Mitochondria Of Tumor Cells Research Articles

GSH-responsive sequential mitochondria-targeting nanoagents for photothermal-enhanced chemodynamic therapy

Mitochondria-targeting nanoparticles have proven to be promising platforms for cancer therapy. However, precise mitochondria targeting in the complex tumor environment is still challenging and requires more ingenious design. Herein, we developed the glutathione (GSH)-responsive nanoagents to target mitochondria in tumor cells precisely for photothermal-enhanced chemodynamic therapy (CDT). The nanoagents were designed by preparing the cubic shape of CuFeS2 nanoparticles that sequentially modified with mitochondrial-targeting peptide (KLAK) and integrin-targeting peptide (RGD), which KLAK and RGD were covalently conjugated via a disulfide bond. After being endocytosed into integrin-overexpressed tumor cells, disulfide bond was broken and RGD was separated from the nanoagents in the presence of overexpressed GSH. Then, the exposure of KLAK on the surface further aid the rustling nanoagents to target mitochondria. Under NIR laser irradiation, the surrounding temperature of the nanoagents would rise due to their excellent photothermal effect, resulting in the improvement of the Fenton reaction from the CuFeS2. It was well demonstrated that this photothermal-enhanced chemodynamic therapy nanoplatform could effectively damage the mitochondrial function and further induce the apoptosis of tumor cells. As a therapeutic platform with both tumor/mitochondria-targeting and PTT-enhanced CDT, our study has provided a new path in the field of cancer therapy.

Exploiting the tumor immune microenvironment and immunometabolism using mitochondria-targeted drugs: Challenges and opportunities in racial disparity and cancer outcome research.

Black and Hispanic cancer patients have a higher incidence of cancer mortality. Many factors (e.g., socioeconomic differences, insufficient access to healthcare) contribute to racial disparity. Emerging research implicates biological disparity in cancer outcomes. Studies show distinct differences in the tumor immune microenvironment (TIME) in Black cancer patients. Studies also have linked altered mitochondrial metabolism to changes in immune cell activation in TIME. Recent publications revealed a novel immunomodulatory role for triphenylphosphonium‐based mitochondrial‐targeted drugs (MTDs). These are synthetically modified, naturally occurring molecules (e.g., honokiol, magnolol, metformin) or FDA‐approved small molecule drugs (e.g., atovaquone, hydroxyurea). Modifications involve conjugating the parent molecule via an alkyl linker chain to a triphenylphosphonium moiety. These modified molecules (e.g., Mito‐honokiol, Mito‐magnolol, Mito‐metformin, Mito‐atovaquone, Mito‐hydroxyurea) accumulate in tumor cell mitochondria more effectively than in normal cells and inhibit mitochondrial respiration, induce reactive oxygen species, activate AMPK and redox transcription factors, and inhibit cancer cell proliferation. Besides these intrinsic effects of MTDs in redox signaling and proliferation in tumors, MTDs induced extrinsic effects in the TIME of mouse xenografts. MTD treatment inhibited tumor‐suppressive immune cells, myeloid‐derived suppressor cells, and regulatory T cells, and activated T cells and antitumor immune effects. One key biological disparity in Black cancer patients was related to altered mitochondrial oxidative metabolism; MTDs targeting vulnerabilities in tumor cells and the TIME may help us understand this biological disparity. Clinical trials should include an appropriate number of Black and Hispanic cancer patients and should validate the intratumoral, antihypoxic effects of MTDs with imaging.

Nuclear genome-derived circular RNA circPUM1 localizes in mitochondria and regulates oxidative phosphorylation in esophageal squamous cell carcinoma

