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Biology subjects

Cayarga, A. A.

Publications and source records attributed to Cayarga, A. A..

2 recordsLinked to original sources
bioRxiv2025

NLRC5 expression in tumor cells is critical to activate adaptive and innate antitumor immune responses

Tumors evade cytotoxic T lymphocyte (CTL)-mediated killing by downregulating MHC class-I, mainly resulting from the loss of its transcriptional activator NLRC5. Expressing full-length NLRC5 (NLRC5-FL) or a shorter NLRC5-CIITA fusion protein termed NLRC5 super-activator (NLRC5-SA) in cancer cells upregulates MHC-I expression and promotes antitumor immunity. To distinguish the role of NLRC5 expressed within tumor cells and antigen presenting cells, we studied B16-F10 melanoma expressing NLRC5-FL (B16-N-FL) or NLRC5-SA (B16-N-SA) in Nlrc5+/+ and Nlrc5-/- mice. Both tumors were efficiently controlled in both Nlrc5+/+ and Nlrc5-/- hosts with abundant immune cell infiltration, enriched for activated and differentiated CD8+ and CD4+ T cells, NK, NKT and iNKT cells. B16-N-FL and B16-N-SA tumors showed increased collagen deposition and vascularization, with upregulation of CCL4 and CXCL9 chemokine genes in B16-N-SA tumors. Depletion of either CD8+ T cells or NK1.1+ cells increased the growth of B16-N-FL and B16-N-SA tumors in Nlrc5+/+ mice, and that of B16-N-SA tumors in Nlrc5-/- hosts. Proteomes of B16-N-FL and B16-N-SA cells showed downmodulation of dominant tumor antigens and upregulation of ubiquitination and protein processing pathway proteins. Differentially expressed proteins shared between B16-N-FL and B16-N-SA cells showed enrichment in phagosome and autophagy pathways. We conclude that tumor cell-intrinsic NLRC5 expression is critical for the activation of adaptive and innate immune cells, and establishment of an immune-supportive tumor microenvironment to permit immune cell infiltration and their effector functions and achieve tumor control. NLRC5 expression in APCs is dispensable to mediate these effects. Delivering NLRC5-SA is a promising approach to restore antitumor immune responses in MHC-I-low immune evasive tumors. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=134 SRC="FIGDIR/small/695247v1_ufig1.gif" ALT="Figure 1"> View larger version (40K): org.highwire.dtl.DTLVardef@1bc4f51org.highwire.dtl.DTLVardef@1fb5b03org.highwire.dtl.DTLVardef@11448edorg.highwire.dtl.DTLVardef@bff26c_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗
bioRxiv2025

Essential role of NLRC5 in cancer immune surveillance and cancer immunoediting

A key mechanism of immune escape from CD8+ T cell-mediated tumor control occurs via downregulation of NLRC5, the IFN{gamma}-induced transcriptional activator of MHC class-I. As NLRC5 deficiency does not abrogate CD8+ T cell development, we investigated whether NLRC5-dependent antitumor immune mechanisms are required for immune surveillance. Development of 3-methylcholanthrene (MCA)-induced endogenous fibrosarcoma was studied in Nlrc5-/- mice with Nlrc5+/+ and Rag1-/- mice serving as controls. Nlrc5-/- and Rag1-/- mice showed increased propensity to develop MCA-induced tumors with elevated growth rate compared to Nlrc5+/+ mice, and displayed significantly reduced survival. Tumors from Nlrc5+/+ and Nlrc5-/-mice, but not from Rag1-/- mice, contained necrotic areas and displayed T cell infiltration. Tumor cell lines established from MCA- induced tumors were evaluated for their sensitivity to immune-mediated growth control following implantation into immunocompetent C57BL/6 and immunodeficient Rag1-/- hosts. Tumors formed by Nlrc5+/+ tumor cell lines progressed unhindered in C57BL/6 hosts that reflected their immunoedited status, whereas cell lines from Nlrc5-/- and Rag1-/-tumors were efficiently controlled, indicating their non-immunoedited status. Proteomic analysis by mass spectrometry followed by pathway analysis revealed enrichment of granzyme-mediated cytolytic pathway in Nlrc5+/+ tumors that were absent in Nlrc5-/- tumors, which showed enrichment of humoral and innate immune pathways. Overall, our findings show that NLRC5 is required for robust tumor immune surveillance and tumor immunoediting and that compensatory humoral and innate immune mechanisms activated by the loss of NLRC5 are insufficient for cancer immune surveillance and cancer immunoediting.

immunology↗