Zebularine elevates STING expression and enhances cGAMP cancer immunotherapy in mice.

Abstract

DNA methylation abnormality is closely related to tumor occurrence and development. Chemical inhibitors targeting DNA methyltransferase (DNMTis) have been used in treating cancer. However, the impact of DNMTis on antitumor immunity has not been well elucidated. In this study, we show that zebularine (a demethylating agent) treatment of cancer cells led to increased levels of interferon response in a cyclic guanosine monophosphate-AMP (cGAMP) synthase (cGAS)- and stimulator of interferon genes (STING)-dependent manner. This treatment also specifically sensitized the cGAS-STING pathway in response to DNA stimulation. Incorporation of zebularine into genomic DNA caused demethylation and elevated expression of a group of genes, including STING. Without causing DNA damage, zebularine led to accumulation of DNA species in the cytoplasm of treated cells. In syngeneic tumor models, administration of zebularine alone reduced tumor burden and extended mice survival. This effect synergized with cGAMP and immune checkpoint blockade therapy. The efficacy of zebularine was abolished in nude mice and in cGAS-/- or STING-/- mice, indicating its dependency on host immunity. Analysis of tumor cells indicates upregulation of interferon-stimulated genes (ISGs) following zebularine administration. Zebularine promoted infiltration of CD8 T cells and natural killer (NK) cells into tumor and therefore suppressed tumor growth. This study unveils the role of zebularine in sensitizing the cGAS-STING pathway to promote anti-tumor immunity and provides the foundation for further therapeutic development.

• Authors: Junzhong Lai, Yajuan Fu, Shuoran Tian, Shanlu Huang, Xuan Luo, Lili Lin, Xing Zhang, Hanze Wang, Zhang Lin, Heng Zhao, Shujin Lin, Junhong Zhao, Shan Xu, Daliang Li, Shaoli Cai, Luna Dong, Jing Qian, Jiadi Liang, Qiumei Li, Yong Zhang, Jiqiang Fan, Robert Balderas, Qi Chen
• Journal: Molecular therapy : the journal of the American Society of Gene Therapy (Mol Ther) Vol. 29 Issue 5 Pg. 1758-1771 (05 05 2021) ISSN: 1525-0024 [Electronic] United States
• PMID: 33571681 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2021 The American Society of Gene and Cell Therapy. Published by Elsevier Inc. All rights reserved.

Chemical References

• Membrane Proteins
• Nucleotides, Cyclic
• STING1 protein, human
• cyclic guanosine monophosphate-adenosine monophosphate
• Cytidine
• pyrimidin-2-one beta-ribofuranoside
• Nucleotidyltransferases
• cGAS protein, human

Topics

• Administration, Oral
• Animals
• CD8-Positive T-Lymphocytes (metabolism)
• Cell Line, Tumor
• Cell Proliferation (drug effects)
• Cell Survival (drug effects)
• Cytidine (administration & dosage, analogs & derivatives, pharmacology)
• Drug Synergism
• Humans
• Killer Cells, Natural (metabolism)
• Melanoma, Experimental (drug therapy, genetics, immunology)
• Membrane Proteins (genetics)
• Mice
• Mice, Nude
• Nucleotides, Cyclic (administration & dosage, pharmacology)
• Nucleotidyltransferases (genetics)
• Promoter Regions, Genetic
• THP-1 Cells
• Tumor Microenvironment
• Xenograft Model Antitumor Assays