Circular RNAs (circRNAs) were shown to play an important role in the occurrence and progression of tumors. However, the functions of nuclear genome-derived circRNAs localized in mitochondria of tumor cells remain largely elusive. Here, we report that circPUM1, a circular RNA derived from back-splicing of pre-mRNAs of nuclear genome PUM1, localizes in mitochondria. The expression level of circPUM1 is positively correlated with HIF1α accumulation under CoCl2-induced intracellular hypoxic-like condition in esophageal squamous cell carcinoma (ESCC) cell lines. Importantly, circPUM1 acts as a scaffold for the interaction between UQCRC1 and UQCRC2 in ESCC cell lines. Knock-down of circPUM1 would result in lower intracellular oxygen concentration, downregulated oxidative phosphorylation, decrease of mitochondrial membrane potential, increase of ROS generation and shrinking of mitochondria, respectively. CircPUM1 depletion induces dysfunction of the mitochondrial complex III and the cleavage of caspase3 spontaneously. Interestingly, disruption of circPUM1 led to pyroptosis that initiates the cell death of ESCC cell lines. Therefore, we conclude that circPUM1 plays a critical role in maintaining the stability of mitochondrial complex III to enhance oxidative phosphorylation for ATP production of ESCC cells and moreover propose that ESCC cells exploit circPUM1 during cell adaptation.

Rational Design 2-Hydroxypropylphosphonium Salts as Cancer Cell Mitochondria-Targeted Vectors: Synthesis, Structure, and Biological Properties.

It has been shown for a wide range of epoxy compounds that their interaction with triphenylphosphonium triflate occurs with a high chemoselectivity and leads to the formation of (2-hydroxypropyl)triphenylphosphonium triflates 3 substituted in the 3-position with an alkoxy, alkylcarboxyl group, or halogen, which were isolated in a high yield. Using the methodology for the disclosure of epichlorohydrin with alcohols in the presence of boron trifluoride etherate, followed by the substitution of iodine for chlorine and treatment with triphenylphosphine, 2-hydroxypropyltriphenylphosphonium iodides 4 were also obtained. The molecular and supramolecular structure of the obtained phosphonium salts was established, and their high antitumor activity was revealed in relation to duodenal adenocarcinoma. The formation of liposomal systems based on phosphonium salt 3 and L-α-phosphatidylcholine (PC) was employed for improving the bioavailability and reducing the toxicity. They were produced by the thin film rehydration method and exhibited cytotoxic properties. This rational design of phosphonium salts 3 and 4 has promising potential of new vectors for targeted delivery into mitochondria of tumor cells.

Mito‐Bomb: Targeting Mitochondria for Cancer Therapy (Adv. Mater. 43/2021)

Cancer Therapy In article number 2007778, Lin Li, Shao Q. Yao, Wei Huang, and co-workers review the different mitochondria-targeting functional units (Mito-Bomb), and various cancer treatment strategies that target mitochondria. In the picture, the commander (scientist or doctor) controls the “Mito-Bomb”, which indicates the accurate destruction of mitochondria in tumor cells to achieve the precise treatment of tumors.

Multiple Myeloma Tumor Cells Are Selectively Killed By Pharmacologically-Dosed Ascorbic Acid

Background: High-dose chemotherapy to treat multiple myeloma (MM) can be life-threatening due to toxicities to normal cells and there is a need to target tumor cells more selectively and/or lower standard drug dosage without losing efficacy. We show that pharmacologically-dosed ascorbic acid (PAA) only in the presence of high intracellular iron leads to the formation of reactive oxygen species (ROS) resulting in cell death.Materials and Methods: CD138+ primary MM cells and CD138− non-MM cells were isolated from 9 MM, 2 smoldering MM, and 2 monoclonal gammopathy of undetermined significance (MGUS) patients. High doses of ascorbic acid alone and combination with standard therapeutic drugs were used to treat MM cells in vitro and in vivo . Electron microscope was used to detect cell necrosis and apoptosis as well as apoptosis-inducing factor 1 (AIF1) nuclear translocation. Overexpression (OE), empty vector (EV) and knockdown (KD) of ferroportin 1 (Fpn1) and AIF1 in MM cells were achieved by lentivirus infection. An In Vivo Imaging System (IVIS) was used to monitor tumor growth in vivo .Results: We show that PAA selectively kills CD138+ primary MM cells derived from MM and SMM, but not from MGUS patients. To confirm the capacity of PAA to induce MM cell death in vivo, xenografted MM mice were treated with PAA alone or combination with carfizomib or melphalan. We observed that PAA inhibited MM cell growth and extended MM mouse survival significantly. Importantly, PAA allowed a dramatic decrease in DNA-alkylating agent melphalan dosage (75%) without loss of efficacy. DFO, an iron chelator, abolished the ability of PAA to reduce cells viability in both EV and OE-Fpn1 OCI-MY5 cells pre-treated with iron. These results suggest that the mechanism of PAA killing of MM cells is indeed iron-dependent. Our data also show that PAA increases AIF1 cleavage and translocation from mitochondria to cytoplasm and nucleus. Overexpression of AIF1 in MM cells increases PAA sensitivity while KD of AIF1 prevents PAA induced MM cell death, indicating AIF1 plays an essential role in mediating PAA-induced MM cell death.Conclusion: Our findings show that PAA only kills tumor cells with high iron content, suggesting that iron is the initiator of PAA cytotoxicity. In addition, combination of PAA with standard therapeutic drugs, such as melphalan, might significantly reduce the dose of melphalan required. Because of the elevated intracellular iron in MM cells, PAA produces highly ROS leading to release of AIF1 from mitochondria of tumor cells with no toxicity to non-tumor cells with low iron content. These results provide a mechanistic rationale to pursue the therapeutic use of PAA in MM and other cancers with high iron content. This is first study testing directly PAA efficacy on primary cancer cells in vitro . DisclosuresNo relevant conflicts of interest to declare.

