PSMA-mediated endosome escape-accelerating polymeric micelles for targeted therapy of prostate cancer and the real time tracing of their intracellular trafficking

Abstract

The cytotoxicity of chemotherapeutic agents to healthy organs and drug resistance of tumor cells are believed to be the main obstacles to the successful cancer chemotherapy in the clinic. To ensure that anticancer drugs could be delivered to the tumor region, are quickly released from carriers in tumor cells and rapidly escape from endo/lysosomes, YPSMA-1-modified pH-sensitive polymeric micelles, which would be advantageous in recognizing the prostate specific membrane antigen (PSMA), were designed and fabricated for targeted delivery of paclitaxel to tumors based on the pH-sensitive diblock copolymer poly(2-ethyl-2-oxazoline)-poly(D,L-lactide) (PEOz-PLA) and YPSMA-1-PEOz-PLA for treating prostate cancer. HOOC-PEOz-PLA with a critical micelle concentration of 5.0 mg L(-1) was synthesized and characterized by (1)H NMR and gel permeation chromatography. The prepared YPSMA-1-modified micelles, about 30 nm in diameter, exhibited a rapid release behavior at endo/lysosome pH and a favorable ability of fast endo/lysosome escape as observed by confocal microscopy. More importantly, we evidenced for the first time that both endosome and lysosome escape existed for pH-sensitive micelles via real time tracing using confocal microscopy, and the real time endo/lysosome escape process was also presented. The YPSMA-1-modified micelles were very effective in enhancing the cytotoxicity of paclitaxel by increasing the cellular uptake in PSMA-positive 22Rv1 cells, which was verified the correlation with PSMA expression in tumor cells by flow cytometric analysis and confocal microscopy. Moreover, the active targeting and pH-sensitivity endowed YPSMA-1-modified micelles with a higher antitumor efficacy and negligible systemic toxicity in 22Rv1 xenograft-bearing nude mice compared with unmodified micelles and Taxol®. These results suggested that the application of combining YPSMA-1 modification with pH-sensitivity to polymeric micelles may be one approach in the efficient delivery of anticancer drugs for treating PSMA-positive prostate cancers.

Poly(2-ethyl-2-oxazoline)–Doxorubicin Conjugate-Based Dual Endosomal pH-Sensitive Micelles with Enhanced Antitumor Efficacy

“…32,38 After which, the mixture was cooled down to room temperature, and the reaction was quenched by adding 10 equiv of methanolic KOH followed by reflux overnight with stirring. 28 Then the resultant mixture was filtered through Sabouraud funnel for 3 times to remove salts.…”

“…30 Our previous work and other report demonstrated that this property of PEOz promoted the release of drugs from micelles at the acidic endocytic pH in which PEOz composed the outer shell. 31,32 In order to integrate the merits of PDC for reduced drug release in circulation, and pH-sensitive micelles for enhanced accumulation in tumor site and quick drug release in tumor cells, we fabricated dual endosomal pH-sensitive PDC micelles to encapsulate DOX based on the conjugate of DOX with PEOz via hydrazone linkers (denoted as PEOz-hyd-DOX). Schematic illustrations depicting the formation of pH-sensitive micelles and the intracellular trafficking were presented in Figure 1.…”

Thioacetate‐Based Initiators for the Synthesis of Thiol‐End‐Functionalized Poly(2‐oxazoline)s

“…This method has been rather parsimoniously used in the synthesis of α‐functional PAOx. Example of protecting groups incorporated in cROP initiators include N ‐alkylphthalimide or tert ‐butyl N ‐monoalkylcarbamate (for amines), [ 52–56 ] tert‐ butyldiphenylsilyl ethers (for hydroxyl), [ 57 ] methyl ester (for carboxylic acid or others through amidation), [ 58–63 ] and furanyl Diels–Alder cycloadduct (for maleimide). [ 64 ] Here, the thioacetate group has been chosen as a stable and economic protection group for thiols.…”

Enhanced antitumor efficacy by cyclic RGDyK-conjugated and paclitaxel-loaded pH-responsive polymeric micelles

“…PTX-loaded polymeric micelles (denoted as PTX/PM) were prepared by film-hydration method as previously reported [22]. The ratio of HOOC-PEOz-PLA to paclitaxel was 10:1 (w/w).…”