All Publications

  • Sensitization of cancer cells to ferroptosis coincident with cell cycle arrest. Cell chemical biology Rodencal, J., Kim, N., He, A., Li, V. L., Lange, M., He, J., Tarangelo, A., Schafer, Z. T., Olzmann, J. A., Long, J. Z., Sage, J., Dixon, S. J. 2023


    Ferroptosis is a non-apoptotic form of cell death that can be triggered by inhibiting the system xc- cystine/glutamate antiporter or the phospholipid hydroperoxidase glutathione peroxidase 4 (GPX4). We have investigated how cell cycle arrest caused by stabilization of p53 or inhibition of cyclin-dependent kinase 4/6 (CDK4/6) impacts ferroptosis sensitivity. Here, we show that cell cycle arrest can enhance sensitivity to ferroptosis induced by covalent GPX4 inhibitors (GPX4i) but not system xc- inhibitors. Greater sensitivity to GPX4i is associated with increased levels of oxidizable polyunsaturated fatty acid-containing phospholipids (PUFA-PLs). Higher PUFA-PL abundance upon cell cycle arrest involves reduced expression of membrane-bound O-acyltransferase domain-containing 1 (MBOAT1) and epithelial membrane protein 2 (EMP2). A candidate orally bioavailable GPX4 inhibitor increases lipid peroxidation and shrinks tumor volumes when combined with a CDK4/6 inhibitor. Thus, cell cycle arrest may make certain cancer cells more susceptible to ferroptosis in vivo.

    View details for DOI 10.1016/j.chembiol.2023.10.011

    View details for PubMedID 37963466

  • A Cell Cycle-Dependent Ferroptosis Sensitivity Switch Governed by EMP2. bioRxiv : the preprint server for biology Rodencal, J., Kim, N., Li, V. L., He, A., Lange, M., He, J., Tarangelo, A., Schafer, Z. T., Olzmann, J. A., Sage, J., Long, J. Z., Dixon, S. J. 2023


    Ferroptosis is a non-apoptotic form of cell death characterized by iron-dependent lipid peroxidation. Ferroptosis can be induced by system xc- cystine/glutamate antiporter inhibition or by direct inhibition of the phospholipid hydroperoxidase glutathione peroxidase 4 (GPX4). The regulation of ferroptosis in response to system xc- inhibition versus direct GPX4 inhibition may be distinct. Here, we show that cell cycle arrest enhances sensitivity to ferroptosis triggered by GPX4 inhibition but not system xc- inhibition. Arrested cells have increased levels of oxidizable polyunsaturated fatty acid-containing phospholipids, which drives sensitivity to GPX4 inhibition. Epithelial membrane protein 2 (EMP2) expression is reduced upon cell cycle arrest and is sufficient to enhance ferroptosis in response to direct GPX4 inhibition. An orally bioavailable GPX4 inhibitor increased markers of ferroptotic lipid peroxidation in vivo in combination with a cell cycle arresting agent. Thus, responses to different ferroptosis-inducing stimuli can be regulated by cell cycle state.

    View details for DOI 10.1101/2023.07.19.549715

    View details for PubMedID 37502927

    View details for PubMedCentralID PMC10370086

  • A Tale of Two Lipids: Lipid Unsaturation Commands Ferroptosis Sensitivity. Proteomics Rodencal, J., Dixon, S. J. 2022: e2100308


    Membrane lipids play important roles in the regulation of cell fate, including the execution of ferroptosis. Ferroptosis is a non-apoptotic cell death mechanism defined by iron-dependent membrane lipid peroxidation. Phospholipids containing polyunsaturated fatty acids (PUFAs) are highly vulnerable to peroxidation and are essential for ferroptosis execution. By contrast, the incorporation of less oxidizable monounsaturated fatty acids (MUFAs) in membrane phospholipids protects cells from ferroptosis. The enzymes and pathways that govern PUFA and MUFA metabolism therefore play a critical role in determining cellular sensitivity to ferroptosis. Here, we review three lipid metabolic processes fatty acid biosynthesis, ether lipid biosynthesis, and phospholipid remodeling-that govern ferroptosis sensitivity by regulating the balance of PUFAs and MUFAs in membrane phospholipids. This article is protected by copyright. All rights reserved.

