Determining Gene Expression, Substrate Specificity and Natural Substrates for Prostate Associated Proteases

摘要

We work on serine proteases of the chymotrypsin fold due to the wealth of information that exists on structure-function relationships regarding this class of enzymes and the existence of potent and specific inhibitors that are readily available for their inhibition. In addition, understanding of the function of these proteases may lead to further insight into cancer biology and may lead to possible therapeutics. We have focused upon an enzyme known as membrane-type serine protease 1 (MT-SPl)that has been implicated in prostate cancer. During our first funding year, we have determined the in vitro cleavage substrate specificity of the enzyme using positional-scanning combinatorial libraries and substrate phage display. The preferred cleavage sequences were found to be .P4-(Arg/Lys) P3-(X) P2-(Ser) Pl-(Arg) Pl'-(Ala) and P4-(X) P3- (Arg/Lys) P2-(Ser) Pi (Arg) Pi (Ala) . where X is a non-basic amino acid. We have also identified two macromolecular substrates, single-chain urokinase-type plasminogen activator (sc-uPA) and protease activated receptor 2 (PAR2). The affinity of MT-SPl for these key extracellular targets suggests an important role in pathological and regulatory events such as tumor cell invasion and metastasis.