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Pancreatic ductal adenocarcinoma (PDAC) has a dismal prognosis largely owing to inefficient diagnosis and tenacious drug resistance. Activation of pancreatic stellate cells (PSCs) and consequent development of dense stroma are prominent features accounting for this aggressive biology. The reciprocal interplay between PSCs and pancreatic cancer cells (PCCs) not only enhances tumour progression and metastasis but also sustains their own activation, facilitating a vicious cycle to exacerbate tumorigenesis and drug resistance. Furthermore, PSC activation occurs very early during PDAC tumorigenesis, and activated PSCs comprise a substantial fraction of the tumour mass, providing a rich source of readily detectable factors. Therefore, we hypothesized that the communication between PSCs and PCCs could be an exploitable target to develop effective strategies for PDAC therapy and diagnosis. Here, starting with a systematic proteomic investigation of secreted disease mediators and underlying molecular mechanisms, we reveal that leukaemia inhibitory factor (LIF) is a key paracrine factor from activated PSCs acting on cancer cells. Both pharmacologic LIF blockade and genetic Lifr deletion markedly slow tumour progression and augment the efficacy of chemotherapy to prolong survival of PDAC mouse models, mainly by modulating cancer cell differentiation and epithelial-mesenchymal transition status. Moreover, in both mouse models and human PDAC, aberrant production of LIF in the pancreas is restricted to pathological conditions and correlates with PDAC pathogenesis, and changes in the levels of circulating LIF correlate well with tumour response to therapy. Collectively, these findings reveal a function of LIF in PDAC tumorigenesis, and suggest its translational potential as an attractive therapeutic target and circulating marker. Our studies underscore how a better understanding of cell-cell communication within the tumour microenvironment can suggest novel strategies for cancer therapy.
Serine threonine kinase 17A (STK17A) is a ubiquitously expressed kinase originally identified as a regulator of apoptosis; however, whether it functionally contributes to colorectal cancer has not been established. Here, we have analyzed STK17A in colorectal cancer and demonstrated decreased expression of STK17A in primary tumors, which is further reduced in metastatic lesions, indicating a potential role in regulating the metastatic cascade. Interestingly, changes in STK17A expression did not modify proliferation, apoptosis, or sensitivity of colorectal cancer cell lines to treatment with the chemotherapeutic 5-fluorouracil. Instead, knockdown induced a robust mesenchymal phenotype consistent with the epithelial-mesenchymal transition, including spindle-like cell morphology, decreased expression of adherens junction proteins, and increased migration and invasion. Additionally, overexpression of decreased cell size and induced widespread membrane blebbing, a phenotype often associated with activation of cell contractility. Indeed, STK17A-overexpressing cells displayed heightened phosphorylation of myosin light chain in a manner dependent on STK17A catalytic activity. Finally, patient-derived tumor organoid cultures were used to more accurately determine STK17A's effect in primary human tumor cells. Loss of STK17A induced morphologic changes, decreased E-cadherin, increased invasion, and augmented organoid attachment on 2D substrates, all together suggesting a more metastatic phenotype. Collectively, these data indicate a novel role for STK17A in the regulation of epithelial phenotypes and indicate its functional contribution to colorectal cancer invasion and metastasis. IMPLICATIONS: Loss of serine threonine kinase 17A occurs in colorectal cancer metastasis, induces mesenchymal morphologies, and contributes to tumor cell invasion and migration in colorectal cancer.
©2019 American Association for Cancer Research.
Esophageal adenocarcinoma (EAC) is a highly aggressive malignancy that is characterized by resistance to chemotherapy and a poor clinical outcome. The overexpression of the receptor tyrosine kinase AXL is frequently associated with unfavorable prognosis in EAC. Although it is well documented that AXL mediates cancer cell invasion as a downstream effector of epithelial-to-mesenchymal transition, the precise molecular mechanism underlying this process is not completely understood. Herein, we demonstrate for the first time that AXL mediates cell invasion through the regulation of lysosomes peripheral distribution and cathepsin B secretion in EAC cell lines. Furthermore, we show that AXL-dependent peripheral distribution of lysosomes and cell invasion are mediated by extracellular acidification, which is potentiated by AXL-induced secretion of lactate through AKT-NF-κB-dependent MCT-1 regulation. Our novel mechanistic findings support future clinical studies to evaluate the therapeutic potential of the AXL inhibitor R428 (BGB324) in highly invasive EAC.
Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.
