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Updated: Nov 5, 2025
Tractable In Vivo Reprogramming of Tumor Cells to Type 1 Conventional Dendritic Cell-like Cells
Published on: August 1, 2025
DNGR-1 limits Flt3L-mediated antitumor immunity by restraining tumor-infiltrating type I conventional dendritic cells
Francisco J Cueto1, Carlos Del Fresno1,2, Paola Brandi1
1Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain.
Background:
Conventional type 1 dendritic cells (cDC1s) are central to antitumor immunity and their presence in the tumor microenvironment associates with improved outcomes in patients with cancer. DNGR-1 (CLEC9A) is a dead cell-sensing receptor highly restricted to cDC1s. DNGR-1 has been involved in both cross-presentation of dead cell-associated antigens and processes of disease tolerance, but its role in antitumor immunity has not been clarified yet.
Methods:
B16 and MC38 tumor cell lines were inoculated subcutaneously into wild-type (WT) and DNGR-1-deficient mice. To overexpress Flt3L systemically, we performed gene therapy through the hydrodynamic injection of an Flt3L-encoding plasmid. To characterize the immune response, we performed flow cytometry and RNA-Seq of tumor-infiltrating cDC1s.
Results:
Here, we found that cross-presentation of tumor antigens in the steady state was DNGR-1-independent. However, on Flt3L systemic overexpression, tumor growth was delayed in DNGR-1-deficient mice compared with WT mice. Of note, this protection was recapitulated by anti-DNGR-1-blocking antibodies in mice following Flt3L gene therapy. This improved antitumor immunity was associated with Batf3-dependent enhanced accumulation of CD8+ T cells and cDC1s within tumors. Mechanistically, the deficiency in DNGR-1 boosted an Flt3L-induced specific inflammatory gene signature in cDC1s, including Ccl5 expression. Indeed, the increased infiltration of cDC1s within tumors and their protective effect rely on CCL5/CCR5 chemoattraction. Moreover, FLT3LG and CCL5 or CCR5 gene expression signatures correlate with an enhanced cDC1 signature and a favorable overall survival in patients with cancer. Notably, cyclophosphamide elevated serum Flt3L levels and, in combination with the absence of DNGR-1, synergized against tumor growth.
Conclusion:
DNGR-1 limits the accumulation of tumor-infiltrating cDC1s promoted by Flt3L. Thus, DNGR-1 blockade may improve antitumor immunity in tumor therapy settings associated to high Flt3L expression.
Insights
DNGR-1 blockade enhances antitumor immunity by promoting the accumulation of beneficial immune cells in tumors, particularly when Flt3L is overexpressed. This strategy shows promise for cancer therapy by improving T cell responses and patient survival.
Area of Science:
- Immunology
- Cancer Biology
- Cell Biology
Background:
- Conventional type 1 dendritic cells (cDC1s) are crucial for antitumor immunity.
- DNGR-1 (CLEC9A) is a receptor on cDC1s involved in dead cell recognition, but its role in antitumor immunity is unclear.
Purpose of the Study:
- To investigate the role of DNGR-1 in antitumor immunity.
- To determine if DNGR-1 blockade can enhance anti-tumor responses, especially in combination with Flt3L therapy.
Main Methods:
- Used wild-type and DNGR-1-deficient mice with B16 and MC38 tumors.
- Employed Flt3L gene therapy to overexpress Flt3L systemically.
- Analyzed immune responses using flow cytometry and RNA-Seq of tumor-infiltrating cDC1s.
Main Results:
- DNGR-1 deficiency delayed tumor growth when Flt3L was overexpressed, an effect mimicked by DNGR-1 blocking antibodies.
- Antitumor immunity was enhanced by increased CD8+ T cell and cDC1 accumulation, dependent on Batf3.
- DNGR-1 deficiency boosted Flt3L-induced cDC1 inflammatory gene expression (e.g., Ccl5), driving cDC1 infiltration via CCL5/CCR5.
- FLT3LG, CCL5, and CCR5 gene signatures correlated with cDC1 presence and improved patient survival.
- Cyclophosphamide increased Flt3L levels, synergizing with DNGR-1 absence against tumors.
Conclusions:
- DNGR-1 limits Flt3L-driven accumulation of tumor-infiltrating cDC1s.
- DNGR-1 blockade represents a potential strategy to enhance antitumor immunity in cancer therapies involving high Flt3L expression.
