liu.seSearch for publications in DiVA
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Impact of Lysosomal Function in Cancer and Apoptosis
Linköping University, Department of Clinical and Experimental Medicine, Experimental Pathology. Linköping University, Faculty of Health Sciences.
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Lysosomes, the recycling units of the cell, participate in the signaling pathway to apoptosis, which has stimulated the search for anti-cancer drugs targeting the lysosomal compartment. Lysosomes are, however, often altered in cancer cells. The aim of this thesis was to investigate the involvement of lysosomes during apoptosis in normal and cancer cells. We developed and used flow cytometric methods to measure cytosolic and lysosomal pH in cells. The cytosolic pH of U937 cells decreased, in a caspase-independent way, by 1.4 pH-units during apoptosis. Concomitantly, the lysosomal pH increased from 4.3 to 5.2, suggesting that proton release from lysosomes might be responsible for cytosolic acidification. When studying the lysosomal pH of head and neck squamous cell carcinoma (HNSCC) cell lines and normal oral keratinocytes (NOKs), the pH was significantly increased in three of five HNSCC cell lines, as compared to NOKs. Moreover, high lysosomal pH correlated to low expression of the B subunit of the vacuolar V0/V1-ATPase, a necessary component of the proton pump responsible for lysosomal acidification, and to reduced intrinsic cisplatin sensitivity. Cisplatin-induced apoptosis was, at least partly, dependent on lysosomal cathepsins. When investigating the colony formation ability of the two HNSCC cell lines LK0412 and SqCC/Y1, both were found to give rise to holoclones, indicating the presence of cells with cancer stem cell properties. Holoclone cells from the LK0412 cell line were less sensitive to cisplatin compared to more differentiated paraclone cells. Moreover, we detected differences in intracellular localization of the lysosomal compartment and expression of cathepsins between holo- and paraclone cells.

This thesis shows that changes found in the lysosomal compartment of cancer cells, such as alteration of lysosomal pH, might influence the outcome of a drug treatment. In addition, differences in drug sensitivity between subpopulations of tumor cells may affect the outcome of an anticancer therapy.

Abstract [sv]

Programmerad celldöd eller apoptos är en viktig mekanism för att upprätthålla balans mellan kroppens celler. Vid exempelvis cancer fungerar inte styrningen av denna process, vilket leder till att för få celler dör och en tumör kan växa ohämmat. Denna avhandling fokuserar på lysosomen, en mycket sur organell i cellen som är ansvarig för nedbrytning av cellmaterial. Hos cancerceller är lysosomerna ofta förändrade. Vi har undersökt lysosomernas roll under apoptos hos normala celler och hos cancerceller. För att kunna undersöka pH-förändringar under apoptos har vi utvecklat metoder att mäta cytosoliskt och lysosomalt pH med hjälp av en teknik som kallas flödescytometri. I apoptotiska celler ser vi att det cytosoliska pH:t sjunker med 1.4 pH-enheter till pH 5.7 samtidigt som det lysosomala pH:t ökar från 4.3 till 5.5. Detta tyder på att läckage av vätejoner från lysosomerna kan orsaka en försurning av cytosolen under apoptos. Genom att studera normala orala keratinocyter och jämföra dessa mot fem olika cellinjer eeablerade från skivepitelcancer från munhåla har vi också funnit ett samband mellan det lysosomala pH:t och känsligheten för cellgiftet cisplatin. Cisplatinbehandling leder till apoptos hos alla celler men en högre dos krävs hos celler som har ett högt lysosomalt pH. Tumörer tros innehålla ett litet antal sk cancerstamceller, som har förmåga att kontinuerligt kopiera sig själva utan att åldras. Överlevnad av dessa celler tros vara orsaken till att en tumör återkommer efter en behandling. Vi visar i denna avhandling att cellinjer från skivepitelcancer innehåller celler som har cancerstamcellsegenskaper, och att dessa celler kan ha en lägre känslighet mot cisplatin jämfört med mer utvecklade cancerceller.

Lysosomerna utgör ett intressant framtida mål för nya cancerläkemedel. I denna avhandling visar vi att förändringar i det lysosomala systemet kan påverka effekten av ett läkemedel och att skillnader mellan olika sub-populationer av celler från samma tumör kan påverka resultatet av en behandling.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press , 2008. , 112 p.
Series
Linköping University Medical Dissertations, ISSN 0345-0082 ; 1080
National Category
Cancer and Oncology
Identifiers
URN: urn:nbn:se:liu:diva-15138ISBN: 978-91-7393-794-8 (print)OAI: oai:DiVA.org:liu-15138DiVA: diva2:54575
Public defence
2008-10-24, Linden, Campus US, Linköpings universitet, Linköping, 09:00 (English)
Opponent
Supervisors
Available from: 2008-10-17 Created: 2008-10-17 Last updated: 2017-08-30Bibliographically approved
List of papers
1. Analysis of cytosolic and lysosomal pH in apoptotic cells by flow cytometry
Open this publication in new window or tab >>Analysis of cytosolic and lysosomal pH in apoptotic cells by flow cytometry
2004 (English)In: Methods in Cell Science, ISSN 1381-5741, Vol. 25, no 3-4, 185-194 p.Article in journal (Refereed) Published
Abstract [en]

