OAS-RNase L innate immune pathway mediates the cytotoxicity of a DNA-demethylating drug.

Abstract

Drugs that reverse epigenetic silencing, such as the DNA methyltransferase inhibitor (DNMTi) 5-azacytidine (AZA), have profound effects on transcription and tumor cell survival. AZA is an approved drug for myelodysplastic syndromes and acute myeloid leukemia, and is under investigation for different solid malignant tumors. AZA treatment generates self, double-stranded RNA (dsRNA), transcribed from hypomethylated repetitive elements. Self dsRNA accumulation in DNMTi-treated cells leads to type I IFN production and IFN-stimulated gene expression. Here we report that cell death in response to AZA treatment occurs through the 2',5'-oligoadenylate synthetase (OAS)-RNase L pathway. OASs are IFN-induced enzymes that synthesize the RNase L activator 2-5A in response to dsRNA. Cells deficient in RNase L or OAS1 to 3 are highly resistant to AZA, as are wild-type cells treated with a small-molecule inhibitor of RNase L. A small-molecule inhibitor of c-Jun NH2-terminal kinases (JNKs) also antagonizes RNase L-dependent cell death in response to AZA, consistent with a role for JNK in RNase L-induced apoptosis. In contrast, the rates of AZA-induced and RNase L-dependent cell death were increased by transfection of 2-5A, by deficiencies in ADAR1 (which edits and destabilizes dsRNA), PDE12 or AKAP7 (which degrade 2-5A), or by ionizing radiation (which induces IFN-dependent signaling). Finally, OAS1 expression correlates with AZA sensitivity in the NCI-60 set of tumor cell lines, suggesting that the level of OAS1 can be a biomarker for predicting AZA sensitivity of tumor cells. These studies may eventually lead to pharmacologic strategies for regulating the antitumor activity and toxicity of AZA and related drugs.

• Authors: Shuvojit Banerjee, Elona Gusho, Christina Gaughan, Beihua Dong, Xiaorong Gu, Elise Holvey-Bates, Manisha Talukdar, Yize Li, Susan R Weiss, Frank Sicheri, Yogen Saunthararajah, George R Stark, Robert H Silverman
• Journal: Proceedings of the National Academy of Sciences of the United States of America (Proc Natl Acad Sci U S A) Vol. 116 Issue 11 Pg. 5071-5076 (03 12 2019) ISSN: 1091-6490 [Electronic] United States
• PMID: 30814222 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2019 the Author(s). Published by PNAS.

Chemical References

• Adaptor Proteins, Signal Transducing
• Isoenzymes
• MAVS protein, human
• Small Molecule Libraries
• JNK Mitogen-Activated Protein Kinases
• 2',5'-Oligoadenylate Synthetase
• Endoribonucleases
• 2-5A-dependent ribonuclease
• Phosphoric Diester Hydrolases
• Azacitidine

Topics

• 2',5'-Oligoadenylate Synthetase (metabolism)
• A549 Cells
• Adaptor Proteins, Signal Transducing (metabolism)
• Azacitidine (pharmacology)
• Cell Death (drug effects)
• DNA Demethylation
• Drug Resistance, Neoplasm (drug effects)
• Endoribonucleases (metabolism)
• Humans
• Immunity, Innate
• Isoenzymes (metabolism)
• JNK Mitogen-Activated Protein Kinases (antagonists & inhibitors, metabolism)
• Phosphoric Diester Hydrolases (metabolism)
• Radiation, Ionizing
• Small Molecule Libraries (pharmacology)