Biology subjects

Ubellacker, J. M.

Publications and source records attributed to Ubellacker, J. M..

6 recordsLinked to original sources

bioRxiv2026

A mouse model of metastasis-induced breast cancer cachexia with non-cachectic controls bearing isogenic primary tumors

Background Patients with advanced cancer frequently develop cachexia, an involuntary weight-loss condition that correlates strongly with metastatic burden. Despite this clinical association, metastasis is rarely considered in preclinical research of cancer cachexia, which is in part due to the lack of rigorously established animal models to investigate metastasis-associated cancer cachexia. Methods To establish an animal model of metastasis-associated cancer cachexia, here we focused on syngeneic mouse models of breast cancer. Using the metastatic 4T1 murine breast cancer cell line and its isogenic non-metastatic 67NR cell line, we generated primary tumors via orthotopic injection into the mammary fat pad and surgically resected the primary tumor to allow sufficient time for spontaneous metastatic outgrowth, or generated experimental lung metastases by direct intravenous injection into the tail vein. Across these tumor-bearing groups, we systematically characterized the metastatic burden and cachectic phenotypes of the mice, including body weight, food intake, body composition, muscle mass, grip strength, locomotor activity, energy expenditure, and respiratory exchange ratio. To isolate the contribution of reduced food intake to the cachectic phenotypes, we pair-fed orthotopic 4T1 tumor-bearing mice (which were non-cachectic) to mice with 4T1 lung metastases (which were cachectic). We further measured muscle atrophy gene expression and profiled circulating cytokines and metabolic hormones for the mouse groups. Results Body weight loss occurred exclusively in mice bearing lung metastases from 4T1 tumors, with no weight loss observed in mice bearing either primary 4T1 tumors or 67NR lung tumors, thus presenting a model of cancer cachexia that is driven by 4T1 lung metastasis. Comprehensive cachexia characterization demonstrated that the 4T1 metastasis model recapitulates all key features of cachexia, manifesting as reduced food intake (or anorexia), depletion of adipose tissues, loss of lean mass including muscle mass loss, and reduced grip strength. Pair-feeding non-cachectic primary 4T1 tumor-bearing mice to 4T1 metastatic mice led to the same losses in body weight, fat, and lean mass as in cachectic mice, but no change in grip strength, indicating that anorexia is the primary driver of tissue wasting whereas muscle weakness arises through a food intake-independent mechanism. Moreover, we identified distinct circulating cytokines and metabolic hormones associated with the metastasis-driven cachexia. Conclusions Our results establish a metastasis-induced breast cancer cachexia model with a tightly matched control group, providing a platform for the field to identify metastasis-derived cachectic mediators and pathways.

cancer biology↗

bioRxiv2025

Overcoming impaired antigen presentation in tumor draining lymph nodes facilitates immunotherapy

Immunotherapies have revolutionized cancer care in recent decades, but approved therapies often fail and currently only target specific steps in the generation of anti-cancer immune responses. Notably, the majority of approved immunotherapies do not target antigen processing and presentation, which are key steps in the development of immune responses and harbor potential as targets to improve immunotherapy. Here, we demonstrate that breast tumors induce locoregional lymph node impairment in antigen presentation--but not in antigen processing--which limits anti-cancer antigen- specific T cell responses. Inhibition of the locoregional T cell response was due to a tumor-mediated reduction of the cytokine IL1{beta} in tumor draining lymph nodes, which impaired antigen presentation. Further, we tested the ability of dendritic cells in lymph nodes at various distances from the primary tumor to be activated utilizing an antigen- agnostic adjuvant delivery strategy. We observed improved anti-tumor T cell responses when the adjuvant was delivered to cancer antigen-positive lymph nodes distant from the tumor, suggesting these lymph nodes can be targeted to improve anti-cancer immune responses. When combined with immune checkpoint blockade, delivery of the adjuvant to distant lymph nodes led to long-term survival and protection from recurrence. Antigen presentation and T cell responses could also be recovered by exogenous delivery of IL1{beta} via intratumoral injection, with improved survival when combined with immune checkpoint blockade. Our study demonstrates that tumor- induced locoregional impairment of antigen presentation can be overcome by the appropriate introduction of immunological adjuvant to tumor-distant lymph nodes or by restoring IL1{beta} to the tumor-draining lymph node. These strategies can induce high- quality, durable immune responses and have clinical implications for expanding the efficacy of immunotherapies. SummaryBreast tumors induce locoregional lymph node impairments in antigen presentation, which can be remedied via either IL1{beta} delivery or antigen-agnostic adjuvant therapies to distant lymph nodes, facilitating better immunotherapy responses.

