Src kinase activation by nitric oxide promotes resistance to anoikis in tumour cell lines

Abstract

Tumour progression involves the establishment of tumour metastases at distant sites. Resistance to anoikis, a form of cell death that occurs when cells lose contact with the extracellular matrix and with neighbouring cells, is essential for metastases. NO has been associated with anoikis. NO treated HeLa cells and murine melanoma cells in suspension triggered a nitric oxide (NO)-Src kinase signalling circuitry that enabled resistance to anoikis. Two NO donors, sodium nitroprusside (SNP) (500 µM) and DETANO (125 µM), protected against cell death derived from detachment of a growth permissive surface (experimental anoikis). Under conditions of NO-mediated Src activation the following were observed: (a) down-regulation of the pro-apoptotic proteins Bim and cleaved caspase-3 and the cell surface protein, E-cadherin, (b) up-regulation of caveolin-1, and (c) the dissociation of cell aggregates formed when cells are detached from a growth permissive surface. Efficiency of reattachment of tumour cells in suspension and treated with different concentrations of an NO donor, was dependent on the NO concentration. These findings indicate that NO-activated Src kinase triggers a signalling circuitry that provides resistance to anoikis, and allows for metastases.

Keywords:

• Nitric oxide
• S-nitrosylation
• Src kinase
• Anoikis
• Anoikis resistance

Acknowledgements

Authors would like to thank Dr Matthew W. Foster and Dr Harvey E. Marshall, for helpful discussions. Authors are grateful for the help from the technicians in the Center for Cellular and Molecular Therapy at Universidade Federal de São Paulo.

Disclosure statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.

Additional information

Funding

Funding for this work was provided by the Fundação de Amparo a Pesquisa do Estado de São Paulo/Brazil (FAPESP) [grant number 2010/19013-7 and 2011/24112-7]; Conselho Nacional de Desenvolvimento Científico e Tecnológico/Brazil (CNPq) [grant number 481154/2013-2], and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior/Brazil (Capes).