TY - JOUR TI - Characterizing the impact of host and tumor autophagy deficiency on the development of anti-tumor immunity DO - https://doi.org/doi:10.7282/t3-ds19-9r05 PY - 2018 AB - Macroautophagy is an important cellular pathway in cancer metabolism with significant impacts on tumor growth and on the development and maintenance of antitumor immune responses. Clinical trials inhibiting autophagy to control tumor growth have shown promising results, but greater understanding of the role of autophagy in anti-tumor immunity is crucial in order to achieve successful therapies. Using CRISPR-Cas9 technology we targeted the key autophagy gene Atg7 and generated Atg7+/+ and Atg7Δ/Δ clones of the male murine urothelial carcinoma tumor line MB49 to examine the importance of functional tumor autophagy on anti-tumor immunity. Deletion of Atg7 led to a number of immune effects in one MB49 clone that generated a significantly stronger anti-tumor immune response compared to Atg7+/+ clones, but the heterogeneity of additional Atg7Δ/Δ clones showed no consistent effects. We next examined the importance of functional host autophagy by using an inducible murine model of Atg7 deletion, and found that whole body inhibition of autophagy led to immune-mediated rejection of multiple cell lines. MB49 was rejected completely in Atg7-deleted female mice (Cre.Atg7Δ/Δ)—with significantly decreased growth in male mice—but not in Atg7-competent mice (Cre.Atg7+/+). Depletion of T-cells by intraperitoneal (i.p.) injection of monoclonal antibodies specific to CD4 and CD8 led to complete rescue of MB49 tumor growth, with most of the effect found in CD4 depletion. The male murine melanoma tumor line YUMM1.1 had similar results when grown in female but not male Cre.Atg7Δ/Δ mice. Having previously shown that regulatory T-cells (Tregs) control MB49 growth we investigated whether autophagy dysfunction impacted the Treg population size or function. The number of Tregs was unchanged between Cre.Atg7+/+ and Cre.Atg7Δ/Δ in both the spleen and tumor, but analysis of RNA expression (Nanostring) revealed decreased Treg signal in the MB49 tumors of Cre.Atg7Δ/Δ mice amid a general upregulation of the immune response. Depletion of Tregs by i.p. injection of a monoclonal antibody specific to CD25 (PC61) led to rejection of MB49 in Cre.Atg7+/+ mice similar to the rejection of untreated tumors in Cre.Atg7Δ/Δ mice. These studies demonstrate the significant impact autophagy can have on immunity, and support the hypothesis that autophagy deficiency can improve tumor outcomes by modulating the immune response. KW - Microbiology and Molecular Genetics KW - Autophagic vacuoles KW - Tumors LA - eng ER -