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Brunk, Ulf
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Publications (10 of 135) Show all publications
Ullio, C., Brunk, U., Urani, C., Melchioretto, P., Bonelli, G., Baccino, F. M. & Autelli, R. (2015). Autophagy of metallothioneins prevents TNF-induced oxidative stress and toxicity in hepatoma cells. Autophagy, 11(12), 2184-2198
Open this publication in new window or tab >>Autophagy of metallothioneins prevents TNF-induced oxidative stress and toxicity in hepatoma cells
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2015 (English)In: Autophagy, ISSN 1554-8627, E-ISSN 1554-8635, Vol. 11, no 12, p. 2184-2198Article in journal (Refereed) Published
Abstract [en]

Lysosomal membrane permeabilization (LMP) induced by oxidative stress has recently emerged as a prominent mechanism behind TNF cytotoxicity. This pathway relies on diffusion of hydrogen peroxide into lysosomes containing redox-active iron, accumulated by breakdown of iron-containing proteins and subcellular organelles. Upon oxidative lysosomal damage, LMP allows relocation to the cytoplasm of low mass iron and acidic hydrolases that contribute to DNA and mitochondrial damage, resulting in death by apoptosis or necrosis. Here we investigate the role of lysosomes and free iron in death of HTC cells, a rat hepatoma line, exposed to TNF following metallothionein (MT) upregulation. Iron-binding MT does not normally occur in HTC cells in significant amounts. Intracellular iron chelation attenuates TNF and cycloheximide (CHX)-induced LMP and cell death, demonstrating the critical role of this transition metal in mediating cytokine lethality. MT upregulation, combined with starvation-activated MT autophagy almost completely suppresses TNF and CHX toxicity, while impairment of both autophagy and MT upregulation by silencing of Atg7, and Mt1a and/or Mt2a, respectively, abrogates protection. Interestingly, MT upregulation by itself has little effect, while stimulated autophagy alone depresses cytokine toxicity to some degree. These results provide evidence that intralysosomal iron-catalyzed redox reactions play a key role in TNF and CHX-induced LMP and toxicity. The finding that chelation of intralysosomal iron achieved by autophagic delivery of MT, and to some degree probably of other iron-binding proteins as well, into the lysosomal compartment is highly protective provides a putative mechanism to explain autophagy-related suppression of death by TNF and CHX.

Place, publisher, year, edition, pages
TAYLOR & FRANCIS INC, 2015
Keywords
autophagy; cell death; hepatoma cells; iron; lysosomes; oxidative stress; TNF
National Category
Clinical Medicine
Identifiers
urn:nbn:se:liu:diva-124499 (URN)10.1080/15548627.2015.1106662 (DOI)000367806300006 ()26566051 (PubMedID)
Note

Funding Agencies|Ministero dellUniversita e della Ricerca; Universita degli Studi di Torino

Available from: 2016-02-02 Created: 2016-02-01 Last updated: 2017-11-30
Wang, S., Huang, Q., Guo, J., Guo, X., Sun, Q., Brunk, U., . . . Zhao, M. (2014). Local thermal injury induces general endothelial cell contraction through p38 MAP kinase activation. Acta Pathologica, Microbiologica et Immunologica Scandinavica (APMIS), 122(9), 832-841
Open this publication in new window or tab >>Local thermal injury induces general endothelial cell contraction through p38 MAP kinase activation
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2014 (English)In: Acta Pathologica, Microbiologica et Immunologica Scandinavica (APMIS), ISSN 0903-4641, E-ISSN 1600-0463, Vol. 122, no 9, p. 832-841Article in journal (Refereed) Published
Abstract [en]

Endothelial cells (ECs) of thin-walled blood vessels form a barrier between blood and tissue. As a response to inflammation, the EC junctions widen and gaps form, resulting in compromised barrier functions. Although the mechanisms behind the establishment of these changes are still incompletely understood, one known reason is actomyosin-dependent actin rearrangement. Here, by using atomic force microscopy and a combination of confocal microscopy methods, we are the first to report that thermal injury induces general venular hyperpermeability and that serum from burned rats induces EC actin rearrangement, contraction, as well as tight-junction damage. Inhibition of the p38 mitogen-activated protein kinase (p38MAPK) largely ameliorates resulting vascular dysfunction by significantly reducing EC stress-fiber formation, contraction, volume changes and tight-junction damage, thereby greatly reducing the appearance of EC gaps. The findings may be of importance for the design of future pharmacotherapies aiming to ease the severe general vascular dysfunction that follows extensive burns.

