Molecular Analysis of Salivary Gland Branching Morphogenesis

AbstractRecently, clinicians and scientists have focused on tissue engineering for regenerative medical therapy. This approach promises to provide remarkable clinical breakthroughs for the future. In oral and craniofacial medicine, most scientific approaches to tissue engineering currently involve tooth and bone, while little progress has been made toward regenerating organs such as salivary gland. To develop strategies for salivary gland regeneration, it will be important to understand the molecular mechanisms of normal salivary development. This mini-review describes a recently developed and tested set of approaches for identifying and characterizing molecules essential for branching morphogenesis and other developmental processes. It shows the value of using laser microdissection and the new process of T7-SAGE for gene discovery of putative candidate molecules that may be crucial regulators or mediators. We describe a stepwise series of associated strategies for reliable identification and functional testing of a candidate molecule, as well as its successful application to a specific candidate molecule originally identified by T7-SAGE

Functional live-cell imaging demonstrates that beta1-integrin promotes type IV collagen degradation by breast and prostate cancer cells.

The ability of tumor cells to adhere to, migrate on, and remodel extracellular matrices is mediated by cell surface receptors such as beta1-integrins. Here we conducted functional live-cell imaging in real time to investigate the effects of modulating beta1-integrin expression and function on proteolytic remodeling of the extracellular matrix. Human breast and prostate cancer cells were grown on reconstituted basement membrane containing a quenched fluorescent form of collagen IV. Generation of cleavage products and the resulting increases in fluorescence were imaged and quantified. Decreases in the expression and activity of beta1-integrin reduced digestion of quenched fluorescent-collagen IV by the breast and prostate cancer cells and correspondingly their invasion through and migration on reconstituted basement membrane. Decreased extracellular matrix degradation also was associated with changes in the constituents of proteolytic pathways: decreases in secretion of the cysteine protease cathepsin B, the matrix metalloproteinase (MMP)-13, and tissue inhibitors of metalloproteinases (TIMP)-1 and 2; a decrease in expression of MMP-14 or membrane type 1 MMP; and an increase in secretion of TIMP-3. This is the first study to demonstrate through functional live-cell imaging that downregulation of beta1-integrin expression and function reduces proteolysis of collagen IV by breast and prostate cancer cells