There are approximately 600 proteases encoded by the human genome; countless others are produced by other animals, plants, bacteria, viruses, and yeast.

As proteases are involved in all kind of cell biological processes and play a role in a huge number of diseases, protease inhibitors are commonly used tools in essentially every Life Science laboratory.

What are the fields of applications for protease inhibitors?

Often protease inhibitors are used as simple tools to protect proteins from proteolytical degradation during protein purification or cell/tissue extract preparation. These can be standalone inhibitors or mixtures. Members of this group of nonspecific inhibitors (Leupeptin, Pepstatin A, etc.) are combined to target all protease categories: aspartic, serine, cysteine, threonine, thermolysin-like proteases, metalloproteases, and aminopeptidases.

Early in 2015, researchers of The University of Queensland Diamantina Institute (Australia) have shown a very sensible approach to the discovery of new biomarkers associated to transition from non-metastatic tumours to metastatic tumours in osteosarcoma. Not to be a spoiler, but they found that the uPA/uPAR axis is crucial for this, and can be used as a prognostic biomarker. In fact, inhibition of this axis can inhibit the metastasis in this type of tumours. (Endo-Muñoz et al. DOI: 10.1371/journal.pone.0133592).

Model of uPA/uPAR signaling in osteosarcoma and the bone microenvironment. Source: Liliana Endo-Munoz; DOI: 10.1371/journal.pone.0133592.

I don’t want to focus on the biomarker per se, but rather, on the process that this lab followed to discover this new biomarker.