Abstract:
Objective The aim of this in vitro study is to assess the reversing effects of arsenic trioxide(As2O3) on multi-drug-resistance(MDR) of SGC7901/adriamycin(ADM) and determine the molecular mechanism associated with Ras/p-ERK downregulation in human gastric cancer cells.
Methods The reversing effects of As2O3 before and after the treatment with an ERK agonist were determined by methyl thiazolyl tetrazolium assay.The molecular mechanism involved was further studied by examining the expressions of Ras and phosphorylated p-ERK by immunocytochemical assay.The process was repeated in pre-and post-intervention of As2O3 and granulocyte colony stimulating factor(G-CSF), respectively.Changes in the cell cycle and apoptotic rates were determined by flow cytometry.
Results SGC7901/ADM was resistant to ADM, and As2O3 could reverse the drug resistance.After the treatment of As2O3 at a dose of 0.5 μmol/L for 48 h, the the multiple of reversed drug resistance was about 6.29 approximately, which was greater compared with that of the normal cells.After administration of As2O3, the IC50decreased dramatically, which shows that As2O3 could reverse MDR.After the G-CSF intervention, the multiple of the reversing effects was only 4.72.Immunocytochemical assay showed higher expressions of Ras in SGC7901/ADM than in the parental cell line SGC7901/S.No obvious difference in the p-ERK expressions of these cell lines was observed. As2O3 could decrease both Ras and p-ERK expressions(q-test, P < 0.01).After pre-treatment with the ERK agonist, Ras and p-ERK expressions decreased(t-test, P < 0.01).Flow cytometry indicated that the proportion of G0-G1 cells and apoptosis rate were higher in the As2O3 –treated group(0.1 and 0.5 μmol/L) than in the control groups.And apoptotic rate of both the cells significantly decreased in the As2O3 group of the same dose after treatment of G-CSF.
Conclusion As2O3 can reduce the MDR of gastric cancer in vitro via the Ras/p-ERK signaling transduction pathway.