Discovery Category Highlights

Viral Expression Cassette Elements to Enhance Transgene Target Specificity and Expression in Gene Therapy

Abstract: Over the last five years, the number of clinical trials involving AAV (adenovirus associated virus) and lentiviral vectors continue to increase by about 150 trials each year. For continued success, AAV and lentiviral expression cassettes need to be designed to meet each disease's specific needs. This review discusses how viral vector expression cassettes can be engineered with elements to enhance target specificity and increase transgene expression. The key differences relating to target specificity between ubiquitous and tissue-specific promoters are discussed, as well as how endogenous miRNAs and their target sequences have been used to restrict transgene expression. Specifically, relevant studies indicating how cis-acting elements such as introns, WPRE, polyadenylation signals, and the CMV enhancer are highlighted to show their utility for enhancing transgene expression in gene therapy applications. All discussion bears in mind that expression cassettes have space constraints. In conclusion, this review can serve as a menu of vector genome design elements and their cost in terms of space to thoughtfully engineer viral vectors for gene therapy. ... Read more

Novel Combinations of Ion Channel Inhibitors for Treatment of Neurotrauma

Abstract: Neurotrauma results in the progressive degeneration of neurons and glia surrounding the initial injury. Disruptions to myelin structure are a feature of these injuries and are thought to be triggered by excess calcium (Ca2+) influx into myelinating oligodendrocytes and/or their precursor cells. Calcium ions enter oligodendrocytes through a range of receptors including voltage gated calcium channels, N-methyl-D-aspartate (NMDA) receptors, Ca2+ permeable α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors, and purinergic P2X7 receptors. Inhibitors have been used to limit excess Ca2+ entry following neurotrauma, but clinical success has been limited. We propose that combinations of calcium channel inhibitors may provide an alternative treatment strategy, whereby entry of excess Ca2+ flux through multiple routes is inhibited simultaneously. ... Read more

Why Is Coinfection with Influenza Virus and Bacteria So Difficult to Control?

Abstract: Influenza viruses are genetically labile pathogens which avoid immune detection by constantly changing their coat proteins. Most human infections are caused by mildly pathogenic viruses which rarely cause life-threatening disease in healthy people, but some individuals with a weakened immune system can experience severe complications. Widespread infections with highly pathogenic strains of influenza virus are less common, but have the potential to cause enormous death tolls among healthy adults if infection rates reach pandemic proportions. Increased virulence has been attributed to a variety of factors, including enhanced susceptibility to coinfection with common strains of bacteria. The mechanisms that facilitate dual infection are a major focus of current research, as preventative measures are needed to avert future pandemics. ... Read more

K-ras-driven Engineered Mouse Models for Pancreatic Cancer

Abstract: Pancreatic cancer (PC) is one of the most fatal cancers largely due to the lack of early diagnosis and effective therapies. Therefore, further understanding the underlying molecular mechanisms of PC development and progression is pivotal to the development of more effective targeted therapies. Emerging evidence has suggested that using mouse models, especially genetically engineered mouse models, is ideal to explore the mechanisms of pancreatic tumorigenesis. To this end, it has been known that a K-ras mutation on codon 12 (K-ras G12D) plays a critical role in the PC development. Thus, most mouse models of PC have been developed by targeting a conditionally mutated K-ras (G12D) together with concomitant deletion or mutation of other key genes to recapitulate the PC progression in human patients. Here, we summarize a number of K-ras-driven engineered mouse models to provide molecular insights into PC disease development and progression. We hope that these mouse models will help design a novel therapeutic strategy and to further improve the treatment of PC patients. ... Read more

Immune Checkpoint Blockade as a Novel Immunotherapeutic Strategy for Renal Cell Carcinoma: A Review of Clinical Trials

Abstract: Renal cell carcinoma (RCC) is a common genitourinary malignancy; when metastatic, it is almost uniformly fatal. For many years non-specific immunotherapy was the mainstay of treatment for metastatic RCC, but led to only modest success and significant side-effects. More recently, seven targeted therapy drugs have been approved to treat metastatic RCC; these drugs impede RCC cell growth, proliferation, and angiogenesis and have had a significant impact on patient outcomes, but with infrequent long term responders. Thus, a renewed emphasis on immunotherapy has emerged over the last several years with the development and testing of a novel class of immunotherapeutic agents called checkpoint inhibitors. These drugs have targeted the programmed cell death 1 (PD-1) and cytotoxic leukocyte antigen 4 (CTLA-4) pathways on regulatory T cells, leading to immune response enhancement and immune-mediated anti-tumor effects in multiple malignancies, including RCC. A number of studies recently reported utilizing checkpoint inhibitors, either alone or in combination with other checkpoint inhibitors or vascular endothelial growth factor targeting agents, and these studies have shown significant and at times durable responses in RCC patients. This has led to the development of further phase I, II, and III trials and this review will discuss the history and currently available data for immune checkpoint blockade in RCC. ... Read more

