Effects of p73 and GADD45α Protein on Cell Cycle Arrest in Di(2-ethylhexyl)phthalate-Treated L02 and Hep3B Cells

Objective To study the effects of p73 and GADD45α protein on the cell cycle arrest in the MEHP-treated Hep3B cells.Methods Both logarithmic phase L02 cells and Hep3B cells were treated with either MEHP at the indicated concentrations(6.25,12.5,25,50 and 100 μmol/L) or dimethyl sulfoxide(DMSO,solvent control,1‰)for 12 h.The cell proliferation rate was detected by the MTT assay.The percentage of cells in each phase of the cell cycle was analyzed by the flow cytometry.The expression of p53,p73 and GADD45α proteins were detected by Western blotling.Results In the MEHP-treated L02 cells,an increase in the cell proliferation rate were observed only in 50 μmol/L MEHP group(P0.05).MEHP induced the S-phase cell cycle arrest in 100 μmol/L treatment group,but no change in the expression of p53,p73 and GADD45α proteins was observed in all treatment groups(P0.05).However,in the Hep3B cells,the decreased cell proliferation rate in all treatment groups was observed(P0.01).The accumulations of the cells in G2 phase of the cell cycle were found in 50 μmol/L and 100 μmol/L treatment groups.The levels of p73 strongly increased in all treatment groups(P0.05).The higher concentrations of MEHP(50 μmol/L and 100 μmol/L)induced the increasing GADD45α protein expression(P0.01).Conclusion The p53-independent G2 arrest of the cell cycle induced by MEHP may be concerned in the up-regulated expression of p73 and GADD45α proteins.