PSMA-Oriented Target Delivery of Novel Anticancer Prodrugs: Design, Synthesis, and Biological Evaluations of Oligopeptide-Camptothecin Conjugates

Abstract

Clinical applications of camptothecin (CPT) have been heavily hindered due to its non-targeted toxicity, active lactone ring instability, and poor water solubility. Targeted drug delivery systems may offer the possibility to overcome the above issues as reported. In this research, a series of prostate-specific membrane antigen (PSMA)-activated CPT prodrugs were designed and synthesized by coupling water-soluble pentapeptide, a PSMA hydrolyzing substrate, to CPT through an appropriate linker. The cytotoxicity of CPT prodrugs was masked temporarily until they were hydrolyzed by the PSMA present within the tumor sites, which restored cytotoxicity. The in vitro selective cytotoxic activities of the prodrugs were evaluated against PSMA-expressing human prostate cancer cells LNCaP-FGC and non-PSMA-expressing cancer cells HepG2, Hela, MCF-7, DU145, PC-3 and normal cells MDCK, LO2 by standard methylthiazol tetrazolium (MTT) assay. Most of the newly synthesized CPT prodrugs showed excellent selective toxicity to PSMA-producing prostate cancer cells LNCaP-FGC with improved water solubility. From among the library, CPT-HT-J-ZL12 showed the best cytotoxic selectivity between the PSMA-expressing and the non-PSMA-expressing cancer cells. For example, the cytotoxicity of CPT-HT-J-ZL12 (IC50 = 1.00 ± 0.20 µM) against LNCaP-FGC (PSMA+) was 40-fold, 40-fold, 21-fold, 5-fold and 40-fold, respectively, higher than that against the non-PSMA-expressing cells HepG2 (IC50 > 40.00 µM), Hela (IC50 > 40.00 µM), MCF-7 (IC50 = 21.68 ± 4.96 µM), DU145 (IC50 = 5.40 ± 1.22 µM), PC-3 (IC50 = 42.96 ± 3.69 µM) cells. Moreover, CPT-HT-J-ZL12 exhibited low cytotoxicity (IC50 > 40 μM) towards MDCK and LO2 cells. The cellular uptake experiment demonstrated the superior PSMA-targeting ability of the CPT-HT-J-ZL12, which was significantly accumulated in LNCaP-FGC (PSMA+), while it was minimized in HepG2 (PSMA−) cells. Further cell apoptosis analyses indicated that it showed a dramatically higher apoptosis-inducing activity in LNCaP-FGC (PSMA+) cells than in HepG2 (PSMA−) cells. Cell cycle analysis indicated that CPT-HT-J-ZL12 could induce cell cycle arrest at the S phase.

Targeting Carbohydrate Mimetics of Tetrahydrofuran-Containing Acetogenins to Prostate Cancer

“…The cytotoxicity of 2 – 5 against the two human prostate tumor cell lines PC-3 and LNCaP was determined by the XTT cell viability assay after 48 h of treatment with the test compounds ( Table 1 and Supplementary Material ). LNCaP is known to overexpress the PSMA receptor, whereas PC-3 is receptor-negative [ 29 ]. The thiophene parent drug 2 showed low-micromolar–nanomolar-range activity, with eight times higher activity against PC-3 compared to LNCaP.…”

Prostate-Specific Membrane Antigen and Esterase Dual Responsive Camptothecin–Oligopeptide Self-Assembled Nanoparticles for Efficient Anticancer Drug Delivery

“…For the synthesis of PSMA-activated prodrug CPT-WT-H, the intermediates CPT-A-L 12 and CPT-B-L 12 were synthesized as shown in Scheme S2 according to our previous report. 50 Then, reaction of CPT-B-L 12 with WT-H in the presence of EDCI, N, N-Diisopropylethylamine (DIPEA), and 1-hydroxybenzotriazole (HOBt) in DCM afforded the corresponding intermediate CPT-WT-H-L 12 , which was further treated with TFA to remove the protective groups, yielding the final prodrug CPT-WT-H ( Scheme S2 ). The structure of CPT-WT-H was confirmed by 1 H NMR and 13 C NMR, HRMS and UV absorbance ( Figures S4 – S7 , Supplementary Materials ).…”

“… 53 , 54 It was reported that structural modifications at the 20-OH of CPT could enhance the stability of the lactone ring. 50 In addition, the formation of stable nanoparticles not only enhanced the aqueous dispersity of CPT but also the stability of the lactone ring. 55 The stability of CPT-WT-H NPs was estimated by DLS and HPLC analysis in this study.…”

Protease-triggered bioresponsive drug delivery for the targeted theranostics of malignancy

“…Considerable achievements have also been made in PSA-mediated drug accumulation and efficacy improvement. Concretely, tumor lesions targeted delivery of PSA-specific motif-conjugated nanocomplexes carrying a variety of therapeutics either alone or in combination, mainly included DOX 181 , 182 , 183 , 184 , 185 , PTX 186 , DTX 187 , SN38 188 , camptothecin 189 , thapsigargin 190 , boron-containing reagents 191 , zinc chelator 192 , antibody-drug conjugates 193 , 194 , kinase inhibitors 195 , siRNA ( Fig. 7 ) 196 , 197 , 198 , 199 , 200 , miRNA 201 , oligonucleotide 202 , therapeutic proteins 203 , and chemotherapy-based combination regimens with molecular targeted therapy 204 , antibiotic therapy 205 , gene therapy 206 , 207 , and anti-inflammatory therapy 208 .…”