OBJECTIVETo investigate changes in biologic properties of non-small-cell lung cancer (NSCLC) A549 cells whose EGF receptor (EGFR) expression was suppressed by short interference RNA (siRNA).

METHODSA549 cells were transfected with synthetic EGFR sequence-specific siRNA by Lipofectamine. EGFR expression was examined by Western blot and flow cytometry. The biological features of the transfected A549 cells were assessed by cell cycle analysis, colony formation and chemosensitivity assay.

RESULTSSequence-specific siRNAs targeting EGFR significantly down-regulated its expression in A549 cells. Cell growth and colony formation were inhibited by 85.0% and 63.3%, respectively, as compared to the non-sequence-specific siRNA treated cells. Decreased EGFR expression was accompanied by 12.7% increase in A549 cells in G(0)-G(1) phase and 6.6% decrease in S-phase. The EGFR sequence-specific siRNA transfected A549 cells were much more sensitive to the cytotoxic effect of cisplatin with a 77.2% decrease in IC(50) compared to the non-sequence-specific iRNA transfected A540 cells.

CONCLUSIONDown regulation of EGFR expression of NSCLC by sequence-specific siRNA may be considered as an additional option in the treatment of EGFR over-expressing cancers, including NSCLC.