Abstract: ObjectiveTo evaluate the effect of oxaliplatin induced autophagy on drug resistance of gastric cancer cells. MethodsGastric cancer SGC7901 cells were cultured in vitro and treated with different concentrations of oxaliplatin. Control group (oxaliplatin 0 μmol/L), oxaliplatin treatment groups (oxaliplatin 1, 2, 4 μmol/L) and oxaliplatin combined with doxorubicin groups (oxaliplatin 0, 1, 2, 4 μmol/L + doxorubicin 4 μmol/L) were set up. Cells were treated with different conditions for 24 hours. Western blotting and flow cytometry were used to detect the expression of autophagyrelated molecule Beclin1. Methyl thiazolyl tetrazolium (MTT) assay was used to detect the cell viability. Flow cytometry was used to analyze the uptake of doxorubicin in SGC7901 cells. ResultsThe expression of Beclin1 increased in gastric cancer cells treated with oxaliplatin. The percentages of positive cells treated with 1, 2 and 4 μmol/L oxaliplatin were respectively (9.51±0.27)%, (13.73±0.80)% and (20.17±1.03)%, control group was (2.17±0.15)%, and the difference was statistically significant (F=111.10, P<0.001). Compared with the control group, Beclin1 expression significantly increased in each treatment group (P<0.05; P<0.001; P<0.001). Different concentrations of 1, 2, 4 μmol/L oxaliplatin combined with doxorubicin were used to treat gastric cancer SGC7901 cells, fluorescence intensities of doxorubicin were 11 567±802, 13 433±808, 15 967±472, control group was 10 257±367, and the difference was statistically significant (F=79.81, P<0.001). Compared with the control group, the fluorescence intensity of doxorubicin significantly increased in each treatment group (P＜0.05; P<0.001; P<0.001). After treatment with oxaliplatin (1, 2, 4 μmol/L) and doxorubicin (4 μmol/L) for 24 hours, the cell viability levels were (68.27±1.64)%, (51.72±1.93)%, (39.60±1.80)% respectively. The cell viability levels of oxaliplatin treated with 1, 2 and 4 μmol/L were respectively (93.70±1.15)%, (76.53±1.10)%, (74.00±1.65)%. Compared with oxaliplatin alone, oxaliplatin combined with doxorubicin decreased cell viability more obviously, and the differences were statistically significant (t=8.91, P<0.001; t=9.21, P<0.001; t=10.34，P<0.001). The doxorubicin fluorescence intensity of oxaliplatin (2 μmol/L) combined with doxorubicin (4 μmol/L) group with pretreatment of autophagy inhibitor was 16 898±105, oxaliplatin combined with doxorubicin group was 22 245±168, and doxorubicin alone group was 17 562±67, and the difference was statistically significant (F=92.16, P<0.001). Compared with the pretreatment group, the doxorubicin fluorescence intensity of oxaliplatin combined with doxorubicin group was significantly increased (P<0.001). On the other hand, the cell viability levels of the above three groups were (81.33±3.54)%, (65.00±2.61)% and (101.02±3.58)%, and the difference was statistically significant (F=90.66, P<0.001). Compared with the pretreatment group, the cell viability level of oxaliplatin combined with doxorubicin group was significantly lower (P<0.001). ConclusionOxaliplatin can reduce the resistance of gastric cancer cells to chemotherapeutics by increasing the level of autophagy in gastric cancer cells, and improve the therapeutic effect of chemotherapy drugs.

Key words: Antineoplastic agents, Autophagy, Stomach neoplasms, Antineoplastic combined chemotherapy protocols