Effect of flotillin-1 gene small interfering RNA combined with curcumin on apoptosis of renal cell carcinoma in vitro

Abstract

Objective To investigate the effect of flotillin-1 (FLOT1) small interfering RNA (siRNA) combined with curcumin on the apoptosis of renal cell carcinoma. Methods FLOT1-siRNA was transfected into 786-0 cells of human renal carcinoma by Lipofectamine™ 2000. The protein expression of FLOT1 in the cells transfected with siRNA was detected by Western blotting. Thereafter, FLOT1-siRNA, curcumin and FLOT1-siRNA+ curcumin were used for cell intervention, and a blank control group was set up. The cell viability and apoptosis rate of four groups were detected by cell counting kit-8 (CCK-8) assay and flow cytometry. H2DCFHDA probe was used to detect the content of ROS in four groups. The expression levels of phosphorylated signal transducer and activators of transcription 3 (p-STAT3), proliferating cell nuclear antigen (PCNA) and B cell lymphoma/leukemia-2 associated X protein (bax) protein were detected by Western blotting. Results The expression of FLOT1 (0.087±0.010) was significantly inhibited in 786-0 cells transfected with FLOT1-siRNA, and the difference was statistically significant as compared with the blank control group (0.454±0.038) (t=16.177, P=0.000). Si-FLOT1 (0.491±0.053) or curcumin (0.542±0.058) could inhibit the activity of 786-0 cells, induce 786-0 cell apoptosis [(18.22±1.07)% and (12.39±0.86)%] and ROS production [(189.5±8.2) and (147.7±7.1)], down-regulate the expression of p-STAT3 [(0.118±0.014) and (0.110±0.012)] and PCNA [(0.229±0.025) and (0.302±0.034)] and up-regulate the expression of bax [(0.206±0.021) and (0.123±0.014)], and the difference was statistically significant as compared with NC group [(0.792±0.065), (1.62±0.25)%, (57.7±3.5), (0.202±0.023), (0.577±0.049), (0.069±0.010)] (t=6.736, 7.378, 12.796, 10.112, 7.186, 2.832, P=0.000, 0.000, 0.000, 0.000, 0.000, 0.022). Combined use of si-FLOT1 and curcumin could inhibit the activity of 786-0 cells [(0.378±0.044)], induce apoptosis [(24.18±1.22)%] and ROS production [(249.3±9.4)], down-regulate the expression of p-STAT3 [(0.054±0.008)] and PCNA [(0.135±0.016)] and up-regulate the expression of bax [(0.411±0.038)], with the difference being statistically significant as compared with single si-FLOT1 group or curcumin group (t=5.132, 4.491, 3.456, 6.140, 10.752, 15.106, P=0.001, 0.002, 0.009, 0.000, 0.000, 0.000). Conclusion FLOT1 siRNA or curcumin can inhibit the viability of renal cell carcinoma cells and induce apoptosis, and the combined use of FLOT1 siRNA and curcumin can be more obvious to cell viability and apoptosis. The mechanism may be related to the increases in intracellular ROS and the inhibition of STAT3 signal. Key words: Renal cell carcinoma; Flotillin-1 gene; Curcumin; Apoptosis; Signal transducer and activators of transcription 3 signaling pathway