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Rohlenova K, Sachaphibulkij K, Stursa J, Bezawork-Geleta A, Blecha J, Endaya B, Werner L, Cerny J, Zobalova R, Goodwin J, Spacek T, Alizadeh Pesdar E, Yan B, Nguyen MN, Vondrusova M, Sobol M, Jezek P, Hozak P, Truksa J, Rohlena J, Dong LF, Neuzil J. Selective Disruption of Respiratory Supercomplexes as a New Strategy to Suppress Her2 high Breast Cancer. Antioxid Redox Signal 2017; 26:84-103. [PMID: 27392540 PMCID: PMC5206771 DOI: 10.1089/ars.2016.6677] [Citation(s) in RCA: 87] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
AIMS Expression of the HER2 oncogene in breast cancer is associated with resistance to treatment, and Her2 may regulate bioenergetics. Therefore, we investigated whether disruption of the electron transport chain (ETC) is a viable strategy to eliminate Her2high disease. RESULTS We demonstrate that Her2high cells and tumors have increased assembly of respiratory supercomplexes (SCs) and increased complex I-driven respiration in vitro and in vivo. They are also highly sensitive to MitoTam, a novel mitochondrial-targeted derivative of tamoxifen. Unlike tamoxifen, MitoTam efficiently suppresses experimental Her2high tumors without systemic toxicity. Mechanistically, MitoTam inhibits complex I-driven respiration and disrupts respiratory SCs in Her2high background in vitro and in vivo, leading to elevated reactive oxygen species production and cell death. Intriguingly, higher sensitivity of Her2high cells to MitoTam is dependent on the mitochondrial fraction of Her2. INNOVATION Oncogenes such as HER2 can restructure ETC, creating a previously unrecognized therapeutic vulnerability exploitable by SC-disrupting agents such as MitoTam. CONCLUSION We propose that the ETC is a suitable therapeutic target in Her2high disease. Antioxid. Redox Signal. 26, 84-103.
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Bezawork-Geleta A, Dong L, Rohlena J, Neuzil J. The Assembly Factor SDHAF2 Is Dispensable for Flavination of the Catalytic Subunit of Mitochondrial Complex II in Breast Cancer Cells. J Biol Chem 2016; 291:21414-21420. [PMID: 27587393 DOI: 10.1074/jbc.c116.755017] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Revised: 08/27/2016] [Indexed: 12/19/2022] Open
Abstract
Mitochondrial complex II or succinate dehydrogenase (SDH) is at the crossroads of oxidative phosphorylation and the tricarboxylic acid cycle. It has been shown that Sdh5 (SDHAF2/SDH5 in mammals) is required for flavination of the subunit Sdh1 (SDHA in human cells) in yeast. Here we demonstrate that in human breast cancer cells, SDHAF2/SDH5 is dispensable for SDHA flavination. In contrast to yeast, CRISPR-Cas9 nickase-mediated SDHAF2 KO breast cancer cells feature flavinated SDHA and retain fully assembled and functional complex II, as well as normal mitochondrial respiration. Our data show that SDHA flavination is independent of SDHAF2 in breast cancer cells, employing an alternative mechanism.
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Rohlenova K, Neuzil J, Rohlena J. The role of Her2 and other oncogenes of the PI3K/AKT pathway in mitochondria. Biol Chem 2016; 397:607-15. [DOI: 10.1515/hsz-2016-0130] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 04/13/2016] [Indexed: 01/01/2023]
Abstract
Abstract
Altered metabolism and resistance to cell death are typical hallmarks of cancer phenotype. Mitochondria are organelles central to cellular metabolism as well as to cell death induction. Hyperactivation of pro-survival and pro-proliferative pathways such as PI3K/AKT leads to cancer initiation, which affects mitochondria. Growing body of evidence indicates that oncogenes such as HER2, EGFR and RAS, as well as the downstream members of the PI3K/AKT signaling pathway, directly regulate mitochondria by translocating to the organelle. Here we discuss evidence of this scenario and consider mechanisms for direct regulation of mitochondrial function. Being in close proximity to mitochondrial bioenergetics machinery as well as to the regulators/executors of programed cell death, oncogenes in mitochondria may be ideally placed to perform this task. This represents a thus far under-explored area, which may be relevant to better understanding of cancer initiation, progression and treatment.