The epithelial-mesenchymal transition (EMT) endows carcinoma cells with traits needed to complete many of the steps leading to metastasis formation, but its contributions specifically to the late step of extravasation remain understudied. We find that breast cancer cells that have undergone an EMT extravasate more efficiently from blood vessels both in vitro and in vivo. Analysis of gene expression changes associated with the EMT program led to the identification of an EMT-induced cell-surface protein, podocalyxin (PODXL), as a key mediator of extravasation in mesenchymal breast and pancreatic carcinoma cells. PODXL promotes extravasation through direct interaction of its intracellular domain with the cytoskeletal linker protein ezrin. Ezrin proceeds to establish dorsal cortical polarity, enabling the transition of cancer cells from a non-polarized, rounded cell morphology to an invasive extravasation-competent shape. Hence, the EMT program can directly enhance the efficiency of extravasation and subsequent metastasis formation through a PODXL-ezrin signaling axis.
Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.
This integrated, multiplatform PanCancer Atlas study co-mapped and identified distinguishing molecular features of squamous cell carcinomas (SCCs) from five sites associated with smoking and/or human papillomavirus (HPV). SCCs harbor 3q, 5p, and other recurrent chromosomal copy-number alterations (CNAs), DNA mutations, and/or aberrant methylation of genes and microRNAs, which are correlated with the expression of multi-gene programs linked to squamous cell stemness, epithelial-to-mesenchymal differentiation, growth, genomic integrity, oxidative damage, death, and inflammation. Low-CNA SCCs tended to be HPV(+) and display hypermethylation with repression of TET1 demethylase and FANCF, previously linked to predisposition to SCC, or harbor mutations affecting CASP8, RAS-MAPK pathways, chromatin modifiers, and immunoregulatory molecules. We uncovered hypomethylation of the alternative promoter that drives expression of the ΔNp63 oncogene and embedded miR944. Co-expression of immune checkpoint, T-regulatory, and Myeloid suppressor cells signatures may explain reduced efficacy of immune therapy. These findings support possibilities for molecular classification and therapeutic approaches.
Published by Elsevier Inc.
Proliferative vitreoretinopathy (PVR) is a common complication of open globe injury and the most common cause of failed retinal detachment surgery. The response by retinal pigment epithelial (RPE) cells liberated into the vitreous includes proliferation and migration; most importantly, epithelial to mesenchymal transition (EMT) of RPE plays a central role in the development and progress of PVR. For the first time, we show that knockdown of BIRC5, a member of the inhibitor of apoptosis protein family, using either lentiviral vector based CRISPR/Cas9 nickase gene editing or inhibition of survivin using the small-molecule inhibitor YM155, results in the suppression of EMT in RPE cells. Knockdown of survivin or inhibition of survivin significantly reduced TGFβ-induced cell proliferation and migration. We further demonstrated that knockdown or inhibition of survivin attenuated the TGFβ signaling by showing reduced phospho-SMAD2 in BIRC5 knockdown or YM155-treated cells compared to controls. Inhibition of the TGFβ pathway using TGFβ receptor inhibitor also suppressed survivin expression in RPE cells. Our studies demonstrate that survivin contributes to EMT by cross-talking with the TGFβ pathway in RPE cells. Targeting survivin using small-molecule inhibitors may provide a novel approach to treat PVR disease.
Copyright © 2018 Elsevier Inc. All rights reserved.
Endothelial-to-mesenchymal transition (EndoMT) is a cellular process often initiated by the transforming growth factor β (TGF-β) family of ligands. Although required for normal heart valve development, deregulated EndoMT is linked to a wide range of pathological conditions. Here, we demonstrate that endothelial fatty acid oxidation (FAO) is a critical in vitro and in vivo regulator of EndoMT. We further show that this FAO-dependent metabolic regulation of EndoMT occurs through alterations in intracellular acetyl-CoA levels. Disruption of FAO via conditional deletion of endothelial carnitine palmitoyltransferase II (Cpt2) augments the magnitude of embryonic EndoMT, resulting in thickening of cardiac valves. Consistent with the known pathological effects of EndoMT, adult Cpt2 mice demonstrate increased permeability in multiple vascular beds. Taken together, these results demonstrate that endothelial FAO is required to maintain endothelial cell fate and that therapeutic manipulation of endothelial metabolism could provide the basis for treating a growing number of EndoMT-linked pathological conditions.
Copyright © 2018 Elsevier Inc. All rights reserved.
BACKGROUND - Pulmonary fibrosis is a late manifestation of acute respiratory distress syndrome (ARDS). Sepsis is a major cause of ARDS, and its pathogenesis includes endotoxin-induced vascular injury. Recently, endothelial-to-mesenchymal transition (EndMT) was shown to play an important role in pulmonary fibrosis. On the other hand, dipeptidyl peptidase (DPP)-4 was reported to improve vascular dysfunction in an experimental sepsis model, although whether DPP-4 affects EndMT and fibrosis initiation during lipopolysaccharide (LPS)-induced lung injury is unclear. The aim of this study was to investigate the anti-EndMT effects of the DPP-4 inhibitor vildagliptin in pulmonary fibrosis after systemic endotoxemic injury.
