ABSTRACT
<p><b>OBJECTIVE</b>To explore the relationship between epidermal growth factor receptor (EGFR) gene expression and radiosensitivity of non-small-cell lung cancer (NSCLC) cells.</p><p><b>METHODS</b>EGFR sequence-specific double-stranded RNA (dsRNA-EGFR) was chemically synthesized. NSCLC cell line SPC-A1 was transfected with dsRNA-EGFR formulated with Lipofectamine 2000. Western blot and real-time PCR were used to determine the EGFR mRNA and protein expression, respectively. Colony inhibition test was adopted to observe the radiosensitizing effect. To establish the nude mouse tumor models, calculate the tumor growth inhibition rate and make the tumor growth curve by measuring its size and weight.</p><p><b>RESULTS</b>EGFR mRNA levels were 1.51 ± 0.22, 1.38 ± 0.15 and 0.45 ± 0.11 in the control group, dsRNA-unrelated group and dsRNA-EGFR group, respectively (F = 482.7, P < 0.01). The contents of EGFR protein were 2340.87 ± 10.99, 2231.85 ± 35.66 and 832.03 ± 39.13 in the control group, dsRNA-unrelated group and dsRNA-EGFR group, respectively (F = 263.3, P < 0.05). Compared with the control group, dsRNA-EGFR sequence specifically decreased the expressions of EGFR mRNA by 70.2% and EGFR protein by 64.5%. The colony inhibition rates of the control group, dsRNA-unrelated combined with radiotherapy group and dsRNA-EGFR combined with radiotherapy group were 9.3%, 12.5% and 65.5%, and the tumor growth inhibition rates were 21.3%, 24.4% and 64.2%, respectively. The combination of dsRNA-EGFR and radiotherapy significantly inhibited the tumor growth in vitro and in vivo.</p><p><b>CONCLUSIONS</b>DsRNA-EGFR shows an apparent inhibitory effect on the expression of EGFR mRNA and protein of NSCLC cells, effectively inhibit the tumor growth in vivo, and enhance the radiosensitivity of NSCLC.</p>