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Tomasetti M, Monaco F, Manzella N, Rohlena J, Rohlenova K, Staffolani S, Gaetani S, Ciarapica V, Amati M, Bracci M, Valentino M, Goodwin J, Nguyen M, Truksa J, Sobol M, Hozak P, Dong LF, Santarelli L, Neuzil J. MicroRNA-126 induces autophagy by altering cell metabolism in malignant mesothelioma. Oncotarget 2016; 7:36338-36352. [PMID: 27119351 PMCID: PMC5095004 DOI: 10.18632/oncotarget.8916] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 03/28/2016] [Indexed: 12/25/2022] Open
Abstract
Autophagy favors both cell survival and cancer suppression, and increasing evidence reveals that microRNAs (MIRs) regulate autophagy. Previously we reported that MIR126 is downregulated in malignant mesothelioma (MM). Therefore, we investigated the role of MIR126 in the regulation of cell metabolism and autophagy in MM models. We report that MIR126 induces autophagic flux in MM cells by downregulating insulin receptor substrate-1 (IRS1) and disrupting the IRS1 signaling pathway. This was specific to MM cells, and was not observed in non-malignant cells of mesothelial origin or in MM cells expressing MIR126-insensitive IRS1 transcript. The MIR126 effect on autophagy in MM cells was recapitulated by IRS1 silencing, and antagonized by IRS1 overexpression or antisense MIR126 treatment. The MIR126-induced loss of IRS1 suppressed glucose uptake, leading to energy deprivation and AMPK-dependent phosphorylation of ULK1. In addition, MIR126 stimulated lipid droplet accumulation in a hypoxia-inducible factor-1α (HIF1α)-dependent manner. MIR126 also reduced pyruvate dehydrogenase kinase (PDK) and acetyl-CoA-citrate lyase (ACL) expression, leading to the accumulation of cytosolic citrate and paradoxical inhibition of pyruvate dehydrogenase (PDH) activity. Simultaneous pharmacological and genetic intervention with PDK and ACL activity phenocopied the effects of MIR126. This suggests that in MM MIR126 initiates a metabolic program leading to high autophagic flux and HIF1α stabilization, incompatible with tumor progression of MM. Consistently, MIR126-expressing MM cells injected into immunocompromised mice failed to progress beyond the initial stage of tumor formation, showing that increased autophagy has a protective role in MM.
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Kluckova K, Sticha M, Cerny J, Mracek T, Dong L, Drahota Z, Gottlieb E, Neuzil J, Rohlena J. Ubiquinone-binding site mutagenesis reveals the role of mitochondrial complex II in cell death initiation. Cell Death Dis 2015; 6:e1749. [PMID: 25950479 PMCID: PMC4669690 DOI: 10.1038/cddis.2015.110] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Revised: 01/22/2015] [Accepted: 02/19/2015] [Indexed: 12/13/2022]
Abstract
Respiratory complex II (CII, succinate dehydrogenase, SDH) inhibition can induce cell death, but the mechanistic details need clarification. To elucidate the role of reactive oxygen species (ROS) formation upon the ubiquinone-binding (Qp) site blockade, we substituted CII subunit C (SDHC) residues lining the Qp site by site-directed mutagenesis. Cell lines carrying these mutations were characterized on the bases of CII activity and exposed to Qp site inhibitors MitoVES, thenoyltrifluoroacetone (TTFA) and Atpenin A5. We found that I56F and S68A SDHC variants, which support succinate-mediated respiration and maintain low intracellular succinate, were less efficiently inhibited by MitoVES than the wild-type (WT) variant. Importantly, associated ROS generation and cell death induction was also impaired, and cell death in the WT cells was malonate and catalase sensitive. In contrast, the S68A variant was much more susceptible to TTFA inhibition than the I56F variant or the WT CII, which was again reflected by enhanced ROS formation and increased malonate- and catalase-sensitive cell death induction. The R72C variant that accumulates intracellular succinate due to compromised CII activity was resistant to MitoVES and TTFA treatment and did not increase ROS, even though TTFA efficiently generated ROS at low succinate in mitochondria isolated from R72C cells. Similarly, the high-affinity Qp site inhibitor Atpenin A5 rapidly increased intracellular succinate in WT cells but did not induce ROS or cell death, unlike MitoVES and TTFA that upregulated succinate only moderately. These results demonstrate that cell death initiation upon CII inhibition depends on ROS and that the extent of cell death correlates with the potency of inhibition at the Qp site unless intracellular succinate is high. In addition, this validates the Qp site of CII as a target for cell death induction with relevance to cancer therapy.