Several reports indicate that the cytosol is acidified during apoptosis although the mechanism is not yet fully elucidated. The most acidic organelle found in the cell is the lysosome, raising the possibility that lysosomal proton release may contribute to the cytosolic acidification. We here describe methods for measurement of the cytosolic and lysosomal pH in U937 cells by a dual-emission ratiometric technique suitable for flow cytometry. Cytosolic pH was analysed in cells loaded with the fluorescent probe BCECF, while lysosomal pH was determined after endocytosis of FITC-dextran. Standard curves were obtained by incubating cells in buffers with different pH in the presence of the proton ionophore nigericin. Apoptosis was induced by exposure of cells to 10ng/ml TNF- for 4h, and apoptotic cells were identified using a fluorescent marker for active caspases. By gating of control and apoptotic cells, the cytosolic and lysosomal pH were calculated in each population. The cytosolic pH was found to decrease from 7.2 ± 0.1 to 5.8s±0.1 and the lysosomal increased from 4.3±0.4 to 5.2±0.3. These methods will be useful in future attempts to evaluate the involvement of lysosomes in the acidification of the cytosol during apoptosis.

Keyword
Apoptosis, Flow cytometry, Lysosomes, pH measurement
National Category
Cell and Molecular Biology
Identifiers
urn:nbn:se:liu:diva-15134 (URN)10.1007/s11022-004-8228-3 (DOI)
Available from: 2008-10-17 Created: 2008-10-17 Last updated: 2017-08-30Bibliographically approved
2. Cytosolic acidification and lysosomal alkalinization during TNF-α induced apoptosis in U937 cells
Open this publication in new window or tab >>Cytosolic acidification and lysosomal alkalinization during TNF-α induced apoptosis in U937 cells
Show others...
2006 (English)In: Apoptosis (London), ISSN 1360-8185, E-ISSN 1573-675X, Vol. 11, no 7, 1149-1159 p.Article in journal (Refereed) Published
Abstract [en]

Apoptosis is often associated with acidification of the cytosol and since loss of lysosomal proton gradient and release of lysosomal content are early events during apoptosis, we investigated if the lysosomal compartment could contribute to cytosolic acidification. After exposure of U937 cells to tumor necrosis factor-α, three populations; healthy, pre-apoptotic, and apoptotic cells, were identified by flow cytometry. These populations were investigated regarding intra-cellular pH and apoptosis-associated events. There was a drop in cytosolic pH from 7.2 ± 0.1 in healthy cells to 6.8 ± 0.1 in pre-apoptotic, caspase-negative cells. In apoptotic, caspase-positive cells, the pH was further decreased to 5.7 ± 0.04. The cytosolic acidification was not affected by addition of specific inhibitors towards caspases or the mitochondrial F0F1-ATPase. In parallel to the cytosolic acidification, a rise in lysosomal pH from 4.3 ± 0.3, in the healthy population, to 4.8 ± 0.3 and 5.5 ± 0.3 in the pre-apoptotic- and apoptotic populations, respectively, was detected. In addition, lysosomal membrane permeability increased as detected as release of cathepsin D from lysosomes to the cytosol in pre-apoptotic and apoptotic cells. We, thus, suggest that lysosomal proton release is the cause of the cytosolic acidification of U937 cells exposed to TNF-α.

Place, publisher, year, edition, pages
Springer Netherlands, 2006
Keyword
Apoptosis, Cathepsin, Cytosolic acidification, Lysosomal alkalinization, pH, TNF-α
National Category
Cell Biology
Identifiers
urn:nbn:se:liu:diva-15135 (URN)10.1007/s10495-006-7108-5 (DOI)
Available from: 2008-10-17 Created: 2008-10-17 Last updated: 2017-12-07Bibliographically approved
3. Intrinsic differences in cisplatin sensitivity of head and neck cancer celllines correlates to lysosomal pH
Open this publication in new window or tab >>Intrinsic differences in cisplatin sensitivity of head and neck cancer celllines correlates to lysosomal pH
2010 (English)In: Head and Neck, ISSN 1043-3074, E-ISSN 1097-0347, Vol. 32, no 9, 1185-1194 p.Article in journal (Refereed) Published
Abstract [en]

Cisplatin is part of the treatment regime of head and neck squamous cell carcinomas (HNSCC). In order to predict the clinical outcome of the treatment, markers for evaluation of the intrinsic cisplatin sensitivity are inquired. In this study we characterize the lysosomal compartment and compare cisplatin sensitivity in five HNSCC lines and normal oral keratinocytes (NOKs). Cisplatin sensitivity differed 3-fold between the least and most sensitive cell lines, and the cisplatin LD50 correlated significantly to lysosomal pH, which varied from 4.3 in NOKs to 4.9 in the most resistant HNSCC line. Lysosomes are acidified by the V0V1-ATPase complex located in the lysosomal membrane. Interestingly, in cell lines exhibiting high lysosomal pH, we found decreased expression of the V0V1-ATPase B2 subunit, possibly explaining the defective acidification. In all cell lines, exposure to cisplatin caused activation of caspase-3. Cisplatin exposure was accompanied by lysosomal membrane permeabilization and inhibition of the llysosomal cathepsins B, D and L partly prevented cell death. No correlation between cisplatin sensitivity and expression of cathepsins B, D and L or secretion of their respective proforms into the culture medium was found in the cell lines studied. We conclude that lysosomal pH and expression of V0V1-ATPase subunits are possible future markers of intrinsic cisplatin sensitivity.

