Let the cells do the work: Production of novel recombinant pre‐miRNAs in E. coli as therapeutic agents

Abstract

Noncoding microRNAs (miRNAs or miRs) have been revealed as critical epigenetic factors in the control of various cellular processes including cell proliferation, survival and disease progression. However, research on miRNA functions and development of miRNA‐based therapy is limited to the use of synthetic RNA and recombinant DNA agents. Recently we have demonstrated that novel human pre‐miRNA agents can be expressed in Escherichia coli on large scale using tRNA‐based recombinant RNA technology. Milligrams of recombinant tRNA/pre‐miRNA chimeras were readily purified to high degrees of homogeneity (> 95%) using chromatography. We further showed that tRNA‐carried pre‐miRNAs were selectively processed to mature miRNAs in human carcinoma cells, which consequently suppressed the expression of miRNA target genes and modulate cell proliferation, apoptosis and chemosensistivity. Furthermore, recombinant miRNAs were active in controlling tumor progression in xenograft tumor mouse models and well tolerated in animal models. Herein we use hsa‐mir‐34a as an example to present our findings on recombinant pre‐miRNA agents, which shall serve as novel tools for the study on miRNA functions and development of RNA‐based therapeutics.