrate-resistant cells produce less total ROS but accumulate more mitochondrial ROS than control cells. Consistently, in citrate-resistant cells, the autophagic pathway is upregulated, possibly sustaining their survival. In conclusion, chronic administration of citrate might select resistant cells, which could jeopardize the benefits of citrate anticancer treatment.

Dysregulated mitochondrial Ca2+ and ROS signaling in skeletal muscle of ALS mouse model

Amyotrophic lateral sclerosis (ALS) is a devastating neuromuscular disease characterized by motor neuron loss and prominent skeletal muscle wasting. Despite more than one hundred years of research efforts, the pathogenic mechanisms underlying neuromuscular degeneration in ALS remain elusive. While the death of motor neuron is a defining hallmark of ALS, accumulated evidences suggested that in addition to being a victim of motor neuron axonal withdrawal, the intrinsic skeletal muscle degeneration may also actively contribute to ALS disease pathogenesis and progression. Examination of spinal cord and muscle autopsy/biopsy samples of ALS patients revealed similar mitochondrial abnormalities in morphology, quantity and disposition, which are accompanied by defective mitochondrial respiratory chain complex and elevated oxidative stress. Detailing the molecular/cellular mechanisms and the role of mitochondrial dysfunction in ALS relies on ALS animal model studies. This review article discusses the dysregulated mitochondrial Ca2+ and reactive oxygen species (ROS) signaling revealed in live skeletal muscle derived from ALS mouse models, and a potential role of the vicious cycle formed between the dysregulated mitochondrial Ca2+ signaling and excessive ROS production in promoting muscle wasting during ALS progression.

Temozolomide-Perillyl alcohol conjugate impairs Mitophagy flux by inducing lysosomal dysfunction in non-small cell lung Cancer cells and sensitizes them to irradiation

BACKGROUND

Temozolomide-perillyl alcohol conjugate (TMZ-POH), a novel Temozolomide (TMZ) analog developed based on the conjugation of TMZ and perillyl alcohol (POH), displayed strong anticancer potency in multiple cancer types. In this study, we aimed to clarify the relationship between TMZ-POH and autophagy, and explore the underlying mechanisms involved in.

METHODS

The proteins involved in autophagy, mitochondrial fission, lysosomal function and membrane traffic were detected by western blots; Autophagosome, mitochondria and lysosome were visualized by transmission electron microscope (TEM) and immunostaining; Apoptosis analysis and fluorescence probe detection were applied by flow cytometry.

RESULTS

TMZ-POH blocked mitophagy flux although the number of autophagosomes which colocalized with mitochondria in the cells was increased via inducing lysosomal dysfunction as evidence from impaired lysosomal acidification, maturation and hampered autophagosome- lysosome fusion, which largely depended on its downregulation on the small GTPase RAB7A via mevalonate pathway. More importantly, our data demonstrated TMZ-POH sensitized cancer cell to irradiation induced apoptosis.

CONCLUSIONS

Temozolomide-perillyl alcohol conjugate impairs mitophagy flux by inducing lysosomal dysfunction in Non-Small Cell Lung Cancer (NSCLC) cells and sensitizes them to irradiation, thereby proposing TMZ-POH as a potential radiosensitizer.

Redox- and pH-Responsive Nanoparticles Release Piperlongumine in a Stimuli-Sensitive Manner to Inhibit Pulmonary Metastasis of Colorectal Carcinoma Cells

Redox-responsive nanoparticles having a diselenide linkage were synthesized to target pulmonary metastasis of cancer cells. Methoxy poly(ethylene glycol)-grafted chitosan (ChitoPEG) was crosslinked using selenocystine-acetyl histidine (Ac-histidine) conjugates (ChitoPEGse) for stimuli-responsive delivery of piperlongumine (PL). ChitoPEGse nanoparticles swelled in an acidic environment and became partially disintegrated in the presence of H2O2, resulting in an increase of particle size and in a size distribution having multimodal pattern. PL release increased under acidic conditions and in the presence of H2O2. Uptake of ChitoPEGse nanoparticles by CT26 cells significantly increased in acidic and redox state. PL-incorporated ChitoPEGse nanoparticles (PL NPs) showed similar anticancer activity in vitro against A549 and CT26 cells compared to PL itself. PL NP showed superior anticancer and antimetastatic activity in an in vivo CT26 cell pulmonary metastasis mouse model. Furthermore, an immunofluorescence imaging study demonstrated that PL NP conjugates were specifically delivered to the tumor mass in the lung. Conclusively, ChitoPEGse nanoparticles were able to be delivered to cancer cells with an acidic- or redox state-sensitive manner and then efficiently targeted pulmonary metastasis of cancer cells since ChitoPEGse nanoparticles have dual pH- and redox-responsiveness.

Astragaloside IV enhances taxol chemosensitivity of breast cancer via caveolin-1-targeting oxidant damage

Accumulating evidence suggests that caveolin-1 (CAV-1) is a stress-related oncotarget and closely correlated to chemoresistance. Targeting CAV-1 might be a promising strategy to improve chemosensitivity for breast cancer treatment. Astragaloside IV (AS-IV), a bioactive compound purified from Astragalus membranaceus, has been shown to exhibit multiple bioactivities, including anticancer. However, the involved molecular targets are still ambiguous. In this study, we investigated the critical role of CAV-1 in mediating the chemosensitizing effects of AS-IV to Taxol on breast cancer. We found that AS-IV could enhance the chemosensitivity of Taxol with minimal direct cytotoxicity on breast cancer cell lines MCF-7 and MDA-MB-231, as well as the nontumor mammary epithelial cell line MCF-10A. AS-IV was further demonstrated to aggravate Taxol-induced apoptosis and G2/M checkpoint arrest. The phosphorylation of mitogen-activated protein kinase (MAPK) signaling extracellular signal-regulated kinase (ERK) and c-Jun N-terminal Kinase (JNK), except p38, was also abrogated by a synergistic interaction between AS-IV and Taxol. Moreover, AS-IV inhibited CAV-1 expression in a dose-dependent manner and reversed CAV-1 upregulation induced by Taxol administration. Mechanism study further demonstrated that AS-IV treatment triggered the eNOS/NO/ONOO^- pathway via inhibiting CAV-1, which led to intense oxidant damage. CAV-1 overexpression abolished the chemosensitizing effects of AS-IV to Taxol by inhibiting oxidative stress. In vivo experiments further validated that AS-IV increased Taxol chemosensitivity on breast cancer via inhibiting CAV-1 expression, followed by activation of the eNOS/NO/ONOO^- pathway. Taken together, our findings not only suggested the potential of AS-IV as a promising candidate to enhance chemosensitivity, but also highlighted the significance of CAV-1 as the target to reverse cancer drug resistance.