IU Indianapolis ScholarWorks :: Browsing by Author "Quilliam, Lawrence A."

Browsing by Author "Quilliam, Lawrence A."

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Activation of Rap1 inhibits NADPH oxidase-dependent ROS generation in retinal pigment epithelium and reduces choroidal neovascularization
(Federation of American Society for Experimental Biology, 2014-01) Wang, Haibo; Jiang, Yanchao; Shi, Dallas; Quilliam, Lawrence A.; Chrzanowska-Wodnicka, Magdalena; Wittchen, Erika S.; Li, Dean Y.; Hartnett, M. Elizabeth; Department of Biochemistry & Molecular Biology, IU School of Medicine
Activation of Rap1 GTPase can improve the integrity of the barrier of the retina pigment epithelium (RPE) and reduce choroidal neovascularization (CNV). Inhibition of NADPH oxidase activation also reduces CNV. We hypothesize that Rap1 inhibits NADPH oxidase-generated ROS and thereby reduces CNV formation. Using a murine model of laser-induced CNV, we determined that reduced Rap1 activity in RPE/choroid occurred with CNV formation and that activation of Rap1 by 2'-O-Me-cAMP (8CPT)-reduced laser-induced CNV via inhibiting NADPH oxidase-generated ROS. In RPE, inhibition of Rap1 by Rap1 GTPase-activating protein (Rap1GAP) increased ROS generation, whereas activation of Rap1 by 8CPT reduced ROS by interfering with the assembly of NADPH oxidase membrane subunit p22phox with NOX4 or cytoplasmic subunit p47phox. Activation of NADPH oxidase with Rap1GAP reduced RPE barrier integrity via cadherin phosphorylation and facilitated choroidal EC migration across the RPE monolayer. Rap1GAP-induced ROS generation was inhibited by active Rap1a, but not Rap1b, and activation of Rap1a by 8CPT in Rap1b(-/-) mice reduced laser-induced CNV, in correlation with decreased ROS generation in RPE/choroid. These findings provide evidence that active Rap1 reduces CNV by interfering with the assembly of NADPH oxidase subunits and increasing the integrity of the RPE barrier.
Angiogenic gene signature in human pancreatic cancer correlates with TGF-beta and inflammatory transcriptomes
(2016-04-11) Craven, Kelly E.; Korc, Murray; Liu, Yunlong; Mosley, Amber L.; Quilliam, Lawrence A.
Pancreatic ductal adenocarcinoma (PDAC), which comprises 85% of pancreatic cancers, is the 4th leading cause of cancer death in the United States with a 5-year survival rate of 8%. While human PDACs (hPDACs) are hypovascular, they also overexpress a number of angiogenic growth factors and receptors. Additionally, the use of anti-angiogenic agents in murine models of PDAC leads to reduced tumor volume, tumor spread, and microvessel density (MVD), and improved survival. Nonetheless, clinical trials using anti-angiogenic therapy have been overwhelmingly unsuccessful in hPDAC. On the other hand, pancreatic neuroendocrine tumors (PNETs) account for only 2% of pancreatic tumors, yet they are very vascular and classically angiogenic, respond to anti-angiogenic therapy, and confer a better prognosis than PDAC even in the metastatic setting. In an eﬀort to compare and contrast the angiogenic transcriptomes of these two tumor types, we analyzed RNA-Sequencing (RNA-Seq) data from The Cancer Genome Atlas (TCGA) and found that a pro-angiogenic gene signature is present in 35% of PDACs and that it is mostly distinct from the angiogenic signature present in PNETs. The pro-angiogenic PDAC subgroup also exhibits a transcriptome that reﬂects active TGF-β signaling, less frequent SMAD4 inactivation than PDACs without the signature, and up-regulation of several pro-inﬂammatory genes, including members of JAK signaling pathways. Consequently, targeting the TGF-β receptor type-1 kinase with SB505124 and JAK1/2 with ruxolitinib blocks proliferative crosstalk between human pancreatic cancer cells (PCCs) and human endothelial cells (ECs). Additionally, treatment of the KRC (oncogenic Kras, homozygous deletion of Rb1) and KPC (oncogenic Kras, mutated Trp53) genetically engineered PDAC mouse models with ruxolitinib suppresses murine PDAC (mPDAC) progression only in the KRC model, which shows superior enrichment and diﬀerential expression of the human pro-angiogenic gene signature as compared to KPC tumors. These ﬁndings suggest that targeting both TGF-β and JAK signaling in the 35% of PDAC patients whose cancers exhibit an pro-angiogenic gene signature should be explored in a clinical trial.
