Effect Of Arsenic Trioxide On Expression Of MDM2 In Adenoid Cystic Carcinoma ACC-2 Cell

Objective: To investigate the inhibition mechanism and apoptosis-inducing effects of arsenic trioxide( As2O3) on adenoid cystic carcinoma-2(ACC-2) cells in vitro, and detect the expression of MDM2 gene from gene and protein level.Methods: ACC-2 cells were cultured in vitro. Arsenic trioxide of different concentrations(2.0、4.0、6.0、8.0μmol/L)and cell culture solution were applied to cells in logarithmic growth phase for different time as experiment groups and control groups. Cell metamorphoses after As2O3 induction were observed under inverted phase contrast microscope. Expression changes of MDM2 m RNA(24、48h) and protein(24、48、72h) were determined by reverse transcription polymerase chain reaction(RT-PCR) and immunohistochemistry respectively.Results:(1)As2O3 could inhibit the proliferation of ACC-2 cells and induce apoptosis in a time anddosedependent manner. Under the microscope: Cells shrinkage, nuclear chromatin condensation, cell-cell contact was decrease, the cell gap became larger and intracellular granule was increased, cell density increased accompanied by vacuolar degeneration.Apoptotic cells increased and the number of viable cells significantly reduced after cultured with different concentrations of As2O3.(2) The results of RT-PCR showed that the MDM2 m RNA expressed in ACC-2 cells in both the experimental group and the control group,and its expression decreased significantly with time and increasing concentrations of As2O3.The data has a statistically significant between the concentration and time groups(P< 0.05);(3)Immunohistochemicalresults showed that MDM2 proteins were expressed in the nucleus and the cytoplasmin ACC-2 cells in both the experimental group and the control group.MDM2 proteins were expressed mainly in the nucleus. The expressions in treatment groups decreased graduallywith the concentration and reaction time increased. The difference was statistically significant(P < 0.05),which was also significantly different to that in the controlgroup(P<0.05).Conclusion:(1)As2O3 might markedly depress the growth of ACC-2 cells cultured in vitro and induce the cell apoptosis in a timeand dosedependent manner;(2) MDM2 was expressed in ACC-2 cells.It may be involved in the ACC-2 cells apoptosis process induced by As2O3.The expression of MDM2 is changed mainly in its protein levels induced by As2O3. The specific mechanism requires a further study.