A Janus-like DNA probekit for simultaneously imaging the homo- and heterodimerization of HER2 and HER3 on living tumor cells

Abstract HER2:HER2 homodimer and HER2:HER3 heterodimer are crucial participants and complicatedly interrelated in tumor progression and therapy. Here, we construct a Janus-like DNA probekit for simultaneously monitoring them on tumor cells. In this probekit, HER2 aptamer with a cytosine-rich stretch extended (Apt2-C) is labeled with FRET donor AF488 and acceptor AF594 at a distance apart; HER3 aptamer with a guanine-rich stretch extended (Apt3-G) is labeled with another FRET acceptor Cy3. Apt2-C and Apt3-G bind to HER2 and HER3 via their aptamers, respectively. Along with homodimerized HER2, two cytosine-rich stretches within Apt2-C are nearer and fold into a bimolecular i-motif, narrowing AF488 and AF594 to germinate FRET for homodimerization indication. Upon HER2:HER3 heterodimerization, Apt2-C and Apt3-G are closer and hybridize on the cytosine-rich and guanine-rich stretches to trigger FRET between AF488 and Cy3 to indicate the heterodimerization. This probekit possesses Janus-like interactions as Apt2-C can interact with both identical Apt2-C and heterogenous Apt3-G, highly similar to the case that HER2 can both homodimerize identical HER2 and heterodimerize HER3. The probekit’s signals were well matched with HER2:HER2 homodimerization and HER2:HER3 heterodimerization, enabling more accurate monitoring of them on living tumor cells, offering a potential tool for related tumor assessment and medication.