Papers by Carol Tucker-Burden
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Cancer stem cells exert enormous influence on neoplastic behavior, in part by governing asymmetri... more Cancer stem cells exert enormous influence on neoplastic behavior, in part by governing asymmetric cell division and the balance between self-renewal and multipotent differentiation. Growth is favored by deregulated stem cell division, which enhances the self-renewing population and diminishes the differentiation program. Mutation of a single gene in Drosophila, Brain Tumor (Brat), leads to disrupted asymmetric cell division resulting in dramatic neoplastic proliferation of neuroblasts and massive larval brain overgrowth. To uncover the mechanisms relevant to deregulated cell division in human glioma stem cells, we first developed a novel adult Drosophila brain tumor model using brat-RNAi driven by the neuroblast-specific promoter inscuteable. Suppressing Brat in this population led to the accumulation of actively proliferating neuroblasts and a lethal brain tumor phenotype. brat-RNAi caused upregulation of Notch signaling, a node critical for self-renewal, by increasing protein exp...
Cancer Research
Lung cancer is among the most commonly diagnosed cancers and the leading cause of cancer-related ... more Lung cancer is among the most commonly diagnosed cancers and the leading cause of cancer-related death globally, with approximately 85% of all lung cancers having non-small cell lung cancer (NSCLC). The protein kinase LKB1 is the 3rd most frequently mutated gene in lung adenocarcinoma, and serves as a master regulator of cell metabolism and growth. LKB1-inactivating mutations have a significant impact on NSCLC development. Although KRAS mutation is most frequently co-mutated with the tumor suppressor p53, the strongest cooperation was seen with homozygous inactivation of LKB1. Loss of LKB1 on a KRAS-mutant (KL) background leads to increased tumor burden, shortened survival time and increased metastasis compared to loss of TP53 (KP). Furthermore, inactivation or loss of LKB1 correlated with poor prognosis, where tumors are typically aggressive and chemoresistant. To discover therapeutic vulnerabilities for this aggressive genetic subtype of lung adenocarcinoma, we evaluated the contr...
Neuro-Oncology, 2017
NEURO-ONCOLOGY • NOVEMBER 2017 only known histone methyltransferase responsible for histone-3-lys... more NEURO-ONCOLOGY • NOVEMBER 2017 only known histone methyltransferase responsible for histone-3-lysine-79 methylation (H3K79me), an epigenetic mark associated with active gene transcription. Previous studies investigating the therapeutic implications of targeting DOT1L in cancer have shown that its inhibition in leukemia results in cancer cell death and, in solid cancers, decreases metastasis. We investigated the role of DOT1L in GBM BTSCs. Long term treatment with the DOT1L inhibitor EPZ-5676 decreased H3K79me2 levels in BTSCs and altered BTSC sphere morphology, sphere initiating frequency, proliferation, migration and invasion. To investigate the mechanism by which DOT1L may regulate GBM tumorigenesis and growth we performed qPCR, flow cytometry, RNA-sequencing and H3K79me2 ChIP-sequencing of BTSC lines, following treatment with EPZ-5676. We found that DOT1L inhibition decreases the expression of GBM stem and progenitor cell genes and increases the expression of genes associated with neuronal and astrocytic differentiation. Furthermore, H3K79me2 ChIP sequencing revealed that DOT1L histone methylation was reduced within the gene body of stem and progenitor cell genes. Flank xenograft studies, of mice treated with EPZ-5676, revealed that DOT1L inhibition promotes neuronal and astrocytic differentiation in tumors. Ongoing pre-clinical studies are assessing the effect of DOT1L inhibition on survival in an orthotopic xenograft model of GBM and investigating rational combinatorial targeting strategies, with a long-term aim of preventing GBM recurrence and improving overall patient survival.
