Inhibitory Effect of Epidermal Growth Factor on the Proliferation of Lung Cancer Cell Lines

Purpose: Epidermal growth factor (EGF) is known to cause cellular proliferation, differentiation and survival. However, there are a few articles that have reported on the cell killing effect of EGF. We evaluated the effects of EGF on the survival of some lung cancer cell lines and we tried to determine the mechanism of action. Materials and Methods: We examined various lung cancer cell lines. The cultured cells were exposed to radiation alone (0, 2, 5, and 10 Gy), EGF alone (0 ∼1,000 nM) or a combination of radiation and EGF (10 nM). Survival was measured using a clonogenic assay and the expressions of epidermal growth factor receptor (EGFR), Ki-67 and cleavedPARP were detected by western blot analysis. K-ras mutations were detected using polymerase chain reaction and sequencing. Results: Treatment of EGF induced cell death in the lung cancer cell lines. The addition of EGF (10 nM) to radiation (0, 2, 5, and 10 Gy) resulted in an increased cell killing effect of radiation. The EGFR expression decreased with the addition of EGF. EGF increased the expression of cleaved-PARP, but it did not increase the expression of Ki-67. The effects of EGF were not correlated with EGFR mutation or K-ras mutation. Conclusion: In our study, EGF inhibited the proliferation of lung cancer cell lines and it induced apoptosis. EGF enhanced the radiosensitivity of lung cancer cells when EGF was combined with radiation. It is suggested that EGF seem to be one of the cytotoxic agents for lung cancer cell lines. (J Lung Cancer 2010;9(2):64 �� 71)