Bidirectional regulation of YAP and ALDH1A1
(2015-08-10) Martien, Matthew F.; Wells, Clark D.; Hurley, Thomas D.; Quilliam, Lawrence A.
Breast cancer is the second leading cause of cancer death for women in the United States. Approximately, 1 in 5 women will recur with cancer within 10 years of completing treatment and recent publications have suggested that breast cancer stem cells confer resistance to therapy. These reports highlight aldehyde dehydrogenase 1A1 (ALDH1A1) and Yes-associated protein (YAP) as a biomarker and key mediator of the stem cell phenotype respectively. To further understand how YAP and ALDH1A1 facilitate chemoresistance, this study investigated how ALDH1A1 specific inhibition affected YAP activity and growth of basal-like breast cancer cells, which are enriched in cancer stem cells. Intriguingly, attenuation of growth by ALDH1A1 inhibition was observed when cells were plated on a reconstituted basement membrane. Further, the inhibition of cell growth correlated with cytosolic retention of YAP and a reduction in YAP signaling. In a complementary analysis, the overexpression of YAP correlated with an increased level of ALDH1A1 transcript. Results from this study indicate a novel mechanism by which basal-like breast cancer cells utilize YAP to maintain the stem cell phenotype and also suggest ALDH1A1 as a potential therapeutic target for breast cancer therapy.
A Cell-Based Model to Study Factors that Drive Diffuse Astrocytoma Development
(2016-08) Folck, Anthony F.; Wells, Clark D.; Goebl, Mark G.; Quilliam, Lawrence A.
Secondary gliomas are an incurable form of brain cancer that are diagnosed in people at a median age of 45 years. Next-generation sequencing has found that secondary glioblastomas have a distinct genetic profile from the more common primary glioblastomas, which are diagnosed in people typically over the age of 60. Over 80% of secondary gliomas contain an IDH1R132H mutation, resulting in neomorphic mutations, which catalyze isocitrate to the oncometabolite D-2-hydroxyglutarate (2-HG) instead of alpha-ketoglutarate (α-KG). As 2-HG accumulates, it induces a hypermethylator phenotype that prevents the cells from differentiating. Acquisition of additional mutations in tumor suppressors such as p53 and/or ATRX likely leads to tumor initiation. Work in the Wells Laboratory has found that loss of the HIPPO adaptor protein AmotL1 is also associated with increased malignancy. AmotL1 inhibits the transcriptional co-activator YAP to suppress both cell growth and migration. To understand the molecular events leading to secondary glioma development, this thesis developed a series of astrocyte cell lines that carry IDH1 and/or p53 mutations. These lines were then studied in 2D and 3D cell culture systems to identify changes that are associated with early secondary glial tumors. Work was also carried out to enable screens for small molecules that can be tested on these cell lines.
Cell-Type Specific Function of STAT4 in an Animal Model of Multiple Sclerosis
(2023-12) Alakhras, Nada S.; Kaplan, Mark H.; Cook-Mills, Joan; Dong, X. Charlie; Quilliam, Lawrence A.
