MEK inhibition by trametinib overcomes chemoresistance in preclinical nasopharyngeal carcinoma models.

The development of chemoresistance is the major cause of treatment failure in nasopharyngeal carcinoma (NPC). Although 'paradoxical' activation of extracellular signal-regulated kinase (ERK) has been shown to contribute resistance to anticancer treatment, the role of ERK in NPC chemoresistance has not been yet revealed. In this work, we report that trametinib, a clinically available mitogen-activated protein kinase inhibitor for melanoma treatment, overcomes NPC chemoresistance via suppressing ERK activation induced by chemotherapy. We first showed that trametinib at nanomolar concentrations was active against NPC cells and acted synergistically with cisplatin. Trametinib remarkably decreased phosphorylation of ERK and its downstream effector in NPC cells. We next showed that cisplatin treatment stimulates ERK signaling, and furthermore that this can be abolished by trametinib. We finally generated cisplatin-resistant NPC models and demonstrated that trametinib was effective in inhibiting cisplatin-resistant NPC growth, colony formation and survival via suppressing ERK signaling in vitro and in vivo. Our work demonstrates the potential of trametinib in overcoming chemoresistance in preclinical NPC models and provides evidence of initializing clinical trials of using trametinib for NPC treatment.