Cort Breuer

All Publications

• Lymph node environment drives FSP1 targetability in metastasizing melanoma. Nature Palma, M., Chaufan, M., Breuer, C. B., Müller, S., Sabatier, M., Fraser, C. S., Szylo, K. J., Yavari, M., Carmona, A., Kaur, M., Melo, L. M., Cansiz, F., Monge-Lorenzo, J., Flores, M., Mishima, E., Nakamura, T., Proneth, B., Labrado, M., Liang, Y., Cayting, N., Zheng, L., Cañeque, T., Colombeau, L., Wahida, A., Friedmann Angeli, J. P., Tasdogan, A., Hui, S., Rodriguez, R., Conrad, M., Reticker-Flynn, N. E., Ubellacker, J. M. 2025

  Abstract

  Ferroptosis has emerged as an actionable target to eliminate therapy-resistant and metastatic cancers1. However, which ferroptosis surveillance systems may offer a therapeutic window to leverage redox maladaptation in cancer remains unclear. In melanoma, glutathione peroxidase 4 (GPX4) impedes ferroptosis during haematogenous metastasis, but is dispensable during lymphatic metastasis2. Here, using a metastatic mouse melanoma model selected for lymph node metastasis, we show that lymph-node-derived metastatic cells exhibit markedly diminished expression of glutamate-cysteine ligase (GCLC) and reduced glutathione (GSH) levels relative to their parental counterparts. This metabolic shift occurs within the hypoxic lymphatic niche. Under comparable low-oxygen conditions, GPX4 undergoes ubiquitination and proteasomal degradation. In response, lymph node metastatic cells acquire increased reliance on ferroptosis suppressor protein 1 (FSP1), which is localized with perinuclear lysosomes. These findings reveal that the reduced reliance on the GPX4 axis enables melanoma cells to shift toward FSP1 dependency. Notably, intratumoural monotherapy with selective FSP1 inhibitors (viFSP1 and FSEN1) effectively suppresses melanoma growth in lymph nodes, but not in subcutaneous tumours, emphasizing a microenvironment-specific dependency on FSP1. Thus, targeting FSP1 in the lymph nodes holds strong potential for blocking melanoma progression.

  View details for DOI 10.1038/s41586-025-09709-1

  View details for PubMedID 41193799

  View details for PubMedCentralID 9273022

• Spontaneous and experimental models of lymph node metastasis. Nature protocols Breuer, C. B., Xiong, Z., Wang, A., Rodriguez, G. E., Abhiraman, G. C., Garcia, K. C., Reticker-Flynn, N. E. 2025

  Abstract

  Lymph node (LN) metastasis is a conserved feature across most solid organ malignancies and portends worse prognoses. Functionally, LN metastases induce systemic tumor-specific immune tolerance and may serve as a reservoir for distant metastases. Nonetheless, there are relatively few preclinical models for interrogating the biology of LN metastasis and its systemic effects at various stages of metastatic progression. We describe a method for modeling LN metastasis of melanoma tumors in mice that enables assessment of tumor and immune cell phenotypes and the functional roles of nodal involvement on distant metastasis. Our model comprises a family of transplantable syngeneic melanoma tumor cell lines evolved to exhibit enhanced LN metastatic potential, which can be used to probe cancer-immune interactions and test new therapeutics. We present both (i) a spontaneous LN metastasis model involving primary tumor implantation and assessment of LN colonization 21-28 d later and (ii) an experimental metastasis model involving implantation of primary tumors followed by direct intra-LN injections of tumor cells. Both models can be extended to assess the impact of LN metastasis on the development of distant metastases through asynchronous intravenous injections of tumors. Finally, we discuss experimental design considerations including when to use spontaneous or experimental models and troubleshooting consistent LN metastasis, making this model accessible for researchers with basic mouse survival-surgery skills. We highlight how LN metastasis models can be used to profile metastatic immune reprogramming, measure the impact of nodal metastases on distant metastases and assess novel anti-metastatic therapeutics.

  View details for DOI 10.1038/s41596-025-01200-5

  View details for PubMedID 40804176

  View details for PubMedCentralID 10511214

• Redirecting immune signaling with cytokine adaptors. Nature communications Abhiraman, G. C., Householder, K. D., Rodriguez, G. E., Glassman, C. R., Saxton, R. A., Breuer, C. B., Wilson, S. C., Su, L., Yen, M., Hsu, C., Pillarisetty, V. G., Reticker-Flynn, N. E., Garcia, K. C. 2025; 16 (1): 2432

