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. 2024 May 28;43(5):114209.
doi: 10.1016/j.celrep.2024.114209. Epub 2024 May 14.

Identification of the extracellular membrane protein ENPP3 as a major cGAMP hydrolase and innate immune checkpoint

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Free article

Identification of the extracellular membrane protein ENPP3 as a major cGAMP hydrolase and innate immune checkpoint

Rachel Mardjuki et al. Cell Rep. .
Free article

Abstract

2'3'-Cyclic guanosine monophosphate (GMP)-AMP (cGAMP) is a second messenger synthesized upon detection of cytosolic double-stranded DNA (dsDNA) and passed between cells to facilitate downstream immune signaling. Ectonucleotide pyrophosphatase phosphodiesterase I (ENPP1), an extracellular enzyme, was the only metazoan hydrolase known to regulate cGAMP levels to dampen anti-cancer immunity. Here, we uncover ENPP3 as the second and likely the only other metazoan cGAMP hydrolase under homeostatic conditions. ENPP3 has a tissue expression pattern distinct from ENPP1's and accounts for all cGAMP hydrolysis activity in ENPP1-deficient mice. Importantly, we also show that, as with ENPP1, selectively abolishing ENPP3's cGAMP hydrolysis activity results in diminished cancer growth and metastasis of certain tumor types in a stimulator of interferon genes (STING)-dependent manner. Both ENPP1 and ENPP3 are extracellular enzymes, suggesting the dominant role that extracellular cGAMP must play as a mediator of cell-cell innate immune communication. Our work demonstrates that ENPP1 and ENPP3 non-redundantly dampen extracellular cGAMP-STING signaling, pointing to ENPP3 as a target for cancer immunotherapy.

Keywords: CP: Immunology; ENPP1; ENPP3; PD-1; STING; breast cancer; cGAMP; clinical trial; hydrolase; immune checkpoint; melanoma.

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Conflict of interest statement

Declaration of interests L.L. and J.C. have filed patents on ENPP1 inhibitors (PCT/US2020/015968 and PCT/US2018/050018) that are licensed to Angarus Therapeutics. L.L. is a co-founder of Angarus Therapeutics.

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