Place, publisher, year, edition, pages
Wiley, 2014
Keywords
endothelial cells; thermal injury; contraction; permeability; p38 MAPK
National Category
Clinical Medicine
Identifiers
urn:nbn:se:liu:diva-110963 (URN)10.1111/apm.12226 (DOI)000341151300016 ()24479891 (PubMedID)
Note

Funding Agencies|National Natural Science Foundation of China [81071549, 81272095]; Natural Science Foundation of Guangdong province [2012B050600002]; Guangdong province talent recruitment foundation; Guangdong Innovative Research Team Program [201001Y0104675344]; Guangdong province university Qianbaishi program

Available from: 2014-10-03 Created: 2014-10-01 Last updated: 2017-12-05
Karlsson, M., Frennesson, C., Gustafsson, T., Brunk, U., Erik Nilsson, S. & Kurz, T. (2013). Autophagy of iron-binding proteins may contribute to the oxidative stress resistance of ARPE-19 cells. Experimental Eye Research, 116, 359-365
Open this publication in new window or tab >>Autophagy of iron-binding proteins may contribute to the oxidative stress resistance of ARPE-19 cells
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2013 (English)In: Experimental Eye Research, ISSN 0014-4835, E-ISSN 1096-0007, Vol. 116, p. 359-365Article in journal (Refereed) Published
Abstract [en]

The objective of this study was to elucidate possible reasons for the remarkable resistance of human retinal pigment epithelial (RPE) cells to oxidative stress. Much oxidative damage is due to hydrogen peroxide meeting redox-active iron in the acidic and reducing lysosomal environment, resulting in the production of toxic hydroxyl radicals that may oxidize intralysosomal content, leading to lipofuscin (LF) formation or, if more extensive, to permeabilization of lysosomal membranes. Formation of LF is a risk factor for age-related macular degeneration (AMD) and known to jeopardize normal autophagic rejuvenation of vital cellular biomolecules. Lysosomal membrane permeabilization causes release of lysosomal content (redox-active iron, lytic enzymes), which may then cause cell death. Total cellular and lysosomal low-mass iron of cultured, immortalized human RPE (ARPE-19) cells was compared to that of another professional scavenger cell line, J774, using atomic absorption spectroscopy and the cytochemical sulfide-silver method (SSM). It was found that both cell lines contained comparable levels of total as well as intralysosomal iron, suggesting that the latter is mainly kept in a non-redox-active state in ARPE-19 cells. Basal levels and capacity for upregulation of the iron-binding proteins ferritin, metallothionein and heat shock protein 70 were tested in both cell lines using immunoblotting. Compared to J774 cells, ARPE-19 cells were found to contain very high basal levels of all these proteins, which could be even further upregulated following appropriate stimulation. These findings suggest that a high basal expression of iron-binding stress proteins, which during their normal autophagic turnover in lysosomes may temporarily bind iron prior to their degradation, could contribute to the unusual oxidative stress-resistance of ARPE-19 cells. A high steady state influx of such proteins into lysosomes would keep the level of lysosomal redox-active iron permanently low. This, in turn, should delay intralysosomal accumulation of LF in RPE cells, which is known to reduce autophagic turnover as well as uptake and degradation of worn out photoreceptor tips. This may explain why severe LF accumulation and AMD normally do not develop until fairly late in life, in spite of RPE cells being continuously exposed to high levels of oxygen and light, as well as large amounts of lipid-rich material.