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Truksa J, Dong LF, Rohlena J, Stursa J, Vondrusova M, Goodwin J, Nguyen M, Kluckova K, Rychtarcikova Z, Lettlova S, Spacilova J, Stapelberg M, Zoratti M, Neuzil J. Mitochondrially targeted vitamin E succinate modulates expression of mitochondrial DNA transcripts and mitochondrial biogenesis. Antioxid Redox Signal 2015; 22:883-900. [PMID: 25578105 DOI: 10.1089/ars.2013.5594] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
AIMS To assess the effect of mitochondrially targeted vitamin E (VE) analogs on mitochondrial function and biogenesis. RESULTS Mitochondrially targeted vitamin E succinate (MitoVES) is an efficient inducer of apoptosis in cancer cells. Here, we show that unlike its untargeted counterpart α-tocopheryl succinate, MitoVES suppresses proliferation of cancer cells at sub-apoptotic doses by way of affecting the mitochondrial DNA (mtDNA) transcripts. We found that MitoVES strongly suppresses the level of the displacement loop transcript followed by those of mtDNA genes coding for subunits of mitochondrial complexes. This process is coupled to the inhibition of mitochondrial respiration, dissipation of the mitochondrial membrane potential, and generation of reactive oxygen species. In addition, exposure of cancer cells to MitoVES led to decreased expression of TFAM and diminished mitochondrial biogenesis. The inhibition of mitochondrial transcription was replicated in vivo in a mouse model of HER2(high) breast cancer, where MitoVES lowered the level of mtDNA transcripts in cancer cells but not in normal tissue. INNOVATION Our data show that mitochondrially targeted VE analogs represent a novel class of mitocans that not only induce apoptosis at higher concentrations but also block proliferation and suppress normal mitochondrial function and transcription at low, non-apoptogenic doses. CONCLUSIONS Our data indicate a novel, selective anti-cancer activity of compounds that act by targeting mitochondria of cancer cells, inducing significant alterations in mitochondrial function associated with transcription of mtDNA-coded genes. These changes subsequently result in the arrest of cell proliferation.
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Tan AS, Baty JW, Dong LF, Bezawork-Geleta A, Endaya B, Goodwin J, Bajzikova M, Kovarova J, Peterka M, Yan B, Pesdar EA, Sobol M, Filimonenko A, Stuart S, Vondrusova M, Kluckova K, Sachaphibulkij K, Rohlena J, Hozak P, Truksa J, Eccles D, Haupt LM, Griffiths LR, Neuzil J, Berridge MV. Mitochondrial genome acquisition restores respiratory function and tumorigenic potential of cancer cells without mitochondrial DNA. Cell Metab 2015; 21:81-94. [PMID: 25565207 DOI: 10.1016/j.cmet.2014.12.003] [Citation(s) in RCA: 517] [Impact Index Per Article: 57.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Revised: 07/10/2014] [Accepted: 12/09/2014] [Indexed: 10/24/2022]
Abstract
We report that tumor cells without mitochondrial DNA (mtDNA) show delayed tumor growth, and that tumor formation is associated with acquisition of mtDNA from host cells. This leads to partial recovery of mitochondrial function in cells derived from primary tumors grown from cells without mtDNA and a shorter lag in tumor growth. Cell lines from circulating tumor cells showed further recovery of mitochondrial respiration and an intermediate lag to tumor growth, while cells from lung metastases exhibited full restoration of respiratory function and no lag in tumor growth. Stepwise assembly of mitochondrial respiratory (super)complexes was correlated with acquisition of respiratory function. Our findings indicate horizontal transfer of mtDNA from host cells in the tumor microenvironment to tumor cells with compromised respiratory function to re-establish respiration and tumor-initiating efficacy. These results suggest pathophysiological processes for overcoming mtDNA damage and support the notion of high plasticity of malignant cells.
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Kluckova K, Dong LF, Bajzikova M, Rohlena J, Neuzil J. Evaluation of respiration of mitochondria in cancer cells exposed to mitochondria-targeted agents. Methods Mol Biol 2015; 1265:181-94. [PMID: 25634276 DOI: 10.1007/978-1-4939-2288-8_14] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Respiration is one of the major functions of mitochondria, whereby these vital organelles use oxygen to produce energy. Many agents that may be of potential clinical relevance act by targeting mitochondria, where they may suppress mitochondrial respiration. It is therefore important to evaluate this process and understand how this is modulated by small molecules. Here, we describe the general methodology to assess respiration in cultured cells, followed by the evaluation of the effect of one anticancer agent targeted to mitochondria on this process, and also how to assess this in tumor tissue.
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Hwang MS, Rohlena J, Dong LF, Neuzil J, Grimm S. Powerhouse down: Complex II dissociation in the respiratory chain. Mitochondrion 2014; 19 Pt A:20-8. [PMID: 24933571 DOI: 10.1016/j.mito.2014.06.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Revised: 05/28/2014] [Accepted: 06/04/2014] [Indexed: 12/12/2022]
Abstract
Complex II of the respiratory chain (RC) recently emerged as a prominent regulator of cell death. In both cancer cells as well as neurodegenerative diseases, mutations in subunits have been found along with other genetic alterations indirectly affecting this complex. Anticancer compounds were developed that target complex II and cause cell death in a tumor-specific way. Our mechanistic understanding of how complex II is activated for cell death induction has recently been made clearer in recent studies, the results of which are covered in this review. This protein assembly is specifically activated for cell death via the dissociation of its SDHA and SDHB subunits from the membrane-anchoring proteins through pH change or mitochondrial Ca(2+) influx. The SDH activity contained in the SDHA/SDHB subcomplex remains intact and then generates, in an uncontrolled fashion, excessive amounts of reactive oxygen species (ROS) for cell death. Future studies on this mitochondrial complex will further elucidate it as a target for cancer treatments and reveal its role as a nexus for many diverse stimuli in cell death signaling.
