[The ubiquitin system for intracellular protein degradation--involvement in human pathologies and therapeutic implications].

The ubiquitin-proteasome pathway has a central role in selective degradation of intracellular proteins. Among the key proteins that are degraded by the system are those involved in the control of inflammation, cell cycle regulation, and gene expression. With so many important cellular pathways affected, derangements in the ubiquitin system have been shown to result in a variety of human diseases. Consequently, proteasome inhibition has a potential as a form of treatment for many human diseases such as cancer and inflammatory conditions. Two proteasome inhibitors, PS-341 and PS-519 are currently under clinical evaluation. PS-341 is currently being evaluated in phase III clinical trial for multiple myeloma, and PS-519 is now on a phase II trial for acute ischemic stroke. In addition, inhibition of the proteasome has been shown to be effective in several animal models for a variety of human diseases such as different malignancies, asthma, rheumatoid arthritis, and arterial restenosis. Future studies will be required to establish whether the promising animal studies could be successfully implicated in human disease states.