miRNA-34a reverses cisplatin resistance of osteosarcoma through targeted inhibition of high mobility group box 1 / 肿瘤研究与临床

ABSTRACT

Objective:To investigate the related mechanism of miRNA-34a (miR-34a) reverses cisplatin resistance of osteosarcoma through targeted inhibition of high mobility group box 1 (HMGB1).Methods:The MG-63 cisplatin-resistant cell line (MG-63/DDP) was constructed by using dose escalation and intermittent action, and then the successfully constructed MG-63/DDP cells were treated with different concentrations of cisplatin (0, 1, 5, 10, 20, 30 μg/ml), and CCK-8 method was used to detect cell survival rate. The MG-63/DDP cells were transfected respectively and then randomly divided into two groups the miR-34a overexpression vector group and the miR-34a empty expression vector (miR-34a-NC) group. Real-time quantitative polymerase chain reaction (qRT-PCR) was used to detect the relative expression level of miR-34a. Transfected cells were treated with different concentrations of cisplatin (0, 1, 5, 10, 20, 30 μg/ml), and CCK-8 method was used to detect cell survival rate, flow cytometry was used to detect cell apoptosis. The dual luciferase reporter gene experiment was used to verify whether miR-34a regulated the expression of HMGB1, and Western blotting method was used to detect the HMGB1 protein expression level of the transfected cells. MG-63/DDP cells were transfected respectively and then randomly divided into two groups HMGB1 gene silencing vector (si-HMGB1) group and its negative control vector (si-NC) group. Western blotting method was used to detect HMGB1 protein expression level and CCK-8 method was used to detect cell survival rate.Results:The MG-63/DDP cell line was successfully constructed. The survival rate of MG-63/DDP cells was higher than that of MG-63 cells when cells were treated with different concentrations of cisplatin (all P < 0.01), and half inhibitory concentration ( IC50) value of MG-63/DDP cells and MG-63 cells on cisplatin was 25.80 μg/ml and 0.47 μg/ml, respectively. qRT-PCR results showed that the relative expression level of miR-34a in MG-63/DDP cells was lower than that in MG-63 cells (0.46±0.04 vs. 1.02±0.05, t = 15.14, P < 0.01); compared with miR-34a-NC group, the relative expression of miR-34a in MG-63/DDP cells was increased in miR-34a overexpression vector group (1.67±0.09 vs. 1.00±0.02, t = -12.58, P < 0.01). Cell survival rate of miR-34a overexpression vector group and miR-34a-NC group was decreased with the increase in the concentration of cisplatin; cell survival rate of miR-34a overexpression vector group was lower than that of miR-34a-NC group when cells were treated with different concentrations of 5- 30 μg/ml cisplatin (all P < 0.01). The apoptotic rate of MG-63/DDP cells in miR-34a-NC group and miR-34a overexpression vector group was (25.1±1.7)% and (42.3±2.3)%, respectively when cells were treated with 20 μg/ml cisplatin; and in miR-34a overexpression vector group, MG-63/DDP cells had a higher rate of apoptosis ( P < 0.01). The dual luciferase reporter gene experiment results showed that compared with miR-34a-NC group, miR-34a overexpression vector group could inhibit the luciferase activity of PGL3- wild-type-HMGB1, and the difference was statistically significant ( t = 6.37, P < 0.01), while miR-34a overexpression vector group had no significant inhibitory effect on the luciferase activity of PGL3- mutant-HMGB1 ( t = 0.35, P = 0.74). The relative expression level of HMGB1 protein in miR-34a overexpression vector group was lower than that in miR-34a-NC group (0.43±0.02 vs. 1.00±0.14, t = 6.98, P < 0.01). Compared with si-NC group, the relative expression level and IC50 value of HMGB1 protein in si-HMGB1 group were reduced (all P < 0.05). Conclusion:Overexpression of miR-34a can enhance the chemosensitivity of osteosarcoma cells MG-63/DDP to cisplatin, and its mechanism may be related to the inhibition of HMGB1 expression.