Conformation-dependent binding and tumor-targeted delivery of siRNA by a designed TRBP2: Affibody fusion protein

Area of Science:

• Biotechnology
• Molecular Biology
• Cancer Research

Background:

• Small interfering RNA (siRNA) holds promise for cancer therapy but faces challenges with targeted delivery and rapid clearance.
• Current methods often lack specificity, limiting siRNA's therapeutic potential in vivo.
• Developing effective delivery systems is crucial for successful siRNA-based cancer treatments.

Purpose of the Study:

• To engineer a novel fusion protein for targeted delivery of siRNA to HER-2 overexpressing cancer cells.
• To evaluate the stability, specificity, and efficacy of the fusion protein-siRNA complex in vitro and in vivo.
• To assess the therapeutic potential of this system in a preclinical cancer model.

Main Methods:

• A fusion protein, TRAF, was designed by combining the dsRNA binding domain of TRBP2 with an ErbB2 binding affibody.
• TRAF was shown to form stable, nuclease-resistant particles with siRNA, enabling specific binding to HER-2 overexpressing cells.
• The efficacy of TRAF:siRNA in silencing AURKB and ErbB2 genes and suppressing tumor growth was evaluated in the SK-OV-3 xenograft mouse model.

Main Results:

• The TRAF fusion protein efficiently and specifically delivered siRNA into HER-2 positive cancer cells and tissues.
• Administration of TRAF:siRNA resulted in significant gene silencing of AURKB and ErbB2.
• Intravenous administration of TRAF:siRNA led to remarkable tumor suppression in a xenograft mouse model.

Conclusions:

• Engineered fusion proteins like TRAF can overcome limitations of systemic siRNA delivery.
• TRAF facilitates targeted delivery of siRNA, enhancing gene silencing in cancer cells.
• This approach shows significant potential for developing effective siRNA-based cancer therapeutics.