Signal transducer and activator of transcription 4 (STAT4) is a critical regulator of inflammation. STAT4 promotes protective immunity and autoimmunity downstream of pro-inflammatory cytokines including IL-12 and IL-23. In experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS), germ-line deletion of STAT4 in mice results in resistance to the development of inflammation and paralysis. In parallel, genome-wide association studies (GWAS) have identified polymorphisms in the STAT4 gene associated with susceptibility to several autoimmune diseases including MS demonstrating a potential role for STAT4 in human autoimmunity. Here, we examined cell-type requirements for STAT4 in EAE. Using conditional Stat4 mutant mice, we found that mice lacking Stat4 in T cells and CD11c+-expressing cells are resistant to EAE, while mice lacking Stat4 in Lyz2+-expressing cells are susceptible to EAE. STAT4 is expressed and activated in CD11c+ dendritic cells (DCs) in the CNS during peak disease severity. Stat4fl/flCD11cCre mice exhibit significantly decreased classical dendritic cell (cDC) expansion in the CNS and this correlates with diminished numbers of infiltrated T cells in the CNS and decreased inflammatory cytokine production. Adoptive transfer of wild type but not Stat4-/- or Il23r-/- DCs into Stat4fl/flCD11cCre rescues the development of EAE. Transferred Il23r-/- DCs were retained in the lymph nodes suggesting that IL-23-STAT4 signaling promotes their migration to and expansion in the CNS. Single-cell RNA-seq analyses of CNS DCs from WT and Stat4fl/flCD11cCre mice identified cDC populations with STAT4-dependent gene expression and migratory phenotypes. Collectively, our results demonstrate that STAT4 in cDCs is required for expansion in the CNS, the development of encephalitogenic T cells, and the clinical symptoms of EAE. Thus, our study reveals previously unrecognized functions of STAT4 in cDCs that provide mechanistic insight into CNS autoimmunity and provide a foundation for identifying new therapeutic targets for the disease.
The Chimeric Fusion Protein SETMAR Functions as a Chromatin Organizing Factor
(2020-08) Bates, Alison Melissa; Georgiadis, Millie M.; Mosley, Amber L.; Quilliam, Lawrence A.; Fehrenbacher, Jill C.
About 50 million years ago, an Hsmar1 transposon invaded an early primate genome and inserted itself downstream of a SET methyltransferase gene, leading to the birth of a new chimeric protein now called SETMAR. While all other Hsmar1 sequences in the human genome have suffered inactivating mutational damage, the transposase domain of SETMAR has remained remarkably intact, suggesting that it has gained a novel, evolutionarily advantageous function. While SETMAR can no longer transpose itself throughout the genome, it has retained its ancestral sequence-specific DNA binding activity, the importance of which is currently unknown. To investigate this, we performed ChIP-seq to examine SETMAR binding in the human genome. We also utilized RNA-sequencing to assess SETMAR overexpression as well as SETMAR deletion on the human transcriptome. Additionally, we explored SETMAR’s transposase-derived chromatin-looping ability using chromosome-conformation-capture-on-ChIP (4C) in the presence of SETMAR overexpression and performed genome-wide Hi-C to assess the impact of complete SETMAR silencing on global chromatin interactions. ChIP-seq revealed that SETMAR amassed 7,332 unique binding sites, 69% of which included a TIR motif. RNA-sequencing in cells overexpressing SETMAR indicated 177 differentially regulated transcripts, including repression of 17 histone transcripts, suggesting a possible role in chromatin dynamics. RNA-sequencing of parental and SETMAR knockout clones highlighted an average of 5,000 altered transcripts in each cell line, with 343 transcripts significantly differentially expressed in all three knockout clones, many of which participate in embryonic development pathways. 4C analysis in the presence of SETMAR overexpression discovered multiple intrachromosomal looping interactions, and Hi-C analysis of SETMAR knockout cell lines uncovered genome-wide loss of chromatin interactions and disruption of TAD boundaries. The prevalence of SETMAR binding in the human genome combined with its chromatin looping capability and its dramatic effects on the transcriptome suggest a previously undiscovered role for SETMAR as a novel chromatin organizing factor.
Contributions of Angiomotin-Like-1 on Astrocytic Morphology: Potential Roles in Regulating Connexin-43-Based Astrocytic Gap Junctions, Remodeling the Actin Cytoskeleton and Influencing Cellular Polarity
(2019-10) Downing, Nicholas Frederick; Wells, Clark D.; Goebl, Mark G.; Quilliam, Lawrence A.
