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| 2. |
- Cumming, Joshua, 1991-
(författare)
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The identification and functional evaluation of novel cancer-associated fibroblast subtypes and matrisome proteins in pancreatic cancer
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal malignancy characterized by an extensive desmoplastic stroma. The stroma is the site of intricate communication between malignant cells and their surrounding environment. This tissue microenvironment (TME) is populated by a heterogenous mixture of cell types and extracellular matrix proteins. Distinct stromal elements confer tumour-restraining or tumour-promoting influences on tumorigenesis. Characterizing stromal composition therefore represents an opportunity to identify candidates for therapeutic intervention to facilitate improved clinical outcomes. In this thesis we identify galectin-4 as an extracellular matrix protein which is upregulated in PDAC. We find that galectin-4 exerts a pro-tumorigenic influence in PDAC through promoting immune suppression, highlighting its potential as a novel therapeutic target. We subsequently provide a comprehensive characterization of mesenchymal cell diversity in PDAC including cancer-associated fibroblasts (CAFs) which represent one of the dominant stromal cellular components. We identify inflammatory CAF (iCAF) and myofibroblastic CAF (myCAF) subtypes in addition to defining a novel interferon-response CAF (ifCAF) subtype. In addition, we demonstrate that pancreatic stellate cells (PSCs) are capable of forming iCAFs, myCAFs and ifCAFs in response to tumour-derived signals using an organoid-based co-culture model and define biological pathways regulating CAF subtype formation. We then perform a high-throughput drug-screen using this co-culture model to identify compounds which can suppress tumour growth indirectly through modifying CAFs. One such compound is GNF-5 which we show can suppress cancer cell proliferation indirectly through manipulating CAF phenotype. Taken together, this thesis augments our understanding of the composition of the PDAC stroma and identifies potential therapeutic targets as well as developing an approach to discover drugs which yield a therapeutic benefit through targeting the PDAC stroma.
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| 3. |
- Jidigam, Vijay K., et al.
(författare)
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Apical constriction and epithelial invagination are regulated by BMP activity
- 2015
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Ingår i: Biology open. - : The Company of Biologists. - 2046-6390. ; 4:12, s. 1782-1791
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Tidskriftsartikel (refereegranskat)abstract
- Epithelial invagination is a morphological process in which flat cell sheets transform into three-dimensional structures through bending of the tissue. It is accompanied by apical constriction, in which the apical cell surface is reduced in relation to the basal cell surface. Although much is known about the intra-cellular molecular machinery driving apical constriction and epithelial invagination, information of how extra-cellular signals affect these processes remains insufficient. In this study we have established several in vivo assays of placodal invagination to explore whether the external signal BMP regulates processes connected to epithelial invagination. By inhibiting BMP activity in prospective cranial placodes, we provide evidence that BMP signals are required for RhoA and F-actin rearrangements, apical constriction, cell elongation and epithelial invagination. The failure of placode invagination after BMP inhibition appears to be a direct consequence of disrupted apical accumulation of RhoA and F-actin, rather than changes in cell death or proliferation. In addition, our results show that epithelial invagination and acquisition of placode-specific identities are two distinct and separable developmental processes. In summary, our results provide evidence that BMP signals promote epithelial invagination by acting upstream of the intracellular molecular machinery that drives apical constriction and cell elongation.
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| 4. |
- Lara-Ramirez, Ricardo, et al.
(författare)
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A Notch-regulated proliferative stem cell zone in the developing spinal cord is an ancestral vertebrate trait
- 2019
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Ingår i: Development. - : Company of Biologists. - 0950-1991 .- 1477-9129. ; 146:1
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Tidskriftsartikel (refereegranskat)abstract
- Vertebrates have evolved the most sophisticated nervous systems we know. These differ from the nervous systems of invertebrates in several ways, including the evolution of new cell types, and the emergence and elaboration of patterning mechanisms to organise cells in time and space. Vertebrates also generally have many more cells in their central nervous systems than invertebrates, and an increase in neural cell number may have contributed to the sophisticated anatomy of the brain and spinal cord. Here, we study how increased cell number evolved in the vertebrate central nervous system, investigating the regulation of cell proliferation in the lamprey spinal cord. Markers of proliferation show that a ventricular progenitor zone is found throughout the lamprey spinal cord. We show that inhibition of Notch signalling disrupts the maintenance of this zone. When Notch is blocked, progenitor cells differentiate precociously, the proliferative ventricular zone is lost and differentiation markers become expressed throughout the spinal cord. Comparison with other chordates suggests that the emergence of a persistent Notch-regulated proliferative progenitor zone was a crucial step for the evolution of vertebrate spinal cord complexity.
