Improving the Cellular Accumulation of Folate-Conjugated Fully Chemically Modified siRNAs via 3' Terminal Conjugation

Area of Science:

• Biomedical Engineering
• Molecular Biology
• Drug Delivery Systems

Background:

• Folic acid (FA) conjugation is a proven method for tumor-specific delivery of small molecules.
• Targeted delivery of oligonucleotides like microRNA and small interfering RNA (siRNA) using FA has been documented.
• The efficacy of FA-conjugated, chemically modified siRNA, a common clinical platform, requires further investigation.

Purpose of the Study:

• To enhance cellular accumulation and gene knockdown (KD) of siRNA using FA conjugation.
• To design and evaluate various FA-siRNA formats for improved delivery and efficacy.
• To investigate the impact of chemical modifications on FA-siRNA performance in FOLR1-expressing cells.

Main Methods:

• Design of various folic acid-conjugated small interfering RNA (FA-siRNA) formats.
• Evaluation of cellular accumulation and gene knockdown (KD) in folate receptor 1 (FOLR1)-expressing cells.
• Assessment of siRNA stabilization through 3' end antisense strand conjugation.

Main Results:

• Conjugation of a substituent at the 3' end of the antisense strand in FA-siRNA enhanced intracellular accumulation.
• This modification potentially stabilized the siRNA structure.
• The developed FA-siRNA formats showed promising gene silencing capabilities in FOLR1-expressing cells.

Conclusions:

• The study presents a novel approach to enhance gene silencing in cancer cells expressing folate receptor 1 (FOLR1).
• Modification of FA-siRNA, particularly at the antisense strand, improves cellular uptake and stability.
• This strategy offers a promising platform for targeted gene therapy in FOLR1-positive tumors.