    View details for DOI 10.1002/pmic.202100308

    View details for PubMedID 36398995

  • Oxaliplatin disrupts nucleolar function through biophysical disintegration. Cell reports Schmidt, H. B., Jaafar, Z. A., Wulff, B. E., Rodencal, J. J., Hong, K., Aziz-Zanjani, M. O., Jackson, P. K., Leonetti, M. D., Dixon, S. J., Rohatgi, R., Brandman, O. 2022; 41 (6): 111629


    Platinum (Pt) compounds such as oxaliplatin are among the most commonly prescribed anti-cancer drugs. Despite their considerable clinical impact, the molecular basis of platinum cytotoxicity and cancer specificity remain unclear. Here we show that oxaliplatin, a backbone for the treatment of colorectal cancer, causes liquid-liquid demixing of nucleoli at clinically relevant concentrations. Our data suggest that this biophysical defect leads to cell-cycle arrest, shutdown of Pol I-mediated transcription, and ultimately cell death. We propose that instead of targeting a single molecule, oxaliplatin preferentially partitions into nucleoli, where it modifies nucleolar RNA and proteins. This mechanism provides a general approach for drugging the increasing number of cellular processes linked to biomolecular condensates.

    View details for DOI 10.1016/j.celrep.2022.111629

    View details for PubMedID 36351392

  • Nucleotide biosynthesis links glutathione metabolism to ferroptosis sensitivity. Life science alliance Tarangelo, A., Rodencal, J., Kim, J. T., Magtanong, L., Long, J. Z., Dixon, S. J. 1800; 5 (4)


    Nucleotide synthesis is a metabolically demanding process essential for DNA replication and other processes in the cell. Several anticancer drugs that inhibit nucleotide metabolism induce apoptosis. How inhibition of nucleotide metabolism impacts non-apoptotic cell death is less clear. Here, we report that inhibition of nucleotide metabolism by the p53 pathway is sufficient to suppress the non-apoptotic cell death process of ferroptosis. Mechanistically, stabilization of wild-type p53 and induction of the p53 target gene CDKN1A (p21) leads to decreased expression of the ribonucleotide reductase (RNR) subunits RRM1 and RRM2 RNR is the rate-limiting enzyme of de novo nucleotide synthesis that reduces ribonucleotides to deoxyribonucleotides in a glutathione-dependent manner. Direct inhibition of RNR results in conservation of intracellular glutathione, limiting the accumulation of toxic lipid peroxides and preventing the onset of ferroptosis in response to cystine deprivation. These results support a mechanism linking p53-dependent regulation of nucleotide metabolism to non-apoptotic cell death.

    View details for DOI 10.26508/lsa.202101157

    View details for PubMedID 35074928

  • Positive feedback amplifies ferroptosis. Nature cell biology Rodencal, J., Dixon, S. J. 1800; 24 (1): 4-5

    View details for DOI 10.1038/s41556-021-00824-5

    View details for PubMedID 35027732

  • Quantification of drug-induced fractional killing using high-throughput microscopy. STAR protocols Inde, Z., Rodencal, J., Dixon, S. J. 2021; 2 (1): 100300


    Anti-cancer drugs kill only a fraction of cells within a population at any given time. Here, we describe a protocol to quantify drug-induced fractional killing over time using high-throughput imaging. This protocol can be used to compare the effect of hundreds of conditions in parallel. We show how this protocol can be used to examine fractional killing in response to inhibitors of the mitogen-activated protein kinase pathway. For complete details on the use and execution of this protocol, please refer to Inde etal. (2020).

    View details for DOI 10.1016/j.xpro.2021.100300

    View details for PubMedID 33532743

  • TAp63-regulated microRNAs suppress cutaneous squamous cell carcinoma through inhibition of a network of cell cycle genes. Cancer research Davis, A. J., Tsinkevich, M., Rodencal, J., Abbas, H. A., Su, X., Gi, Y., Fang, B., Rajapakshe, K., Coarfa, C., Gunaratne, P. H., Koomen, J. M., Tsai, K. Y., Flores, E. R. 2020


    TAp63 is a p53 family member and potent tumor and metastasis suppressor. Here, we show that TAp63-/- mice exhibit an increased susceptibility to UVR-induced cutaneous squamous cell carcinoma (cuSCC). A human-to-mouse comparison of cuSCC tumors identified miR-30c-2* and miR-497 as underexpressed in TAp63-deficient cuSCC. Reintroduction of these microRNAs significantly inhibited the growth of cuSCC cell lines and tumors. Proteomic profiling of cells expressing either microRNA showed downregulation of cell cycle progression and mitosis associated proteins. A mouse to human and cross-platform comparison of RNA-Seq and proteomics data identified a 7-gene signature, including AURKA, KIF18B, PKMYT1, and ORC1, which were overexpressed in cuSCC. Knockdown of these factors in cuSCC cell lines suppressed tumor cell proliferation and induced apoptosis. Additionally, selective inhibition of AURKA suppressed cuSCC cell proliferation, induced apoptosis, and showed anti-tumor effects in vivo. Finally, treatment with miR-30c-2* or miR-497 microRNA mimics was highly effective in suppressing cuSCC growth in vivo. Our data establishes TAp63 as an essential regulator of novel microRNAs that can be therapeutically targeted for potent suppression of cuSCC.

    View details for DOI 10.1158/0008-5472.CAN-19-1892

    View details for PubMedID 32156775