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| 5. |
- Lara-Ramirez, Ricardo, et al.
(författare)
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Characterization of two neurogenin genes from the brook lamprey lampetra planeri and their expression in the lamprey nervous system
- 2015
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Ingår i: Developmental Dynamics. - : Wiley. - 1058-8388 .- 1097-0177. ; 244:9, s. 1096-1108
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Tidskriftsartikel (refereegranskat)abstract
- Background: Neurogenins are required for the specification of neuronal precursors and regulate the expression of basic Helix-Loop-Helix genes involved in neuronal differentiation. Jawed vertebrates possess three Neurogenin paralogy groups and their combined expression covers the entire nervous system, apart from the autonomic nervous system. Results: Here we report the isolation of two Neurogenin genes, LpNgnA and LpNgnB, from the lamprey Lampetra planeri. Phylogenetic analyses show both genes have orthologues in other lamprey species and in a hagfish. Neither gene shows evidence of orthology to specific jawed vertebrate Neurogenin paralogues. LpNgnA is expressed in the ventricular zone of regions of the brain and spinal cord, with expression in the brain demarcating brain sub-compartments including the pallium, tegmentum, tectum, and dorsal thalamus. In the peripheral nervous system, LpNgnA is expressed in cranial sensory placodes and their derivatives, and in the dorsal root ganglia. LpNgnB is expressed transiently in placodal head ectoderm and throughout the central nervous system in early development, and in a small population cells that form part of the macula. Conclusions: Combined, LpNgnA and LpNgnB were detected in most cell populations marked by Neurogenin gene expression in jawed vertebrates, with the exception of the cerebellum, retina and the non-neural expression sites. (c) 2015 Wiley Periodicals, Inc.
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| 6. |
- Lara-Ramirez, Ricardo, et al.
(författare)
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The structure, splicing, synteny and expression of lamprey COE genes and the evolution of the COE gene family in chordates
- 2017
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Ingår i: Development, Genes and Evolution. - : SPRINGER. - 0949-944X .- 1432-041X. ; 227:5, s. 319-338
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Tidskriftsartikel (refereegranskat)abstract
- COE genes encode transcription factors that have been found in all metazoans examined to date. They possess a distinctive domain structure that includes a DNA-binding domain (DBD), an IPT/TIG domain and a helix-loop-helix (HLH) domain. An intriguing feature of the COE HLH domain is that in jawed vertebrates it is composed of three helices, compared to two in invertebrates. We report the isolation and expression of two COE genes from the brook lamprey Lampetra planeri and compare these to COE genes from the lampreys Lethenteron japonicum and Petromyzon marinus. Molecular phylogenetic analyses do not resolve the relationship of lamprey COE genes to jawed vertebrate paralogues, though synteny mapping shows that they all derive from duplication of a common ancestral genomic region. All lamprey genes encode conserved DBD, IPT/TIG and HLH domains; however, the HLH domain of lamprey COE-A genes encodes only two helices while COE-B encodes three helices. We also identified COE-B splice variants encoding either two or three helices in the HLH domain, along with other COE-A and COE-B splice variants affecting the DBD and C-terminal transactivation regions. In situ hybridisation revealed expression in the lamprey nervous system including the brain, spinal cord and cranial sensory ganglia. We also detected expression of both genes in mesenchyme in the pharyngeal arches and underlying the notochord. This allows us to establish the primitive vertebrate expression pattern for COE genes and compare this to that of invertebrate chordates and other animals to develop a model for COE gene evolution in chordates.
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| 7. |
- Lidström, Tommy, et al.
