Targeting c‐met receptor tyrosine kinase by the DNA aptamer SL1 as a potential novel therapeutic option for myeloma

Hepatocyte growth factor (HGF)/c‐met pathway activation has been implicated in the pathogenesis of multiple myeloma (MM), and blocking this pathway has been considered a rational therapeutic strategy for treating MM. Aptamers are single‐stranded nucleic acid molecules that fold into complex 3D structures and bind to a variety of targets. Recently, it was reported that DNA aptamer SL1 exhibited high specificity and affinity for c‐met and inhibited HGF/c‐met signaling in SNU‐5 cells. However, as the first c‐met‐targeted DNA aptamer to be identified, application of SL1 to myeloma treatment requires further investigation. Here, we explore the potential application of SL1 in MM. Our results indicated that c‐met expression is gradually increased in MM patients and contributes to poor outcomes. SL1 selectively bound to c‐met‐positive MM cells but not to normal B cells and suppressed the growth, migration and adhesion of MM cells in vitro in a co‐culture model performed with HS5 cells, wherein SL1 inhibited HGF‐induced activation of c‐met signaling. In vivo and ex vivo fluorescence imaging showed that SL1 accumulated in the c‐met positive tumour areas. In addition, SL1 was active against CD138+ primary MM cells and displayed a synergistic inhibition effect with bortezomib. Collectively, our data suggested that SL1 could be beneficial as a c‐met targeted antagonist in MM.