Biology subjects

Fearon, D. T.

Publications and source records attributed to Fearon, D. T..

5 recordsLinked to original sources

bioRxiv2025

Crosslinked CXCR4 Signals Decreased Motility and Increased Adhesion of T Cells

Pancreatic ductal adenocarcinoma (PDA) is a highly aggressive cancer known for its ability to evade immune surveillance, primarily through mechanisms that prevent T cell infiltration. While the coating of cancer cells with the chemokine, CXCL12, is required for the exclusion of T cells, the precise molecular mechanisms behind the failure of T cell migration into the tumor remain unclear. In this study, we identify a potential mechanism by demonstrating that crosslinking CXCR4 is associated with decreased motility of T cells secondary to their adhesion to fibronectin. Using human lymphoblastoid T cells and primary human T cells, we show that polymeric CXCL12-induced crosslinked CXCR4 triggers the non-G i-dependent pathway of tyrosine phosphorylation of FAK-related proline-rich tyrosine kinase 2 (PTK2B) in T cells. This response is necessary for the decreased motility and increased adhesion of T cells. We also find that the downstream cellular reactions of this pathway is secondary to CXCR4-crosslinking and require the integrin subunit, 4, and TNF stimulation of TNFRSF1B. These findings provide insights into the mechanisms mediating the exclusion of T cells from nests of PDA cells and further support therapeutic strategies aimed at blocking the interaction of CXCR4 on T cells with the CXCL12-coating of PDA cells.

immunology↗

bioRxiv2025

Signal peptide-independent secretion of keratin-19 by pancreatic cancer cells

The exclusion of T cells causes immune escape of pancreatic ductal adenocarcinoma (PDA). T cell exclusion is mediated by the interaction between CXCR4 on T cells and its ligand, CXCL12, which is complexed to keratin-19 (KRT19) on the surface of PDA cells. KRT19 secretion by PDA cells is essential to this process but is unusual because KRT19 lacks an endoplasmic reticulum (ER)-directing signal peptide (SP). By using biotinylation by an ER-restricted TurboID system and a split-GFP assay in PDA cells, we demonstrate that KRT19 enters the ER via its "head" domain. Additionally, KRT19 is shown to interact with the signal recognition particle and its secretion is sensitive to canonical protein secretion inhibitors. In vivo, mouse tumors formed with ER-TurboID-expressing PDA cells contain biotinylated KRT19. In contrast, keratin-8 (KRT8), which colocalizes with KRT19 on the surface of PDA cells, does not enter the ER. Rather, KRT8 is externalized via secretory autophagy possibly in a complex with KRT19. Thus, despite lacking a classical SP, PDA cells secrete KRT19 to capture CXCL12 and protect against immune attack. Significance StatementPancreatic ductal adenocarcinoma (PDA) is resistant to immunotherapy because T cells are excluded from cancer cell nests. Cancer cells capture cancer associated fibroblast sourced CXCL12, which ligates T cell CXCR4, to exclude T cells from cancer cell nests. CXCL12 is captured by cancer cells via the externalization of the normally intracellular intermediate filament keratin-19 (KRT19). We studied the unconventional secretion of KRT19 and found it is secreted by signal peptide independent entry into the endoplasmic reticulum, as well as via secretory autophagy. Thus, PDA externalized immunosuppressive KRT19 through two unconventional means.

cell biology↗

bioRxiv2022

T cell-mediated development of stromal fibroblasts with an immune-enhancing chemokine profile

Stromal fibroblasts reside in inflammatory tissues that are characterized by either immune suppression or immune activation, but whether these cells adapt to these contrasting microenvironments is not known. Cancer-associated fibroblasts (CAFs) mediate immune quiescence by producing the chemokine CXCL12 that coats cancer cells to suppress T cell infiltration. We examined whether CAFs can adopt an immune-promoting chemokine profile. Single-cell RNA-sequencing of CAFs from mouse pancreatic adenocarcinomas identified a sub-population with decreased expression of CXCL12 and increased expression of the T cell-attracting chemokine, CXCL9, that was expanded when tumors were infiltrated with T cells. Conditioned media from activated CD8+ T cells containing TNF and IFN{gamma} converted the chemokine profile of stromal fibroblasts from a CXCL12+/CXCL9- immune suppressive phenotype into a CXCL12-/CXCL9+ immune-activating phenotype. Studies with recombinant cytokines showed that TNF acted synergistically with IFN{gamma} to induce CXCL9 expression, and alone was mainly responsible for suppressing CXCL12 expression. This coordinated chemokine switch demonstrates that stromal fibroblasts have a phenotypic plasticity that allow their adaptation to contrasting immune tissue microenvironments. SummaryIt is unclear whether and how stromal fibroblasts adapt and contribute to varying tissue microenvironments. This study shows immune-suppressive cancer-associated fibroblasts (CAFs) have the capacity to develop an immune-promoting chemokine profile in response to cytokines from infiltrating T cells.

immunology↗

bioRxiv2018

Cancer cell CCR2 orchestrates suppression of the adaptive immune response

C-C chemokine receptor type 2 (CCR2) is expressed on monocytes and facilitates their recruitment to tumors. Though breast cancer cells also express CCR2, its functions in these cells are unclear. We found that Ccr2 deletion in cancer cells led to reduced tumor growth and [~]2-fold longer survival in an orthotopic, isograft breast cancer mouse model. Deletion of Ccr2 in cancer cells resulted in multiple alterations associated with better immune control: increased infiltration and activation of cytotoxic T lymphocytes (CTLs) and CD103+ cross-presenting dendritic cells (DCs), as well as upregulation of MHC class I and downregulation of checkpoint regulator PD-L1 on the cancer cells. Pharmacological or genetic targeting of CCR2 increased cancer cell sensitivity to CTLs and enabled the cancer cells to induce DC maturation toward the CD103+ subtype. Consistently, Ccr2-/- cancer cells did not induce immune suppression in Batf3-/- mice lacking CD103+ DCs. Our results establish that CCR2 signaling in cancer cells can orchestrate suppression of the immune response. SummaryC-C chemokine receptor type 2 (CCR2) expressed on monocytes facilitates their recruitment to tumors. Here, CCR2 signaling in cancer cells is shown to suppress immune control of tumors, in part by reducing CD103+ dendritic cell recruitment.

cancer biology↗

bioRxiv2017

Endoplasmic reticulum stress engenders immune-resistant, latent pancreatic cancer metastases

Patients who have had their primary pancreatic ductal adenocarcinoma (PDA) surgically resected often develop metastatic disease, exemplifying the problem of latent metastases. Livers from patients and mice with PDA contained single, disseminated cancer cells (DCCs) with an unusual phenotype of being cytokeratin-19 (CK19)- and MHC class I (MHCI)-. We created a mouse model to determine how DCCs develop, their relationship to metastatic latency, and the role of immunity. Intra-portal injection of immunogenic PDA cells into pre-immunized mice seeded livers only with single, non-replicating DCCs lacking MHCI and CK19; naive recipients had macro-metastases. Transcriptomic analysis of PDA cells with the DCC phenotype demonstrated an endoplasmic reticulum (ER) stress response. Relieving ER stress with a chemical chaperone, in combination with T cell-depletion, stimulated outgrowth of macro-metastatic lesions containing PDA cells expressing MHCI and CK19. The ER stress response is the cell-autonomous reaction that enables DCCs to escape immunity and establish latent metastases.\n\nOne sentence summaryLatent pancreatic cancer metastases are created when T cells select disseminated cancer cells in which immune resistance and quiescence have been imposed by endoplasmic stress.

immunology↗