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Dong LF, Jameson VJA, Tilly D, Prochazka L, Rohlena J, Valis K, Truksa J, Zobalova R, Mahdavian E, Kluckova K, Stantic M, Stursa J, Freeman R, Witting PK, Norberg E, Goodwin J, Salvatore BA, Novotna J, Turanek J, Ledvina M, Hozak P, Zhivotovsky B, Coster MJ, Ralph SJ, Smith RAJ, Neuzil J. Corrigendum to: "Mitochondrial targeting of α-tocopheryl succinate enhances its pro-apoptotic efficacy: A new paradigm for effective cancer therapy" [Free Radic Biol Med. 50 (2011) 1546-1555]. Free Radic Biol Med 2013; 65:895-896. [PMID: 30184722 DOI: 10.1016/j.freeradbiomed.2013.08.164] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Accepted: 08/14/2013] [Indexed: 11/25/2022]
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Rohlena J, Dong LF, Neuzil J. Targeting the mitochondrial electron transport chain complexes for the induction of apoptosis and cancer treatment. Curr Pharm Biotechnol 2013; 14:377-89. [PMID: 22201598 DOI: 10.2174/1389201011314030011] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2010] [Revised: 09/06/2010] [Accepted: 09/12/2010] [Indexed: 11/22/2022]
Abstract
Treatment of cancer is by no means universally successful and often manifests harmful side effects. The best way to improve the success rate and reduce the side effects would be to develop compounds that are able to kill cancer cells while leaving normal cells unaffected. In this respect, mitocans (an acronym from 'mitochondria' and 'cancer'), a summary term we proposed for compounds that induce cell death by targeting mitochondria, show an encouraging trend. Here we provide an overview of mitocans specific for the mitochondrial electron transport chain. These mitocans are particularly interesting, because a frequent consequence of electron transport chain inhibition is the induction of superoxide formation resulting in the preferential killing of cancer cells, as these tend to be more sensitive than normal cells to sudden increases in oxidative stress. Furthermore, macromolecular complexes of the electron transport chain only rarely mutate in cancer, and represent useful targets for anti-cancer drug development when widely-applicable agents are sought.
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Kluckova K, Bezawork-Geleta A, Rohlena J, Dong L, Neuzil J. Mitochondrial complex II, a novel target for anti-cancer agents. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2012; 1827:552-64. [PMID: 23142170 DOI: 10.1016/j.bbabio.2012.10.015] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Revised: 10/28/2012] [Accepted: 10/29/2012] [Indexed: 12/22/2022]
Abstract
With the arrival of the third millennium, in spite of unprecedented progress in molecular medicine, cancer remains as untamed as ever. The complexity of tumours, dictating the potential response of cancer cells to anti-cancer agents, has been recently highlighted in a landmark paper by Weinberg and Hanahan on hallmarks of cancer [1]. Together with the recently published papers on the complexity of tumours in patients and even within the same tumour (see below), the cure for this pathology seems to be an elusive goal. Indisputably, the strategy ought to be changed, searching for targets that are generally invariant across the landscape of neoplastic diseases. One such target appears to be the mitochondrial complex II (CII) of the electron transfer chain, a recent focus of research. We document and highlight this particularly intriguing target in this review paper and give examples of drugs that use CII as their molecular target. This article is part of a Special Issue entitled: Respiratory complex II: Role in cellular physiology and disease.
