Development of gemcitabine-modified multimodal miR-129 mimic as a novel therapeutic in non-small cell lung cancer.

Resistance to chemotherapy and tyrosine kinase inhibitor (TKI)-based therapy is the main reason for treatment failure in non-small cell lung cancer (NSCLC). Therefore, there is an urgent need to develop novel strategies to combat resistance. In this study, we designed and developed a novel, multi-targeted microRNA (miRNA) approach to overcome resistance to EGFR inhibitors. Specifically, the guide strand of the tumor suppressor miR-129 was modified by replacing cytidine with the nucleoside analog gemcitabine (Gem). The therapeutic potential of Gem-miR-129 was investigated in both in vitro and in vivo NSCLC model systems. Our results demonstrate that Gem-miR-129 is a potent inhibitor, with an IC50 in the low nanomolar range in NSCLC cell lines. Gem-miR-129 retains same nanomolar activity in both erlotinib- and osimertinib-resistant NSCLC cell lines. This potency is achieved through the dual mechanisms of the multi-targeted tumor suppressor miR-129, which suppresses HMGB1, YAP1, and PBX3, in conjunction with the expected therapeutic contribution of Gem following degradation of Gem-miR-129. A unique feature of Gem-miR-129 is its vehicle-free uptake in cultured NSCLC cells. Gem-miR-129 effectively inhibits NSCLC growth in a mouse model and significantly prolongs survival without overt toxicity under the tested conditions. Overall, Gem-miR-129 provides proof-of-concept for a novel tumor-suppressor miRNA-based therapeutic strategy for NSCLC and for overcoming TKI resistance.