Molecular and Cellular Biology / Genetics, 2019
The major cause of cancer-associated mortality is tumor metastasis, but our understanding of this... more The major cause of cancer-associated mortality is tumor metastasis, but our understanding of this process is far from complete. During successful dissemination, tumor cells invade the surrounding tissue of the primary tumor, intravasate into blood and lymphatic vessels, translocate to distant tissues, extravasate, adapt to the new microenvironment, and eventually seed, proliferate, and colonize to form metastases. Because dissemination mostly occurs through the blood, circulating tumor cells (CTCs) that have been shed into the vasculature and may be on their way to potential metastatic sites are of obvious interest (1). KRAS mutations are the most frequent oncogenic drivers of non-small cell lung cancer and when associated with co-mutations lead to a decrease in overall survival. We have previously established a lenti-Cre-induced Kras and Lkb1 mutant and Kras and p53 mutant genetically engineered mouse modes (KLLenti) and (KPLenti) that develop 100% lung adenocarcinoma to conduct the first study to isolate and maintain primary, CTC and metastatic cells that are KLLenti or KPLenti. We are able to isolate TTF-1+ and pan-cytokeratin+ CTCs from the KLlenti and KPlenti mice and validated their mutational status by genotyping, western blot, and immunofluorescence. Moreover, lkb1-mutant or p53-mutant primary tumor cells have different 3-D invasive properties and patterns, as well as the respective CTCs and metastatic cells when compared across different genetic sub-types. To further study gene expression patterns between primary, CTC, and metastatic sites RNAseq will be employed to identify pathways that drive metastasis within the genetic sub-types. Citation Format: Liza J. Burton, Junghui Koo, Carol Tucker-Burden, Wei Zhou, Melissa Gilbert-Ross, Chunzi Huang, Gabriel Sica, Adam Marcus. Isolation of circulating tumors cells from genetically engineered mouse models of lung adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 865.
Cell Reports, 2018
Highlights d Drosophila Cdk5 promotes stemness by altering asymmetric division of brain tumor ste... more Highlights d Drosophila Cdk5 promotes stemness by altering asymmetric division of brain tumor stem cells d CDK5 regulates self-renewal by directly activating CREB1 independently of PKA/cAMP d CDK5 inhibitor CP681301 reduces self-renewal in mouse glioma xenografts d CDK5 and asymmetric stem cell division markers segregate in non-mesenchymal tumors
Scientific reports, Jan 15, 2017
Glioblastoma (GBM) contains diverse microenvironments with uneven distributions of oncogenic alte... more Glioblastoma (GBM) contains diverse microenvironments with uneven distributions of oncogenic alterations and signaling networks. The diffusely infiltrative properties of GBM result in residual tumor at neurosurgical resection margins, representing the source of relapse in nearly all cases and suggesting that therapeutic efforts should be focused there. To identify signaling networks and potential druggable targets across tumor microenvironments (TMEs), we utilized 5-ALA fluorescence-guided neurosurgical resection and sampling, followed by proteomic analysis of specific TMEs. Reverse phase protein array (RPPA) was performed on 205 proteins isolated from the tumor margin, tumor bulk, and perinecrotic regions of 13 previously untreated, clinically-annotated and genetically-defined high grade gliomas. Differential protein and pathway signatures were established and then validated using western blotting, immunohistochemistry, and comparable TCGA RPPA datasets. We identified 37 proteins d...
Molecular oncology, Mar 18, 2017
Glioblastoma (GBM) is the most malignant form of primary brain tumor, and GBM stem-like cells (GS... more Glioblastoma (GBM) is the most malignant form of primary brain tumor, and GBM stem-like cells (GSCs) contribute to the rapid growth, therapeutic resistance, and clinical recurrence of these fatal tumors. STAT3 signaling supports the maintenance and proliferation of GSCs, yet regulatory mechanisms are not completely understood. Here, we report that tri-partite motif-containing protein 8 (TRIM8) activates STAT3 signaling to maintain stemness and self-renewing capabilities of GSCs. TRIM8 (also known as 'glioblastoma-expressed ring finger protein') is expressed equally in GBM and normal brain tissues, despite its hemizygous deletion in the large majority of GBMs, and its expression is highly correlated with stem cell markers. Experimental knockdown of TRIM8 reduced GSC self-renewal and expression of SOX2, NESTIN, and p-STAT3, and promoted glial differentiation. Overexpression of TRIM8 led to higher expression of p-STAT3, c-MYC, SOX2, NESTIN, and CD133, and enhanced GSC self-rene...
