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RESEARCH PRODUCT

Broad-spectrum Cross-resistance to Anticancer Drugs Mediated by Epidermal Growth Factor Receptor

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BACKGROUND The oncogenic role of epidermal growth factor receptor (EGFR) has been intensively studied. However, its emerging role in drug resistance has not been fully addressed. MATERIALS AND METHODS This study systematically investigated the correlation of mRNA and protein expression of EGFR, as well as gene amplification and mutations with the log-transformed half-maximal inhibitory concentration (log10IC50) values obtained from the NCI panel of 60 human tumor cell lines against 83 standard anticancer agents and the top 10 natural cytotoxic products previously screened by us. RESULTS EGFR protein expression, rather than other measurements, was most frequently associated with drug response. Log10IC50 and EGFR protein level were significantly positively correlated under all investigated DNA topoisomerase (TOPO) II inhibitors, followed by 81% of alkylating agents and platinum-based compounds, 71% of anti-hormones, 66% of TOPO I inhibitors and 50% of antibiotics. Furthermore, 60% of cytotoxic natural products did not reveal significant correlations. CONCLUSION Collectively, we showed a broad-spectrum of cross-resistance towards clinical drugs mediated by EGFR. Natural cytotoxic products may be further developed as novel drugs to overcome EGFR-associated resistance to clinically established anticancer drugs.