DAP kinase links the control of apoptosis to metastasis

Abstract

DAP kinase is a new type of calcium/calmodulin-dependent enzyme that phosphorylates serine/threonine residues on proteins. Its structure contains ankyrin repeats and the 'death' domain, and it is associated with the cell cytoskeleton. The gene encoding DAP kinase was initially isolated as a positive mediator of apoptosis induced by interferon-gamma, by using a strategy of functional cloning. We have now tested whether this gene has tumour-suppressive activity. We found that lung carcinoma clones, characterized by their highly aggressive metastatic behaviour and originating from two independent murine lung tumours, did not express DAP kinase, in contrast to their low-metastatic counterparts. Restoration of DAP kinase to physiological levels in high-metastatic Lewis carcinoma cells suppressed their ability to form lung metastases after intravenous injection into syngeneic mice, and delayed local tumour growth in a foreign 'microenvironment' Conversely, in vivo selection of rare lung lesions following injection into syngeneic mice of low-metastatic Lewis carcinoma cells or of DAP kinase transfectants, was associated with loss of DAP kinase expression. In situ TUNEL staining of tumour sections revealed that DAP kinase expression from the transgene raised the incidence of apoptosis in vivo. DAP-kinase transfectants also showed increased sensitivity in vitro to apoptotic stimuli, of the sort encountered by metastasizing cells at different stages of malignancy. We propose that loss of DAP kinase expression provides a unique mechanism that links suppression of apoptosis to metastasis.

Death-associated protein kinase 2 is a new calcium/calmodulin-dependent protein kinase that signals apoptosis through its catalytic activity

“…DAP kinase signi®cantly induced apoptosis upon overexpression and IFN-g-induced apoptosis was inhibited by transfection of the kinase negative mutant of DAP kinase . Furthermore, cells transfected with DAP kinase were more sensitive to apoptosis induced by TNF-a and the cells costimulated with TNF-a and cycloheximide resulted in faster migration of the DAP kinase protein on SDS ± PAGE, probably due to protein modi®cations such as protein phosphorylation or cleavage by proteases (Inbal et al, 1997). These results suggest that DAP kinase may be a key signaling molecule in not only IFN-g but also TNF-a-mediated apoptosis.…”

“…It was shown that the reduced expression of DAP kinase mediated by antisense mRNA protected HeLa cells from apoptosis induced by IFN-g, and overexpression of DAP kinase induced apoptosis . DAP kinase has been reported to function as a possible tumor suppressor gene (Kissil et al, 1997;Inbal et al, 1997). Recently, ZIP kinase has been identi®ed by the yeast two-hybrid screening in which the leucine zipper domain of ATF4, a member of Activating Transcription Factor/ cAMP responsive element binding protein (ATF/CREB) family of transcriptional factor was used as a bait .…”

Dependence receptors: a new paradigm in cell signaling and cancer therapy

“…Moreover, DAPK loss of expression is associated with a more malignant tumor phenotype and increased metastatic capacity. DAPK is absent in highly metastatic variants of mouse lung cancer cell lines, and is present in the low metastatic variants of those same cell lines (Inbal et al, 1997). In lung and head and neck cancers, DAPK promoter methylation was associated with aggressive disease and poor survival (Sanchez-Cespedes A new paradigm in cell signaling and cancer therapy D Goldschneider and P Mehlen et al, 2000;Tang et al, 2000;Kim et al, 2001;Kong et al, 2005).…”

Hypoxia selects for high-metastatic Lewis lung carcinoma cells overexpressing Mcl-1 and exhibiting reduced apoptotic potential in solid tumors

“…In all, 300 ml of EF5 solution (3 mg/ml) was injected intraperitoneally into mice bearing subcutaneous tumors (Inbal et al, 1997). After 1 h, tumors were surgically removed and frozen in OCT compound.…”

“…There is accumulating evidence that developing resistance to common apoptotic stimuli is one of the factors that confer high metastatic capability to tumor cells (Glinsky and Glinsky, 1996;McConkey et al, 1996;Bufalo et al, 1997;Glinsky, 1997;Inbal et al, 1997;Shtivelman, 1997;Takaoka et al, 1997;Fernandez et al, 2000;Lowe and Lin, 2000;Wong et al, 2001). The apoptosis-resistant phenotype may be advantageous for tumor cells to survive in the metastatic process.…”