Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.627947
Title: Regulation of contact inhibition of locomotion by Eph-ephrin signalling
Author: Batson, Jennifer
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2013
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Abstract:
Metastatic prostate cancer cells display EphB receptor-mediated attraction when they contact stromal fibroblasts but EphA-driven repulsion and contact inhibition of locomotion (CIL) when they contact one another. The impact of these social interactions between cells during cancer cell invasion and the signalling mechanisms downstream of Eph receptors are unclear. Here, I show that EphA receptors drive prostate cancer cell dissemination in a 20 dispersal assay and a 3D cancer cell" spheroid assay by activating repulsive interactions and CIL between contacting prostate cancer cells. I show that EphA receptors interact with the exchange factor Vav2 to activate RhoA, and that both Vav2 and RhoA are required for prostate cancer cell-cell repulsion. Using pharmacological inhibitors I show actomyosin contractility is not a key driver of CIL. I find instead that microtubule dynamics are important for generating the front-rear polarity switch required during CIL, and that EphA2/EphA4, Vav2 and RhoA affect microtubule stability in prostate cancer cells. Furthermore, I find that in EphA2/EphA4, Vav2 or RhoA knockdown cells, contact repulsion can be restored by partial microtubule destabilisation. I propose that EphAVav2- RhoA-mediated repulsion between contacting cancer cells at the tumour edge could enhance their local metastatic invasion and dissemination from the primary tumour. Subsequently, EphB-mediated attractive migration and failure of CIL, between prostate cancer cells contacting ephrin-B2· expressing fibroblasts, could facilitate cancer cell invasion through the surrounding stroma. Stimulation of prostate cancer cells with ephrin-B2lFc leads to filopodia formation and activation of Cdc42. I show that Cdc42-silenced PC-3 cells have significantly impaired migration towards surface coated ephrin-B2 compared with control siRNA-treated cells. Furthermore, Cdc42 is required for attractive migration and defective CIL during collisions b~tween advanced prostate cancer cells and ephrin-B2-expressing fibroblasts. Using organotypic 3D gel invasion assays, I show that ephrin-B2 expressing fibroblasts enhance prostate cancer cell invasion. These data suggest that EphB-Cdc42-mediated attractive interactions with fibroblasts and defective CIL might facilitate prostate cancer cell invasion through the surrounding stroma.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.627947  DOI: Not available
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