Synthetic short mRNA prevents metastasis via innate-adaptive immunity

Although most cancer deaths are caused by metastasis, there are no effective therapeutic approaches. This study describes the efficacy of a short synthetic mRNA (s-mRNA) designed by the sequence of non-vesicular extracellular IL1β-mRNA found in the pre-metastatic lung of tumor-bearing mice. The administration of s-mRNA inhibits murine lung metastasis by inducing the innate and adaptive immune systems. s-mRNA binds to ZC3H12D, an RNA-binding protein on natural killer cells and cytotoxic T lymphocytes. The ZC3H12D-s-mRNA complex translocated to the nucleus without being involved in translation. This process induces cytolytic activity and cell death in cancer cells without inducing a cytokine storm, and immune cells retain their antitumor activity. Although the antitumor activity of cytotoxic lymphocytes declines as the disease progresses in cancer patients, s-mRNA induces sustained high killing capacities of natural killer cells and cytotoxic T lymphocytes from colon cancer patients. Therefore, s-mRNA could be a breakthrough solution to prevent metastasis. Extracellular mRNAs are found to play an important role in premetastatic organs. Here this group reports the non-vesicular extracellular IL1β-mRNA complexes binding to ZC3H12D followed by the translocation into nucleus without being translated, thereby killing NK cells/CTLs and inhibiting lung metastasis in a preclinical colon cancer model.