Synthesis and Evaluation of Multifunctional Fluorescent Inhibitors with Synergistic Interaction of Prostate-Specific Membrane Antigen and Hypoxia for Prostate Cancer

Bioconjug Chem. 2019 Jan 16;30(1):90-100. doi: 10.1021/acs.bioconjchem.8b00767. Epub 2018 Dec 11.

Abstract

Prostate cancer is one of the most common cancers in the world. It is widely known that prostate-specific membrane antigen (PSMA) is highly expressed in prostate cancer, and hypoxia is a common characteristic of many solid tumors, including prostate cancer. In this study, we designed multifunctional fluorescent inhibitors to target PSMA and tumor hypoxia in order to increase the tumor uptake of inhibitors. Novel PSMA inhibitors were prepared using lysine as the backbone to connect three different functional groups: the glutamate-urea-lysine (GUL) structure for inhibiting PSMA, 2-nitroimidazole for the hypoxia-sensitive moiety, and a near-infrared fluorophore (sulfo-Cyanine 5.5). According to the in vitro PSMA binding assay, novel fluorescent inhibitors were demonstrated to have nanomolar binding affinities. Multifunctional inhibitor 2 with one 2-nitroimidazole had a similar inhibitory activity to inhibitor 1 that did not contain the hypoxia targeting moiety, but multifunctional inhibitor 3 with two 2-nitroimidazoles showed lower inhibitory activity than inhibitor 1 due to the bulky structure of the hypoxia-sensitive group. However, in vivo optical imaging and ex vivo biodistribution studies indicated that both multifunctional inhibitors 2 and 3 had higher accumulation in tumors than inhibitor 1 due to a synergistic combination of PSMA and hypoxia targeting moieties. These observations suggest that this novel multifunctional strategy might be a promising approach to improve the diagnosis and therapy of prostate cancer.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigens, Surface / metabolism*
  • Cell Hypoxia*
  • Cell Line, Tumor
  • Female
  • Fluorescent Dyes / chemical synthesis*
  • Fluorescent Dyes / chemistry
  • Fluorescent Dyes / metabolism*
  • Glutamate Carboxypeptidase II / metabolism*
  • Glutamic Acid / chemistry
  • Heterografts
  • Humans
  • Lysine / chemistry
  • Male
  • Mice
  • Mice, Inbred BALB C
  • Prostatic Neoplasms / metabolism*
  • Prostatic Neoplasms / pathology
  • Tissue Distribution
  • Urea / chemistry

Substances

  • Antigens, Surface
  • Fluorescent Dyes
  • Glutamic Acid
  • Urea
  • FOLH1 protein, human
  • Glutamate Carboxypeptidase II
  • Lysine