Light-Induced Reactive Oxygen Species (ROS) Generator for Tumor Therapy through an ROS Burst in Mitochondria and AKT-Inactivation-Induced Apoptosis.

Mitochondria are identified as a valuable target for cancer therapy owing to their primary function in energy supply and cellular signal regulation. Mitochondria in tumor cells are depicted by excess reactive oxygen species (ROS), which lead to numerous detrimental results. Hence, mitochondria-targeting ROS-associated therapy is an optional therapeutic strategy for cancer. In this contribution, a light-induced ROS generator (TBTP) is developed for evaluation of the efficacy of mitochondria-targeting ROS-associated therapy and investigation of the mechanism underlying mitochondrial-injure-mediated therapy of tumors. TBTP serves as an efficient ROS generator with low cytotoxicity, favorable biocompatibility, excellent photostability, mitochondria-targeted properties, and NIR emission. In vivo and in vitro experiments reveal that TBTP exhibits effective anticancer potential. ROS generated from TBTP could destroy the integrity of mitochondria, downregulate ATP, decrease the mitochondrial membrane potential, secrete Cyt-c into cytoplasm, activate Caspase-3/9, and induce cell apoptosis. Moreover, RNA-seq analysis highlights that an ROS burst in mitochondria can kill tumor cells via inhibition of the AKT pathway. All these results prove that mitochondrial-targeted ROS-associated therapy hold great potential in cancer therapy.

The state of apoptosis factor system in mitochondria of skin and tumor cells in standard and stimulated growth of B16/F10 melanoma in female C57BL/6 mice

Purpose of the study. Studying the dynamics of factors of apoptosis in mitochondria of skin and tumors cells in female mice with melanoma growth stimulated by chronic neurogenic pain. Material and methods. The study included female С57ВL/6 mice (n=56) with a model of chronic neurogenic pain (CNP) produced by the bilateral sciatic nerve ligation and with transplanted B16/F10 melanoma. After 1–3 weeks of the tumor growth, levels of cytochrome C, caspase‑9 (Bioscience, Austria), Bcl‑2 (Thermo Fisher Scientific, Austria), and AIF (RayBiotech, USA) were determined by ELISA, and levels of calcium (Са2+) were determined by the Arsenazo III method (Abris+, Russia) in mitochondria of tumors cells and skin not affected by the tumor growth. Results. In the CNP state, mitochondria of the skin cells showed a significant increase in Са2+ by 96.7 times, AIF by 1.4 times and Bcl‑2 by 5.9 times, while caspase‑9 decreased by 2.6 times, compared to the levels in intact mice. In the CNP‑stimulated melanoma growth, mitochondria of cells of the skin not affected by the tumor growth demonstrated a decrease in all studied indices, except caspase‑9 – its levels increased by 4.6 times after 3 weeks of the tumor growth. In mitochondria of the tumor cells within 1–3 weeks, levels of Са2+ decreased over time by 37.2–96.1 times, respectively, AIF by 49.4–2.0 times, Bcl‑2 by 3.0–1.5 times, cytochrome C by 15.3–8.8 times, and caspase‑9 increased by 1.7–4.4 times compared with the level in animals with pain. Conclusions. In general, the growth of melanoma stimulated by chronic pain and the standard melanoma growth were characterized by the opposite dynamics of levels of apoptosis factor both in mitochondria of skin cells and in mitochondria of tumor cells, with the exception of cytochrome C. Mitochondria of melanoma cells and of the unchanged skin have a similar tendency to change the levels of apoptosis factors, which may indicate their functioning in the conditions of the mitochondrial network at the level of one organ. Mitochondria of tumor cells provide the anti‑apoptotic state of the tumor itself and of the skin not affected by the malignant process, probably due to the stress state of the skin.

