Trypsin-like Proteases as Metastatic Agents in Breast Cancer
Creators: name: University Of California Office Of The President
Publisher: name: University of California Office of the President
publisherIdentifier: https://ror.org/00dmfq477
publisherIdentifierScheme: ROR
Year: 2024

description: The ability of tumors to metastasize from their original location to the brain, bone and lymphatic tissue, is not well addressed by current therapies. Normal cells exist in contact with a complex protein network, called the extracellular matrix (ECM). The ECM is a barrier to cell movement and cancer cells must devise ways to break their attachments, degrade, and move through the ECM in order to metastasize. Proteases are enzymes that degrade other proteins and have long been thought to aid in freeing the tumor cells from their original location by chewing up the ECM. Recent studies have suggested that they may promote cell shape changes and motility through the activation of a protein in the tumor cell membrane called Protease-Activated Receptor-2 (PAR2). This leads to a cascade of intracellular reactions that activates the motility apparatus of the cell. Thus, the ECM-degrading proteases serve two functions by, (1) reducing the extracellular resistance to cell movement, and (2) activating the motility processes inside of cells though specific receptors. Because a number of inhibitors of the proteases that activate PAR2 are already commercially available, understanding the precise mechanisms by which PAR2 leads to metastatic changes in tumor cells could lead to the development of a new class of anti-metastatic agents.
 
 
 
 
 
 
 
 In this project we first aim to investigate whether PAR2 can: (a) make cells form extensions, called lamelipods, (b) induce net cell motility, and (c) activate key cell surface receptors, called integrins in breast cancer cells. Because lamelipods are composed primarily of a protein called actin, we will watch these structures form by observing the movement of fluorescently-tagged actin in the presence and absence of proteases and protease inhibitors. Changes in the structure and shape of cells mediated by PAR2 will be determined using a video microscope. Cell motility will be measured by growing cells on a grid and monitoring their movement across the grid in response to proteases and protease inhibitors over time, either in real time using a video microscope or at fixed intervals by counting the cells that have moved a specific distance. Second, we will identify other proteins involved in the PAR2 cascade using a radioactive label to tag proteins modified in response to PAR2 activation and mass spectrometry to analyze these modified proteins. We will then test these proteins for their role in cell shape change, motility and integrin activation. Finally, we will assess the efficiency of inhibiting PAR2, either using protease inhibitors or other chemicals that block PAR2 action, on the metastasis of tumors in a mouse model of breast cancer. With an increased understanding of the biology of PAR2, we will be able to assay inhibitors of different steps of the PAR2 pathway to see which ones are most effective at blocking metastasis. 
 
 
 
 
 
 
 
 These studies have the potential to provide a host of new anti-metastatic agents that could prevent tumor cell migration at early stages. Additionally, identification of other proteins involved in this pathway may provide a new diagnostic tool for identifying tumors that are likely to metastasize or provide targets for other anti-metastatic drugs. Such therapies, when used with anti-growth therapies, could greatly reduce the lethality of breast cancer.