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Oncol Lett. 2018 Jan;15(1):741-746. doi: 10.3892/ol.2017.7376. Epub 2017 Nov 9.

Lentiviral delivery of CTLA-4 shRNA improves the expansion of cytokine-induced killer cells and enhances cytotoxic activity in vitro.

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Department of Gastroenterology, Zhejiang Provincial Hospital of Traditional Chinese Medicine, Hangzhou, Zhejiang 310000, P.R. China.
Department of Oncology, Zhejiang Provincial People's Hospital, Hangzhou, Zhejiang 310014, P.R. China.
Department of Gastroenterology, Zhejiang Provincial People's Hospital, Hangzhou, Zhejiang 310014, P.R. China.


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.


CTLA-4; cytokine-induced killer cell; cytotoxicity; proliferation

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