Fig. 4

Lycorine’s suppression effects on EGF-induced EGFR signaling pathway. a In vitro EGFR kinase inhibition by Lycorine. Half maximal inhibitory concentration (IC₅₀) values of Lycorine and positive control Gefitinib. b U251 cells were incubated with various concentrations of Lycorine (from 0 μM to 50 μM) for 48 h. Effects on the expression of CL–caspase 3 and PARP were determined by Western blotting. Human β-actin served as a loading control. c Suppression by Lycorine of EGFR phosphorylation and its downstream AKT, ERK, mTOR, p27, p21, Bcl-2, Cyclin D1, MMP9 in U251 cell lines. For detecting the phosphorylation of EGFR and its downstream signaling pathways, U251 cells were pretreated with 100 ng/mL human recombinant protein EGF for 6 h, then treated with Lycorine for indicated concentration for another 24 h; and cell lysates were subjected to Western blotting analysis with indicated antibodies. d U251 cells exposed to 100 ng/mL human recombinant protein EGF for indicated time points (0, 15, 30, 45 and 60 min) then followed with 25 μM Lycorine for 1 h or with no treatment. The expression of EGFR and p-EGFR were detected by western blotting. e Statistical result of Fig. 4d