Influence of B16/F10 melanoma growth variant on calcium levels in mitochondria in various organs of female mice

Purpose of the study. To analyze the calcium levels in mitochondria of cells in different organs in standard and stimulated growth of experimental В16/F10 melanoma. Materials and Methods. The study included female С57ВL/6 mice (n=168). Experimental groups: intact group (n=21), group with a model of chronic neurogenic pain (CNP) (n=21), group M – B16/F10 melanoma (n=63), group M+CNP – mice (n=63) with transplantation of B16/F10 melanoma 3 weeks after CNP model creation. The concentration of calcium in mitochondrial samples was determined by a biochemical method (Abris+, Russia). Results were statistically analyzed using the Statistica 10.0 program. Results. CNP decreased calcium levels in mitochondria of cells in the brain by 1.4 (р=0.00153) times, liver by 2.6 times and heart by 3.2 times and increased the levels in the skin by 97.1 times. In standard growth of experimental melanoma, levels of calcium in cell mitochondria in most of the studied organs increased at the initial stage of the melanoma growth, and decreased to intact values and lower by the terminal stage. In the mitochondria of tumor cells, calcium levels were stably high at all stages of standard tumor growth. At the initial stage of CNP‑stimulated tumor growth, a decrease in calcium in the mitochondria of the skin by 5.7 times and its accumulation in the mitochondria of the brain by 6.6 times, heart, and kidneys were recorded by 1.5 times. At the terminal stage of stimulated melanoma growth, extremely low calcium values were recorded in the mitochondria of all organs. A stably low level of calcium was registered in the mitochondria of tumor cells at all stages of stimulated melanoma growth. Conclusions. The growth of experimental B16/F10 melanoma in female mice is accompanied by mitochondrial dysfunction affecting most organs. Stimulation of the growth of experimental melanoma with chronic neurogenic pain, unlike the standard growth variant, changes accumulation of calcium in the mitochondria of cells both in organs and in the tumor itself. The chronic pain syndrome accompanying a malignant process can influence its course with the involvement of mitochondria and the modification of their functions.

An effective in vivo mitochondria-targeting nanocarrier combined with a π-extended porphyrin-type photosensitizer.

A photochemical reaction mediated by light-activated molecules (photosensitizers) in photodynamic therapy (PDT) causes molecular oxygen to be converted into highly reactive oxygen species (ROS) that are beneficial for cancer therapy. As the active oxygen consumer and the primary regulator of apoptosis, mitochondria are known as an important target for optimizing PDT outcomes. However, most of the clinically used photosensitizers exhibited a poor tumor accumulation profile as well as lack of mitochondria targeting ability. Therefore, by applying a nanocarrier platform, mitochondria-specific delivery of photosensitizers can be materialized. The present research develops an effective mitochondria-targeting liposome-based nanocarrier system (MITO-Porter) encapsulating a π-extended porphyrin-type photosensitizer (rTPA), which results in a significant in vivo antitumor activity. A single PDT treatment of the rTPA–MITO-Porter resulted in a dramatic tumor inhibition against both human and murine tumors that had been xenografted in a mouse model. Furthermore, depolarization of the mitochondrial membrane was observed, implying the damage of the mitochondrial membrane due to the photochemical reaction that occurred specifically in the mitochondria of tumor cells. The findings presented herein serve to verify the significance of the mitochondria-targeted nanocarrier system for advancing the in vivo PDT effectivity in cancer therapy regardless of tumor type.

