KIAA1199 serves as a novel cell migration-promoting gene and plays a critical role in maintaining cancer mesenchymal status.

Oxidative stress caused by high levels of reactive oxygen species (ROS) has been correlated with prostate cancer (PCa) aggressiveness. Expression of membrane-type 1-matrix metalloproteinase (MT1-MMP), which has been implicated in cancer invasion and metastasis, is associated with advanced PCa. We demonstrate here that MT1-MMP plays a key role in eliciting oxidative stress in PCa cancer cells. Stable MT1-MMP expression in less invasive LNCaP prostate cancer cells with low endogenous MT1-MMP increased activity of ROS, whereas MT1-MMP knockdown in DU145 cells with high endogenous MT1-MMP decreased ROS. Expression of MT1-MMP increased oxidative DNA damage in LNCaP and in DU145 cells, indicating MT1-MMP-mediated induction of ROS caused oxidative stress. MT1-MMP expression promoted a more aggressive phenotype in LNCaP cells that was dependent on elaboration of ROS. Blocking ROS activity using the ROS scavenger, N-acetylcysteine (NAC), abrogated MT1-MMP-mediated increase in cell migration and invasion. MT1-MMP-expressing LNCaP cells displayed an enhanced ability to grow in soft agar that required increased ROS. Employing cells expressing MT1-MMP mutant cDNAs, we demonstrated that ROS activation entails cell surface MT1-MMP proteolytic activity. Induction of ROS in PCa cells expressing MT1-MMP required adhesion to extracellular matrix (ECM) proteins and was impeded by anti-β1 integrin antibodies. These results highlight a novel mechanism of malignant progression in PCa cells that involves β1 integrin-mediated adhesion, in concert with MT1-MMP proteolytic activity, to elicit oxidative stress and induction of a more invasive phenotype.

Membrane type 1-matrix metalloproteinase (MT1-MMP, MMP-14) is associated with cancer invasion and metastasis leading to poor patient prognosis. MT1-MMP mediates cancer cell invasion via degradation of basement membrane and extracellular matrix, and induction of cell migration. However, MT1-MMP expression in the cancer stroma can drive invasion of carcinoma cells in vivo, suggesting MT1-MMP may also promote cancer invasiveness via paracrinemediated mechanisms. A major step in cancer cell metastasis is thought to be an epithelial-mesenchymal transition (EMT), in which carcinoma cells evolve from a stationary epithelial phenotype to a more motile mesenchymal phenotype. We demonstrate here that EMT is triggered by MT1-MMP-mediated activation of TGF-. signaling, involving induction of CUTL1 and subsequently, of Wnt5a. Mesenchymal-like cancer cells expressing endogenous MT1-MMP reverted to an epithelial phenotype when MT1-MMP, SMAD4, CUTL1, or Wnt5a expression or TGF-. activity was inhibited. Wnt5a knockdown in MT1- MMP expressing LNCaP cells caused decreased cell migration and cell growth in soft agar. While MT1-MMP expression did not affect total TGF-. level, MT1-MMP catalytic activity increased the availability of active TGF-., enabling MT1-MMP-expressing cells to activate the EMT in nearby cells. MT1-MMP-expressing cells induced co-cultured non-MT1-MMP-expressing cells to undergo EMT by a TGF-.-dependent process. These results highlight a pathway by which tumor invasiveness may be expanded via MT1-MMP-mediated activation of TGF-. signaling, enabling autocrine and paracrine-mediated induction of EMT.