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Rohlena J, Truksa J, Dong L, Vondrusova M, Kluckova K, Neuzil J. 542 The Experimental Anti-cancer Drug Mitochondrially-targeted Vitamin E Succinate Inhibits Mitochondrial Transcription. Eur J Cancer 2012. [DOI: 10.1016/s0959-8049(12)72339-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Neuzil J, Dong LF, Rohlena J, Truksa J, Ralph SJ. Classification of mitocans, anti-cancer drugs acting on mitochondria. Mitochondrion 2012; 13:199-208. [PMID: 22846431 DOI: 10.1016/j.mito.2012.07.112] [Citation(s) in RCA: 137] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2012] [Revised: 07/15/2012] [Accepted: 07/22/2012] [Indexed: 12/13/2022]
Abstract
Mitochondria have emerged as an intriguing target for anti-cancer drugs, inherent to vast majority if not all types of tumours. Drugs that target mitochondria and exert anti-cancer activity have become a focus of recent research due to their great clinical potential (which has not been harnessed thus far). The exceptional potential of mitochondria as a target for anti-cancer agents has been reinforced by the discouraging finding that even tumours of the same type from individual patients differ in a number of mutations. This is consistent with the idea of personalised therapy, an elusive goal at this stage, in line with the notion that tumours are unlikely to be treated by agents that target only a single gene or a single pathway. This endows mitochondria, an invariant target present in all tumours, with an exceptional momentum. This train of thoughts inspired us to define a class of anti-cancer drugs acting by way of mitochondrial 'destabilisation', termed 'mitocans'. In this communication, we define mitocans (many of which have been known for a long time) and classify them into several classes based on their molecular mode of action. We chose the targets that are of major importance from the point of view of their role in mitochondrial destabilisation by small compounds, some of which are now trialled as anti-cancer agents. The classification starts with targets at the surface of mitochondria and ending up with those in the mitochondrial matrix. The purpose of this review is to present in a concise manner the classification of compounds that hold a considerable promise as potential anti-cancer drugs.
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Rohlena J, Dong LF, Kluckova K, Zobalova R, Goodwin J, Tilly D, Stursa J, Pecinova A, Philimonenko A, Hozak P, Banerjee J, Ledvina M, Sen CK, Houstek J, Coster MJ, Neuzil J. Mitochondrially targeted α-tocopheryl succinate is antiangiogenic: potential benefit against tumor angiogenesis but caution against wound healing. Antioxid Redox Signal 2011; 15:2923-35. [PMID: 21902599 PMCID: PMC3201633 DOI: 10.1089/ars.2011.4192] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
AIMS A plausible strategy to reduce tumor progress is the inhibition of angiogenesis. Therefore, agents that efficiently suppress angiogenesis can be used for tumor suppression. We tested the antiangiogenic potential of a mitochondrially targeted analog of α-tocopheryl succinate (MitoVES), a compound with high propensity to induce apoptosis. RESULTS MitoVES was found to efficiently kill proliferating endothelial cells (ECs) but not contact-arrested ECs or ECs deficient in mitochondrial DNA, and suppressed angiogenesis in vitro by inducing accumulation of reactive oxygen species and induction of apoptosis in proliferating/angiogenic ECs. Resistance of arrested ECs was ascribed, at least in part, to the lower mitochondrial inner transmembrane potential compared with the proliferating ECs, thus resulting in the lower level of mitochondrial uptake of MitoVES. Shorter-chain homologs of MitoVES were less efficient in angiogenesis inhibition, thus suggesting a molecular mechanism of its activity. Finally, MitoVES was found to suppress HER2-positive breast carcinomas in a transgenic mouse as well as inhibit tumor angiogenesis. The antiangiogenic efficacy of MitoVES was corroborated by its inhibitory activity on wound healing in vivo. INNOVATION AND CONCLUSION We conclude that MitoVES, a mitochondrially targeted analog of α-tocopheryl succinate, is an efficient antiangiogenic agent of potential clinical relevance, exerting considerably higher activity than its untargeted counterpart. MitoVES may be helpful against cancer but may compromise wound healing.
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Rohlena J, Dong LF, Ralph SJ, Neuzil J. Anticancer drugs targeting the mitochondrial electron transport chain. Antioxid Redox Signal 2011; 15:2951-74. [PMID: 21777145 DOI: 10.1089/ars.2011.3990] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
SIGNIFICANCE Mitochondria are emerging as highly intriguing organelles showing promise but that are yet to be fully exploited as targets for anticancer drugs. RECENT ADVANCES A group of compounds that induce mitochondrial destabilization, thereby affecting the physiology of cancer cells, has been defined and termed 'mitocans.' Based on their mode of action of targeting in and around mitochondria, we have placed these agents into several groups including hexokinase inhibitors, compounds targeting Bcl-2 family proteins, thiol redox inhibitors, VDAC/ANT targeting drugs, electron transport chain-targeting drugs, lipophilic cations targeting the inner membrane, agents affecting the tricarboxylic acid cycle, drugs targeting mtDNA, and agents targeting other presently unknown sites. CRITICAL ISSUES Mitocans have a potential to prove highly efficient in suppressing various malignant diseases in a selective manner. They include compounds that are currently in clinical trial and offer substantial promise to become clinically applied drugs. Here we update and redefine the individual classes of mitocans, providing examples of the various members of these groups with a particular focus on agents targeting the electron transport chain, and indicate their potential application in clinical practice. FUTURE DIRECTIONS Even though reactive oxygen species induction is important for the anticancer activity of many mitocans, the precise sequence of events preceding and following this pivotal event are not yet fully clarified, and warrant further investigation. This is imperative for effective deployment of these compounds in the clinic.