Medicinal Chemistry Targeting Mitochondria: From New Vehicles and Pharmacophore Groups to Old Drugs with Mitochondrial Activity.

Interest in tumor cell mitochondria as a pharmacological target has been rekindled in recent years. This attention is due in part to new publications documenting heterogenous characteristics of solid tumors, including anoxic and hypoxic zones that foster cellular populations with differentiating metabolic characteristics. These populations include tumor-initiating or cancer stem cells, which have a strong capacity to adapt to reduced oxygen availability, switching rapidly between glycolysis and oxidative phosphorylation as sources of energy and metabolites. Additionally, this cell subpopulation shows high chemo- and radioresistance and a high capacity for tumor repopulation. Interestingly, it has been shown that inhibiting mitochondrial function in tumor cells affects glycolysis pathways, cell bioenergy, and cell viability. Therefore, mitochondrial inhibition may be a viable strategy for eradicating cancer stem cells. In this context, medicinal chemistry research over the last decade has synthesized and characterized “vehicles” capable of transporting novel or existing pharmacophores to mitochondrial tumor cells, based on mechanisms that exploit the physicochemical properties of the vehicles and the inherent properties of the mitochondria. The pharmacophores, some of which have been isolated from plants and others, which were synthesized in the lab, are diverse in chemical nature. Some of these molecules are active, while others are prodrugs that have been evaluated alone or linked to mitochondria-targeted agents. Finally, researchers have recently described drugs with well-proven safety and efficacy that may exert a mitochondria-specific inhibitory effect in tumor cells through noncanonical mechanisms. The effectiveness of these molecules may be improved by linking them to mitochondrial carrier molecules. These promising pharmacological agents should be evaluated alone and in combination with classic chemotherapeutic drugs in clinical studies.

Prohibitin, STAT3 and SH2D4A physically and functionally interact in tumor cell mitochondria

Chromosome 8p is frequently deleted in various cancer entities and has been shown to correlate with poor patient survival. SH2D4A is located on chromosome 8p and prevents the nuclear translocation of the pro-tumorigenic transcription factor STAT3. Here, we investigated the interaction of SH2D4A and STAT3 to shed light on the non-canonical functions of STAT3 in cooperation with the tumor suppressor SH2D4A. Using an immunoprecipitation-mass spectrometry (IP-MS) approach, we identified the mitochondrial scaffold proteins prohibitin 1 (PHB1) and prohibitin 2 (PHB2) among other proteins to potentially bind to SH2D4A. Co-immunoprecipitation and proximity ligation assays confirmed direct interactions of STAT3, PHB1, and SH2D4A in situ and in vitro. In addition, cell fractionation and immunofluorescence staining revealed co-localization of these proteins with mitochondria. These interactions were selectively interrupted by the small molecule and PHB ligand FL3. Furthermore, FL3 led to a reduction of STAT3 protein levels, STAT3 transcriptional activity, and HIF1α protein stabilization upon dimethyloxalylglycine (DMOG) treatment. Besides, mitochondrial fusion and fission markers, L-OPA1, Mfn1, and FIS1, were dysregulated upon FL3 treatment. This dysregulated morphology was accompanied by significant reduction of mitochondrial respiration, thus, FL3 significantly diminished mitochondrial respirational capacity. In contrast, SH2D4A knockout increased mitochondrial respiration, whereas FL3 reversed the effect of SH2D4A knockout. The here described results indicate that the interaction of SH2D4A and PHB1 is involved in the mitochondrial function and integrity. The demonstrated interaction with STAT3, accompanied by its reduction of transcriptional activity, further suggests that SH2D4A is linking STAT3 to its mitochondrial functions, and inhibition of PHB-interaction may have therapeutic effects in tumor cells with STAT3 activation.

Aggregation-induced Emission Based Fluorogens for Mitochondria-targeted Tumor Imaging and Theranostics.

