Anti-epidermal growth factor receptor tyrosine kinase activities of traditional Chinese medicine for cancer treatment

Introduction: The epidermal growth factor receptor (EGFR) is a validated target for different human malignancies. EGFR tyrosine kinase inhibitors considerably extend progression-free survival in EGFR-mutant non-small cell lung cancer. Monoclonal antibodies targeting EGFR also improve the efficacy outcomes in KRAS wild-type colorectal cancer. At present, gefitinib and erlotinib are considered the most representative of these types of drugs approved by the FDA for cancer treatment. However, only a few studies have screened the active compounds of traditional Chinese medicines. Methods: In this study, the EGFR inhibitory activities of Chinese medicinal herb extracts traditionally prescribed to treat cancer were determined in a 384-well plate-based assay using the homogeneous time-resolved fluoroimmunoassay method. Petroleum ether, ethanol, ethyl acetate, and aqueous extracts of 49 traditional Chinese medicinal herbs (183 extracts total) were tested. The inhibitory effects were expressed as percentage of inhibition. Dose-dependent inhibitory assays were also performed for the herbal extracts that exhibited significant inhibition. Results: The ethyl acetate extracts of Artemisia argyi, Lonicera macranthoides, Spatholobus suberectus, Curcuma longa, and Galla chinensis, as well as the ethanol extract of Eriobotrya japonica exhibited significant EGFR inhibitory activities at a concentration of 50 mu g/ml. The IC50 values were 8.848, 2.027, 2.277, 3.621, 4.339 and 5.528 mu g/mL, respectively. The EA extracts of L. macranthoides, S. suberectus had the best activities. Conclusion: Our results indicate that screening traditional Chinese herbs for EGFR inhibitory activity may identify a large number of potential lead compounds for the development of new drugs to treat cancer. (C) 2014 Elsevier GmbH. All rights reserved.