Glioblastoma is a lethal cancer that arises from support cells in the nervous system and kills around 20,000 people in the United States each year. While much is known about the highly malignant primary glioblastoma, the natural history of lower grade glioma (LGG) is less understood. While the majority of LGGs are initiated by a mutation in isocitrate dehydrogenase, the events leading to their malignant progression into a grade IV tumor are not known. Analysis of primary tumor sample data has revealed that low transcript levels of Angiomotin-like-1 (AmotL1) strongly associate with poor outcomes of patients with these cancers. Follow-up RNA-sequencing of human embryonic astrocytes with AmotL1 silencing revealed the downregulation of many transcripts that encode proteins mediating gap junctions (GJ) between astrocytes, especially connexin-43 (Cx43). Cx43 protein oligomerizes to form functional channels comprising the astrocytic GJ. AmotL1 knockdown through RNA interference decreases Cx43 transcript and protein levels while increasing its distribution to GJs. This suggests increased GJ formation and intercellular communication, as similar localization patterns are observed in differentiated astrocytes. Astrocytes with AmotL1 knockdown also display a pronounced pancake-like morphology, suggesting that the actin cytoskeleton is affected. Imaging reveals that cells with reduced AmotL1 have characteristic losses in both stress fibers and focal actin under the cell body but notable increases in cortical F-actin. Consistent with previous studies, AmotL1 may promote increases in the number and thickness of F-actin fibers. Because actin binding to related angiomotins is inhibited by phosphorylation from the LATs kinases, I define the effects of expressing wildtype AmotL1 versus mutants that mimic or prevent phosphorylation by LATs1/2. Interestingly, expression of AmotL1 S262D in combination with NEDD4-1, a ubiquitin ligase, results in a profound loss of actin stress fibers. Dependence on NEDD4-1 suggests that this phenotype is due to the induced degradation of proteins that promote F-actin, e.g. RhoA. These results directly support a model in which phosphorylated AmotL1 specifically inhibits F-actin formation as opposed to unphosphorylated AmotL1 which is known to promote stress fiber formation. Thus, in addition to regulating polarity and YAP/TAZ transcriptional co-activators, AmotL1 plays major functions in dictating cellular F-actin dynamics.
The effects of verteporfin on non-small cell lung cancer
(2016-08) Ackerman, Todd R., Jr; Quilliam, Lawrence A.; Wells, Clark D.; Goebl, Mark G.
Non-small cell lung cancer (NSCLC) accounts for 85% of lung cancers and is the leading cause of cancer death in the Unites States. Better treatments must be devised in order to improve the prognosis of this disease. Verteporfin, an FDA approved drug, has recently been reported to downregulate a potential core pathway of NSCLC, the Hippo pathway. The pathway consists of a kinase cascade to control the transcriptional coactivators YAP and TAZ. When these transcriptional coactivators lack phosphorylation of key residues, they are able to translocate into the nucleus and bind to the TEAD member of transcription factors. This augments transcription for genes responsible for proliferation, survival, and stem maintenance. In this study, we report that verteporfin limits proliferation and survival of NSCLC and may potentially be a viable treatment option. Inhibition of cell survival dose-dependently correlated with inhibition of YAP-TEAD transcription target CTGF. We also report the covalent homo-oligomerization of p62, a prominent protein involved with autophagy, with the introduction of verteporfin into NSCLC cells.
