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Full-Text Articles in Cancer Biology
Quantification Of Protoporphyrin Ix Accumulation In Glioblastoma Cells – A New Technique, Johnathan Lawrence, Ashish Patel, Richard Rovin, Robert Belton, Catherine Bammert, Robert Winn
Quantification Of Protoporphyrin Ix Accumulation In Glioblastoma Cells – A New Technique, Johnathan Lawrence, Ashish Patel, Richard Rovin, Robert Belton, Catherine Bammert, Robert Winn
Johnathan Lawrence
Introduction. 5-Aminolevulinic Acid (5-ALA) is a precursor of heme synthesis. A metabolite, protoporphyrin IX (PpIX), selectively accumulates in neoplastic tissue including glioblastoma. Presurgical administration of 5-ALA forms the basis of fluorescence-guided resection (FGR) of glioblastoma (GBM) tumors. However, not all gliomas accumulate sufficient quantities of PpIX to fluoresce, thus limiting the utility of FGR. We therefore developed an assay to determine cellular and pharmacological factors that impact PpIX fluorescence in GBM. This assay takes advantage of a GBM cell line engineered to express yellow fluorescent protein. Methods. The human GBM cell line U87MG was transfected with a YFP expression vector. …
Phenytoin Reduces 5-Ala Mediated Fluorescence In Glioblastoma Cells, Christopher Steele, Johnathan E. Lawrence, Richard A. Rovin, Robert J. Winn
Phenytoin Reduces 5-Ala Mediated Fluorescence In Glioblastoma Cells, Christopher Steele, Johnathan E. Lawrence, Richard A. Rovin, Robert J. Winn
Johnathan Lawrence
Glioblastoma multiforme (GBM) is a devastating form of cancer, and essentially all GBM tumors recur causing fatality. A new surgical technique, fluorescence-guided resection of GBM using 5-aminolevulinic acid (5-ala), improves the extent of resection and positively impacts the length and quality of patient survival. The fluorescence achieved in neoplastic tissue depends directly on the accumulation of porphyrins derived from the metabolism of the 5-ala prodrug within the cancer cell. However, 5-ala induced fluorescence has been reported to be inconsistent. In an effort to determine the cause of the inconsistent fluorescence, the authors investigated the effect of medications commonly prescribed to …
Glioblastoma Derived Exosomes Induce Apoptosis In Cytotoxic T Cells Through A Fas Ligand Mediated Mechanism, Keith Sabin, Richard Rovin, Johnathan Lawrence, Robert Belton, Robert Winn
Glioblastoma Derived Exosomes Induce Apoptosis In Cytotoxic T Cells Through A Fas Ligand Mediated Mechanism, Keith Sabin, Richard Rovin, Johnathan Lawrence, Robert Belton, Robert Winn
Johnathan Lawrence
INTRODUCTION: Glioblastoma multiforme deploy s a number of weapons to thwart the immune system. Within the tumor microenvironment, cytotoxic T cells fall victim to Fas ligand (FasL) induced apoptosis. In prostate and colorectal cancer, exosomes can mediate this FasL induced T cell apoptosis. Exosomes are tiny, membrane bound vesicles that are released from a cell. They contain functional mRNA and protein and have cell surface molecules representative of their parent cell. It is not known if GBM derived exosomes can also mediate FasL triggered apoptosis. In this study, the role of tumor derived exosomes as the delivery vehicle for FasL …
Leptin Promotes Glioblastoma, Johnathan Lawrence, Nicholas Cook, Richard Rovin, Robert Winn
Leptin Promotes Glioblastoma, Johnathan Lawrence, Nicholas Cook, Richard Rovin, Robert Winn
Johnathan Lawrence
The hormone leptin has a variety of functions. Originally known for its role in satiety and weight loss, leptin more recently has been shown to augment tumor growth in a variety of cancers. Within gliomas, there is a correlation between tumor grade and tumor expression of leptin and its receptor. This suggests that autocrine signaling within the tumor microenvironment may promote the growth of high-grade gliomas. Leptin does this through stimulation of cellular pathways that are also advantageous for tumor growth and recurrence: antiapoptosis, proliferation, angiogenesis, and migration. Conversely, a loss of leptin expression attenuates tumor growth. In animal models …
