Enhanced NK cell adoptive antitumor effects against breast cancer in vitro via blockade of the transforming growth factor-β signaling pathway

Abstract

Yue Zhao,1,* Jinyue Hu,2,* Rongguo Li,1 Jian Song,1 Yujuan Kang,1 Si Liu,1 Dongwei Zhang1 1Department of General Surgery, Second Affiliated Hospital of Harbin Medical University, Harbin, 2Department of Breast and Thyroid Surgery, The Third Hospital of Zhengzhou, Zhengzhou, People’s Republic of China *These authors contributed equally to this work Abstract: Natural killer (NK) cells have great potential for improving cancer immunotherapy. Adoptive NK cell transfer, an adoptive immunotherapy, represents a promising nontoxic anticancer therapy. However, existing data indicate that tumor cells can effectively escape NK cell-mediated apoptosis through immunosuppressive effects in the tumor microenvironment, and the therapeutic activity of adoptive NK cell transfer is not as efficient as anticipated. Transforming growth factor-beta (TGF-β) is a potent immunosuppressant. Genetic and epigenetic events that occur during mammary tumorigenesis circumvent the tumor-suppressing activity of TGF-β, thereby permitting late-stage breast cancer cells to acquire an invasive and metastatic phenotype in response to TGF-β. To block the TGF-β signaling pathway, NK cells were genetically modified with a dominant-negative TGF-β type II receptor by optimizing electroporation using the Amaxa Nucleofector system. These genetically modified NK cells were insensitive to TGF-β and resisted the suppressive effect of TGF-β on MCF-7 breast cancer cells in vitro. Our results demonstrate that blocking the TGF-β signaling pathway to modulate the tumor microenvironment can improve the antitumor activity of adoptive NK cells in vitro, thereby providing a new rationale for the treatment of breast cancer. Keywords: transforming growth factor-beta, natural killer cells, breast cancer, adoptive immunotherapy