Selective oncolysis via oncomiR-driven DNA self assembly

Introduction: Artificial nucleic acids attract significant attention as cancer immunotherapy materials because they can be recognized by various extracellular and intracellular nucleic acid sensors and stimulate innate immune responses. However, their low selectivity for cancer cells causes severe systemic immunotoxicity, hindering the realization of immune cancer therapy using artificial nucleic acid molecules. To address this challenge, we propose a hairpin DNA self-assembly technology that induces cytotoxicity through cancer-selective immune activation. Here, we discuss cancer growth suppression via DNA self-assembly triggered by overexpressed oncomiRs. Experimental Design: Two hairpin DNA sequences were designed based on predictions of nucleic acid structural thermal stability (oHP-1 and oHP-2). This pair of hairpin DNAs (oHPs) triggered binding with one oncomiR, miR-21, forming a double-stranded DNA over 500 bp in length as a DNA aggregate. This structure is sufficiently large to induce innate immune activation. We examined the immune response induced by oHPs using cancer cells and tumor-bearing mice. Results: DNA aggregates formed by oHPs bound to cGAS within cancer cells that abundantly express miR-21. Consequently, IFN-beta was produced through the cGAS-STING pathway, resulting in selective cell killing. When oHPs were administered into tumors of cancer-bearing mice using an appropriate DDS, tumor growth was strongly suppressed. CD8 + T cells and CD4 + T cells were observed to accumulate at the periphery of the tumor tissue. While sufficient tumor growth suppression was observed with oHPs alone, higher efficacy was observed when combined with anti-PD-1 antibody. Conclusions: This approach represents the first technology enabling selective tumor lysis derived from intracellular DNA self-assembly, providing a potent therapeutic modality for cancer treatment. The engineered oHPs assemble into long double-stranded DNA via cancer-associated miR-21, functioning as a selective immune amplifier and booster circuit for targeted tumor lysis. This design exhibits non-responsiveness in miR-21-deficient cells and immunodeficient cells, demonstrating significant potential as an efficient targeted cancer therapy.