Effects Of Ss3-Adrenergic Receptor Agonist On Gene Expression Of Leptin In Glioblastoma, Johnathan E. Lawrence, Nicholas J. Cook, Richard A. Rovin, Robert J. Belton, Robert J. Winn
Effects Of Ss3-Adrenergic Receptor Agonist On Gene Expression Of Leptin In Glioblastoma, Johnathan E. Lawrence, Nicholas J. Cook, Richard A. Rovin, Robert J. Belton, Robert J. Winn
Johnathan Lawrence
In the 25 years since temozolomide entered phase I clinical trials, few new primary or adjuvant therapies have been developed for the treatment of glioblastoma multiforme (GBM) tumors. Our laboratory has been exploring novel methods for the treatment of GBMs. Recent studies indicate that the expression of the hormone leptin and its receptor (OBR) increases in gliomas and positively correlates with the malignancy of the tumor. Interestingly, ß3-adrenergic receptor agonists are known to decrease leptin expression in adipocytes but have not been examined in GBM cells. We hypothesized that b3-adrenergic agonists downregulate the expression of leptin and its receptor. In …
Β3-Adrenergic Agonists Mimic Eustress Response And Reduce Leptin-Mediated Proliferation In A Gbm Cell Line, Johnathan E. Lawrence, Nicholas J. Cook, Richard A. Rovin, Robert J. Winn
Β3-Adrenergic Agonists Mimic Eustress Response And Reduce Leptin-Mediated Proliferation In A Gbm Cell Line, Johnathan E. Lawrence, Nicholas J. Cook, Richard A. Rovin, Robert J. Winn
Johnathan Lawrence
A great deal of mental stress, depression, and anxiety often overwhelm cancer patients; those diagnosed with glioblastoma multiforme (GBM) are no exception. Different types of stress invariably impact what has been termed “the brain-adipocyte BDNF/leptin axis” (Dr. Cao and colleagues of the Comprehensive Cancer Center at The Ohio State University). For example, eustress (good stress) and distress (bad stress) both lead to increased sympathetic activity and adrenal gland stimulation, yet eustress reduces leptin levels and attenuates tumor growth while distress increases leptin levels and augments tumor growth. Complicating matters in GBM is that leptin and its receptor are expressed at …
Glioblastoma Derived Exosomes Contribute To Tumor Immune Evasion, Keith Z. Sabin, Danny Lebert, Vanessa Thibado, Richard A. Rovin, Johnathan E. Lawrence, Robert J. Winn
Glioblastoma Derived Exosomes Contribute To Tumor Immune Evasion, Keith Z. Sabin, Danny Lebert, Vanessa Thibado, Richard A. Rovin, Johnathan E. Lawrence, Robert J. Winn
Johnathan Lawrence
Glioblastoma multiforme (GBM) is the most frequent and lethal primary brain tumor in adults. Despite intense biomedical research, the median survival after diagnosis is 15 months. One factor contributing to this poor prognosis is the immune protection afforded by the tumor microenvironment. Tumors have a diverse repertoire of immune-evasive techniques. One method of evasion not well explored is the release of tumor-derived exosomes. Exosomes are tiny membrane-bound vesicles of endocytic origin that contain viable mRNA and functional proteins that can affect the physiology of recipient cells. Exosome release has been reported for numerous cancer types, including GBM. Exosomes from colon …
Expression Of Hcmv Ie1 In The U87mg Cell Line Augments Resistance To Temozolomide, Richard Rovin, Johnathan Lawrence, Justin Segula, Robert Winn
Expression Of Hcmv Ie1 In The U87mg Cell Line Augments Resistance To Temozolomide, Richard Rovin, Johnathan Lawrence, Justin Segula, Robert Winn
Johnathan Lawrence
INTRODUCTION: Human cytomegalovirus (HCMV) DNA and protein are found in gliomas but not in normal brain or other primary brain tumors. The role of HCMV infection in glioma biology is unclear. While it is unlikely that HCMV infection causes glioma, viral proteins might impart a proliferative and antiapoptotic phenotype that confers a survival advantage. Does this oncomodulation translate into a clinically relevant effect in glioma cells? To answer this question, we compared the response of the U87IE1 and U87MG malignant glioma cell lines to temozolomide. U87IE1 cells are U87MG cells that have been genetically engineered to produce HCMV IE1 protein. …