Abstract:

Objective To investigate the synergistic effect of sunitinib combined with NK cells on the renal clear cell carcinoma 786-0 cells,and to clarify the mechanism. Methods The 786-0 cells were cultivated by routine method in vitro and divided into untreated group and sunitinib group,meanwhile positive control group (K562 cells) was set up.The human NK cells were isolated by magnetic activated cell sorting (MACS).The sensitivity of 786-0 cells to sunitinib was analyzed by MTT assay.Flow cytometry was used to evaluate the purity of isolated cells and the expression rates of NKG2D-ligands (NKG2DLs) on the target cells before and after treatment of sunitinib.Subsequently,the cytotoxic sensitivities of 786-0 cells to NK cells in untreated group,positive control group and sunitinib group were measured by LDH releasing assay. Results The IC₅₀ values of sunitinib for 786-0 cells was (4.45±0.65) μmol·L^-1.More than 72% of isolated NK cells showed to be CD3^-CD16⁺CD56⁺ cells which would definitely meet the needs of experiments. The expressions rates of MICA,MICB,ULBP2 on the target cells incubated with sunitinib were respectively increased from (3.52±0.29)%,(3.10±0.73)%,(5.12±4.77)% to (15.45±2.14)%,(21.95±3.08)%,(51.71±5.33)%.Compared with untreated group,the expression rates of MICA,MICB and ULBP2 in treatment group were significantly increased(P<0.05).At the E:T ratio of 10:1 and 20:1,the cytotoxic sensitivities of 786-0 cells to NK cells were increased from (9.71±0.88)% and (21.28±0.32)% in untreated group to (20.83±1.28)% and (35.11±0.70)% in sunitinib group(F＝166.18,P＝0.000;F=52.87,P=0.000);the cytotoxic sensitivities of NK cells to the 786-0 cells in sunitinib group were higher than that in untreated group (P<0.05). Conclusion Sunitinib can selectively regulate the expressions of NKG2DLs (MICA/B and ULBP2) in the 786-0 cells,which can result in higher cytotoxic sensitivity to NK cells.Sunitinib combined with NK cells has synergistic effect on the renal clear cell carcinoma cells.

Key words: sunitinib, natural killer cells, renal clear cell carcinoma, natural killer group 2 member D