Efficacy of AUY922 in lung cancer cell lines with the acquired resistance to epidermal growth factor receptor-tyrosine kinase inhibitor

Abstract

The vast majority of non-small cell lung cancer patients have developed resistance towards epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI), despite of the favorable responses during the initial periods. Resistance to EGFR-TKI therapy can occur via the introduction of a secondary T790M mutation, or the activation of bypass signals, such as MET or AXL, etc. Because heat shock protein 90 (HSP90) is essential for stability and maturation of many oncoproteins, HSP90 inhibitors have been recognized as an attractive therapeutic agent for the treatment of malignancies. The AUY922 is a newly developed HSP90 inhibitor with low toxicity and nano-molar potency. We report the efficacy of AUY922 to inhibit the EGFR-TKI resistance in non-small cell lung cancer cell lines that had acquired resistance through T790M mutations, MET- or AXL- bypass. We established EGFR-TKI resistant PC-9 and HCC827 cell lines through continuous exposing to gefitinib or erlotinib more than 6 months, and named PC-9/GR, PC-9/ER, HCC827/GR, and HCC827/ER, respectively. Using pyrosequencing and western blotting, we confirmed that PC-9 cells acquired resistance to EGFR-TKIs via T790M mutation, HCC827/GR cells via MET activation, and HCC827/ER cells via AXL bypass. We confirmed that AUY922 is effective in inhibiting the resistant lung cancer cell lines in dose- and time- dependent manner. We have also confirmed that AUY922 can suppress not only major oncoproteins, such as EGFR, MET or AXL but also their downstream signaling proteins, such as Akt and Erk. AUY922 induced apoptosis and cell cycle arrest, and inhibited the cellular ability to migrate and invade as well. The antitumor effect of AUY922 was also verified in a xenograft mouse model using HCC827/GR and /ER cells. Our study shows that AUY922 is a promising agent to overcome resistant non-small cell lung cancers via three major mechanisms of resistance, namely T790M mutation, MET- or AXL- bypass.