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Dong LF, Jameson VJA, Tilly D, Prochazka L, Rohlena J, Valis K, Truksa J, Zobalova R, Mahdavian E, Kluckova K, Stantic M, Stursa J, Freeman R, Witting PK, Norberg E, Goodwin J, Salvatore BA, Novotna J, Turanek J, Ledvina M, Hozak P, Zhivotovsky B, Coster MJ, Ralph SJ, Smith RAJ, Neuzil J. Mitochondrial targeting of α-tocopheryl succinate enhances its pro-apoptotic efficacy: a new paradigm for effective cancer therapy. Free Radic Biol Med 2011; 50:1546-55. [PMID: 21402148 DOI: 10.1016/j.freeradbiomed.2011.02.032] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2010] [Revised: 02/16/2011] [Accepted: 02/25/2011] [Indexed: 12/20/2022]
Abstract
Mitochondria are emerging as intriguing targets for anti-cancer agents. We tested here a novel approach, whereby the mitochondrially targeted delivery of anti-cancer drugs is enhanced by the addition of a triphenylphosphonium group (TPP(+)). A mitochondrially targeted analog of vitamin E succinate (MitoVES), modified by tagging the parental compound with TPP(+), induced considerably more robust apoptosis in cancer cells with a 1-2 log gain in anti-cancer activity compared to the unmodified counterpart, while maintaining selectivity for malignant cells. This is because MitoVES associates with mitochondria and causes fast generation of reactive oxygen species that then trigger mitochondria-dependent apoptosis, involving transcriptional modulation of the Bcl-2 family proteins. MitoVES proved superior in suppression of experimental tumors compared to the untargeted analog. We propose that mitochondrially targeted delivery of anti-cancer agents offers a new paradigm for increasing the efficacy of compounds with anti-cancer activity.
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Dong LF, Jameson VJA, Tilly D, Cerny J, Mahdavian E, Marín-Hernández A, Hernández-Esquivel L, Rodríguez-Enríquez S, Stursa J, Witting PK, Stantic B, Rohlena J, Truksa J, Kluckova K, Dyason JC, Ledvina M, Salvatore BA, Moreno-Sánchez R, Coster MJ, Ralph SJ, Smith RAJ, Neuzil J. Mitochondrial targeting of vitamin E succinate enhances its pro-apoptotic and anti-cancer activity via mitochondrial complex II. J Biol Chem 2011; 286:3717-28. [PMID: 21059645 PMCID: PMC3030374 DOI: 10.1074/jbc.m110.186643] [Citation(s) in RCA: 152] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2010] [Revised: 10/28/2010] [Indexed: 12/27/2022] Open
Abstract
Mitochondrial complex II (CII) has been recently identified as a novel target for anti-cancer drugs. Mitochondrially targeted vitamin E succinate (MitoVES) is modified so that it is preferentially localized to mitochondria, greatly enhancing its pro-apoptotic and anti-cancer activity. Using genetically manipulated cells, MitoVES caused apoptosis and generation of reactive oxygen species (ROS) in CII-proficient malignant cells but not their CII-dysfunctional counterparts. MitoVES inhibited the succinate dehydrogenase (SDH) activity of CII with IC(50) of 80 μM, whereas the electron transfer from CII to CIII was inhibited with IC(50) of 1.5 μM. The agent had no effect either on the enzymatic activity of CI or on electron transfer from CI to CIII. Over 24 h, MitoVES caused stabilization of the oxygen-dependent destruction domain of HIF1α fused to GFP, indicating promotion of the state of pseudohypoxia. Molecular modeling predicted the succinyl group anchored into the proximal CII ubiquinone (UbQ)-binding site and successively reduced interaction energies for serially shorter phytyl chain homologs of MitoVES correlated with their lower effects on apoptosis induction, ROS generation, and SDH activity. Mutation of the UbQ-binding Ser(68) within the proximal site of the CII SDHC subunit (S68A or S68L) suppressed both ROS generation and apoptosis induction by MitoVES. In vivo studies indicated that MitoVES also acts by causing pseudohypoxia in the context of tumor suppression. We propose that mitochondrial targeting of VES with an 11-carbon chain localizes the agent into an ideal position across the interface of the mitochondrial inner membrane and matrix, optimizing its biological effects as an anti-cancer drug.
