IGF2BP2-dependent activation of ERBB2 signaling contributes to acquired resistance to tyrosine kinase inhibitor in differentiation therapy of radioiodine-refractory papillary thyroid cancer.

Acquired drug resistance represents a major obstacle to tyrosine kinase inhibitor (TKI)-induced differentiation therapy of radioiodine-refractory papillary thyroid cancer (RR-PTC); thus, there is an urgent need to elucidate the underlying mechanisms. Here, selumetinib-resistant PTC (PTCSR) cell lines, which were characterized by loss of sodium/iodide symporter expression, enhanced insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2), and activated V-Erb-B2 avian erythroblastic leukemia viral oncogene homolog 2 (ERBB2) signaling, were initially established using a dose escalation method. Upon knockdown of IGF2BP2 in PTCSR cells, ERBB2 signaling was inhibited, and the acquired drug resistance was partially reversed. Mechanistically, the luciferase activity assay showed that IGF2BP2 bound to the N6-methyladenosine-binding site in the coding sequence of ERBB2 mRNA, yielding an increased ERBB2 translation efficacy revealed by polysome profiling. Inhibition of ERBB2 and IGF2BP2 by lapatinib robustly rescued the PTCSR cells from acquired dedifferentiation. Our study demonstrated that IGF2BP2-dependent ERBB2 signaling activation contributes to acquired resistance to TKI, which may be a promising differentiation strategy for RR-PTC by targeting IGF2BP2.