Tumour metastasis is the major cause of death in cancer patients who have suffered from a primary solidtumour and chemotactic signalling has been shown to play a significant role in tumour invasion andspreading. One of the important representatives of this system are the chemokine ligand CXCL12 and itsreceptor, CXCR4, as they are most commonly found on human and murine cancer cells. The binding ofCXCL12 to CXCR4 initiates divergent signalling pathways downstream of ligand binding by activation ofthe heterotrimeric G-proteins, which subsequently promote the recruitment of G-protein coupled receptorkinases that induce site-specific phosphorylation at the C-terminus. This would then result in the bindingof arrestins to the phosphorylated receptor. Arrestin recruitment leads to the uncoupling of CXCR4 fromG-protein and it induces receptor internalisation. In addition to their classical role as signal terminators, arrestins have also been known to serve as ascaffold for a number of downstream effectors and function as a signal transducer itself, which potentiallyleads to numerous cellular responses such as cell migration. Arrestins are expressed ubiquitously in allcells and tissues. Throughout the years, various signalling molecules that are involved in CXCR4 triggeredmigration have been discovered, however, there is still some ambiguity about which pathways are directlyinvolved in cell migration. Hence, one of the aims is to investigate the role of different arrestins’ subtypesin CXCL12-induced migration. To understand this, MCF-7 cells (breast cancer cells) were transfectedchemically while Jurkat cells (T-lymphocyte cells) were transfected by electroporation transfection withdifferent arrestins’ DNA plasmids and pEGFP.C2 as the control during the experiments. Wound healingassays were used to quantify migration of adherent MCF-7 cells while ChemoTX 5 µm pore chemotaxisplates were used to perform chemotaxis assays for suspension Jurkat cells. The experiments show that CXCL12 activation leads to a movement of arrestin 3 in MCF-7 cells andarrestin 3 is required for CXCL12-induced chemotaxis in Jurkat cells. Arrestin 3 seems to be the importantarrestin subytype that is involved in migration of suspension and adherent cells. These studiesdemonstrated that CXCL12-induced migration may be arrestin 3-mediated, therefore this research hasidentified potential signaling molecules that can be targeted to interfere with migration of cells, toprevent tumour metastasis in cancer patients.B E Y O N D | O C T . T O D E C . 2 0 1 9 | I S S U E 1 9 | R E S E A R C H I S S U E R O L E O F A R R E S T I N S I N C X C L 1 2 - I N D U C E DM I G R A T I O N I N V A R I O U S C A N C E R C E L L L I N E S 7D r . G o h P o h H u i , L e c t u r e rOverexpression of arrestins in MCF-7 cells upon CXCL12 activationMicrographs of MCF-7 monolayers treated with 10 nM CXCL12. MCF-7 cells were (a) mock transfected (basal) asnegative control, chemically transfected with plasmid DNA coding (b) EGFP-tagged arrestin 2 (pArr2.EGFP), (c)EGFP-tagged arrestin 3 (pArr3.EGFP) for 24 hours. Images represent population of cells and were acquired with aLeica imaging suite (63X magnification). This research has identified potential signaling molecules that can betargeted to prevent tumour metastasis in cancer patients.
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