Genetic screen in myeloid cells identifies TNF-α autocrine secretion as a factor increasing MDSC suppressive activity via Nos2 up-regulation

Abstract

The suppressive microenvironment of tumors remains one of the limiting factors for immunotherapies. In tumors, the function of effector T cells can be inhibited by cancer cells as well as myeloid cells including tumor associated macrophages and myeloid-derived suppressor cells (MDSC). A better understanding of how myeloid cells inhibit T cell function will guide the design of therapeutic strategies to increase anti-tumor responses. We have previously reported the in vitro differentiation of MDSC from immortalized mouse hematopoietic progenitors and characterized the impact of retinoic acid and 3-deazaneplanocin A on MDSC development and function. We describe here the effect of these compounds on MDSC transcriptome and identify genes and pathway affected by the treatment. In order to accelerate the investigation of gene function in MDSC suppressive activity, we developed protocols for CRISPR/Cas9-mediated gene editing in MDSC. Through screening of 217 genes, we found that autocrine secretion of TNF-α contributes to MDSC immunosuppressive activity through up-regulation of Nos2. The approach described here affords the investigation of gene function in myeloid cells such as MDSC with unprecedented ease and throughput.

The combined action of monocytic myeloid‐derived suppressor cells and mucosal‐associated invariant T cells promotes the progression of cervical cancer

“…Studies have suggested that inflammatory factors could contribute to the expansion and recruitment of MDSCs, such as C-X-C motif chemokine ligand 2 (CXCL2), hepatocyte growth factor (HGF) or tumor necrosis factor alpha (TNF-α). [42][43][44] Nevertheless, a direct association between MDSC and these mediators has not been identified.…”

Tumor Necrosis Factor α Blockade: An Opportunity to Tackle Breast Cancer

“…For example, in ovarian cancer cell lines, TNFα can behave as a signaling molecule within the producing cell or among the surrounding ones, and can induce CXCR4 expression through NF-κB, enhancing in this way cell invasion (170,171). Moreover, it has been proved that TNFα secretion by MDSCs in the tumor bed acted as an autocrine cytokine that enhances their T lymphocyte suppressive activity by upregulating different genes associated with immunosuppression, like Nos2 (172).…”

CRISPR-Cas, a robust gene-editing technology in the era of modern cancer immunotherapy

“…Several CRISPR-mediated investigations have performed to determine key regulatory elements contributing to cancer immunotherapy and the results have revealed the role of granulocyte–macrophage colony-stimulating factor in CD19 CAR T-cells administration [ 141 ], TNF-α autocrine level in performance of myeloid-derived suppressor cells [ 142 ], lysosome-associated membrane protein type 2a in regulation of tumor-associated macrophages [ 143 ], histone demethylase LSD1 in stimulation of anti-tumor responses [ 144 ], transcriptional co-activator with PDZ-binding motif in PD-L1 level [ 145 ], and Foxp3 + Treg cells in tumor advancement [ 146 ], to name a few.…”