Study of erythromycin and cisplatin on cell cycle distributions and apoptosis in A549 cells exposed to cigarette smoke extract

Objective To study the apoptosis of lung adenocarcinoma cell (A549) treated with erythromycin (EM) and cisplatin (CDDP). Methods Taking A549 cells as research object, differential concentrations of CDDP were prepared as 0.25, 0.5, 1, 2, 4, 8 mg/L, respectively, Stimulated activity of A549 cells treated with different concentrations of CDDP for 48 h. The half inhibition concentration of CDDP (IC50) calculated by Cell Counting Kit-8 method.The research was divided as the blank control group (only 10% inactivation of fetal boxine serum RPMI-1640 cell culture medium), the 10 mg/L EM group, the 10 mg/L EM+ IC50-CDDP group and the IC50-CDDP group.They were cultured for 48 h, then their apoptosis and cell cycle percentage were detected by flow cytometry.Real time quantative PCR and Western blot were used to detect the expression of HDAC2, Caspase-9, Caspase-3, cyclinD1 mRNA and proteins. Results A549 cells growth was inhibited by differential concentrations of CDDP in 48 h, and the inhibitory effect was concentration-dependent, the higher the concentration, the greater the inhibitory effect of cells growth (P 0.05). The cells apoptosis of A549 were obviously incresed in 10 mg/L EM+ IC50-CDDP group and IC50-CDDP gruop (both P<0.05). Compared with the blank control group, the expression levels of HDAC2, Caspase-9, Caspase-3, cyclinD1 mRNA and proteins were increasd in 10 mg/L EM group and 10 mg/L EM+ IC50-CDDP group, but the expression level of cyclinD1 mRNA and protein were decreased, the differences were statistically significant (all P<0.05). Conclusions EM can decrease cyclinD1 activity and enhance the blocking effect of CDDP on A549 cells.It also increases the expression of Caspase-3 and Caspase-9, and enhance the apoptosis effect of CDDP on A549 cells.The mechanism may be related to the increase of HDAC2 expression in A549 cells by EM.Therefore, EM and CDDP can be considered as a new treatment method available for lung adenocarcinoma. Key words: Erythromycin; Cisplatin; Cell cycle; Cell apoptosis