Targeting intratumoral regulatory T cells by CD137 aptamer-shRNA chimeras

Area of Science:

• Immunology
• Molecular Biology
• Cancer Research

Background:

• CD137 (4-1BB) is a T cell costimulatory molecule involved in immune regulation.
• Regulatory T cells (Tregs) utilize CD137 in a negative feedback loop to prevent autoimmune damage.
• CD137 expression on intratumoral Tregs correlates with poor prognosis in cancer patients and is also found on malignant cells.

Purpose of the Study:

• To investigate CD137 as a therapeutic target in cancer immunotherapy.
• To develop novel CD137-targeting agents for cancer treatment.

Main Methods:

• Development of a CD137-specific aptamer capable of binding and internalization by CD137-expressing cells.
• Fusion of the CD137 aptamer with short hairpin RNAs (shRNAs) targeting Enhancer of zeste homolog 2 (EzH2) or neuropilin-1 (Nrp1).

Main Results:

• The CD137 aptamer successfully bound to and was internalized by malignant cells and T cells expressing CD137.
• The CD137 aptamer-shRNA chimeras effectively downregulated EzH2 and Nrp1 in CD137-positive malignant cells and Tregs.
• CD137 expression distinguishes intra- from extratumoral Tregs, with CD137+ Tregs being more immunosuppressive.

Conclusions:

• CD137 is a validated target for tumor immunotherapy.
• CD137 aptamer-shRNA chimeras represent a promising new class of therapeutic tools for cancer treatment.