Biology subjects

Lee, J. V.

Publications and source records attributed to Lee, J. V..

8 recordsLinked to original sources

bioRxiv2026

Methionine metabolism and the NOP2 methyltransferase are essential for MYC-Driven liver tumorigenesis.

Hepatocellular carcinoma (HCC) represents the third leading cause of cancer-related death worldwide and has been increasing in developed nations.1,2 The MYC oncogene or its paralogs are frequently amplified or overexpressed in subtypes of cancer associated with stem cell-like features and worse clinical outcomes,3,4 including in liver cancer.5 Unfortunately, selective inhibitors that target MYC or its transcriptional program are not yet clinically available for therapy of HCC. Here, we identified methionine metabolism as a selective vulnerability for MYC but not RAS-driven liver cancers. MYC-driven liver cancer cells are methionine dependent, with markedly diminished tumor growth when mice are fed a methionine low diet. While RAS-driven liver cancer was resistant to a low methionine diet. S-adenosylmethionine (SAM), the predominant methyl donor, partially rescues cell proliferation following methionine depletion, suggesting that methylation processes are especially critical in the context of MYC high tumor cells. Heavy isotope methionine tracing in MYC high cells identified increased levels of m5C nucleotides. We found NOP2, an rRNA m5C-methyltransferase, was regulated by both MYC overexpression and methionine abundance linking the two processes. Methionine depletion reduced methylation of multiple 28S rRNA residues as did NOP2 knockdown. Depletion of NOP2 selectively inhibited MYC liver cancer cell proliferation and in vivo tumor growth. Thus, methionine catabolism is critical for MYC-driven liver tumorigenesis and the rRNA methyltransferase NOP2 may serve as a new therapeutic target in liver cancer.

cancer biology↗

bioRxiv2025

Alanine Catabolism as a Targetable Vulnerability for MYC-Driven Liver Cancer

Liver cancer is a leading cause of cancer-related death world-wide in part due to the shortage of effective therapies, and MYC overexpression defines an aggressive and especially difficult to treat subset of patients. Given MYCs ability to reprogram cancer cell metabolism, and the livers role as a coordinator of systemic metabolism, we hypothesized that MYC induces metabolic dependencies that could be targeted to attenuate liver tumor growth. We discovered that MYC-driven liver cancers catabolize alanine in a GPT2-dependent manner to sustain their growth. GPT2 is the predominant alanine-catabolizing enzyme expressed in MYC-driven liver tumors and genetic ablation of GPT2 limited MYC-driven liver tumorigenesis. In vivo isotope tracing studies uncovered a role for alanine as a substrate for a repertoire of pathways including the tricarboxylic acid cycle, nucleotide production, and amino acid synthesis. Treating transgenic MYC-driven liver tumor mouse models with L-Cycloserine, a compound that inhibits GPT2, was sufficient to diminish the frequency of mouse tumor formation and attenuate growth of established human liver tumors. Thus, we identify a new targetable metabolic dependency that MYC-driven liver tumors usurp to ensure their survival.

cancer biology↗

bioRxiv2025

Gut bacterial lactate stimulates lung epithelial mitochondria and exacerbates acute lung injury