cancer biology↗

bioRxiv2025

Riboflavin metabolism shapes FSP1-driven ferroptosis resistance

Membrane protection against oxidative insults is achieved by the concerted action of glutathione peroxidase 4 (GPX4) and endogenous lipophilic antioxidants such as ubiquinone and vitamin E. Deficiencies in these protective systems lead to an increased propensity to phospholipid peroxidation and ferroptosis. More recently, ferroptosis suppressor protein 1 (FSP1) was identified as a critical ferroptosis inhibitor acting via regeneration of membrane-embedded antioxidants. Yet, regulators of FSP1 are largely uncharacterised, and their identification is essential for understanding the mechanisms buffering phospholipid peroxidation and ferroptosis. Here, we conducted a focused CRISPR-Cas9 screen to uncover factors influencing FSP1 function, identifying riboflavin (vitamin B2) as a new modulator of ferroptosis sensitivity. We demonstrate that riboflavin, unlike other vitamins that act as radical-trapping antioxidants, supports FSP1 stability and the recycling of lipid-soluble antioxidants, thereby mitigating phospholipid peroxidation. Furthermore, we show that the riboflavin antimetabolite roseoflavin markedly impairs FSP1 function and sensitises cancer cells to ferroptosis. Thus, we uncover a direct and actionable role for riboflavin in maintaining membrane integrity by promoting membrane tolerance to lipid peroxidation. Our findings provide a rational strategy to modulate the FSP1-antioxidant recycling pathway and underscore the therapeutic potential of targeting riboflavin metabolism, with implications for understanding the interaction of nutrients and their contributions to a cells antioxidant capacity.

cell biology↗

bioRxiv2023

Lymphatic muscle cells are unique cells that undergo aging induced changes

Lymphatic muscle cells (LMCs) within the wall of collecting lymphatic vessels exhibit tonic and autonomous phasic contractions, which drive active lymph transport to maintain tissue-fluid homeostasis and support immune surveillance. Damage to LMCs disrupts lymphatic function and is related to various diseases. Despite their importance, knowledge of the transcriptional signatures in LMCs and how they relate to lymphatic function in normal and disease contexts is largely missing. We have generated a comprehensive transcriptional single-cell atlas--including LMCs--of collecting lymphatic vessels in mouse dermis at various ages. We identified genes that distinguish LMCs from other types of muscle cells, characterized the phenotypical and transcriptomic changes in LMCs in aged vessels, and uncovered a pro-inflammatory microenvironment that suppresses the contractile apparatus in advanced-aged LMCs. Our findings provide a valuable resource to accelerate future research for the identification of potential drug targets on LMCs to preserve lymphatic vessel function as well as supporting studies to identify genetic causes of primary lymphedema currently with unknown molecular explanation.

cell biology↗

bioRxiv2023

Cancer immunotherapy responses persist after lymph node resection

Lymphatic transport facilitates the presentation of cancer antigens in tumor-draining lymph nodes (tdLNs), leading to T cell activation and the generation of systemic anti-cancer immune surveillance. Surgical removal of tdLNs to control cancer progression is routine in clinical practice. However, whether removing tdLNs impairs immune checkpoint blockade (ICB) is still controversial. Our analysis demonstrates that melanoma patients remain responsive to PD-1 checkpoint blockade after regional LN dissection. We were able to recapitulate the persistent response to ICB after regional LN resection in murine melanoma and mammary carcinoma models. Mechanistically, soluble antigen is diverted to distant LNs after tdLN dissection. Consistently, robust ICB responses in patients with head and neck cancer after primary tumor and tdLN resection correlated with the presence of reactive LNs in distant sites. These findings indicate that distant LNs sufficiently compensate for the removal of direct tdLNs and sustain the response to ICB.

cancer biology↗

bioRxiv2020

Metabolomic profiling of rare cell populations isolated by flow cytometry from tissues

Little is known about the metabolic regulation of rare cell populations because most metabolites are hard to detect in small numbers of cells. We previously described a method for metabolomic profiling of flow cytometrically-isolated hematopoietic stem cells (HSCs) that detects approximately 60 metabolites in 10,000 cells (Agathocleous et al., 2017). Here we describe a new method involving hydrophilic liquid interaction chromatography (HILIC) and high-sensitivity orbitrap mass spectrometry that detected approximately 160 metabolites in 10,000 HSCs, including many more glycolytic and lipid intermediates. We improved chromatographic separation, increased mass resolution, minimized ion suppression, extracted with acetonitrile, and eliminated sample drying. Most metabolites did not significantly change during cell preparation and sorting. We used this method to profile HSCs and circulating melanoma cells. HSCs exhibited increased glycerophospholipid metabolites relative to unfractionated bone marrow cells and altered purine biosynthesis after methotrexate treatment in vivo. Circulating melanoma cells were depleted for purine intermediates relative to subcutaneous tumors, suggesting they decrease purine synthesis during metastasis. These methods facilitate the routine metabolomic analysis of rare cell populations from tissues. Impact statementWe developed a method for metabolomic analysis of small numbers of flow cytometrically isolated cells from rare cell populations such as hematopoietic stem cells and circulating cancer cells.

cell biology↗