Breast cancer secretes anti-ferroptotic MUFAs and depends on selenoprotein synthesis for metastasis

ADAR1 Regulates Lipid Remodeling through MDM2 to Dictate Ferroptosis Sensitivity

Triple-negative breast cancer (TNBC), lacking expression of estrogen, progesterone, and HER2 receptors, is aggressive and lacks targeted treatment options. An RNA editing enzyme, adenosine deaminase acting on RNA 1 (ADAR1), has been shown to play important roles in TNBC tumorigenesis. We posit that ADAR1 functions as a homeostatic factor protecting TNBC from internal and external pressure, including metabolic stress. We tested the hypothesis that the iron- dependent cell death pathway, ferroptosis, is a ADAR1-protected metabolic vulnerability in TNBC by showing that ADAR1 knockdown sensitizes TNBC cells to GPX4 inhibitors. By performing single-reaction monitoring-based liquid chromatography coupled to mass spectrometry (LC-MS) to measure intracellular lipid contents, we showed that ADAR1 loss increased the abundance of polyunsaturated fatty acid phospholipids (PUFA-PL), of which peroxidation is the primary driver of ferroptosis. Transcriptomic analyses led to the discovery of the proto-oncogene MDM2 contributing to the lipid remodeling in TNBC upon ADAR1 loss. A phenotypic drug screen using a ferroptosis-focused library was performed to identify FDA- approved cobimetinib as a drug-repurposing candidate to synergize with ADAR1 loss to suppress TNBC tumorigenesis. By demonstrating that ADAR1 regulates the metabolic fitness of TNBC through desensitizing ferroptosis, we aim to leverage this metabolic vulnerability to inform basic, pre-clinical, and clinical studies to develop novel therapeutic strategies for TNBC.

Engineering Modular Peptide Nanoparticles for Ferroptosis-Enhanced Tumor Immunotherapy

Indoleamine 2,3-dioxygenase 1 (IDO1) inhibitors are promising for treating tumors but have limited efficacy due to the immunosuppressive tumor microenvironment. In this study, we develop an orchestrated nanoparticle system using modular peptide assemblies, where the co-assembled sequences are designed for the specific binding to the hydrophobic and hydrophilic domains, guiding the assembly process and enabling the customization of nanoparticle properties. We exploit the modularity of this platform to integrate a hydrophobic ferroptosis precursor, an IDO1 inhibitor, and a hydrophilic peptidic PD-L1 antagonist for optimizing therapeutic outcomes through ferroptosis-enhanced tumor immunotherapy. The resulting nanoparticles induce immunogenic ferroptosis, enhance the intratumoral function of T lymphocytes, suppress regulatory T cells, and effectively modulate the immunosuppressive tumor microenvironment, thereby facilitating regression of tumor growth. This work provides a modular peptide-based nanoparticle engineering strategy and holds significant potential for advancing cancer treatment.

Troubling bonds: lipid unsaturation promotes selenium dependency and sensitivity to ferroptosis

J. P. Friedmann-Angeli and A. F. dos Santos highlight two complementary studies recently published in EMBO Mol. Med . reporting examples of alterations in lipid metabolism that can promote targetable vulnerabilities for breast tumors with poor prognosis.