METHODS - A septic lung injury model was established by intraperitoneal injection of lipopolysaccharide (LPS) in eight-week-old male mice (5 mg/kg for five consecutive days). The mice were then treated with vehicle or vildagliptin (intraperitoneally, 10 mg/kg, once daily for 14 consecutive days from 1 day before the first administration of LPS.). Flow cytometry, immunohistochemical staining, and quantitative polymerase chain reaction (qPCR) analysis was used to assess cell dynamics and EndMT function in lung samples from the mice.
RESULTS - Lung tissue samples from treated mice revealed obvious inflammatory reactions and typical interstitial fibrosis 2 days and 28 days after LPS challenge. Quantitative flow cytometric analysis showed that the number of pulmonary vascular endothelial cells (PVECs) expressing alpha-smooth muscle actin (α-SMA) or S100 calcium-binding protein A4 (S100A4) increased 28 days after LPS challenge. Similar increases in expression were also confirmed by qPCR of mRNA from isolated PVECs. EndMT cells had higher proliferative activity and migration activity than mesenchymal cells. All of these changes were alleviated by intraperitoneal injection of vildagliptin. Interestingly, vildagliptin and linagliptin significantly attenuated EndMT in the absence of immune cells or GLP-1.
CONCLUSIONS - Inhibiting DPP-4 signaling by vildagliptin could ameliorate pulmonary fibrosis by downregulating EndMT in systemic LPS-induced lung injury.
Endothelial-to-mesenchymal transition (EndMT) is a process in which endothelial cells lose polarity and cell-to cell contacts, and undergo a dramatic remodeling of the cytoskeleton. It has been implicated in initiation and progression of pulmonary arterial hypertension (PAH). However, the characteristics of cells which have undergone EndMT cells in vivo have not been reported and so remain unclear. To study this, sugen5416 and hypoxia (SuHx)-induced PAH was established in Cdh5-Cre/Gt(ROSA)26Sor/J double transgenic mice, in which GFP was stably expressed in pan-endothelial cells. After 3 wk of SuHx, flow cytometry and immunohistochemistry demonstrated CD144-negative and GFP-positive cells (complete EndMT cells) possessed higher proliferative and migratory activity compared with other mesenchymal cells. While CD144-positive and α-smooth muscle actin (α-SMA)-positive cells (partial EndMT cells) continued to express endothelial progenitor cell markers, complete EndMT cells were Sca-1-rich mesenchymal cells with high proliferative and migratory ability. When transferred in fibronectin-coated chamber slides containing smooth muscle media, α-SMA robustly expressed in these cells compared with cEndMT cells that were grown in maintenance media. Demonstrating additional paracrine effects, conditioned medium from isolated complete EndMT cells induced enhanced mesenchymal proliferation and migration and increased angiogenesis compared with conditioned medium from resident mesenchymal cells. Overall, these findings show that EndMT cells could contribute to the pathogenesis of PAH both directly, by transformation into smooth muscle-like cells with higher proliferative and migratory potency, and indirectly, through paracrine effects on vascular intimal and medial proliferation.
The hyperactivated Wnt/β-catenin signaling acts as a switch to induce epithelial to mesenchymal transition and promote colorectal cancer. However, due to its essential role in gut homeostasis, therapeutic targeting of this pathway has proven challenging. Additionally, IL-6/Stat-3 signaling, activated by microbial translocation through the dysregulated mucosal barrier in colon adenomas, facilitates the adenoma to adenocarcinomas transition. However, inter-dependence between these signaling pathways and key mucosal barrier components in regulating colon tumorigenesis and cancer progression remains unclear. In current study, we have discovered, using a comprehensive investigative regimen, a novel and tissue-specific role of claudin-3, a tight junction integral protein, in inhibiting colon cancer progression by serving as the common rheostat of Stat-3 and Wnt-signaling activation. Loss of claudin-3 also predicted poor patient survival. These findings however contrasted an upregulated claudin-3 expression in other cancer types and implicated role of the epigenetic regulation. Claudin-3-/- mice revealed dedifferentiated and leaky colonic epithelium, and developed invasive adenocarcinoma when subjected to colon cancer. Wnt-signaling hyperactivation, albeit in GSK-3β independent manner, differentiated colon cancer in claudin-3-/- mice versus WT-mice. Claudin-3 loss also upregulated the gp130/IL6/Stat3 signaling in colonic epithelium potentially assisted by infiltrating immune components. Genetic and pharmacological studies confirmed that claudin-3 loss induces Wnt/β-catenin activation, which is further exacerbated by Stat-3-activation and help promote colon cancer. Overall, these novel findings identify claudin-3 as a therapeutic target for inhibiting overactivation of Wnt-signaling to prevent CRC malignancy.