Abstract

Background: Both apurinic/apyrimidinic endodeoxyribonuclease 1 (APE1) inhibition and melatonin suppress prostate cancer (PCa) growth.

Objective: This study evaluated the therapeutic efficiency of self-assembled and prostate-specific membrane antigen (PSMA)-targeted nanocarrier loading ¹²⁵I radioactive particles and encapsulating siRNA targeting APE1 (siAPE1) and melatonin for PCa.

Methods: The linear polyarginine R12 polypeptide was prepared using Fmoc-Arg-Pbf-OH. The PSMA-targeted polymer was synthesized by conjugating azide-modified R12 peptide to PSMA monoclonal antibody (mAb). Before experiments, the PSMA-R12 nanocarrier was installed with melatonin and siAPE1, which were subsequently labeled by ¹²⁵I radioactive particles. In vitro biocompatibility and cytotoxicity of nanocomposites were examined in LNCaP cells and in vivo biodistribution and pharmacokinetics were determined using PCa tumor-bearing mice.

Results: PSMA-R12 nanocarrier was ~120 nm in size and was increased to ~150 nm by melatonin encapsulation. PSMA-R12 nanoparticles had efficient loading capacities of siAPE1, melatonin, and ¹²⁵I particles. The co-delivery of melatonin and siAPE1 by PSMA-R12-¹²⁵I showed synergistic effects on suppressing LNCaP cell proliferation and Bcl-2 expression and promoting cell apoptosis and caspase-3 expression. Pharmacokinetics analysis showed that Mel@PSMA-R12-¹²⁵I particles had high uptake activity in the liver, spleen, kidney, intestine, and tumor, and were accumulated in the tumor sites within the first 8 h p.i., but was rapidly cleared from all the tested organs at 24 h p.i. Administration of nanoparticles to PCa tumors in vivo showed that Mel@PSMA-R12- ¹²⁵I/siAPE1 had high efficiency in suppressing PCa tumor growth.

Conclusion: The PSMA-targeted nanocarrier encapsulating siAPE1 and melatonin is a promising therapeutic strategy for PCa and can provide a theoretical basis for patent applications.