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Niit M, Arulanandam R, Cass J, Geletu M, Hoskin V, Côté G, Gunning P, Elliott B, Raptis L. Regulation of HC11 mouse breast epithelial cell differentiation by the E-cadherin/Rac axis. Exp Cell Res 2017; 361:112-125. [PMID: 29031557 DOI: 10.1016/j.yexcr.2017.10.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Revised: 09/29/2017] [Accepted: 10/08/2017] [Indexed: 10/18/2022]
Abstract
It was previously demonstrated that differentiation of some established breast epithelial cell lines requires confluence and stimulation with hydrocortisone, insulin and prolactin inducers. We and others previously demonstrated that E-cadherin engagement, which is favored under conditions of confluence, increases the levels and activity of the Rac small GTPase. To investigate the functional relationship between the transforming ability of Rac and its role as an integral component of the differentiative E-cadherin signaling pathway, we introduced a mutationally activated form of Rac, RacV12, into the mouse breast epithelium-derived cell line, HC11. Our results demonstrate that the strength of the Rac signal is key for the outcome of the differentiation process; cRac1 is critically required for differentiation, and at low levels, mutationally activated RacV12 is able to increase differentiation, presumably reinforcing the E-cadherin/Rac differentiative signal. However, high RacV12 expression blocked differentiation concomitant with E-cadherin downregulation, while inducing neoplastic transformation. Therefore, the intensity of the Rac signal is a central determinant in the balance between cell proliferation vs differentiation, two fundamentally opposed processes, a finding which could also have important therapeutic implications.
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Affiliation(s)
- Maximilian Niit
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada K7L 3N6; Department of Pathology and Molecular Medicine, Queen's University, Kingston, Ontario, Canada K7L3N6
| | - Rozanne Arulanandam
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada K7L 3N6; Centre for Innovative Cancer Therapeutics, Ottawa Hospital Research Institute, Ottawa, ON, Canada K1H 8L6
| | - Jamaica Cass
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada K7L 3N6
| | - Mulu Geletu
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada K7L 3N6; Department of Chemical and Physical Sciences, University of Toronto, Mississauga, Ontario, Canada L5L 1C6
| | - Victoria Hoskin
- Department of Pathology and Molecular Medicine, Queen's University, Kingston, Ontario, Canada K7L3N6
| | - Graham Côté
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada K7L 3N6
| | - Patrick Gunning
- Department of Chemical and Physical Sciences, University of Toronto, Mississauga, Ontario, Canada L5L 1C6
| | - Bruce Elliott
- Department of Pathology and Molecular Medicine, Queen's University, Kingston, Ontario, Canada K7L3N6
| | - Leda Raptis
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada K7L 3N6; Department of Pathology and Molecular Medicine, Queen's University, Kingston, Ontario, Canada K7L3N6.
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