Objective      To investigate the inhibitory effect of curcumin on the proliferation in A549 cells and to explore possible mechanisms.       Methods       After A549 cells were treated with different concentrations of curcumin

cell clone formation and proliferation were determined by colony formation assay and MTT assay

respectively. A549 cells were treated with 20 μmol/L curcumin for 24 h

48 h and 72 h

respectively and the cell cycle was measured by flow cytometry (FCM). mRNA and protein levels of P53

P21

PCNA and eIF4E were detected by RT-PCR and Western blotting.       Results       A549 cells treated with 20 μmol/L curcumin showed an arrest of cell cycle at S phase

inhibition of cell proliferation and reduction of clone formation; the treatment for 24 h resulted in an increased mRNA and protein levels of p53 and p21

which became more obvious after 48 h and 72 h treatment. In addition

the cells treated with 20 μmol/L curcumin for 48 h showed decreased expressions of eIF4E and PCNA at mRNA and protein levels

and the decrease became more obvious after 72 h treatment.       Conclusion      Curcumin can inhibit clone formation and cell proliferation in A549 cells. The mechanism may be related to up-regulation of P53 and P21 and down-regulation of PCNA and eIF4E.