Place, publisher, year, edition, pages
Elsevier, 2013
Keywords
oxidative stress, ARPE-19, retinal pigment epithelium, iron, metallothionein, HSP70, ferritin, age-related macular degeneration
National Category
Cell and Molecular Biology
Identifiers
urn:nbn:se:liu:diva-102718 (URN)10.1016/j.exer.2013.10.014 (DOI)000327562500041 ()
Note

Funding Agencies|Crown Princess Margaretas Foundation for the Visually Handicapped||Edvin Jordan Foundation for Ophthalmological Research||Linkoping University Hospital Research Fund (ALF)||

Available from: 2013-12-19 Created: 2013-12-19 Last updated: 2018-01-11
Bironaite, D., Brunk, U. & Venalis, A. (2013). Protective Induction of Hsp70 in Heat-Stressed Primary Myoblasts: Involvement of MAPKs. Journal of Cellular Biochemistry, 114(9), 2024-2031
Open this publication in new window or tab >>Protective Induction of Hsp70 in Heat-Stressed Primary Myoblasts: Involvement of MAPKs
2013 (English)In: Journal of Cellular Biochemistry, ISSN 0730-2312, E-ISSN 1097-4644, Vol. 114, no 9, p. 2024-2031Article in journal (Refereed) Published
Abstract [en]

The involvement of extracellular signal-regulated kinases 1 and 2 (ERK1,2), stress kinase p38 and c-Jun NH2-terminal kinases 1 and 2 (JNK1,2) on Hsp70-upregulation following mild heat shock, and resulting cell protection, was studied on rabbit primary myoblasts. Cells subjected to heat stress (42 degrees C; 60min) showed a significantly enhanced amount of heat-shock-induced protein 70 (Hsp70), correlating with sustained phosphorylation of MAP kinases ERK1,2, inhibition of p38 and JNK1,2 activation. Induced Hsp70 did not autocrinally suppress activation of transcription factor c-Jun, suggesting involvement of the latter in the protection of myoblasts following heat shock. The inhibition of stress kinases p38, JNK1,2, and MEK1,2 by SP600125, SB203580, and UO126, respectively, established the involvement of JNK1,2 and p38 as upstream, and ERK1,2 as downstream targets of Hsp70 induction. Moreover, the effect of the MEK1,2 inhibitor UO126 revealed a new pathway of c-Jun activation by ERK1,2 in myogenic heat-stressed stem cells. The presented data show that transient activation of JNK1, JNK2, and p38 is necessary for Hsp70 induction and ensuing cell protection. In conclusion, affecting myogenic stem cell protective mechanisms might be a useful strategy in improving stem cell survival and their expanded application in therapy.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2013
Keywords
STEM CELLS, SIGNALING, MAPK, HSP, HEAT STRESS
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-102789 (URN)10.1002/jcb.24550 (DOI)000327699500009 ()
Note

Funding Agencies|Lithuanian State Science and Studies Foundation|T-65/07U-04001C-07023|

Available from: 2014-01-07 Created: 2013-12-26 Last updated: 2017-12-06
Zhu, M., Yuan, H., Guo, W., Li, X., Jin, L., Brunk, U., . . . Liu, Y. (2012). Dietary Mustard Seeds (Sinapis alba Linn) Suppress 1,2-Dimethylhydrazine-Induced Immuno-Imbalance and Colonic Carcinogenesis in Rats. Nutrition and Cancer, 64(3), 464-472
Open this publication in new window or tab >>Dietary Mustard Seeds (Sinapis alba Linn) Suppress 1,2-Dimethylhydrazine-Induced Immuno-Imbalance and Colonic Carcinogenesis in Rats
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2012 (English)In: Nutrition and Cancer, ISSN 0163-5581, E-ISSN 1532-7914, Vol. 64, no 3, p. 464-472Article in journal (Refereed) Published
Abstract [en]