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Valis K, Prochazka L, Boura E, Chladova J, Obsil T, Rohlena J, Truksa J, Dong LF, Ralph SJ, Neuzil J. Hippo/Mst1 stimulates transcription of the proapoptotic mediator NOXA in a FoxO1-dependent manner. Cancer Res 2011; 71:946-54. [PMID: 21245099 DOI: 10.1158/0008-5472.can-10-2203] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The proapoptotic protein Noxa, a member of the BH3-only Bcl-2 protein family, can effectively induce apoptosis in cancer cells, although the relevant regulatory pathways have been obscure. Previous studies of the cytotoxic effects of α-tocopheryl succinate (α-TOS) on cancer cells identified a mechanism whereby α-TOS caused apoptosis requiring the Noxa-Bak axis. In the present study, ab initio analysis revealed a conserved FoxO-binding site (DBE; DAF-16 binding element) in the NOXA promoter, and specific affinity of FoxO proteins to this DBE was confirmed by fluorescence anisotropy. FoxO1 and FoxO3a proteins accumulated in the nucleus of α-TOS-treated cells, and the drug-induced specific FoxO1 association with the NOXA promoter and its activation were validated by chromatin immunoprecipitation. Using siRNA knockdown, a specific role for the FoxO1 protein in activating NOXA transcription in cancer cells was identified. Furthermore, the proapoptotic kinase Hippo/Mst1 was found to be strongly activated by α-TOS, and inhibiting Hippo/Mst1 by specific siRNA prevented phosphorylation of FoxO1 and its nuclear translocation, thereby reducing levels of NOXA transcription and apoptosis in cancer cells exposed to α-TOS. Thus, we have demonstrated that anticancer drugs, exemplified by α-TOS, induce apoptosis by a mechanism involving the Hippo/Mst1-FoxO1-Noxa pathway. We propose that activation of this pathway provides a new paradigm for developing targeted cancer treatments.
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Dong LF, Freeman R, Liu J, Zobalova R, Marin-Hernandez A, Stantic M, Rohlena J, Valis K, Rodriguez-Enriquez S, Butcher B, Goodwin J, Brunk UT, Witting PK, Moreno-Sanchez R, Scheffler IE, Ralph SJ, Neuzil J. Suppression of Tumor Growth In vivo by the Mitocan α-tocopheryl Succinate Requires Respiratory Complex II. Clin Cancer Res 2009; 15:1593-600. [DOI: 10.1158/1078-0432.ccr-08-2439] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Rohlena J, Volger OL, van Buul JD, Hekking LHP, van Gils JM, Bonta PI, Fontijn RD, Post JA, Hordijk PL, Horrevoets AJG. Endothelial CD81 is a marker of early human atherosclerotic plaques and facilitates monocyte adhesion. Cardiovasc Res 2008; 81:187-96. [PMID: 18805782 DOI: 10.1093/cvr/cvn256] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
AIMS In a recent report, we established at the genome-wide level those genes that are specifically upregulated in the endothelium of atherosclerotic plaques in human arteries. As the transcriptome data revealed that mRNA for the tetraspanin family member CD81 is significantly and specifically upregulated in the endothelium overlying early atheroma, we set out to validate these results on the protein level, and investigate the functional consequences of CD81 upregulation. METHODS AND RESULTS Immunohistochemical analysis in an independent set of donor arteries verified in the endothelium of early human atherosclerotic lesions the enhanced expression of CD81, which appears oxidative stress-dependent. Using lentiviral overexpression and silencing in human umbilical endothelial cells, we established in an in vitro flow adhesion assay that elevated endothelial CD81 is associated with increased monocyte adhesion to non-activated CD81-transduced endothelial cells, approaching the levels normally only attained after tumour necrosis factor alpha stimulation. The CD81 effect was dependent on both intracellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1), as it was abolished in the presence of a mixture of anti-ICAM-1 and anti-VCAM-1 antibodies. Flow cytometry revealed that increased CD81 levels did not increase total ICAM-1 and VCAM-1 surface expression. Instead, it concentrated the available adhesion molecules into membrane clusters, as indicated by confocal and electron microscopy. CD81 also colocalized with ICAM-1 and VCAM-1 in the adhesion rings around bound monocytes. CONCLUSION Endothelial CD81 upregulated in early human atheroma has the potential to play a crucial role in the initial stages of atherosclerotic plaque formation by increasing monocyte adhesion prior to the full-blown inflammatory response.
