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Functional characterisation of EFA6R, a possible biomarker for Epithelial Ovarian Cancer / Salman Tamaddon-Jahromi

DOI (Published version): 10.23889/Suthesis.48974

Abstract

Background: EFA6R functions as a guanine nucleotide exchange factor for Arf6 – a Ras-like GTPase protein that potently regulates tumour progression. EFA6R is consistently expressed in healthy ovarian epithelium, but is drastically downregulated in the vast majority of Epithelial Ovarian Cancers (EOC...

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Published: 2018
Institution: Swansea University
Degree level: Doctoral
Degree name: Ph.D
URI: https://cronfa.swan.ac.uk/Record/cronfa48974
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fullrecord <?xml version="1.0"?><rfc1807><datestamp>2019-02-26T09:30:58.8330250</datestamp><bib-version>v2</bib-version><id>48974</id><entry>2019-02-25</entry><title>Functional characterisation of EFA6R, a possible biomarker for Epithelial Ovarian Cancer</title><swanseaauthors/><date>2019-02-25</date><abstract>Background: EFA6R functions as a guanine nucleotide exchange factor for Arf6 &#x2013; a Ras-like GTPase protein that potently regulates tumour progression. EFA6R is consistently expressed in healthy ovarian epithelium, but is drastically downregulated in the vast majority of Epithelial Ovarian Cancers (EOC). Therefore, EFA6R could be a novel biomarker for EOC. Aim: 1. Study EFA6R expression in Epithelial Ovarian Cancer (EOC) cell lines and tissues. 2. Identify the mechanisms of EFA6R downregulation and its role in mediating cellular phenotype. 3. Delineate the expression, localisation and cellular functions of EFA6R isoforms. Results: In EOC Tissue cDNA array, 73% of 192 samples exhibited little or significantly less EFA6R expression than healthy samples. In tissue microarrays containing 80 individual cases of different grades, EFA6R expression was lost with tumour progression. Similar downregulation was observed in tissue lysates (6/7 samples) and 10/10 OC cell lines. In SKOV-3 cells treated with demethylation agent 5-aza-2&#x2019;deoxycytidine (5-Aza-Cdr) EFA6R expression was restored at mRNA and protein level; ~10-fold increase in EFA6R expression corresponded with significant attenuation of cell migration (~60% decrease in migration observed in Ibidi wound healing assay and ~ 5-fold decrease in migration and invasion in transwell assay). Exogenous expression of EFA6R plasmid DNA constructs showed that EFA6R localisation to the plasma membrane requires the PH and to a lesser extent, the CC domain. There, it functions as an Arf6-specific GEF, modulating actin stress fibres. Endogenous expression of EFA6R was observed in HEK293 and ReN cells. In the former, it potentially regulates b-integrin expression and in the latter, it plays a part in neuronal differentiation. Conclusion: EFA6R loss of function can be attributed to epigenetic mechanisms. Its downregulation, increases migration and metastasis through Arf6-independent pathways. One of the EFA6R isoforms has limited expression in some cell lines where it may play an important physiological role.</abstract><type>E-Thesis</type><journal/><publisher/><keywords>Cancer biomarker, cancer cell biology, cancer epigenetics, molecular biology, Arf6, EFA6R</keywords><publishedDay>31</publishedDay><publishedMonth>12</publishedMonth><publishedYear>2018</publishedYear><publishedDate>2018-12-31</publishedDate><doi>10.23889/Suthesis.48974</doi><url/><notes>A selection of third party content is redacted or is partially redacted from this thesis.</notes><college>COLLEGE NANME</college><CollegeCode>COLLEGE CODE</CollegeCode><institution>Swansea University</institution><degreelevel>Doctoral</degreelevel><degreename>Ph.D</degreename><degreesponsorsfunders>Health and Care Research Wales</degreesponsorsfunders><apcterm/><lastEdited>2019-02-26T09:30:58.8330250</lastEdited><Created>2019-02-25T15:59:15.2775381</Created><path><level id="1">Faculty of Medicine, Health and Life Sciences</level><level id="2">Swansea University Medical School - Medicine</level></path><authors><author><firstname>Salman</firstname><surname>Tamaddon-Jahromi</surname><order>1</order></author></authors><documents><document><filename>0048974-25022019160944.pdf</filename><originalFilename>Tamaddon_Jahromi_Salman_PhD_Thesis_Final_Redacted.pdf</originalFilename><uploaded>2019-02-25T16:09:44.1600000</uploaded><type>Output</type><contentLength>42869255</contentLength><contentType>application/pdf</contentType><version>Redacted version - open access</version><cronfaStatus>true</cronfaStatus><embargoDate>2021-01-01T00:00:00.0000000</embargoDate><copyrightCorrect>true</copyrightCorrect></document></documents><OutputDurs/></rfc1807>
spelling 2019-02-26T09:30:58.8330250 v2 48974 2019-02-25 Functional characterisation of EFA6R, a possible biomarker for Epithelial Ovarian Cancer 2019-02-25 Background: EFA6R functions as a guanine nucleotide exchange factor for Arf6 – a Ras-like GTPase protein that potently regulates tumour progression. EFA6R is consistently expressed in healthy ovarian epithelium, but is drastically downregulated in the vast majority of Epithelial Ovarian Cancers (EOC). Therefore, EFA6R could be a novel biomarker for EOC. Aim: 1. Study EFA6R expression in Epithelial Ovarian Cancer (EOC) cell lines and tissues. 2. Identify the mechanisms of EFA6R downregulation and its role in mediating cellular phenotype. 