In a Wistar rat model, prolonged supplementation of mustard seed (MS) to the diet significantly ameliorates the induction of colorectal carcinomas by 1,2-dimethylhydrazine (DMH). The expression of the splenocyte major histocompatibility complex class I (MHCI) was found significantly enhanced, whereas that of the major histocompatibility complex class II (MHCII) was significantly decreased. Compared to that of control animals, the proportion of spleenic B- and dendritic cells (DC) was amplified in the MS group. The expressions of MHCI, as well as that of MHCII, were increased in DC cells; whereas in B cells, MHCI expression was augmented but that of MHCII moderately decreased. The percentages of CD8+CD28+ and CD4+CD28+ cells were increased in the MS group, while the CD4+CD25+Foxp3+ subset was depressed. Plasma analysis showed that DMH-exposure induced amplified amounts of interleukin (IL)-4, IL-5, IL-10, and transforming growth factor-beta, whereas MS feeding counteracted this effect but enhanced IL-2,IL12p70,IL21, TNF-alpha, and interferon-gamma. In the SW480 colon adenocarcinoma cell-line, the cytotoxicity of spleenic T-cells from MS-fed animals was significantly increased. In the DMH-exposed rats, the expression of perforin in the spleenic T-cells was dramatically decreased, whereas MS abolished this depression. In summary, dietary MS suppresses DMH-induced immuno-imbalance as well as colon carcinogenesis in rats.

Place, publisher, year, edition, pages
Taylor and Francis (Routledge): STM, Behavioural Science and Public Health Titles / Taylor and Francis (Routledge), 2012
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-77874 (URN)10.1080/01635581.2012.658948 (DOI)000303702600012 ()
Note
Funding Agencies|National Natural Science Foundation of China|81071549|Guangdong Natural Science Foundation|9151040701000025|Guangdong Science and Technology Foundation|2010B060900054|Foundation for Introduction of Innovative R & D Team in Guangdong Province||Nanfang Hospital Foundation|2009B011|Guangdong Talent Person Import Foundation||Southern Medical University Talent Person Import Foundation||China Chunhui Plan||Available from: 2012-05-31 Created: 2012-05-31 Last updated: 2017-12-07
Klionsky, D. J., Abdalla, F. C., Abeliovich, H., Abraham, R. T., Acevedo-Arozena, A., Adeli, K., . . . Zuckerbraun, B. (2012). Guidelines for the use and interpretation of assays for monitoring autophagy. Autophagy, 8(4), 445-544
Open this publication in new window or tab >>Guidelines for the use and interpretation of assays for monitoring autophagy
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2012 (English)In: Autophagy, ISSN 1554-8627, Vol. 8, no 4, p. 445-544Article, review/survey (Refereed) Published
Abstract [en]

In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process vs. those that measure flux through the autophagy pathway (i.e., the complete process); thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from stimuli that result in increased autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field.

Place, publisher, year, edition, pages
Landes Bioscience, 2012
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-82027 (URN)10.4161/auto.19496 (DOI)000305403400002 ()22966490 (PubMedID)
Available from: 2012-09-28 Created: 2012-09-28 Last updated: 2017-01-16
Wang, X., Song, R., Ning Bian, H., Brunk, U., Zhao, M. & Zhao, K.-s. (2012). Polydatin, a natural polyphenol, protects arterial smooth muscle cells against mitochondrial dysfunction and lysosomal destabilization following hemorrhagic shock. American Journal of Physiology. Regulatory Integrative and Comparative Physiology, 302(7), R805-R814
Open this publication in new window or tab >>Polydatin, a natural polyphenol, protects arterial smooth muscle cells against mitochondrial dysfunction and lysosomal destabilization following hemorrhagic shock
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2012 (English)In: American Journal of Physiology. Regulatory Integrative and Comparative Physiology, ISSN 0363-6119, E-ISSN 1522-1490, Vol. 302, no 7, p. R805-R814Article in journal (Refereed) Published
Abstract [en]

The main objective of this study was to investigate the activity of polydatin on mitochondrial dysfunction and lysosomal stability of arteriolar smooth muscle cells (ASMCs) in severe shock. The experimental animals (rats) were divided into five groups: control, hemorrhagic shock, shock + CsA, shock + Res, and shock + PD (exposed to cyclosporin A, resveratrol, or polydatin following induction of hemorrhagic shock, respectively). The calcein-Co2+ technique revealed opening of ASMC mitochondrial permeability transition pores (mPTP) after shock with resulting mitochondrial swelling, decreased mitochondrial membrane potential (Delta Psi m), and reduced intracellular ATP levels. These alterations were all inhibited by exposure to PD, which was significantly more effective than CsA and Res. PD also preserved lysosomal stability, suppressed activation of K-ATP channels, ASMC hyperpolarization, and reduced vasoresponsiveness to norepinephrine that normally follows severe shock. The results demonstrate that exposure to PD after initiation of severe shock effectively preserves ASMC mitochondrial integrity and has a significant therapeutic effect in severe shock. The effects may partially result from lysosomal stabilization against shock-induced oxidative stress and depressed relocation of hydrolytic enzymes and redox-active lysosomal iron that, in turn, may induce mPTP opening.

