Synthesis of PSA Inhibitors as SPECT- and PET-Based Imaging Agents for Prostate Cancer

摘要

Prostate-Specific Antigen (PSA) is a well known serine protease used extensively as a biomarker for prostate cancer. PSA is produced by the normal epithelial cells of the prostate. High levels of enzymatically active PSA (high g to mg/ml concentrations, in the extracellular fluid) are produced by androgen dependent as well as androgen independent prostate cancers. Even though the expression of PSA is closely related to the cancer progression its role in the cancer pathobiology is not well established. To aid the better understanding of PSA role in prostate cancer development and to expand the number of possible therapeutic agents we prepared a library of novel peptidyl boronic acid based inhibitors. Protease inhibitors commonly bind to their targets through intermolecular hydrogen bonds and/or disulfide bonds. To prepare more selective inhibitors we modified the S1 binding site of the inhibitors to incorporated bromopropylglycine group. This allowed the inhibitors to reach deeper in the specificity pocket and participate in halogen bond formation. The new candidates for targeted inhibition were screened for their ability to inhibit PSA and chymotrypsin.