Place, publisher, year, edition, pages
John Wiley & Sons, 2010
Keyword
apoptosis, cathepsin, chemotherapy resistance, lysosome, V0V1-ATPase
National Category
Cell and Molecular Biology
Identifiers
urn:nbn:se:liu:diva-15136 (URN)10.1002/hed.21317 (DOI)000281528100008 ()
Note

The previous status of this article was Manuscript and the working title was Radiation and cisplatin sensitivity in head and neck cancer cells with stem cell properties.

Available from: 2008-10-17 Created: 2008-10-17 Last updated: 2017-12-07Bibliographically approved
4. Intrinsic differences in cisplatin sensitivity of head and neck cancer celllines correlates to lysosomal pH
Open this publication in new window or tab >>Intrinsic differences in cisplatin sensitivity of head and neck cancer celllines correlates to lysosomal pH
2010 (English)In: Head and Neck, ISSN 1043-3074, E-ISSN 1097-0347, Vol. 32, no 9, 1185-1194 p.Article in journal (Refereed) Published
Abstract [en]

Cisplatin is part of the treatment regime of head and neck squamous cell carcinomas (HNSCC). In order to predict the clinical outcome of the treatment, markers for evaluation of the intrinsic cisplatin sensitivity are inquired. In this study we characterize the lysosomal compartment and compare cisplatin sensitivity in five HNSCC lines and normal oral keratinocytes (NOKs). Cisplatin sensitivity differed 3-fold between the least and most sensitive cell lines, and the cisplatin LD50 correlated significantly to lysosomal pH, which varied from 4.3 in NOKs to 4.9 in the most resistant HNSCC line. Lysosomes are acidified by the V0V1-ATPase complex located in the lysosomal membrane. Interestingly, in cell lines exhibiting high lysosomal pH, we found decreased expression of the V0V1-ATPase B2 subunit, possibly explaining the defective acidification. In all cell lines, exposure to cisplatin caused activation of caspase-3. Cisplatin exposure was accompanied by lysosomal membrane permeabilization and inhibition of the llysosomal cathepsins B, D and L partly prevented cell death. No correlation between cisplatin sensitivity and expression of cathepsins B, D and L or secretion of their respective proforms into the culture medium was found in the cell lines studied. We conclude that lysosomal pH and expression of V0V1-ATPase subunits are possible future markers of intrinsic cisplatin sensitivity.

Place, publisher, year, edition, pages
John Wiley & Sons, 2010
Keyword
apoptosis, cathepsin, chemotherapy resistance, lysosome, V0V1-ATPase
National Category
Cell and Molecular Biology
Identifiers
urn:nbn:se:liu:diva-15136 (URN)10.1002/hed.21317 (DOI)000281528100008 ()
Note

The previous status of this article was Manuscript and the working title was Radiation and cisplatin sensitivity in head and neck cancer cells with stem cell properties.

Available from: 2008-10-17 Created: 2008-10-17 Last updated: 2017-12-07Bibliographically approved

Open Access in DiVA

fulltext(638 kB)2609 downloads
File information
File name FULLTEXT01.pdfFile size 638 kBChecksum SHA-512
cea573c53e7d7121e8d583a4ac8c9eb13fc9c248191c259dc75575744ede1e1a18134ecce04e76b00796b3152b57890b1f1f1adde83abe07a4f0201f31978574
Type fulltextMimetype application/pdf
cover(135 kB)88 downloads
File information
File name COVER01.pdfFile size 135 kBChecksum SHA-512
78c80d175f636e62488d92199880a2c0ba09aaa62efad6c3cf6743592c6c336762b498a8a494b6d5dc463e6b3bfa52e1a28e53a32ed65eab7d51747a4f36ee35
Type coverMimetype application/pdf
popular summary(11 kB)164 downloads
File information
File name POPULARSUMMARY01.pdfFile size 11 kBChecksum SHA-512
a806a2bef7fe2621caf35c9bee3e7e3249dcdc6d7c738099a58d07444769e4764cb3001cfdd74a77aefba4bd1b384ef75712a8d337e5df6a900b37d8fb160057
Type popularsummaryMimetype application/pdf

Authority records BETA

Nilsson, Cathrine

Search in DiVA

By author/editor
Nilsson, Cathrine
By organisation
Experimental PathologyFaculty of Health Sciences
Cancer and Oncology

Search outside of DiVA

GoogleGoogle Scholar
Total: 2609 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 1565 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf