TRDMT1 methyltransferase gene knockout attenuates STING-based cell death signaling during self-extracellular RNA-mediated response in drug-induced senescent osteosarcoma cells

TL;DR

This study shows that knocking out the TRDMT1 gene reduces immune responses and cell death in drug-resistant osteosarcoma cells triggered by self-RNA.

Contribution

The study reveals a novel role of TRDMT1 in modulating STING-based immune signaling in senescent osteosarcoma cells.

Findings

TRDMT1 gene knockout prevents STING activation and proinflammatory responses in senescent osteosarcoma cells.

TRDMT1 KO leads to replication stress and increased APOBEC3A/G levels when exposed to self-RNA.

RNA D and RNA S induce immune responses and cell death in proliferating osteosarcoma cells.

Abstract

Under stress conditions, endogenous biomolecules such as nucleic acids or proteins can be released from damaged cells and considered as damage-associated molecular patterns (DAMPs) activating innate immune system and context-dependent responses. In the present study, self-extracellular RNA was obtained from dying (RNA D) and senescent (RNA S) cellular models of osteosarcoma (OS), characterized by NGS, and tested against proliferating and non-proliferating (etoposide-indued senescent) OS cells (U-2 OS, SaOS-2, MG-63, 143B). RNA D and RNA S induced apoptosis, nitro-oxidative stress, nucleic acid sensing pathways and cytokine production, and RNA m5C methyltransferase-based responses (TRDMT1 and NSUN2) in proliferating OS cells. In drug-induced senescent OS cells, TRDMT1 gene knockout (KO) prevented STING activation, related proinflammatory response, and cell death. Furthermore, IFN-β binding RNA partners were identified, namely NSUN2, NSUN5, NSUN6, CDKN1A, MYC, and RAD51 transcripts and these interactions were compromised in TRDMT1 KO cells and upon RNA D and RNA S treatment. TRDMT1 KO also resulted in replication stress in OS cells that was potentiated by RNA D and RNA S stimulation and associated with elevated levels of APOBEC3A and APOBEC3G, members of the cytidine deaminase protein family. In conclusion, we showed that TRDMT1 KO restricted STING-based immune and cell death response to RNA D and RNA S in non-proliferating drug resistant OS cells that might have potential therapeutic implications.

The online version contains supplementary material available at 10.1007/s00018-025-05835-1.

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