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Platelet-derived growth factor-D and Rho GTPases regulate recruitment of cancer-associated fibroblasts in cholangiocarcinoma.

ABSTRACT: Cholangiocarcinoma (CCA) is characterized by an abundant stromal reaction. Cancer-associated fibroblasts (CAFs) are pivotal in tumor growth and invasiveness and represent a potential therapeutic target. To understand the mechanisms leading to CAF recruitment in CCA, we studied (1) expression of epithelial-mesenchymal transition (EMT) in surgical CCA specimens and CCA cells, (2) lineage tracking of an enhanced green fluorescent protein (EGFP)-expressing human male CCA cell line (EGI-1) after xenotransplantation into severe-combined-immunodeficient mice, (3) expression of platelet-derived growth factors (PDGFs) and their receptors in vivo and in vitro, (4) secretion of PDGFs by CCA cells, (5) the role of PDGF-D in fibroblast recruitment in vitro, and (6) downstream effectors of PDGF-D signaling. CCA cells expressed several EMT biomarkers, but not alpha smooth muscle actin (?-SMA). Xenotransplanted CCA masses were surrounded and infiltrated by ?-SMA-expressing CAFs, which were negative for EGFP and the human Y-probe, but positive for the murine Y-probe. CCA cells were strongly immunoreactive for PDGF-A and -D, whereas CAFs expressed PDGF receptor (PDGFR)?. PDGF-D, a PDGFR? agonist, was exclusively secreted by cultured CCA cells. Fibroblast migration was potently induced by PDGF-D and CCA conditioned medium and was significantly inhibited by PDGFR? blockade with Imatinib and by silencing PDGF-D expression in CCA cells. In fibroblasts, PDGF-D activated the Rac1 and Cdc42 Rho GTPases and c-Jun N-terminal kinase (JNK). Selective inhibition of Rho GTPases (particularly Rac1) and of JNK strongly reduced PDGF-D-induced fibroblast migration.CCA cells express several mesenchymal markers, but do not transdifferentiate into CAFs. Instead, CCA cells recruit CAFs by secreting PDGF-D, which stimulates fibroblast migration through PDGFR? and Rho GTPase and JNK activation. Targeting tumor or stroma interactions with inhibitors of the PDGF-D pathway may offer a novel therapeutic approach.

SUBMITTER: Cadamuro M

PROVIDER: S-EPMC3732815 | biostudies-literature | 2013 Sep

REPOSITORIES: biostudies-literature

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Platelet-derived growth factor-D and Rho GTPases regulate recruitment of cancer-associated fibroblasts in cholangiocarcinoma.

Cadamuro Massimiliano M Nardo Giorgia G Indraccolo Stefano S Dall'olmo Luigi L Sambado Luisa L Moserle Lidia L Franceschet Irene I Colledan Michele M Massani Marco M Stecca Tommaso T Bassi Nicolò N Morton Stuart S Spirli Carlo C Fiorotto Romina R Fabris Luca L Strazzabosco Mario M

Hepatology (Baltimore, Md.) 20130722 3

<h4>Unlabelled</h4>Cholangiocarcinoma (CCA) is characterized by an abundant stromal reaction. Cancer-associated fibroblasts (CAFs) are pivotal in tumor growth and invasiveness and represent a potential therapeutic target. To understand the mechanisms leading to CAF recruitment in CCA, we studied (1) expression of epithelial-mesenchymal transition (EMT) in surgical CCA specimens and CCA cells, (2) lineage tracking of an enhanced green fluorescent protein (EGFP)-expressing human male CCA cell line ...[more]