Occurrence and development of cancer are multifactorial and multistep processes which involve complicated cellular signaling pathways. Mitochondria, as the energy producer in cells, play key roles in tumor cell growth and division. Since mitochondria of tumor cells have a more negative membrane potential than those of normal cells, several fluorescent imaging probes have been developed for mitochondria-targeted imaging and photodynamic therapy. Conventional fluorescent dyes suffer from aggregation-caused quenching effect, while novel aggregation-induced emission (AIE) probes are ideal candidates for biomedical applications due to their large stokes shift, strong photo-bleaching resistance, and high quantum yield. This review aims to introduce the recent advances in the design and application of mitochondria-targeted AIE probes. The comprehensive review focuses on the structure-property relationship of these imaging probes, expecting to inspire the development of more practical and versatile AIE fluorogens (AIEgens) as tumor imaging and therapy agents for preclinical and clinical use.

Tumor microenvironment changes tumor cell sensitivity to action of energy metabolism modifiers.

Taking into account differences in the bioenergetics between malignant and normal cells a search of antitumor drugs among the modifiers of tumor metabolism has a reasonable excuse. Earlier it was found that the cytotoxic/cytostatic action of sodium dichloroacetate (DCA) against Lewis lung carcinoma (LLC) cells in vitro was enhanced in the case of its combination with metformin (MTF). To study the antitumor action of DCA in combination with MTF against LLC in vivo. LLC/R9, a low metastatic variant of LLC cells, was used. LLC/R9bearing mice were treated with MTF (at a total dose 0.15g/kg b.w.) alone or in combination with DCA (at a total dose of 0.75g/kg b.w.). LLC/R9growth kinetics and the primary tumor growth and metastasis indices on the 23rd day after tumor cell inoculation were evaluated by routine procedures. The state of the electron transport chain of mitochondria in tumor cells was studied using electron paramagnetic resonance. The content of lactate and glucose in blood plasma from mice was measured by enzymatic methods using biochemical analyzer. The number of tumor-associated macrophages (TAMs) and their distribution by M1/M2phenotype were estimated by flow cytometry using antibodies against CD68and CD206. In LLC/R9-bearing mice treated with DCA in combination with MTF, tumor growth and metastasis indices, as well as circulating glucose and lactate levels were not significantly different from those in the control group. The level of nitrosylation of non-heme and heme proteins and the content of iron-sulfur centers in the mitochondria of tumor cells in LLC/R9-bearing mice administered with DCA in combination with MTF did not also differ from the corresponding indices in control. Instead, in tumors treated with MTF alone and in combination with DCA the total CD68+ TAMs count was almost 27% (p< 0.05) and 43% lower (p< 0.05) correspondingly than that in control, but this decrease was not accompanied by redistribution of CD68+/CD206+ and CD68+/D206- subsets. DCA in combination with MTF, at least in doses applied, did not affect LLC/R9growth and metastasis in vivo. The complete absence of an antitumor effect of DCA in combination with MTF was simultaneously associated with the absence of significant changes in the functional state of electron transport chain of mitochondria in tumor cells, circulating glucose and lactate levels, and the decrease of the TAMs amount in tumors. It suggests that the antitumor activity of DCA and MTF could be determined by both their local effects within a tumor and their multiple systemic impacts.

The Regulatory Mechanisms of Dynamin-Related Protein 1 in Tumor Development and Therapy.

Background: Various types of tumors are likely to acquire drug resistance over time. Hence, the development of novel therapies to overcome drug resistance is critical. Studies have demonstrated that drug resistance is closely associated with the dynamic regulation of mitochondria in tumor cells. The dynamin-related protein 1 (Drp1) is involved in the regulation of mitochondrial fission and plays an important role in maintaining mitochondrial morphology, function, and distribution. It is a key protein in mitochondrial quality control. Drp1 is a GTPase localized to the cytoplasm and is a potential target in cancer therapy. A variety of drugs targeting Drp1 have shown great promise in reducing the viability and proliferation of cancer cells. The dynamic regulation of Drp1-mediated mitochondria is closely associated with tumor development, and treatment. Aim: In this article, the authors reviewed the occurrence and progression of mitochondrial fission regulated by Drp1, and its influence on cell cycle, autophagy, apoptosis, migration, invasion, the molecular mechanism of tumor stemness, and metabolic reprogramming. Targeted inhibition of Drp1 and mitochondrial fission could reduce or prevent tumor occurrence and progression in a variety of cancers. Drp1 inhibitors could reduce tumor stemness and enhance tumor sensitivity to chemotherapeutic drugs. Conclusion: Research into identifying compounds that could specifically target Drp1 will be valuable for overcoming drug resistance in tumors.

