Effect of PEG anchor in PEGylation of folate-modified cationic liposomes with PEG-derivatives on systemic siRNA delivery into the Tumor

Abstract

In this study, we prepared small interfering RNA (siRNA)/cationic liposome complexes (lipoplexes) modified with folate (FA)-polyethylene glycol (PEG, MW 2000, 3400 or 5000)-1,2-distearoyl-sn-glycero-3-phosphoethanolamine (DSPE) to facilitate their uptake into tumor cells via folate receptor (FR), and with PEG₁₆₀₀-cholesterol (PEG₁₆₀₀-Chol) or PEG₂₀₀₀-chondroitin sulfate conjugate (PEG₂₀₀₀-CS), to enhance their systemic stability. Among the FA-PEG-modified siRNA lipoplexes, 0.5 mol% FA-PEG₅₀₀₀-DSPE-modified lipoplexes with 2.5 mol% PEG₂₀₀₀-CS or PEG₁₆₀₀-Chol (LP-0.5F₅/2.5P₂-CS and LP-0.5F₅/2.5P_1.6-CL, respectively) exhibited selective growth inhibition of human nasopharyngeal carcinoma KB cells through transduction with polo-like kinase 1 (PLK1) siRNA. Furthermore, the LP-0.5F₅/2.5P₂-CS and LP-0.5F₅/2.5P_1.6-CL lipoplexes exhibited decreased agglutination with erythrocytes through PEGylation, and markedly decreased the accumulation of siRNA in murine lungs after systemic injection. Finally, systemic injection of LP-0.5F₅/2.5P₂-CS and LP-0.5F₅/2.5P_1.6-CL lipoplexes resulted in accumulation of siRNA in KB tumor xenografts. These findings suggest that PEGylation of FA-PEG₅₀₀₀-DSPE-modified siRNA lipoplexes with PEG₂₀₀₀-CS or PEG₁₆₀₀-Chol might improve their systemic stability without the loss of selective transfection activity in tumor cells.

Keywords:

• Cationic liposome
• PEGylation
• folate
• folate receptor
• siRNA delivery
• gene knock-down

Acknowledgments

We thank Ms. Megumi Nakata, Mr. Ren Ozawa, Ms. Ayami Seki, and Ms. Yuka Sotooka (Department of Molecular Pharmaceutics, Hoshi University) for assistance with the experimental work.

Authors’ contributions

YH conceived and designed the study. Experiments were performed by MT, SS, KK and HO. YH wrote the manuscript. All authors have read and approved the final manuscript.

Disclosure statement

The authors declare that they have no competing interests.

Institutional review board statement

All animal experiments were conducted in accordance with the ‘Guide for the Care and Use of Laboratory Animals’ adopted by the Institutional Animal Care and Use Committee of Hoshi University (Tokyo, Japan) (which is accredited by the Ministry of Education, Culture, Sports, Science, and Technology, Japan). Ethical approval for this study was obtained from the Institutional Animal Care and Use Committee of Hoshi University (Permission no. P21-040).

Additional information

Funding

This project was supported in part by a Grant-in-Aid for Scientific Research (C) from the Japan Society for the Promotion of Science (KAKENHI Grant Number 20K07142).