OBJECTIVETo investigate the antitumor effect of natural killer (NK) cells on human colorectal cancer cells HT-29 in vitro by blocking transforming growth factor-β (TGF-β) signaling in NK cells transfected with vector containing dominant negative TGF-β type 2 receptor (DNTβR2).

METHODSTGF-β1 was added at the final concentration of 10 ng/ml for HT-29 cells. Primary NK cells were transfected with recombinant plasmid pIRES2-AcGFP-DNTβR2 and control plasmid pIRES2-AcGFP using Amaxa Nucleofector technology respectively. The cytotoxicity of these two types of NK cells to HT-29 cells was detected and analyzed by cell counting kit-8.

RESULTSThe transfection efficiency of primary NK cells was 18.85% for the plasmid pIRES2-AcGFP-DNTβR2 and 35.28% for the control plasmid pIRES2-AcGFP. The expression of DNTβR2 in NK cells was confirmed by Western blotting and RT-PCR. Primary NK cells displayed significantly lower cytotoxicity against HT-29 cells incubated with TGF-β1 than that without TGF-β1 (effect-target cell ratio 10:1,14.40%∓ 2.00% vs. 26.14% ∓ 2.50%, P > 0.05; effect-target cell ratio 20:1, 19.18% ∓ 2.49% vs. 40.81% ∓ 3.50%, P > 0.05). The cytotoxicity of NK cells transfected with DNTβR2 vector was significantly higher than that with control vector against HT-29 cells cultured with 10 ng/ml TGF-β1 (effect-target cell ratio 10:1, 21.17% ∓ 2.49% vs. 11.48% ∓ 1.11% ,P > 0.05; and effect-target cell ratio 20:1, 35.30% ∓ 3.78% vs. 17.19% ∓ 2.29%, P > 0.05).

CONCLUSIONNK cells transfected with DNTβR2 vector show better antitumor effect, which may provide new method for NK-based adoptive immunotherapy for cancer.