FASEB journal : official publication of the Federation of American Societies for Experimental Biology, Dec 29, 2016
We investigated the intersection of epidermal growth factor receptor (EGFR) and CCAAT enhancer bi... more We investigated the intersection of epidermal growth factor receptor (EGFR) and CCAAT enhancer binding protein (C/EBP)-β signaling in glioblastoma (GBM), given that both gene products strongly influence neoplastic behavior. C/EBP-β is known to drive the mesenchymal transcriptional signature in GBM, likely through strong microenvironmental influences, whereas the genetic contributions to its up-regulation in this disease are not well described. We demonstrated that stable overexpression and activation of WT EGFR (U87MG-WT) led to elevated C/EBP-β expression, as well as enhanced nuclear translocation and DNA-binding activity, leading to up-regulation of C/EBP-β transcription and translation. Deeper investigation identified bidirectional regulation, with C/EBP-β also causing up-regulation of EGFR that was at least partially dependent on the STAT3. Based on ChIP-based studies, we also found that that the translational isoforms of C/EBP-β [liver-enriched transcription-activating protein ...
Cancer Research, 2016
Cancer stem cells exert enormous influence on neoplastic behavior, in part by governing asymmetri... more Cancer stem cells exert enormous influence on neoplastic behavior, in part by governing asymmetric cell division and the balance between self-renewal and multipotent differentiation. Growth is favored by deregulated stem cell division, which enhances the self-renewing population and diminishes the differentiation program. Mutation of a single gene in Drosophila, Brain Tumor (Brat), leads to disrupted asymmetric cell division resulting in dramatic neoplastic proliferation of neuroblasts and massive larval brain overgrowth. To uncover the mechanisms relevant to deregulated cell division in human glioma stem cells, we first developed a novel adult Drosophila brain tumor model using brat-RNAi driven by the neuroblast-specific promoter inscuteable. Suppressing Brat in this population led to the accumulation of actively proliferating neuroblasts and a lethal brain tumor phenotype. brat-RNAi caused upregulation of Notch signaling, a node critical for self-renewal, by increasing protein exp...
Cancer Research, 2014
Cancer stem cells, capable of self-renewal and multipotent differentiation, influence tumor behav... more Cancer stem cells, capable of self-renewal and multipotent differentiation, influence tumor behavior through a complex balance of symmetric and asymmetric cell divisions. Mechanisms regulating the dynamics of stem cell and their progeny in human cancer are poorly understood. In Drosophila, mutation of brain tumor (brat) leads to loss of normal asymmetric cell division by developing neural cells and results in a massively enlarged brain composed of neuroblasts with neoplastic properties. Brat promotes asymmetric cell division and directs neural differentiation at least partially through its suppression on Myc. We identified TRIM3 (11p15.5) as a human ortholog of Drosophila brat and demonstrate its regulation of asymmetric cell division and stem cell properties of glioblastoma (GBM), a highly malignant human brain tumor. TRIM3 gene expression is markedly reduced in human GBM samples, neurosphere cultures and cell lines and its reconstitution impairs growth properties in vitro and in v...
Transplantation, 2001
Blockade of the CD40 and CD28 pathways is a powerful strategy to inhibit CD4-mediated alloimmune ... more Blockade of the CD40 and CD28 pathways is a powerful strategy to inhibit CD4-mediated alloimmune responses. In this study, we examine the relative roles of the CD40 and CD28 pathways on CD4-mediated allograft rejection responses, and further characterize the role of these pathways on CD4+ T-cell activation, priming for cytokine production, and cell proliferation in response to alloantigen in vivo. BALB/c skin allografts were transplanted onto C57BL/6 Rag 1-/- recipients reconstituted with CD4 cells from CD28-/- or CD40L-/- donors. The popliteal lymph node assay was used to study the role of these pathways on CD4-cell activation and priming in vivo. To investigate the role of CD40 and CD28 blockade on CD4-cell proliferation, the fluorescein dye carboxyfluorescein diacetate succinimidyl ester was used. We performed heterotopic cardiac transplantation using CD40-/- mice to evaluate the role of CD40 on donor versus recipient cells in CD4-mediated rejection. B6 Rag 1-/- recipients reconstituted with CD28-/- CD4+ T cells acutely rejected allografts (median survival time 15 days), whereas recipients reconstituted with CD40L-/- CD4+ T cells had significantly prolonged survival of BALB/c skin grafts (MST 71 days). CD40L blockade was equivalent to or inferior to CD28 blockade in inhibition of in vivo CD4-cell activation, priming for cytokine production, and proliferation responses to alloantigen. BALB/c recipients depleted of CD8 cells promptly rejected donor B6 CD40-/- cardiac allografts, whereas B6 CD40-/- recipients depleted of CD8 cells had significantly prolonged survival of BALB/c wild-type cardiac allografts. The CD40/CD40L pathway, but not the CD28/B7 pathway, is critical for CD4-mediated rejection responses, however, the responsible mechanisms remain unclear.
