Biology subjects

Bradley, L. M.

Publications and source records attributed to Bradley, L. M..

4 recordsLinked to original sources

bioRxiv2025

Disabling PSGL-1 abrogates immune suppression and resistance to PD-1 blockade in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is a lethal cancer for which there is a critical need to identify novel therapeutic targets. Herein we define PSGL-1 as a checkpoint inhibitor using a syngeneic orthotopic model of PDAC. As with PDAC patients, CD8+ T cells within murine PDAC tumors expressed high levels of PSGL-1. PSGL-1-/- mice displayed striking T cell-dependent control of primary tumors and lung metastases. Extensive spatial remodeling within PDAC tumors occurred in PSGL-1-/- mice with a dramatic loss of proliferating tumor cells and an increase in CD8+ T cell engagement of antigen-presenting cells. The prominent CD8+ T cell infiltrates included subsets of pre-exhausted T cells retaining hallmarks of stemness and multifunctional effector capacity. These changes enabled a near complete response of PDAC to therapeutic PD-1 blockade. Our findings identify PSGL-1 as a key regulator of anti-tumor immunity in PDAC, highlighting its potential as a therapeutic target to limit CD8+ T cell exhaustion and enhance immunotherapy response. SummaryHope et al describe a pivotal function of PSGL-1 in CD8+ T cell responses to pancreatic ductal adenocarcinoma. Genetic deletion of PSGL-1 elicits tumor control by increasing T cell infiltration and maintaining functional subsets, thereby promoting sensitivity to PD-1 blockade.

immunology↗

bioRxiv2024

Macropinocytosis controls metabolic stress-driven CAF subtype identity in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) tumors are deficient in glutamine, an amino acid that tumor cells and CAFs use to sustain their fitness. In PDAC, both cell types stimulate macropinocytosis as an adaptive response to glutamine depletion. CAFs play a critical role in sculpting the tumor microenvironment, yet how adaptations to metabolic stress impact the stromal architecture remains elusive. In this study, we find that macropinocytosis functions to control CAF subtype identity when glutamine is limiting. Our data demonstrate that metabolic stress leads to an intrinsic inflammatory CAF (iCAF) program driven by MEK/ERK signaling. Utilizing in vivo models, we find that blocking macropinocytosis alters CAF subtypes and reorganizes the tumor stroma. Importantly, these changes in stromal architecture can be exploited to sensitize PDAC to immunotherapy and chemotherapy. Our findings demonstrate that metabolic stress plays a role in shaping the tumor microenvironment, and that this attribute can be harnessed for therapeutic impact. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=173 SRC="FIGDIR/small/625709v1_ufig1.gif" ALT="Figure 1"> View larger version (32K): org.highwire.dtl.DTLVardef@40b38eorg.highwire.dtl.DTLVardef@1cc6a3borg.highwire.dtl.DTLVardef@15283e8org.highwire.dtl.DTLVardef@5214d2_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2022

Control of alveolar macrophage differentiation by Siah1a/2 ubiquitin ligases limits carcinogen-induced lung adenocarcinoma

Tumor microenvironment components, including T and myeloid cells, play important roles in lung adenocarcinoma (LADC) progression and response to therapy. Here, we identify a role for Siah1a/2 ubiquitin ligases in controlling alveolar macrophage (AM) differentiation and urethane-induced LADC. Genetic ablation of Siah1a/2 in AMs enriched their immature state, coinciding with increased pro-tumorigenic and inflammatory gene signatures and abundance of Siah1a/2 substrates NRF2 and {beta}-catenin. Urethane administration to mice enriched the population of monocytic and immature-like AMs, which were more prevalent in the lungs of mice carrying Siah1a/2-ablated macrophages. While resembling transitional profibrotic macrophages often seen in lung fibrosis, enrichment of immature AMs coincided with the development of more frequent and larger lung tumors in urethane-treated mice harboring Siah1a/2 ablated macrophages compared with controls. Gene expression signature of Siah1a/2 ablated immature-like AMs is associated with increased infiltration of CD14+ immune cells and worse survival of LADC patients. Our findings identify Siah1a/2 as gatekeepers of cancer development by controlling AM differentiation and profibrotic phenotypes contributing to carcinogen-induced lung cancer.

cancer biology↗

bioRxiv2022

PSGL-1 directs early TCR signaling to repress metabolism and promote T cell exhaustion by modulating the TCF-1/TOX axis in CD8+ T cells.

Summary/AbstractWe previously identified the adhesion molecule PSGL-1 as a T cell intrinsic immune checkpoint regulator of T cell exhaustion. Here we show that the ability of PSGL-1 to restrain TCR sginaling correlates with decreased expression of the Zap70 inhibitor Ubash3b (Sts-1) in PSGL-1-deficient T cells. PSGL-1-deficency in T cells supports antitumor responses to a PD-1 blockade resistant melanoma wherein tumor-specific CD8+ T cells sustain an enhanced metabolic state, with an elevated metabolic gene signature that promotes increased glycolysis and glucose uptake to support effector functions. In models of chronic virus infection and cancer, this outcome was associated with CD8+ T cell stemness, as PSGL-1 deficient CD8+ T cells displayed increased TCF-1 and decreased TOX expression, a phenotype shown to be crucial for responsiveness to checkpoint inhibition. Further, we demonstrate that PSGL-1 signaling promotes development of exhaustion in human CD8+ T cells. Finally, pharmacologic blockade of PSGL-1 was sufficient to curtail T cell exhaustion and enhance functionality both with melanoma tumors and chronic LCMV infection, demonstrating that PSGL-1 represents a therapeutic target for immunotherapy for PD-1/PD-L1 resistant tumors.

immunology↗