Caffeic acid phenethyl ester surmounts acquired resistance of AZD9291 in non‐small cell lung cancer cells

Abstract

AbstractEpithelial growth factor receptor tyrosine kinase inhibitors (EGFR‐TKIs) are the first‐line therapy for EGFR mutated non‐small cell lung cancer (NSCLC); however, resistance rapidly develops. The objective of this study was therefore to establish and characterize a gefitinib resistant NSCLC line (HCC827GR) and evaluate the therapeutic effects of natural products in combination with third‐generation EGFR‐TKI, AZD9291. The IC50 of gefitinib and AZD9291 in HCC827GR were significantly higher than those of HCC827 (p < 0.05). Furthermore, anchorage‐independent colony assay indicated that HCC827GR cells were more aggressive than their predecessors. This was reflected by the gene/protein expression changes observed in HCC827GR versus HCC827 profiled by cancer drug resistance real‐time polymerase chain reaction (RT‐PCR) array and Western blot. Three natural products were screened and caffeic acid phenethyl ester (CAPE) exhibited the most significant combinative cytotoxic effect with AZD9291. Specifically, flow cytometry revealed that AZD9291 + CAPE considerably increased the fraction of cell in pre‐G1 of the cell cycle and caspase‐Glo3/7 assay showed a dramatic increase in apoptosis when compared to AZD9291 alone. Furthermore, Western blot showed significant downregulation of p‐EGFR/p‐AKT in HCC827GR cells treated with AZD9291 + CAPE as compared to AZD9291. Moreover, it is evident that AZD9291 + CAPE specifically resulted in a marked reduction in the protein expressions of the cell‐proliferation‐related genes p21, cyclin D1, and survivin. Finally, refined RT‐PCR/Western blot data indicated that AZD9291 + CAPE may at least partially exert its synergistic effects via the PLK2 pathway. Together, these results suggest that CAPE is a clinically relevant compound to aid AZD9291 in treating EGFR‐TKI resistant cells through modulating critical genes/proteins involved in cancer resistance/therapy.