(författare)
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Coordination and cooperation of immunosuppressive mechanisms in pancreatic ductal adenocarcinoma
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The ability to evade the immune system is crucial for cancer cells to survive. In pancreatic ductal adenocarcinoma (PDAC), various mechanisms contributing to immunosuppression have been described, including the recruitment of suppressive immune cells like M2 macrophages, the expression of cell membrane attached proteins like PDL-1, or secretion of extracellular proteins inducing immune cell apoptosis. PDAC is characterized by a rich stroma, consisting of large quantities of extracellular matrix (ECM) proteins, immune cells, fibroblasts and blood vessels. Cancer cell-derived proteins deposited in the stroma can inhibit immune cell function and thereby contribute to the progression of the disease. Galectin 4 (gal 4) is highly expressed by PDAC cancer cells and is secreted into the stroma and has recently been shown to have the capacity to induce T-cell apoptosis in PDAC tumor. High levels of gal 4 is also associated to poor prognosis and reduced immune activity in PDAC patients. Here we show that sets of immunosuppressive genes form groups based on correlation of expression levels. Gal 4 gene expression correlates with other galectin family proteins, collectively clustering into a distinct immune evasion group. This cluster has negative correlation to other more classical immunosuppressive factors, such as PDL-1, CXCL12, and TGFBI, indicating that a subset of tumors mainly relies on galectins to achieve immune evasion. Conversely, tumors with low expression of gal 4 have high expression of one or more of the classical immunosuppressive factors. These results indicate that different tumors rely on different mechanisms to achieve immune evasion and emphasize the need for personalized treatment strategies when targeting immunosuppression in PDAC.
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| 8. |
- Lidström, Tommy, et al.
(författare)
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Extracellular galectin 4 drives immune evasion and promotes T-cell apoptosis in pancreatic cancer
- 2023
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Ingår i: Cancer immunology research. - : American Association for Cancer Research. - 2326-6066 .- 2326-6074. ; 11:1, s. 72-92
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Tidskriftsartikel (refereegranskat)abstract
- Pancreatic ductal adenocarcinoma (PDAC) is characterized by rich deposits of extracellular matrix (ECM), affecting the pathophysiology of the disease. Here, we identified galectin 4 (gal 4) as a cancer cell produced protein deposited into the ECM of PDAC tumors and detected high circulating levels of gal 4 in PDAC patients. In orthotopic transplantation experiments we observed increased infiltration of T-cells and prolonged survival in immunocompetent mice transplanted with cancer cells with reduced expression of gal 4. Increased survival was not observed in immunodeficient RAG1-/- mice, demonstrating that the effect was mediated by the adaptive immune system. Furthermore, by performing single-cell RNA-sequencing we found that the myeloid compartment and cancer-associated fibroblast (CAF) subtypes were altered in the transplanted tumors. Reduced gal 4 expression was associated with higher proportion of myofibroblastic CAFs and reduced numbers of inflammatory CAFs. We also found higher proportions of M1 macrophages, T-cells and antigen presenting dendritic cells in tumors with reduced gal 4 expression. Using a co-culture system, we observed that extracellular gal 4 induced apoptosis in T-cells by binding N-glycosylation residues on CD3 epsilon/delta. Hence, we show that gal 4 is involved in immune evasion and identify gal 4 as a promising drug target for overcoming immunosuppression in PDAC.
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| 9. |
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| 10. |
- Olander, Susanne, et al.
(författare)
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Convergent Wnt and FGF signaling at the gastrula stage induce the formation of the isthmic organizer.
- 2006
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Ingår i: Mechanisms of Development. - : Elsevier BV. - 0925-4773 .- 1872-6356. ; 123:2, s. 166-176
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Tidskriftsartikel (refereegranskat)abstract
- The development of the vertebrate brain depends on the formation of local organizing centres within the neural tube that express secreted signals that refine local neural progenitor identity. The isthmic organizer (IsO) forms at the isthmic constriction and is required for the growth and ordered development of mesencephalic and metencephalic structures. The formation of the IsO, which is characterized by the generation of a complex pattern of cells at the midbrain-hindbrain boundary, has been described in detail. However, when neural plate cells are initially instructed to form the IsO, the molecular nature of the inductive signals remain poorly defined. We now provide evidence that convergent Wnt and FGF signaling at the gastrula stage are required to generate the complex polarized pattern of cells characteristic of the IsO, and that Wnt and FGF signals in combination are sufficient to reconstruct, in naïve forebrain cells, an IsO-like structure that exhibits an organizing activity that mimics the endogenous IsO when transplanted into the diencephalon of chick embryos.
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