Mitochondria-targeting nanomedicine self-assembled from GSH-responsive paclitaxel-ss-berberine conjugate for synergetic cancer treatment with enhanced cytotoxicity

Mitochondria play a fundamental role in plenty of cellular metabolic processes, and mitochondria-homing drug delivery is a promising and effective strategy for cancer treatment. Paclitaxel (PTX) is a broad-spectrum anticancer drug, but its therapeutic effect is highly limited due to the development of multidrug resistance. Berberine (BBR) can selectively accumulate in tumor cell mitochondria and inhibit the growth of cancer cells with different biological action mechanism from PTX. Here, these two “old” drug molecules, BBR and PTX were linked together by a disulfide bond rope to construct GSH-responsible drug-drug conjugate (PTX-ss-BBR). Molecular dynamics simulation results revealed that PTX-ss-BBR conjugate could be self-assembled in water to form nanoparticles (PTX-ss-BBR NPs) forced by π-π stacking and hydrophobic interactions and the average size of NPs was around 165 nm measured by DLS. The better in vitro potency of PTX-ss-BBR NPs against A549 cells might be ascribed to the simultaneous drug release and mitochondria-targeting delivery, which dissipated mitochondria membrane potential, upregulated ROS levels in cancer cells, arrested cells in phase G2/M, elicited apoptosis of cancer cells and inhibited the growth of tumors. Furthermore, PTX-ss-BBR NPs also exerted efficacy better than or comparable to BBR on S. aureus and E. coli, which were closely associated with the development of lung cancer. The synergistic effect of PTX and BBR enhanced the treatment effect of conventional chemotherapy drugs against A549 cells.

Chasing the FOXO3: Insights into Its New Mitochondrial Lair in Colorectal Cancer Landscape.

Colorectal cancer (CRC) poses a formidable challenge in terms of molecular heterogeneity, as it involves a variety of cancer-related pathways and molecular changes unique to an individual’s tumor. On the other hand, recent advances in DNA sequencing technologies provide an unprecedented capacity to comprehensively identify the genetic alterations resulting in tumorigenesis, raising the hope that new therapeutic approaches based on molecularly targeted drugs may prevent the occurrence of chemoresistance. Regulation of the transcription factor FOXO3a in response to extracellular cues plays a fundamental role in cellular homeostasis, being part of the molecular machinery that drives cells towards survival or death. Indeed, FOXO3a is controlled by a range of external stimuli, which not only influence its transcriptional activity, but also affect its subcellular localization. These regulation mechanisms are mediated by cancer-related signaling pathways that eventually drive changes in FOXO3a post-translational modifications (e.g., phosphorylation). Recent results showed that FOXO3a is imported into the mitochondria in tumor cells and tissues subjected to metabolic stress and cancer therapeutics, where it induces expression of the mitochondrial genome to support mitochondrial metabolism and cell survival. The current review discusses the potential clinical relevance of multidrug therapies that drive cancer cell fate by regulating critical pathways converging on FOXO3a.

Targeting the mitochondrial apoptosis pathway by a newly synthesized COX-2 inhibitor in pediatric ALL lymphocytes.

