Conclusions
OSU-53, a novel dual-AMPK activator/mTOR inhibitor, effectively inhibits growth in a variety of thyroid cancer cell lines and is most potent in cells with activating mutations in RAS or BRAF.
Objective
The objective of the study was to assess the in vitro effects of OSU-53 treatment in a panel of thyroid cancer cells. Design: Experiments were performed to determine the effects of OSU-53 on cell growth, oncogenic signaling, apoptosis, autophagy, and cell rescue after selective knockdown of AMPK.
Results
OSU-53 inhibited in vitro cell growth of all seven thyroid cancer cells tested and induced activation of AMPK. Cell lines with activating mutations in RAS or BRAF, compared with cells with phosphatase and tensin homolog deleted from chromosome 10 null and RET/papillary thyroid carcinoma mutations, were more sensitive to drug treatment and demonstrated a more robust AMPK activation, inhibition of mTOR signaling, and autophagy stimulation. After selective knockdown of AMPK, cell rescue from OSU-53 treatment was not observed. We demonstrated an off-target effect of direct mTOR inhibition by OSU-53. Increased autophagy was observed in cells with activation RAS or BRAF mutations. Conclusions: OSU-53, a novel dual-AMPK activator/mTOR inhibitor, effectively inhibits growth in a variety of thyroid cancer cell lines and is most potent in cells with activating mutations in RAS or BRAF.