Place, publisher, year, edition, pages
American Physiological Society, 2012
Keywords
hemorrhagic shock, hypotension, polydatin, lysosomes
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-76951 (URN)10.1152/ajpregu.00350.2011 (DOI)000302348600002 ()
Note
Funding Agencies|National Natural Science Foundation of China|3067217930971202|Program for Changjiang Scholars||Innovative Research Team in University, China|IRTO731|Available from: 2012-05-02 Created: 2012-04-27 Last updated: 2017-12-07
Ullio, C., Casas, J., Brunk, U., Sala, G., Fabrias, G., Ghidoni, R., . . . Autelli, R. (2012). Sphingosine mediates TNF alpha-induced lysosomal membrane permeabilization and ensuing programmed cell death in hepatoma cells. Journal of Lipid Research, 53(6), 1134-1143
Open this publication in new window or tab >>Sphingosine mediates TNF alpha-induced lysosomal membrane permeabilization and ensuing programmed cell death in hepatoma cells
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2012 (English)In: Journal of Lipid Research, ISSN 0022-2275, E-ISSN 1539-7262, Vol. 53, no 6, p. 1134-1143Article in journal (Refereed) Published
Abstract [en]

Normally, cell proliferation and death are carefully balanced in higher eukaryotes, but one of the most important regulatory mechanisms, apoptosis, is upset in many malignancies, including hepatocellular-derived ones. Therefore, reinforcing cell death often is mandatory in anticancer therapy. We previously reported that a combination of tumor necrosis factor-alpha (TNF) and cycloheximide (CHX) efficiently kill HTC cells, a rat hepatoma line, in an apoptosis-like mode. Death is actively mediated by the lysosomal compartment, although lysosomal ceramide was previously shown not to be directly implicated in this process. In the present study, we show that TNF/CHX increase lysosomal ceramide that is subsequently converted into sphingosine. Although ceramide accumulation does not significantly alter the acidic compartment, the sphingosine therein generated causes lysosomal membrane permeabilization (LMP) followed by relocation of lysosomal cathepsins to the cytoplasm. TNF/CHX-induced LMP is effectively abrogated by siRNAs targeting acid sphingomyelinase or acid ceramidase, which prevent both LMP and death induced by TNF/CHX. Taken together, our results demonstrate that lysosomal accumulation of ceramide is not detrimental per se, whereas its degradation product sphingosine, which has the capacity to induce LMP, appears responsible for the observed apoptotic-like death.-Ullio, C., J. Casas, U. T. Brunk, G. Sala, G. Fabrias, R. Ghidoni, G. Bonelli, F. M. Baccino, and R. Autelli. Sphingosine mediates TNF alpha-induced lysosomal membrane permeabilization and ensuing programmed cell death in hepatoma.

Place, publisher, year, edition, pages
American Society for Biochemistry and Molecular Biology, 2012
Keywords
ceramide, hepatocellular carcinoma, lysosomes, sphingolipids, tumor necrosis factor-alpha
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-77861 (URN)10.1194/jlr.M022384 (DOI)000303913200010 ()
Note
Funding Agencies|Ministero dellUniversita e della Ricerca, Regione Piemonte|SAF2008-00706|Ministerio de Ciencia e Innovacion|SAF2011-22444|Available from: 2012-05-31 Created: 2012-05-31 Last updated: 2017-12-07
Zhao, H., Brunk, U. & Garner, B. (2011). Age-related lysosomal dysfunction: an unrecognized roadblock for cobalamin trafficking?. Cellular and Molecular Life Sciences (CMLS), 68(24), 3963-3969
Open this publication in new window or tab >>Age-related lysosomal dysfunction: an unrecognized roadblock for cobalamin trafficking?
2011 (English)In: Cellular and Molecular Life Sciences (CMLS), ISSN 1420-682X, E-ISSN 1420-9071, Vol. 68, no 24, p. 3963-3969Article in journal (Refereed) Published
Abstract [en]