Acute lymphoblastic leukemia (ALL) is known as a barely curable malignancy. Particular mutations involved in apoptosis may have a main role in the onset of ALL in the pediatric patients. It has been proven that cycloxygenase-2 is capable of impairing the apoptosis pathway through mitochondria in tumor cells. In this study, we investigated selective toxicity of a newly synthesized chalconeferrocenyl derivative as a selective cycloxygenase-2 inhibitor in ALL and healthy B-lymphocytes, and also isolated mitochondria obtained from them. For this purpose, we evaluated the cellar parameters like viability, apoptosis/necrosis, caspase-3 activation and ATP content, and also mitochondrial parameters like mitochondrial membrane potential decline, reactive oxygen species formation, cytochrome C release and mitochondrial swelling. Our results implied that this compound can selectively induce cellular and mitochondrial toxicity in cancerous ALL B-lymphocytes and obtained mitochondria from them without any detrimental effects on healthy subjects.

Mitochondrial control of store-operated Ca2+ channels in cancer: Pharmacological implications.

Intracellular Ca2+ is a pleiotropic second messenger involved in control of different cell and physiological functions including long-term processes such as cell proliferation, migration and survival. Agonist-induced Ca2+ entry in most cells, especially in non-excitable cells including epithelial cells, is mediated by store-operated Ca2+ entry (SOCE), a Ca2+ entry pathway activated by agonist-induced release of Ca2+ from intracellular stores in the endoplasmic reticulum (ER). This pathway is modulated also by mitochondria which, acting as Ca2+ sinks, take up Ca2+, thus limiting Ca2+-dependent inactivation of Ca2+-release activated Ca2+ channels (CRAC). Compelling evidence shows that SOCE is upregulated in a large variety of cancer cells and this change contribute to cancer hallmarks. Mechanisms for enhanced SOCE include changes in expression of members of the Orai, Stromal interaction molecule (STIM) and canonical transient receptor potential channel (TRPc) gene families. Tumor cell mitochondria may contribute to SOCE upregulation in cancer as well. Molecular players involved in enhancing mitochondrial Ca2+ uptake are upregulated in tumor cells whereas negative modulators are repressed. Furthermore, mitochondrial potential, the driving force for mitochondrial Ca2+ uptake, is enhanced in tumor cells due to the Warburg effect. Finally, SOCE in tumor cells may be sustained further by the gain of function of non-selective TRPC channels permeable to Na+ that favour Ca2+ exit from mitochondria in exchange for Na+, thus limiting Ca2+-dependent inactivation of Orai1 channels. Therefore, tumor cell mitochondria may efficiently contribute to enhance and sustain SOCE in cancer. Interestingly, this effect could be counterbalanced by selected non-steroidal anti-inflammatory drugs (NSAIDs) reported to prevent colorectal cancer and other forms of cancer.

Syntaphilin Ubiquitination Regulates Mitochondrial Dynamics and Tumor Cell Movements.

Syntaphilin (SNPH) inhibits the movement of mitochondria in tumor cells, preventing their accumulation at the cortical cytoskeleton and limiting the bioenergetics of cell motility and invasion. Although this may suppress metastasis, the regulation of the SNPH pathway is not well understood. Using a global proteomics screen, we show that SNPH associates with multiple regulators of ubiquitin-dependent responses and is ubiquitinated by the E3 ligase CHIP (or STUB1) on Lys111 and Lys153 in the microtubule-binding domain. SNPH ubiquitination did not result in protein degradation, but instead anchored SNPH on tubulin to inhibit mitochondrial motility and cycles of organelle fusion and fission, that is dynamics. Expression of ubiquitination-defective SNPH mutant Lys111→Arg or Lys153→Arg increased the speed and distance traveled by mitochondria, repositioned mitochondria to the cortical cytoskeleton, and supported heightened tumor chemotaxis, invasion, and metastasis in vivo Interference with SNPH ubiquitination activated mitochondrial dynamics, resulting in increased recruitment of the fission regulator dynamin-related protein-1 (Drp1) to mitochondria and Drp1-dependent tumor cell motility. These data uncover nondegradative ubiquitination of SNPH as a key regulator of mitochondrial trafficking and tumor cell motility and invasion. In this way, SNPH may function as a unique, ubiquitination-regulated suppressor of metastasis.Significance: These findings reveal a new mechanism of metastasis suppression by establishing the role of SNPH ubiquitination in inhibiting mitochondrial dynamics, chemotaxis, and metastasis. Cancer Res; 78(15); 4215-28. ©2018 AACR.