Acute respiratory distress syndrome (ARDS) is an often fatal critical illness where lung epithelial injury leads to intrapulmonary fluid accumulation. ARDS became widespread during the COVID-19 pandemic, motivating a renewed effort to understand the complex etiology of this disease. Rigorous prior work has implicated lung endothelial and epithelial injury in response to an insult such as bacterial infection; however, the impact of microorganisms found in other organs on ARDS remains unclear. Here, we use a combination of gnotobiotic mice, cell culture experiments, and re-analyses of a large metabolomics dataset from ARDS patients to reveal that gut bacteria impact lung cellular respiration by releasing metabolites that alter mitochondrial activity in lung epithelium. Colonization of germ-free mice with a complex gut microbiota stimulated lung mitochondrial gene expression. A single human gut bacterial species, Bifidobacterium adolescentis, was sufficient to replicate this effect, leading to a significant increase in mitochondrial membrane potential in lung epithelial cells. We then used genome sequencing and mass spectrometry to confirm that B. adolescentis produces L-lactate, which was sufficient to increase mitochondrial activity in lung epithelial cells. Finally, we found that serum lactate was significantly associated with disease severity in patients with ARDS from the Early Assessment of Renal and Lung Injury (EARLI) cohort. Together, these results emphasize the importance of more broadly characterizing the microbial etiology of ARDS and other lung diseases given the ability of gut bacterial metabolites to remotely control lung cellular respiration. Our discovery of a single bacteria-metabolite pair provides a proof-of-concept for systematically testing other microbial metabolites and a mechanistic biomarker that could be pursued in future clinical studies. Furthermore, our work adds to the growing literature linking the microbiome to mitochondrial function, raising intriguing questions as to the bidirectional communication between our endo- and ecto-symbionts.

molecular biology↗

bioRxiv2023

Stability of navigation in catheter-based endovascular procedures

Endovascular procedures provide surgeons and other interventionalists with minimally invasive methods to treat vascular diseases by passing guidewires, catheters, sheaths and treatment devices into the vasculature to and navigate toward a treatment site. The efficiency of this navigation affects patient outcomes, but is frequently compromised by catheter "herniation", in which the catheter-guidewire system bulges out from the intended endovascular pathway so that the interventionalist can no longer advance it. Here, we showed herniation to be a bifurcation phenomenon that can be predicted and controlled using mechanical characterizations of catheter-guidewire systems and patientspecific clinical imaging. We demonstrated our approach in laboratory models and, retrospectively, in patients who underwent procedures involving transradial neurovascular procedures with an endovascular pathway from the wrist, up in the arm, around the aortic arch, and into the neurovasculature. Our analyses identified a mathematical navigation stability criterion that predicted herniation in all of these settings. Results show that herniation can be predicted through bifurcation analysis, and provide a framework for selecting catheter-guidewire systems to avoid herniation in specific patient anatomy.

bioengineering↗

bioRxiv2022

Dissecting the contributions of tumor heterogeneity on metastasis at single-cell resolution

Metastasis is the leading cause of cancer-related deaths, but metastasis research is challenged by limited access to patient material and a lack of experimental models that appropriately recapitulate tumor heterogeneity. Here, we analyzed single-cell transcriptomes of matched primary tumor and metastasis from patient-derived xenograft models of breast cancer, demonstrating that primary tumor and metastatic cells show profound transcriptional differences across heterogeneous tumors. While primary tumor cells upregulated several metabolic genes, metastatic cells displayed a motility phenotype in micrometastatic lesions and increased stress response signaling during metastatic progression. Additionally, we identified gene signatures that are associated with the metastatic potential and correlated with patient outcomes. Poorly metastatic primary tumors showed increased immune-regulatory control that may prevent metastasis, whereas highly metastatic primary tumors upregulated markers of epithelial-mesenchymal transition (EMT). We found that intra-tumor heterogeneity is dominated by epithelial-mesenchymal plasticity (EMP) which presented as a dynamic continuum with intermediate cell states that were characterized by novel, specific markers. These intermediate EMP markers correlated with worse patient outcomes and could serve as potential new therapeutic targets to block metastatic development.

