Peptide-based siRNA delivery for tumor-specific targeting of lactate dehydrogenase C

Background: Breast cancer is the most common cancer worldwide and the leading cause of female cancer-related deaths, highlighting the pressing need for novel therapeutic interventions. Treatment of triple negative breast cancer in particular remains a challenge due to disease aggressiveness and the lack of durable treatment options. We speculate that targeting of Lactate Dehydrogenase C (LDHC) could be a novel approach given its highly tumor specific expression and immunogenic properties. We recently demonstrated that LDHC acts as a key regulator of the DNA damage response and tumor mitotic fidelity. Moreover, silencing of LDHC significantly improved treatment response to DNA damage response related anti-cancer drugs, highlighting its therapeutic potential for cancer precision medicine.

Methods: We characterized and evaluated several cell penetrating peptide-siRNA complexes for efficient silencing of LDHC in tumor cells using a 10R polyarginine peptide or bifunctional 10R-RGD, cRGD-10R or iRGD-10R peptides with tumor homing and penetrating abilities.

Results: Peptide-siRNA complex formation and tumor cellular uptake was confirmed using gel retardation assays and fluorescent confocal imaging. Biophysiochemical characterization and transmission electron microscopy revealed the complexes to be uniform in size with a low polydispersity index and positive zeta potentials. LDHC silencing in breast cancer cells using the peptide complexes demonstrated a 30-53% reduction in LDHC expression, with the 10R-siRNA and cRGD-10R-siRNA complexes showing the highest silencing efficiency. In 3D breast cancer spheroids, transfection with the 10R-siRNA complex resulted in a 20% downregulation of LDHC expression. Further analysis of the bifunctional-siRNA complexes in 3D cultures is ongoing as well as cytotoxicity analyses on non-cancerous cell lines.

Conclusions: Our findings demonstrate that peptide-mediated delivery of LDHC siRNA can reduce LDHC expression in 2D and 3D breast cancer cultures, suggesting that they could be used as a valuable approach for therapeutic intervention.