Elucidating the role of SMAD7 in pancreatic cancer through in vivo studies
(2017-09) Savant, Sudha Satish; Korc, Murray; Wek, Ronald C.; Quilliam, Lawrence A.; Xie, Jing Wu
Pancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of death with a mere 9% survival rate. PDACs harbor KRAS (92-95%) and CDKN2A (90%) mutations, overexpress tyrosine kinase receptors, their ligands, and transforming growth factor-β (TGF-β) isoforms. Canonical TGF-β signaling is mediated via Smad2, Smad3 and Smad4, whereas inhibitory Smad6 and Smad7 attenuate TGF-β signaling. Smad7 is overexpressed in PDAC and blocks TGF-β-mediated growth inhibition in vitro. However, the exact role of Smad7 in PDAC is not known. We have established a genetically engineered mouse model of PDAC in which conditional expression of Smad7 and oncogenic KrasG12D are driven in the pancreas by Pdx1-Cre. These LSL KrasG12D;SMAD7;Pdx1-Cre(KS7C) mice exhibit accelerated progression of pancreatic intraepithelial neoplasia (PanIN) to PDAC by comparison with LSL-KrasG12D;Pdx1-Cre (KC) mice harboring the KrasG12D mutation alone, whereas in the absence of oncogenic Kras, pancreatic histology remains normal in spite of a 9- fold increase in Smad7 mRNA levels. KS7C pancreata exhibit increased PanIN and pancreatic cancer cell proliferation, and these changes are recapitulated in a tetracycline (tet) inducible mouse model of Smad7 (KtetS7C). In both models, pre-neoplastic lesions and PDACs exhibited increased levels of anterior gradient 2 (AGR2), hyper-phosphorylated retinoblastoma protein (p-pRb) and p-Smad2, but low levels of p-Smad3 and p21. Smad7 overexpression in human pancreatic cancer cells (hPCCs) results in downregulated p21 and upregulated AGR2 mRNA and protein levels, and decreased binding of Smad3/4 complex to the AGR2 promoter. Smad3 silencing in hPCCS also resulted in downregulated p21 mRNA and upregulated AGR2 mRNA levels. These findings indicate that Smad7 blocks TGF-β pathways, in part, by preferentially decreasing Smad3 phosphorylation and enhancing AGR2 expression in PDAC, and suggest that targeting Smad7 may constitute a novel therapeutic approach in PDAC.
Endothelial Colony Forming Cells (ECFCs): Identification, Specification and Modulation in Cardiovascular Diseases
(2009-12) Huang, Lan; Pescovitz, Mark D.; Quilliam, Lawrence A.; Ingram, David A., Jr.; Pescovitz, Mark D.
A hierarchy of endothelial colony forming cells (ECFCs) with different levels of proliferative potential has been identified in human circulating blood and blood vessels. High proliferative potential ECFCs (HPP-ECFCs) display properties (robust proliferative potential in vitro and vessel-forming ability in vivo) consistent with stem/progenitor cells for the endothelial lineage. Corneal endothelial cells (CECs) are different from circulating and resident vascular endothelial cells (ECs). Whereas systemic vascular endothelium slowly proliferates throughout life, CECs fail to proliferate in situ and merely expand in size to accommodate areas of CEC loss due to injury or senescence. However, we have identified an entire hierarchy of ECFC resident in bovine CECs. Thus, this study provides a new conceptual framework for defining corneal endothelial progenitor cell potential. The identification of persistent corneal HPP-ECFCs in adult subjects might contribute to regenerative medicine in corneal transplantation. While human cord blood derived ECFCs are able to form vessels in vivo, it is unknown whether they are committed to an arterial or venous fate. We have demonstrated that human cord blood derived ECFCs heterogeneously express gene transcripts normally restricted to arterial or venous endothelium. They can be induced to display an arterial gene expression pattern after vascular endothelial growth factor 165 (VEGF165) or Notch ligand Dll1 (Delta1ext-IgG) stimulation in vitro. However, the in vitro Dll1 primed ECFCs fail to display significant skewing toward arterial EC phenotype and function in vivo upon implantation, suggesting that in vitro priming is not sufficient for in vivo specification. Future studies will determine whether ECFCs are amenable to specification in vivo by altering the properties of the implantation microenvironment. There is emerging evidence suggesting that the concentration of circulating ECFCs is closely related to the adverse progression of cardiovascular disorders. In a pig model of acute myocardial ischemia (AMI), we have demonstrated that AMI rapidly mobilizes ECFCs into the circulation, with a significant shift toward HPP-ECFCs. The exact role of the mobilized HPP-ECFCs in homing and participation in repair of the ischemic tissue remains unknown. In summary, these studies contribute to an improved understanding of ECFCs and suggest several possible therapeutic applications of ECFCs.

Browsing by Author "Quilliam, Lawrence A."

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