3. Delineate the expression, localisation and cellular functions of EFA6R isoforms. Results: In EOC Tissue cDNA array, 73% of 192 samples exhibited little or significantly less EFA6R expression than healthy samples. In tissue microarrays containing 80 individual cases of different grades, EFA6R expression was lost with tumour progression. Similar downregulation was observed in tissue lysates (6/7 samples) and 10/10 OC cell lines. In SKOV-3 cells treated with demethylation agent 5-aza-2’deoxycytidine (5-Aza-Cdr) EFA6R expression was restored at mRNA and protein level; ~10-fold increase in EFA6R expression corresponded with significant attenuation of cell migration (~60% decrease in migration observed in Ibidi wound healing assay and ~ 5-fold decrease in migration and invasion in transwell assay). Exogenous expression of EFA6R plasmid DNA constructs showed that EFA6R localisation to the plasma membrane requires the PH and to a lesser extent, the CC domain. There, it functions as an Arf6-specific GEF, modulating actin stress fibres. Endogenous expression of EFA6R was observed in HEK293 and ReN cells. In the former, it potentially regulates b-integrin expression and in the latter, it plays a part in neuronal differentiation. Conclusion: EFA6R loss of function can be attributed to epigenetic mechanisms. Its downregulation, increases migration and metastasis through Arf6-independent pathways. One of the EFA6R isoforms has limited expression in some cell lines where it may play an important physiological role. E-Thesis Cancer biomarker, cancer cell biology, cancer epigenetics, molecular biology, Arf6, EFA6R 31 12 2018 2018-12-31 10.23889/Suthesis.48974 A selection of third party content is redacted or is partially redacted from this thesis. COLLEGE NANME COLLEGE CODE Swansea University Doctoral Ph.D Health and Care Research Wales 2019-02-26T09:30:58.8330250 2019-02-25T15:59:15.2775381 Faculty of Medicine, Health and Life Sciences Swansea University Medical School - Medicine Salman Tamaddon-Jahromi 1 0048974-25022019160944.pdf Tamaddon_Jahromi_Salman_PhD_Thesis_Final_Redacted.pdf 2019-02-25T16:09:44.1600000 Output 42869255 application/pdf Redacted version - open access true 2021-01-01T00:00:00.0000000 true
title Functional characterisation of EFA6R, a possible biomarker for Epithelial Ovarian Cancer
spellingShingle Functional characterisation of EFA6R, a possible biomarker for Epithelial Ovarian Cancer
,
title_short Functional characterisation of EFA6R, a possible biomarker for Epithelial Ovarian Cancer
title_full Functional characterisation of EFA6R, a possible biomarker for Epithelial Ovarian Cancer
title_fullStr Functional characterisation of EFA6R, a possible biomarker for Epithelial Ovarian Cancer
title_full_unstemmed Functional characterisation of EFA6R, a possible biomarker for Epithelial Ovarian Cancer
title_sort Functional characterisation of EFA6R, a possible biomarker for Epithelial Ovarian Cancer
author ,
author2 Salman Tamaddon-Jahromi
format E-Thesis
publishDate 2018
institution Swansea University
doi_str_mv 10.23889/Suthesis.48974
college_str Faculty of Medicine, Health and Life Sciences
hierarchytype
hierarchy_top_id facultyofmedicinehealthandlifesciences
hierarchy_top_title Faculty of Medicine, Health and Life Sciences
hierarchy_parent_id facultyofmedicinehealthandlifesciences
hierarchy_parent_title Faculty of Medicine, Health and Life Sciences
department_str Swansea University Medical School - Medicine{{{_:::_}}}Faculty of Medicine, Health and Life Sciences{{{_:::_}}}Swansea University Medical School - Medicine
document_store_str 1
active_str 0
description Background: EFA6R functions as a guanine nucleotide exchange factor for Arf6 – a Ras-like GTPase protein that potently regulates tumour progression. EFA6R is consistently expressed in healthy ovarian epithelium, but is drastically downregulated in the vast majority of Epithelial Ovarian Cancers (EOC). Therefore, EFA6R could be a novel biomarker for EOC. Aim: 1. Study EFA6R expression in Epithelial Ovarian Cancer (EOC) cell lines and tissues. 2. Identify the mechanisms of EFA6R downregulation and its role in mediating cellular phenotype. 3. Delineate the expression, localisation and cellular functions of EFA6R isoforms. Results: In EOC Tissue cDNA array, 73% of 192 samples exhibited little or significantly less EFA6R expression than healthy samples. In tissue microarrays containing 80 individual cases of different grades, EFA6R expression was lost with tumour progression. Similar downregulation was observed in tissue lysates (6/7 samples) and 10/10 OC cell lines. In SKOV-3 cells treated with demethylation agent 5-aza-2’deoxycytidine (5-Aza-Cdr) EFA6R expression was restored at mRNA and protein level; ~10-fold increase in EFA6R expression corresponded with significant attenuation of cell migration (~60% decrease in migration observed in Ibidi wound healing assay and ~ 5-fold decrease in migration and invasion in transwell assay). Exogenous expression of EFA6R plasmid DNA constructs showed that EFA6R localisation to the plasma membrane requires the PH and to a lesser extent, the CC domain. There, it functions as an Arf6-specific GEF, modulating actin stress fibres. Endogenous expression of EFA6R was observed in HEK293 and ReN cells. In the former, it potentially regulates b-integrin expression and in the latter, it plays a part in neuronal differentiation. Conclusion: EFA6R loss of function can be attributed to epigenetic mechanisms. Its downregulation, increases migration and metastasis through Arf6-independent pathways. One of the EFA6R isoforms has limited expression in some cell lines where it may play an important physiological role.
published_date 2018-12-31T03:59:41Z
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score 11.013731

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