Novel trimethyl lock-based prostate-specific membrane antigen targeted Conjugates: Design, synthesis, and biological activity evaluation

Prostate cancer, a leading malignancy in men globally, faces challenges such as poor targeting, systemic toxicity, and drug resistance. This study developed an innovative multifunctional linker based on the trimethyl lock (TML) system, enabling parallel conjugation of key modules for targeted drug delivery. The linker integrates three functional components: (1) a targeting module (ACUPA), (2) a drug module (docetaxel, DTX), and (3) a trigger module (GSH-responsive disulfide bond). This "three-in-one" design allows flexible adjustment of physicochemical properties. Two conjugates were designed and formulated into nanoparticles. Physicochemical characterization demonstrated their excellent self-assembly and GSH-responsive release properties. Cellular assays showed that the conjugates exhibited comparable inhibitory activity against PSMA-positive 22Rv1 cells to DTX, while their activity against PSMA-negative PC 3 cells was lower. Cellular uptake confirmed higher internalization in 22Rv1 cells than in PC 3 cells. In vivo, low-dose PEG3.4k-TML-DTX nanoparticles (10 mg/kg) achieved tumor inhibition rates similar to free DTX without causing weight loss, demonstrating favorable biosafety. This study provides a novel strategy for targeted chemotherapy with tumor microenvironment responsiveness and low toxicity.