Vitamin-B(12) is a generic term for corrinoid compounds that exhibit the biological activity of cyanocobalamin and are collectively referred to as cobalamins. Methylcobalamin and 5-deoxyadenosylcobalamin are the active cobalamins in human metabolism. Cobalamin plays a crucial role in the maintenance of homocysteine and methylmalonyl-CoA homeostasis and is required for erythrocyte formation and DNA synthesis. Data from human and animal studies indicate that cobalamin deficiency impairs neuronal function; a process that is thought to contribute to age-related cognitive decline and dementia. Cobalamin deficiency also results in dysfunction of the peripheral nervous system; among other disorders. Although there is a detailed understanding of the biochemical pathways that are perturbed in cobalamin deficiency, the mechanisms underlying age-related dyshomeostasis in such pathways remain to be addressed. Because cobalamin utilization is dependent on its efficient transit through lysosomes, and mounting evidence indicates that lysosomal function deteriorates in aging long-lived post-mitotic cells such as neurons, in the present article we review published data that supports the proposition that impaired lysosomal processing of cobalamin may play a significant role in age-related (neuro) degenerative diseases.

Place, publisher, year, edition, pages
Springer Verlag (Germany), 2011
Keywords
Aging; Lysosomes; Lipofuscin; Vitamin-B12; Neurodegeneration
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-73325 (URN)10.1007/s00018-011-0861-9 (DOI)000297349900001 ()
Available from: 2012-01-03 Created: 2012-01-02 Last updated: 2017-12-08
Lovejoy, D. B., Jansson, P. J., Brunk, U., Wong, J., Ponka, P. & Richardson, D. R. (2011). Antitumor Activity of Metal-Chelating Compound Dp44mT Is Mediated by Formation of a Redox-Active Copper Complex That Accumulates in Lysosomes. Cancer Research, 71(17), 5871-5880
Open this publication in new window or tab >>Antitumor Activity of Metal-Chelating Compound Dp44mT Is Mediated by Formation of a Redox-Active Copper Complex That Accumulates in Lysosomes
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2011 (English)In: Cancer Research, ISSN 0008-5472, E-ISSN 1538-7445, Vol. 71, no 17, p. 5871-5880Article in journal (Refereed) Published
Abstract [en]

The metal-chelating compound Dp44mT is a di-2-pyridylketone thiosemicarbazone (DpT) which displays potent and selective antitumor activity. This compound is receiving translational attention, but its mechanism is poorly understood. Here, we report that Dp44mT targets lysosome integrity through copper binding. Studies using the lysosomotropic fluorochrome acridine orange established that the copper-Dp44mT complex (Cu[Dp44mT]) disrupted lysosomes. This targeting was confirmed with pepstatin A-BODIPY FL, which showed redistribution of cathepsin D to the cytosol with ensuing cleavage of the proapoptotic BH3 protein Bid. Redox activity of Cu[Dp44mT] caused cellular depletion of glutathione, and lysosomal damage was prevented by cotreatment with the glutathione precursor N-acetylcysteine. Copper binding was essential for the potent antitumor activity of Dp44mT, as coincubation with nontoxic copper chelators markedly attenuated its cytotoxicity. Taken together, our studies show how the lysosomal apoptotic pathway can be selectively activated in cancer cells by sequestration of redox-active copper. Our findings define a novel generalized strategy to selectively target lysosome function for chemotherapeutic intervention against cancer.

Place, publisher, year, edition, pages
American Association for Cancer Research, 2011
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-70738 (URN)10.1158/0008-5472.CAN-11-1218 (DOI)000294454700028 ()
Note
Funding Agencies|National Health and Medical Research Council||Cancer Institute NSW||Available from: 2011-09-16 Created: 2011-09-16 Last updated: 2017-12-08
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