Transplantation, 2009
Background. The long-term metabolic function of microencapsulated xenogeneic adult porcine islets... more Background. The long-term metabolic function of microencapsulated xenogeneic adult porcine islets (API) was assessed in a murine model of type 1 diabetes mellitus. Methods. API were encapsulated in barium-gelled alginate and transplanted intraperitoneally in diabetic nonobese diabetic (NOD) mice given no immunosuppression or given costimulatory blockade (CoB; CTLA4-Igϩanti-CD154 mAb). Control mice received nonencapsulated API under the kidney capsule. Graft function was monitored by measurement of random blood glucose levels, serum glycosylated hemoglobin (HbA1c), serum porcine C peptide, in vivo glucose tolerance tests, and histologic analyses of host pancreas and graft biopsies. Host immune responses to the islet xenografts were characterized by phenotyping peritoneal cellular infiltrates and by measuring serum antiporcine antibody levels. Results. Without immunosuppression, nonencapsulated API functioned for less than 1 week, and microencapsulated API functioned for 35Ϯ14 days before rejection, associated with both a cellular and a humoral immune response. With continuous CoB, nonencapsulated API functioned for 27Ϯ4 days, whereas microencapsulated API functioned for Ͼ450 days with measurable levels of serum porcine C peptide, near normal in vivo glucose tolerance tests and HbA1c levels, and intact microcapsules containing viable, insulin-positive porcine islets. Conclusions. Microencapsulated API restored normoglycemia for more than 1 year in spontaneously diabetic NODs given dual CoB. To our knowledge, this is the first study to document long-term normalized HbA1c, porcine C peptide, and near normal glucose tolerance in immunosuppressed diabetic NOD mice transplanted intraperitoneally with microencapsulated API. Our study suggests that transplantation of microencapsulated porcine islet xenografts may be a future treatment for patients with type 1 diabetes mellitus.
Transplantation, 2000
It has been hypothesized that regimens to induce transplantation tolerance and long-term hematopo... more It has been hypothesized that regimens to induce transplantation tolerance and long-term hematopoietic chimerism require recipient conditioning with whole body irradiation or a cytoablative regimen to create space within the marrow microenvironment to permit pluripotent stem cell engraftment. The purpose of this study was to determine if transplantation of an intact bone marrow microenvironment in the form of a bone graft would permit stable hematopoietic stem cell engraftment, shape the repertoire of developing T cells, and induce donor-specific unresponsiveness in the absence of a conditioning regimen. Fragments of femur were transplanted under the kidney capsule of recipient mice. At defined time points after bone graft transplantation recipients were assayed for chimerism, bone graft viability, and responses to donor and third party alloantigens in vitro and in vivo. In the absence of an immunological barrier, bone graft transplantation resulted in long-term multi-lineage hematopoietic chimerism in the peripheral blood. Nude bone graft transplantation into SCID recipients resulted in development of donor- derived T cells that underwent negative selection on bone graft derived I-E+ cells within the thymus. Across a fully allogeneic barrier in immunocompetent recipients treated with combined blockade of the CD40 and CD28 pathways bone graft transplantation resulted in long-term donor-specific hyporesponsiveness in vitro and acceptance of donor specific skin grafts. Transplantation of bone marrow in the form of a bone graft may facilitate the production of hematopoietic chimerism and lead to long-term donor-specific hyporesponsiveness in the absence of a cytoreductive conditioning regimen.
