Dense fibrillar collagen is a potent inducer of invadopodia via a specific signaling network.

Cell interactions with the extracellular matrix (ECM) can regulate multiple cellular activities and the matrix itself in dynamic, bidirectional processes. One such process is local proteolytic modification of the ECM. Invadopodia of tumor cells are actin-rich proteolytic protrusions that locally degrade matrix molecules and mediate invasion. We report that a novel high-density fibrillar collagen (HDFC) matrix is a potent inducer of invadopodia, both in carcinoma cell lines and in primary human fibroblasts. In carcinoma cells, HDFC matrix induced formation of invadopodia via a specific integrin signaling pathway that did not require growth factors or even altered gene and protein expression. In contrast, phosphoproteomics identified major changes in a complex phosphosignaling network with kindlin2 serine phosphorylation as a key regulatory element. This kindlin2-dependent signal transduction network was required for efficient induction of invadopodia on dense fibrillar collagen and for local degradation of collagen. This novel phosphosignaling mechanism regulates cell surface invadopodia via kindlin2 for local proteolytic remodeling of the ECM.

3-D extracellular matrix from sectioned human tissues.

Cell adhesion, migration, and signaling in physiologically normal and pathological processes depend highly on the extracellular matrix that the cell interacts with. A variety of in vitro models of two-dimensional and three-dimensional extracellular matrices have been developed to study multiple aspects of cellular behavior. However, there is a profound need for in vitro models of extracellular matrices to closely mimic both biochemical and physical aspects of a three-dimensional in vivo cellular environment. This unit outlines the preparation of human-tissue-derived, cell-free, three-dimensional extracellular matrices for studying cellular behavior and cell-extracellular matrix interactions ex vivo. These protocols can be used to prepare cell-free matrices from a variety of normal and cancerous tissues. This unit also provides protocols for quality control of acellular matrix preparations, and for immunostaining of cells for specific cellular proteins as well as of extracellular matrices for their components.