PMID: 23505219

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Project description:Although the importance of platelet-derived growth factor receptor (PDGFR)-? signaling during normal alveogenesis is known, it is unclear whether this signaling pathway can regulate realveolarization in the adult lung. During alveolar development, PDGFR-?-expressing cells induce ? smooth muscle actin (?-SMA) and differentiate to interstitial myofibroblasts. Fibroblast growth factor (FGF) signaling regulates myofibroblast differentiation during alveolarization, whereas peroxisome proliferator-activated receptor (PPAR)-? activation antagonizes myofibroblast differentiation in lung fibrosis. Using left lung pneumonectomy, the roles of FGF and PPAR-? signaling in differentiation of myofibroblasts from PDGFR-?-positive precursors during compensatory lung growth were assessed. FGF receptor (FGFR) signaling was inhibited by conditionally activating a soluble dominant-negative FGFR2 transgene. PPAR-? signaling was activated by administration of rosiglitazone. Changes in ?-SMA and PDGFR-? protein expression were assessed in PDGFR-?-green fluorescent protein (GFP) reporter mice using immunohistochemistry, flow cytometry, and real-time PCR. Immunohistochemistry and flow cytometry demonstrated that the cell ratio and expression levels of PDGFR-?-GFP changed dynamically during alveolar regeneration and that ?-SMA expression was induced in a subset of PDGFR-?-GFP cells. Expression of a dominant-negative FGFR2 and administration of rosiglitazone inhibited induction of ?-SMA in PDGFR-?-positive fibroblasts and formation of new septae. Changes in gene expression of epithelial and mesenchymal signaling molecules were assessed after left lobe pneumonectomy, and results demonstrated that inhibition of FGFR2 signaling and increase in PPAR-? signaling altered the expression of Shh, FGF, Wnt, and Bmp4, genes that are also important for epithelial-mesenchymal crosstalk during early lung development. Our data demonstrate for the first time that a comparable epithelial-mesenchymal crosstalk regulates fibroblast phenotypes during alveolar septation.

Project description:BackgroundPrevious research demonstrated that small Rho GTPases, modulators of the actin cytoskeleton, are drivers of podocyte foot-process effacement in glomerular diseases, such as FSGS. However, a comprehensive understanding of the regulatory networks of small Rho GTPases in podocytes is lacking.MethodsWe conducted an analysis of podocyte transcriptome and proteome datasets for Rho GTPases; mapped in vivo, podocyte-specific Rho GTPase affinity networks; and examined conditional knockout mice and murine disease models targeting Srgap1. To evaluate podocyte foot-process morphology, we used super-resolution microscopy and electron microscopy; in situ proximity ligation assays were used to determine the subcellular localization of the small GTPase-activating protein SRGAP1. We performed functional analysis of CRISPR/Cas9-generated SRGAP1 knockout podocytes in two-dimensional and three-dimensional cultures and quantitative interaction proteomics.ResultsWe demonstrated SRGAP1 localization to podocyte foot processes in vivo and to cellular protrusions in vitro. Srgap1fl/fl*Six2Cre but not Srgap1fl/fl*hNPHS2Cre knockout mice developed an FSGS-like phenotype at adulthood. Podocyte-specific deletion of Srgap1 by hNPHS2Cre resulted in increased susceptibility to doxorubicin-induced nephropathy. Detailed analysis demonstrated significant effacement of podocyte foot processes. Furthermore, SRGAP1-knockout podocytes showed excessive protrusion formation and disinhibition of the small Rho GTPase machinery in vitro. Evaluation of a SRGAP1-dependent interactome revealed the involvement of SRGAP1 with protrusive and contractile actin networks. Analysis of glomerular biopsy specimens translated these findings toward human disease by displaying a pronounced redistribution of SRGAP1 in FSGS.ConclusionsSRGAP1, a podocyte-specific RhoGAP, controls podocyte foot-process architecture by limiting the activity of protrusive, branched actin networks. Therefore, elucidating the complex regulatory small Rho GTPase affinity network points to novel targets for potentially precise intervention in glomerular diseases.

Dataset Information

Platelet-derived growth factor-D and Rho GTPases regulate recruitment of cancer-associated fibroblasts in cholangiocarcinoma.

Publications

Platelet-derived growth factor-D and Rho GTPases regulate recruitment of cancer-associated fibroblasts in cholangiocarcinoma.

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