# Artemis (DCLRE1C) Acts as a Target to Enhance Radiotherapy Response in Triple-Negative Breast Cancer

## TL;DR

This study shows that targeting Artemis can improve radiotherapy outcomes in triple-negative breast cancer by increasing tumor sensitivity to radiation.

## Contribution

Artemis is identified as a novel radiosensitizing target and biomarker in triple-negative breast cancer.

## Key findings

- Artemis knockout or inhibition increased radiosensitivity in TNBC cells.
- Artemis depletion combined with radiotherapy prolonged survival in animal models.
- RNA-seq analysis linked Artemis depletion to activation of cellular senescence.

## Abstract

Patients with triple-negative breast cancer (TNBC) often experience poor patient outcomes due to a lack of reliable biomarkers and effective strategies to overcome radioresistance. In this study, we identify the novel roles of Artemis, both as a biomarker for radiosensitivity and a therapeutic target in TNBC. Using a genome-wide CRISPR-knockout screen, we identified Artemis as a key radiosensitizing target. Artemis knockout or pharmacological inhibition increased the sensitivity of TNBC cells to radiotherapy (RT), enhancing its anti-tumor effects. In animal models, Artemis knockout, in combination with RT, prolonged survival. Furthermore, RNA-seq analysis revealed that the activation of cellular senescence contributed to this enhanced therapeutic response in TNBC. Overall, our findings suggest that targeting Artemis could offer a new strategy to tailor and improve RT outcomes in TNBC patients.

Background/Objectives: The lack of canonical biomarkers and strategies to target radioresistance contribute to poor patient outcomes in triple-negative breast cancer (TNBC). Identifying and targeting novel radioresistance genes will benefit in enhancing radiotherapy response and treatment outcomes in TNBC patients. Methods: A genome-wide CRISPR screen was performed to identify radioresistance genes in the TNBC cell line. An in vitro clonogenic assay was used to assess the antiproliferative effects of Artemis knockout or pharmacologic inhibition of Artemis, either alone or in combination with RT. Tumor doubling time and animal survival were assessed using an in vivo xenograft model. RNA-seq analysis was performed to identify genes and pathways deregulated under Artemis knockout conditions, both alone and in combination with RT. Cellular senescence was evaluated using a β-galactosidase assay. Results: Our CRISPR screen identified Artemis as a top hit in RT-treated TNBC cells, whose depletion led to radiosensitization in TNBC. Artemis knockout significantly reduced cell proliferation and enhanced the antiproliferative effects of RT in vitro. Compared to mice-bearing control MDA-MB-231 xenografts, Artemis knockout exhibited prolonged survival that was further enhanced with RT. Bulk RNA-sequencing indicated that the antiproliferative and radiosensitization effects of Artemis depletion were mediated by the activation of cellular senescence which was confirmed with a β-galactosidase assay. Conclusions: Taken together, our results highlight the critical role of Artemis in TNBC cell proliferation and response to radiation. Our findings identify Artemis as a potential biomarker indicative of sensitivity to radiation and a putative target that could be inhibited to enhance the efficacy of RT in TNBC.