Programmable Loading of a Multivalent LRPPRC Aptamer onto a Rectangular DNA Tile Inhibits the Proliferation of Lung Adenocarcinoma Cells

Since cancer biomarkers for lung adenocarcinoma can lead to early intervention and treatment, they have been the focus of much research attention. DNA aptamers, which are functional oligonucleotides, exhibit high specificity and binding affinity to different types of cancer biomarkers. Through DNA aptamer screening, a leucine-rich PPR-motif-containing protein (LRPPRC) was discovered as a potential biomarker for lung adenocarcinoma therapeutics. It is an RNA-binding protein that helps in regulating post-transcriptional gene expression in mitochondria. Interestingly, the first LRPPRC-targeted small-molecule drug showed significant antitumor effects. Apart from biomarker discovery, DNA aptamers have also shown promise in cancer therapeutics, but challenges in the programmable delivery of aptamers have limited applications. Herein, we have addressed these challenges in two steps. First, after obtaining purified protein LRPPRC, we verified aptamer R14 as its high-affinity binding ligand. Second, for programmable delivery, a rectangular DNA tile (RDT) was constructed to improve cellular internalization. In particular, DNA handles on the surface of this DNA nanostructure serve as overhangs for loading multivalent R14, and both A549 and PC9 cells treated with R14-RDT targeted to LRPPRC showed significant inhibition of cancer cell proliferation. We then investigated the molecular mechanism(s) underlying the interaction between multivalent aptamer R14 loaded on an RDT and its cognate target protein such that the result is inhibition of cancer cell proliferation. Based on our findings, we hypothesized that R14-RDT-LRPPRC interaction triggers significant gene transcription and RNA processing events that result in inhibiting mitochondria-related genes and RNA transcriptional processing, while causing an immune inflammatory response that ultimately leads to the inhibition of cancer cell proliferation. Therefore, this research offers an instructive paradigm for programmable loading of a multivalent aptamer onto a two-dimensional DNA nanostructure to improve targeted cancer therapeutics through intervening with the cell's transcriptome.