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Meijer AB, Rohlena J, van der Zwaan C, van Zonneveld AJ, Boertjes RC, Lenting PJ, Mertens K. Functional duplication of ligand-binding domains within low-density lipoprotein receptor-related protein for interaction with receptor associated protein, alpha2-macroglobulin, factor IXa and factor VIII. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2007; 1774:714-22. [PMID: 17512806 DOI: 10.1016/j.bbapap.2007.04.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2006] [Revised: 04/01/2007] [Accepted: 04/05/2007] [Indexed: 10/23/2022]
Abstract
The low-density lipoprotein receptor-related protein (LRP) binds a range of proteins including receptor associated protein (RAP), activated alpha2-macroglobulin (alpha2M*), factor IXa (FIXa), and factor VIII (FVIII) light chain. The binding is mediated by the complement-type repeats, which are clustered in four distinct regions within LRP. Cluster II of 8 repeats (CR3-10) and cluster IV of 11 repeats (CR21-31) have been implicated in ligand-binding. Previous studies have aimed to identify the cluster II repeats involved in binding alpha2M* and RAP. We now evaluated the binding to RAP, alpha2M*, FIXa and FVIII light chain of triplicate repeat-fragments of not only clusters II but also of cluster IV. Employing surface plasmon resonance analysis, we found that most efficient ligand-binding was displayed by the repeats within region CR4-8 of cluster II and within region CR24-28 of cluster IV. Whereas the binding to RAP could be attributed to two consecutive repeats (CR5-6, CR26-27), combinations of three repeats showed most efficient binding to FIXa (CR6-8, CR26-28), FVIII light chain (CR5-7, CR6-8, CR24-26), and alpha2M* (CR4-6, CR24-26). The results imply that there is an internal functional duplication of complement-type repeats within LRP resulting in two clusters that bind the same ligands.
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Fledderus JO, van Thienen JV, Boon RA, Dekker RJ, Rohlena J, Volger OL, Bijnens APJJ, Daemen MJAP, Kuiper J, van Berkel TJC, Pannekoek H, Horrevoets AJG. Prolonged shear stress and KLF2 suppress constitutive proinflammatory transcription through inhibition of ATF2. Blood 2007; 109:4249-57. [PMID: 17244683 DOI: 10.1182/blood-2006-07-036020] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Absence of shear stress due to disturbed blood flow at arterial bifurcations and curvatures leads to endothelial dysfunction and proinflammatory gene expression, ultimately resulting in atherogenesis. KLF2 has recently been implicated as a transcription factor involved in mediating the anti-inflammatory effects of flow. We investigated the effect of shear on basal and TNF-alpha-induced genomewide expression profiles of human umbilical vein endothelial cells (HUVECs). Cluster analysis confirmed that shear stress induces expression of protective genes including KLF2, eNOS, and thrombomodulin, whereas basal expression of TNF-alpha-responsive genes was moderately decreased. Promoter analysis of these genes showed enrichment of binding sites for ATF transcription factors, whereas TNF-alpha-induced gene expression was mostly NF-kappaB dependent. Furthermore, human endothelial cells overlying atherosclerotic plaques had increased amounts of phosphorylated nuclear ATF2 compared with endothelium at unaffected sites. In HUVECs, a dramatic reduction of nuclear binding activity of ATF2 was observed under shear and appeared to be KLF2 dependent. Reduction of ATF2 with siRNA potently suppressed basal proinflammatory gene expression under no-flow conditions. In conclusion, we demonstrate that shear stress and KLF2 inhibit nuclear activity of ATF2, providing a potential mechanism by which endothelial cells exposed to laminar flow are protected from basal proinflammatory, atherogenic gene expression.
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Fontijn RD, Rohlena J, van Marle J, Pannekoek H, Horrevoets AJG. Limited contribution of claudin-5-dependent tight junction strands to endothelial barrier function. Eur J Cell Biol 2006; 85:1131-44. [PMID: 16959372 DOI: 10.1016/j.ejcb.2006.07.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2006] [Revised: 07/20/2006] [Accepted: 07/24/2006] [Indexed: 10/25/2022] Open
Abstract
Members of the claudin family are involved in formation of barriers that control access to the paracellular space of epithelia. Likewise, endothelium-specific claudin-5 is involved in the function of the blood-brain barrier (BBB). Here, we assessed the role of claudin-5 in non-BBB endothelial barriers using lentiviral-driven overexpression and silencing of claudin-5 in its native environment of primary vascular endothelial cells. Effects were monitored using macromolecular tracers between 342Da and 40kDa. Measurements were made both in absence and presence of transmigrating leukocytes. Freeze-fracture preparations were analyzed for effects at the ultrastructural level. We show that overexpression of claudin-5 leads to formation of elaborate networks of junction strands, which are absent in untransduced endothelial cells. Concomitantly, a modest, non-size-selective enhancement of the barrier function was observed. In contrast, silencing of endogenous claudin-5 does not influence barrier function. The efficient sealing of the endothelium during diapedesis of monocytes or granulocytes is also claudin-5 independent. Collectively, these data provide evidence for a limited contribution of claudin-5 to the barrier function of human umbilical vein endothelial cells (HUVEC), implying that, unlike selective barriers in epithelia, the barrier of non-BBB endothelium seems largely independent of claudin-directed tight junction structures.
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Fontijn RD, Rohlena J, van Marle J, Pannekoek H, Horrevoets AJ. Limited contribution of claudin-5 dependent tight junction strands to endothelial barrier function. Vascul Pharmacol 2006. [DOI: 10.1016/j.vph.2006.08.226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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