Abstract
PTK6/Brk is a non-receptor tyrosine kinase overexpressed in cancer. Here we demonstrate that cytosolic PTK6 is rapidly and robustly induced in response to hypoxic conditions in a HIF-1-independent manner. Furthermore, a proportion of hypoxic PTK6 subsequently re-localized to the cell membrane. We observed that the rapid stabilization of PTK6 is associated with a decrease in PTK6 ubiquitylation and we have identified c-Cbl as a putative PTK6 E3 ligase in normoxia. The consequences of hypoxia-induced PTK6 stabilization and subcellular re-localization to the plasma membrane include increased cell motility and invasion, suggesting PTK6 targeting as a therapeutic approach to reduce hypoxia-regulated metastatic potential. This could have particular significance for breast cancer patients with triple negative disease.
Disclosure of Potential Conflicts of Interest
No potential conflicts of interest were disclosed.
Acknowledgments
We would like to thank Dr Anderson Ryan, Dr Jason Parsons, Dr Stephen Maher, and Professor John Greenman for useful discussions. A Breast Cancer Campaign pilot grant awarded to E.M.H. supported this study. I.M.P. is supported by University of Hull HEFCE funding, and Royal Society and Breast Cancer Campaign pilot grants. S.A.E. is supported by ICR HEFCE funding and Cancer Research UK program grant C309/A11566. A.H. is supported by Brunel University HEFCE funding. E.M.H. is supported by a Cancer Research UK grant.