Lentiviral delivery of CTLA‑4 shRNA improves the expansion of cytokine‑induced killer cells and enhances cytotoxic activity in vitro
- Tao Rui
- Xiangdong Cheng
- Hao Wu
- Fuwei Wang
- Zaiyuan Ye
- Guoqing Wu
Published online on: November 9, 2017
Copyright: © Rui et al.
This is an open access article distributed under the terms of Creative Commons Attribution License.
Cytokine‑induced killer (CIK) cells are in vitro‑expanded cells harboring potent toxicity against tumor cells. Recently, it was identified that the cytotoxicity and proliferation of CIK cells are restricted by a prolonged CIK cell culture period. Cytotoxic T lymphocyte‑associated antigen 4 (CTLA‑4) serves a negative role in T cell activation and proliferation. This study aims to determine whether CTLA‑4 expression is associated with the inhibition of CIK cells. CIK cells were generated from peripheral blood mononuclear cells (PBMCs), and CTLA‑4 shRNA (shCTLA‑4) lentivirus was applied to knockdown CTLA‑4 expression in CIK cells. The proliferation of CIK cells was evaluated following shCTLA‑4 lentiviral transduction, and the cytotoxicity of CIK cells was investigated using the CytoTox 96 Non‑Radioactive Cytotoxicity assay. The expression of CTLA‑4 in CIK cells was significantly increased, compared with that in PBMCs. The shCTLA‑4 lentivirus efficiently knocked down the expression of CTLA‑4 in CIK cells. The shCTLA‑4 lentivirus transduction of CIK cells promoted the proliferation of CIK cells in vitro (3.18±0.19‑fold vs. 2.42±0.29‑fold). Furthermore, the cytotoxicity of shCTLA‑4 lentivirus‑transduced CIK cells was significantly improved when compared with that of control shRNA lentivirus‑transduced CIK cells (54.5±2.13% vs. 30.5±1.67%). Thus, the suppression of CTLA‑4 expression increases cytotoxicity and ex vivo expansion of CIK cells, which indicates a clinical significance for CTLA‑4 blockade in CIK cell therapy.