cancer biology↗

bioRxiv2021

Combinatorial immunotherapies overcome MYC-driven immune evasion

For many human cancers, including triple negative breast cancer (TNBC), a modest number of patients benefit from immune checkpoint inhibitors, and few experience cancer remission1. Expression of programed death-ligand 1 (PD-L1), tumor immune infiltration, or tumor mutation burden have been widely investigated for predicting cancer immunotherapy response1-5. Whether specific oncogenes diminish response to immunotherapy6-10 and whether these effects are reversible remains poorly understood. We predicted that MYC, an oncogene that is frequently overexpressed11,12 and is associated with worse prognosis12, may predict immunotherapy response in patients with TNBC. Here, we report that MYC-elevated TNBCs are resistant to immune checkpoint inhibitors. Using mouse models of TNBC and patient data we report that MYC signaling is associated with low tumor cell PD-L1, low overall immune cell infiltration, and low tumor cell MHC-I expression. Restoring interferon signaling in the tumor reduces MYC expression and increases MHC-I expression. By combining a TLR9 agonist and an agonistic antibody against OX40 with anti-PD-L1, most mice experience complete tumor regression and are protected from new TNBC tumor outgrowth. Our findings demonstrate that MYC-dependent immune evasion is reversible and druggable, and if strategically targeted, may improve outcomes for patients treated with immune checkpoint inhibitors.

cancer biology↗

bioRxiv2020

In vivo optical metabolic imaging of long-chain fatty acid uptake in orthotopic models of triple negative breast cancer

Targeting a tumors metabolic dependencies is a clinically actionable therapeutic approach, but identifying subtypes of tumors likely to respond remains difficult. The use of lipids as a nutrient source is of particular importance, especially in breast cancer. Imaging techniques offer the opportunity to quantify nutrient use in preclinical models to aid in the development of new drugs to restrict uptake or utilization of these nutrients. We describe a fast and dynamic approach to image fatty acid uptake in vivo, a tool relevant to study tumor metabolic reprogramming or for studying the effectiveness of drugs targeting lipid metabolism spanning beyond breast cancer and optical imaging alone. Specifically, we developed a quantitative optical approach to spatially and longitudinally map the kinetics of long-chain fatty acid uptake in in vivo murine models of breast cancer using a fluorescently labeled palmitate molecule, Bodipy FL c16. We chose intra-vital microscopy of mammary tumor windows to validate our approach in two orthotopic breast cancer models: a MYC-overexpressing transgenic triple-negative breast cancer (TNBC) model and a murine model of the 4T1 family. Following injection, Bodipy FL c16 fluorescence increased and reached its maximum after approximately 30 minutes, with the signal remaining stable during the 30-80-minute post-injection period. We used the fluorescence at 60 minutes (Bodipy60), the mid-point in the plateau region, as a summary parameter to quantify Bodipy FL c16 fluorescence in subsequent experiments. Using our imaging platform, we observed a two- to four-fold decrease in fatty acid uptake in response to the downregulation of the MYC oncogene consistent with findings from in vitro metabolic assays. In contrast, our imaging studies report an increase in fatty acid uptake with tumor aggressiveness (6NR, 4T07, and 4T1), and uptake was significantly decreased after treatment with a fatty acid transport inhibitor, perphenazine, in both normal mammary pads and in the most aggressive 4T1 tumor model. Our approach fills an important gap between in vitro assays, which provide rich metabolic information but at static time points, and imaging approaches that can visualize metabolism in whole organs, but which suffer from poor resolution.

bioengineering↗

bioRxiv2020

Increased mTOR activity and metabolic efficiency in mouse and human cells containing the African-centric tumor-predisposing p53 variant Pro47Ser

The Pro47Ser variant of p53 exists in African-descent populations, and is associated with increased cancer risk in humans and mice. This variant, hereafter S47, shows altered regulation of the cystine importer Slc7a11, and S47 cells possess increased cysteine and glutathione (GSH) accumulation compared to cells with wild type p53. In this study we show that mice containing the S47 variant have increased mTOR activity, increased oxidative metabolism, larger size, and improved metabolic efficiency. Mechanistically, we show that there is increased association between mTOR and its positive regulator Rheb in S47 cells, due to altered redox state of GAPDH, which normally binds and sequesters Rheb. Compounds that decrease glutathione in S47 cells normalize GAPDH-Rheb complex formation and mTOR activity. The enhanced metabolic efficiency may have been selected for in early Africa, making the S47 variant one of a growing number of cancer-predisposing genetic variants that possesses other positive, potentially selectable attributes.

cancer biology↗