ZYS-1 is not an ADAR1 inhibitor

Area of Science:

• Molecular Biology
• Oncology
• Biochemistry

Background:

• Adenosine deaminase acting on RNA 1 (ADAR1) plays a role in cancer progression by editing double-stranded RNA (dsRNA).
• ADAR1 upregulation is common in various cancers, making it a potential therapeutic target.
• In ADAR1-dependent cells, ADAR1 depletion activates dsRNA sensors, leading to apoptosis and type I interferon production.

Purpose of the Study:

• To validate the efficacy and specificity of the small molecule ZYS-1 as a direct inhibitor of ADAR1.
• To assess the impact of ZYS-1 on cell viability in both ADAR1-dependent and independent cell lines.
• To determine if ZYS-1 affects cellular A-to-I editing and dsRNA sensing pathways.

Main Methods:

• In vitro and cellular experiments were conducted to evaluate ZYS-1's effects.
• Cell viability assays were performed on various cell lines, including ADAR1 knockout cells.
• Assays measured the activation of PKR, induction of IFN stimulated genes, and A-to-I editing at known ADAR1 sites.

Main Results:

• ZYS-1 exhibited similar cytotoxicity in ADAR1-dependent and independent cell lines, as well as wild-type and ADAR1 knockout cells.
• ZYS-1 treatment minimally affected PKR activation and IFN stimulated gene induction.
• Crucially, ZYS-1 did not reduce cellular A-to-I editing or inhibit in vitro ADAR1 activity.

Conclusions:

• The small molecule ZYS-1 does not selectively inhibit ADAR1.
• These findings challenge the proposed mechanism of ZYS-1 as a direct ADAR1 inhibitor.
• Further research is needed to identify selective ADAR1 inhibitors for cancer therapy.