RACK1 stabilises the activity of PP2A to regulate the transformed phenotype in mammary epithelial cells.
Conflicting reports implicate the scaffolding protein RACK1 in the progression of breast cancer. RACK1 has been identified as a key regulator downstream of growth factor and adhesion signalling and as a direct binding partner of PP2A. Our objective was to further characterise the interaction between PP2A and RACK1 and to advance our understanding of this complex in breast cancer cells. We examined how the PP2A holoenzyme is assembled on the RACK1 scaffold in MCF-7 cells. We used immobilized peptide arrays representing the entire PP2A-catalytic subunit to identify candidate amino acids on the C subunit of PP2A that might be involved in binding of RACK1. We identified the RACK1 interaction sites on PP2A. Stable cell lines expressing PP2A with FR69/70AA, R214A and Y218F substitutions were generated and it was confirmed that the RACK1/PP2A interaction is essential to stabilise PP2A activity. We used Real-Time Cell Analysis and a series of assays to demonstrate that disruption of the RACK1/PP2A complex also reduces the adhesion, proliferation, migration and invasion of breast cancer cells and plays a role in maintenance of the cancer phenotype. This work has significantly advanced our understanding of the RACK1/PP2A complex and suggests a pro-carcinogenic role for the RACK1/PP2A interaction. This work suggests that approaches to target the RACK1/PP2A complex are a viable option to regulate PP2A activity and identifies a novel potential therapeutic target in the treatment of breast cancer.
Graduate Entry Medical School, Materials and Surface Science Institute and Health Research Institute, University of Limerick, Ireland.
Maeve
M
Kiely
Institute of Chemical Sciences, Heriot-Watt University, Riccarton Campus, Edinburgh EH14AS, UK.
David R
DR
Adams
Graduate Entry Medical School, Materials and Surface Science Institute and Health Research Institute, University of Limerick, Ireland.
Sheri L
SL
Hayes
Cell Biology Laboratory, Department of Biochemistry, BioSciences Institute, University College Cork, Cork, Ireland.
Rosemary
R
O'Connor
Institute of Cardiovascular & Medical Science, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK.
George S
GS
Baillie
Graduate Entry Medical School, Materials and Surface Science Institute and Health Research Institute, University of Limerick, Ireland. Electronic address: Patrick.Kiely@ul.ie.
Patrick A
PA
Kiely
D019943:Amino Acid Substitution / Q000235:genetics; D001943:Breast Neoplasms / Q000235:genetics* / Q000473:pathology; D063646:Carcinogenesis / Q000235:genetics*; D020134:Catalytic Domain / Q000235:genetics; D005260:Female; D006801:Humans; D061986:MCF-7 Cells; D009363:Neoplasm Proteins / Q000235:genetics* / Q000378:metabolism; D010641:Phenotype; D010766:Phosphorylation; D011485:Protein Binding; D060066:Protein Interaction Maps / Q000235:genetics; D054648:Protein Phosphatase 2 / Q000235:genetics* / Q000378:metabolism; D000075370:Receptors for Activated C Kinase / Q000235:genetics* / Q000378:metabolism
D009363:Neoplasm Proteins; C419368:RACK1 protein, human; D000075370:Receptors for Activated C Kinase; D054648:Protein Phosphatase 2
Breast cancer; PP2A; Protein-protein interactions; RACK1