Abstract
The Ral (Ras-like) GTP-binding proteins (RalA and RalB), as effectors of the proto-oncogene Natural killer (NK) cells are an important component of the anti-tumor response. Tumor recognition by NK cells was found to be partly triggered by molecules termed natural cytotoxic receptors (NCRs). Adoptive transfer of genetically-engineered tumor-reactive T-lymphocytes can mediate remarkable tumor regressions mostly in melanoma and leukemia patients. Yet, the application of such treatments to other cancers is needed and dependent on the isolation of receptors that could facilitate efficient recognition of these malignancies. Herein, we aimed at combining NK tumor recognition capability with the genetic modification of T-cells to provide the latter with a means to recognize several tumors in a non-MHC restricted way. Consequently, we generated and evaluated several chimeric receptors based on the extracellular domain of NCR1 (NKp46) fused to multiple signaling moieties and assess their antitumor activity when retrovirally expressed in T-cells. Following co-culture with different tumors, primary human T-lymphocytes expressing a chimeric NCR1 molecule recognized target cells derived from lung, cervical carcinoma, leukemia and pancreatic cancer. In addition, this receptor mediated an upregulation of surface activation markers and significant antitumor cytotoxicity both in vitro and in vivo. These results have meaningful implications for the immunotherapeutic treatment of cancer using gene-modified T-cells.
Highlights
Tumor development and progression has often been reported to be associated with the lack of specific recognition of cancer cells by the immune system [1]
We generated various NCR1-based chimeric receptors by cloning out the cDNA encoding NCR1 from human Natural killer (NK)-cells and by fusing its extracellular domain to different co-stimulatory/activating domains (Figure 1A). These and the wild-type NCR1 receptor (N1) were cloned into the pGEM-4Z/64A vector and we produced mRNA encoding these receptors which were expressed by electroporation into Jurkat cells
As NCR1 has been shown to contribute to anti-tumor immunity [10;11;15;16], in the present work we have explored the use of NCR1 as a targeting moiety to redirect T-cells anti-tumor activity against a panel of different malignancies
Summary
Tumor development and progression has often been reported to be associated with the lack of specific recognition of cancer cells by the immune system [1]. Natural killer (NK) cells are an important component of the anti-tumor response and their lytic capability depends on the integrated balance between activating and inhibitory signals [2;3]. Positive signals mediated by receptors are needed for full NK activation and tumor cell lysis [5]. NCR1 was the first NCR isolated and is a type I-transmembrane receptor that contains 2 Ig-domains and that associates with either CD3ζ or FcεRIγ in order to signal [7;8]. Though it has been demonstrated that heparan sulfate, which can be upregulated by cancer cells, can bind to NCR1 [17], the precise identification of the cellular ligands of NCR1 remains a challenge [6;18]
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