HD-PTP (PTPN23) is a non-trans
me
mbrane protein tyrosine phosphatase which contributes to the signal transduction pathways involved in the regulation of cell
migration and invasion. We here de
monstrate in T24 bladder carcino
ma cells that HD-PTP undergoes calciu
m-dependent degradation which can be prevented by specific
calpain inhibitors. In addition, treat
ment of the cells with the
calpain inhibitor calpeptin results in the redistribution of endogenous HD-PTP to the periphery of the cells.
Since (i) calpains are overexpressed in some tumors and (ii) the downregulation of HD-PTP enhances cell migration and invasion, we propose that HD-PTP degradation by calpains might result in the acquisition of a more aggressive phenotype in neoplastic cells.