Invasion/Microenvironment

Cancer invasion is a cell and tissue-driven process for which the physical, cellular, and molecular determinants adapt and react throughout the progression of the disease. Cancer invasion is initiated and maintained by signaling pathways that control cytoskeletal dynamics in tumor cells and the turnover of cell-matrix and cell-cell junctions, followed by cell migration into the adjacent tissue. Cancer invasion and metastasis are landmark events that transform a locally growing tumor into a systemic, metastatic, and live-threatening disease. The initial steps of local invasion include the activation of signaling pathways that control cytoskeletal dynamics in tumor cells and the turnover of cellmatrix and cell-cell junctions, followed by active tumor cell migration into the adjacent tissue. Metastasis then occurs when invading tumor cells engage with blood and lymph vessels, penetrate basement membranes and endothelial walls, and disseminate through the vessel lumen to colonize distant organs. Like cells in primary tumors, cells in metastases also proliferate, invade, and enter blood vessels, leading to secondary metastasis.