Fig. 1

High-dose arecoline is cytotoxic to NFs and CAL27 cells but low-dose arecoline promotes the proliferation of NFs and CAL27 cells. A-B CCK-8 assay showing the viability of NFs and CAL27 cells after exposure to various concentrations of arecoline from 0.0004 μg/ml to 640 μg/ml for 24 h. Growth inhibition was detected in triplicate samples, and significant differences compared with control were noted by asterisks. ** p < 0.01; *** p < 0.001. C-D Effects of low-dose arecoline on cell cycle progression of NFs and CAL27 cells. Arecoline was treated NFs at 0.625 μg/ml (C) and CAL27 cells at 1.25 μg/ml (D) for 24 h. Changes in the percentage of cells in the G0/G1, S and G2/M phase in NFs and CAL27 cells with or without arecoline treatment were examined. Results were expressed as a percentage of cells in different phases (mean ± SE). Asterisks represented a significant difference when compared with controls. * p < 0.05, *** p < 0.001, **** p < 0.0001