Investigating the function of PINK1 in cancer development and pathogenesis

Show simple item record

dc.contributor.advisor O'Neill, Cora en
dc.contributor.author O'Flanagan, Ciara
dc.date.accessioned 2014-01-27T16:47:37Z
dc.date.issued 2013
dc.date.submitted 2013
dc.identifier.citation O'Flanagan, C. 2013. Investigating the function of PINK1 in cancer development and pathogenesis. PhD Thesis, University College Cork. en
dc.identifier.endpage 211
dc.identifier.uri http://hdl.handle.net/10468/1339
dc.description.abstract PTEN‐induced kinase 1 (PINK1) was identified initially in cancer cells as a gene up‐regulated by overexpression of the central tumour suppressor, PTEN. Loss‐of‐function mutations in PINK1 were discovered subsequently to cause autosomal recessive Parkinsonʹs disease (ARPD). Despite much research focusing on the proposed mechanism(s) through which loss of PINKI function causes neurodegeneration, few studies have focused on a direct role for this serine/threonine kinase in cancer biology. The focus of this thesis was to examine a direct role for PINK1 function in tumourigenesis. Initial studies showed that loss of PINK1 reduces tumour‐associated phenotypes including cell growth, colony formation and invasiveness, in several cell types in vitro, indicating a pro‐tumourigenic role for PINK1 in cancer. Furthermore, results revealed for the first time that PINK1 deletion, examined in mouse embryonic fibroblasts (MEFS) from PINK1 knock‐out animals, causes cell cycle defects, whereby cells arrest at in cytokinesis, giving rise to a highly significant increase in the number of multinucleated cells. This results in several key changes in the expression profile of cell cycle associated protein. In addition, PINK1‐deficient MEFs were found to resist cell cycle exit, with a proportion of cells remaining in proliferative phases upon removal of serum. The ability of cells to progress through mitosis conferred by PINK1 expression was independent of its kinase activity, while the cell cycle exit following serum withdrawal was kinase dependent. Investigations into the mechanism through which loss of PINK1 function gives rise to cell cycle defects revealed that dynamin related protein 1 (Drp1)‐mediated mitochondrial fission is enhanced in PINK1‐ deficient MEFs, and that increased expression of Drp1 on mitochondria and activation of Drp1 is highly significant in PINK1‐deficient multinucleated cells. Deregulated and increased levels and activation of mitochondrial fission via Drp1 was shown to be a major feature of cell cycle defects caused by PINK1 deletion, both during progression through G2/M and cell cycle exit following serum removal. Altered PINK1 localisation was also observed during progression of mitosis, and upon serum deprivation. Thus, PINK1 dissociated from the mitochondria during the mitotic phases and localised to mitochondria upon serum withdrawal. During serum withdrawal deletion of PINK1 disabled the ability of MEFs to increase mitochondrial membrane potential (ΔΨm), and increase autophagy. This was co‐incident with increased mitochondrial fission, and increased localisation of Drp1 to mitochondria following serum deprivation. Together, this indicates an inability of PINK1‐negative cells to respond protectively to this stress‐induced state, primarily via impaired mitochondrial function. In contrast, PINK1 overexpression was found to protect cells from DNA damage following treatment with oxidants. In addition, deletion of PINK1 blocked the ability of cells to re‐enter the cell cycle in response to insulin‐like growth factor‐1 (IGF‐1), a major cancer promoting agonistwhich acts primarily via PI3‐kinase/Akt activation. Furthermore, PINK1 mRNA expression was significantly increased following serum deprivation of MCF‐7 cells, and this was rendered more significant upon additional inhibition of PI3‐kinase. Conversely, IGF‐1 activation of PI3‐kinase/Akt causes a time‐dependent and significant reduction of PINK1 mRNA expression that was PI3‐kinase dependent. Together these results indicate that PINK1 expression is necessary for IGF‐1 signalling and is regulated reciprocally in the absence and presence of IGF‐1, via PI3‐kinase/Akt, a signalling system which has major tumour‐promoting capacity in cancer cell biology. The results of this thesis indicate PINK1 is a candidate tumour-promoting gene which has a significant function in the regulation of the cell cycle, and growth factor responses, at key cell cycle checkpoints, namely, during progression through G2/M and during exit of the cell cycle following removal of serum. Furthermore, the results reveal that the regulation of mitochondrial fission and Drp1 function is mechanistically important in the regulation of cell cycle control by PINK1. As deregulation of the cell cycle is linked to both tumourigenesis and neurodegeneration, the findings of this thesis are of importance not just for understanding cancer biology, but also in the context of PINK1‐associated neurodegeneration. en
dc.description.sponsorship Health Research Board (PhD Scholars’ Programme in Cancer Biology) en
dc.format.mimetype application/pdf en
dc.language.iso en en
dc.publisher University College Cork en
dc.rights © 2013, Ciara O'Flanagan. en
dc.rights.uri http://creativecommons.org/licenses/by-nc-nd/3.0/ en
dc.subject Cancer en
dc.subject Mitochondria en
dc.subject Cell en
dc.subject Cycle en
dc.subject PTEN‐induced kinase 1 (PINK1) en
dc.subject.lcsh Cell cycle--Regulation en
dc.subject.lcsh Cancer--Molecular aspects en
dc.title Investigating the function of PINK1 in cancer development and pathogenesis en
dc.type Doctoral thesis en
dc.type.qualificationlevel Doctoral Degree (Structured) en
dc.type.qualificationname PhD Scholars Programme in Cancer Biology en
dc.internal.availability Full text not available en
dc.check.info Indefinite en
dc.check.date 10000-01-01
dc.description.version Accepted Version
dc.contributor.funder Health Research Board en
dc.description.status Not peer reviewed en
dc.internal.school Biochemistry en
dc.internal.school Biosciences Institute en
dc.check.reason This thesis is due for publication or the author is actively seeking to publish this material en
dc.check.opt-out No en
dc.thesis.opt-out false
dc.check.entireThesis Entire Thesis Restricted
dc.check.embargoformat E-thesis on CORA only en
ucc.workflow.supervisor cora@ucc.ie
dc.internal.conferring Autumn Conferring 2013 en


Files in this item

Files Size Format View

There are no files associated with this item.

This item appears in the following Collection(s)

Show simple item record

© 2013, Ciara O'Flanagan. Except where otherwise noted, this item's license is described as © 2013, Ciara O'Flanagan.
This website uses cookies. By using this website, you consent to the use of cookies in accordance with the UCC Privacy and Cookies Statement. For more information about cookies and how you can disable them, visit our Privacy and Cookies statement