  Abstract

  Cytokines are signaling molecules that coordinate complex immune processes and are frequently dysregulated in disease. While cytokine blockade has become a common therapeutic modality, cytokine agonism has had limited utility due to the widespread expression of cytokine receptors with pleiotropic effects. To overcome this limitation, we devise an approach to engineer molecular switches, termed cytokine adaptors, that transform one cytokine signal into an alternative signal with a different functional output. Endogenous cytokines act to nucleate the adaptors, converting the cytokine-adaptor complex into a surrogate agonist for a different cytokine pathway. In this way, cytokine adaptors, which have no intrinsic agonist activity, can function as conditional, context-dependent agonists. We develop cytokine adaptors that convert IL-10 or TGF-β into IL-2 receptor agonists to reverse T cell suppression. We also convert the pro-inflammatory cytokines IL-23 or IL-17 into immunosuppressive IL-10 receptor agonists. Thus, we show that cytokine adaptors can convert immunosuppressive cytokines into immunostimulatory cytokines, or vice versa. Unlike other methods of immune conversion that require cell engineering, cytokine adaptors are soluble molecules that leverage endogenous cues from the microenvironment to drive context-specific signaling.

  View details for DOI 10.1038/s41467-025-57681-1

  View details for PubMedID 40069219

  View details for PubMedCentralID 4804829

• Type I interferon signaling instills divergent metastatic phenotypes and immunotherapy responses bioRxiv Breuer, C. B., Labrado, M., Rodriguez, G. E., Garcia, K., Reticker-Flynn, N. E. 2025

  View details for DOI 10.1101/2025.09.18.677123

• Bioengineered in vitro models of leukocyte-vascular interactions BIOCHEMICAL SOCIETY TRANSACTIONS Lee, J., Breuer, C. B., Lee, E. 2021; 49 (2): 693-704

  Abstract

  Leukocytes continuously circulate our body through the blood and lymphatic vessels. To survey invaders or abnormalities and defend our body against them, blood-circulating leukocytes migrate from the blood vessels into the interstitial tissue space (leukocyte extravasation) and exit the interstitial tissue space through draining lymphatic vessels (leukocyte intravasation). In the process of leukocyte trafficking, leukocytes recognize and respond to multiple biophysical and biochemical cues in these vascular microenvironments to determine adequate migration and adhesion pathways. As leukocyte trafficking is an essential part of the immune system and is involved in numerous immune diseases and related immunotherapies, researchers have attempted to identify the key biophysical and biochemical factors that might be responsible for leukocyte migration, adhesion, and trafficking. Although intravital live imaging of in vivo animal models has been remarkably advanced and utilized, bioengineered in vitro models that recapitulate complicated in vivo vascular structure and microenvironments are needed to better understand leukocyte trafficking since these in vitro models better allow for spatiotemporal analyses of leukocyte behaviors, decoupling of interdependent biological factors, better controlling of experimental parameters, reproducible experiments, and quantitative cellular analyses. This review discusses bioengineered in vitro model systems that are developed to study leukocyte interactions with complex microenvironments of blood and lymphatic vessels. This review focuses on the emerging concepts and methods in generating relevant biophysical and biochemical cues. Finally, the review concludes with expert perspectives on the future research directions for investigating leukocyte and vascular biology using the in vitro models.

  View details for DOI 10.1042/BST20200620

  View details for Web of Science ID 000647324100013

  View details for PubMedID 33843967

• In vivo engineering of lymphocytes after systemic exosome-associated AAV delivery SCIENTIFIC REPORTS Breuer, C. B., Hanlon, K. S., Natasan, J., Volak, A., Meliani, A., Mingozzi, F., Kleinstiver, B. P., Moon, J. J., Maguire, C. A. 2020; 10 (1): 4544

  Abstract

  Ex-vivo gene therapy using stem cells or T cells transduced by retroviral or lentiviral vectors has shown remarkable efficacy in the treatment of immunodeficiencies and cancer. However, the process is expensive, technically challenging, and not readily scalable to large patient populations, particularly in underdeveloped parts of the world. Direct in vivo gene therapy would avoid these issues, and such approaches with adeno-associated virus (AAV) vectors have been shown to be safe and efficacious in clinical trials for diseases affecting differentiated tissues such as the liver and CNS. However, the ability to transduce lymphocytes with AAV in vivo after systemic delivery has not been carefully explored. Here, we show that both standard and exosome-associated preparations of AAV8 vectors can effectively transduce a variety of immune cell populations including CD4+ T cells, CD8+ T cells, B cells, macrophages, and dendritic cells after systemic delivery in mice. We provide direct evidence of T cell transduction through the detection of AAV genomes and transgene mRNA, and show that intracellular and transmembrane proteins can be expressed. These findings establish the feasibility of AAV-mediated in vivo gene delivery to immune cells which will facilitate both basic and applied research towards the goal of direct in vivo gene immunotherapies.

  View details for DOI 10.1038/s41598-020-61518-w

  View details for Web of Science ID 000560154600003

  View details for PubMedID 32161326

  View details for PubMedCentralID PMC7066196