Stem Cells and Development, 2012
Glioblastoma (GBM) is a highly aggressive primary brain tumor with a poor prognosis. Despite aggr... more Glioblastoma (GBM) is a highly aggressive primary brain tumor with a poor prognosis. Despite aggressive therapy with surgery, radiotherapy, and chemotherapy, nearly all patients succumb to disease within 2 years. Several studies have supported the presence of stem-like cells in brain tumor cultures that are CD133-positive, are capable of self-renewal, and give rise to all cell types found within the tumor, potentially perpetuating growth. CD133 is a widely accepted marker for glioma-derived cancer stem cells; however, its reliability has been questioned, creating a need for other identifiers of this biologically important subpopulation. We used a panel of 20 lectins to identify differences in glycan expression found in the glycocalyx of undifferentiated gliomaderived stem cells and differentiated cells that arise from them. Fluorescently labeled lectins that specifically recognize aN -acetylgalactosamine (GalNAc) and aN -acetylglucosamine (GlcNAc) differentially bound to the cell surface based on the state of cellular differentiation. GalNAc and GlcNAc were highly expressed on the surface of undifferentiated cells and showed markedly reduced expression over a 12-day duration of differentiation. Additionally, the GalNAc-recognizing lectin Dolichos biflorus agglutinin was capable of specifically selecting and sorting glioma-derived stem cell populations from an unsorted tumor stock and this subpopulation had proliferative properties similar to CD133 + cells in vitro and also had tumor-forming capability in vivo. Our preliminary results on a single cerebellar GBM suggest that GalNAc and GlcNAc are novel biomarkers for identifying glioma-derived stem cells and can be used to isolate cancer stem cells from unsorted cell populations, thereby creating new cell lines for research or clinical testing.
Science Signaling, 2013
An allosteric inhibitor of the kinase JAK2 impedes the growth of aggressive glioblastoma.
Nature, 1996
The receptor-ligand pairs CD28-B7 and CD40-gp39 are essential for the initiation and amplificatio... more The receptor-ligand pairs CD28-B7 and CD40-gp39 are essential for the initiation and amplification of T-cell-dependent immune responses. CD28-B7 interactions provide 'second signals' necessary for optimal T-cell activation and IL-2 production, whereas CD40-gp39 signals co-stimulate B-cell, macrophage, endothelial cell and T-cell activation. Nonetheless, blockade of either of these pathways alone is not sufficient to permit engraftment of highly immunogenic allografts. Here we report that simultaneous but not independent blockade of the CD28 and CD40 pathways effectively aborts T-cell clonal expansion in vitro and in vivo, promotes long-term survival of fully allogeneic skin grafts, and inhibits the development of chronic vascular rejection of primarily vascularized cardiac allografts. The requirement for simultaneous blockade of these pathways for effective inhibition of alloimmunity indicates that, although they are interrelated, the CD28 and CD40 pathways are critical independent regulators of T-cell-dependent immune responses.
The Journal of Immunology, 2000
Tolerance to self is a necessary attribute of the immune system. It is thought that most autoreac... more Tolerance to self is a necessary attribute of the immune system. It is thought that most autoreactive T cells are deleted in the thymus during the process of negative selection. However, peripheral tolerance mechanisms also exist to prevent development of autoimmune diseases against peripheral self-Ags. It has been proposed that T cells develop tolerance to peripheral self-Ags encountered in the absence of inflammation or “danger” signals. We have used immunodeficient Rag 1−/− mice to study the response of T cells to neo-self peripheral Ags in the form of well-healed skin and vascularized cardiac allografts. In this paper we report that skin and cardiac allografts without evidence of inflammation are vigorously rejected by transferred T cells or when recipients are reconstituted with T cells at a physiologic rate by nude bone graft transplantation. These results provide new insights into the role of inflammation or “danger” in the initiation of T cell-dependent immune responses. The...
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Papers by Carol Tucker-Burden