Targeted Therapy for Hereditary Cancer Syndromes: Neurofibromatosis Type 1, Neurofibromatosis Type 2, and Gorlin Syndrome

Abstract: Hereditary cancer syndromes are well known in the oncology community, typically affecting children, adolescents, and young adults and thereby resulting in great cumulative morbidity and mortality. These syndromes often lag behind their de novo counterparts in the development of approved novel treatment options due to their rarity in the general population. Recent work has allowed the identification of molecular aberrations and associated targeted therapies that may effectively treat these conditions. In this review, we seek to characterize some of the involved aberrations and associated targeted therapies for several germline malignancies, including Neurofibromatosis types 1 and 2, and Gorlin syndrome. Though patients with hereditary cancer syndromes may be too rare to effectively include in large clinical trials, by understanding the pathophysiology of these diseases, clinicians can attain insights into the use of targeted therapies in their own practice when treating affected individuals. ... Read more

Targeted Therapy for Hereditary Cancer Syndromes: Hereditary Breast and Ovarian Cancer Syndrome, Lynch Syndrome, Familial Adenomatous Polyposis, and Li-Fraumeni Syndrome

Abstract: Cancer genetics has rapidly evolved in the last two decades. Understanding and exploring the several genetic pathways in the cancer cell is the foundation of targeted therapy. Several genomic aberrations have been identified and their role in carcinogenesis is being explored. In contrast to most cancers where these mutations are acquired, patients with hereditary cancer syndromes have inherited genomic aberrations. The understanding of the molecular pathobiology in hereditary cancer syndromes has advanced dramatically. In addition, many molecularly targeted therapies have been developed that could have potential roles in the treatment of patients with hereditary cancer syndromes. In this review, we outline the presentation, molecular biology, and possible targeted therapies for two of the most widely recognized hereditary cancer syndromes -- hereditary breast and ovarian cancer syndrome and hereditary non-polyposis colorectal cancer syndrome (Lynch syndrome). We will also discuss other syndromes such as familial adenomatous polyposis and Li-Fraumeni syndrome (TP53). ... Read more

The Contribution of Non-human Primate Models to the Development of Human Vaccines

Abstract: The non-human primates (NHPs) model in biomedical research has contributed to the study of human infectious, autoimmune, oncogenic, and neurological diseases. This review focuses on the importance of NHP models in vaccine development for tuberculosis, pertussis, Dengue, group A streptococcus (Streptococcus pyogenes) infection, HIV infection, and certain diseases in the elderly (influenza, for example). From understanding disease pathogenesis and mechanisms of protection, to assessing vaccine safety and efficacy, we discuss selected cases where the importance of the use of NHP models is highlighted. ... Read more

Exome Sequencing on Malignant Meningiomas Identified Mutations in Neurofibromatosis Type 2 (NF2) and Meningioma 1 (MN1) Genes

Abstract: Background: Meningiomas are tumors originating from the membranous layers surrounding the central nervous system, and are generally regarded as "benign" tumors of the brain. Malignant meningiomas are rare and are typically associated with a higher risk of local tumor recurrence and a poorer prognosis (median survival time <2 years). Previous genome-wide association studies and exome sequencing studies have identified genes that play a role in susceptibility to meningiomas, but these studies did not focus specifically on malignant tumors. Methods: We performed exome sequencing on five malignant meningiomas on the Illumina HiSeq2000 platform using Agilent SureSelect Human All Exon kits. We used wANNOVAR web server to annotate and prioritize variants, identified candidate genes with recurrent mutations, and validated selected mutations by Sanger sequencing. We next designed custom NimbleGen targeted region arrays on five candidate genes, and sequenced four additional malignant meningiomas. Results: From exome sequencing data, we identified several frequently mutated genes including NF2, MN1, ARID1B, SEMA4D, and MUC2, with private mutations in tumors. We sequenced these genes in four additional samples and identified potential driver mutations in NF2 (neurofibromatosis type 2) and MN1 (meningioma 1). Conclusions: We confirmed that mutations in NF2 may play a role in progression of meningiomas, and nominated MN1 as a candidate gene for malignant transformation of meningiomas. Our sample size is limited by the extreme rarity of malignant meningiomas, but our study represents one of the first sequencing studies focusing on the malignant subtype. ... Read more

Involvement of Pituitary Tumor Transforming Gene 1 in Psoriasis, Seborrheic Keratosis, and Skin Tumors

Abstract: Accumulating evidence suggests that pituitary tumor transforming gene 1 (PTTG1) is a potential biomarker for cancer malignancy and a cell-cycle regulatory protein. This investigation was performed to address the subcellular localization of PTTG1 and its possible involvement in proliferative skin diseases. In vitro primary-cultured keratinocytes and skin samples from psoriasis, seborrheic keratosis (SK), basal cell carcinoma (BCC), and squamous cell carcinoma (SCC) were investigated by immunofluorescence and real-time PCR. In normal skin, PTTG1 is localized predominantly in 10% of basal keratinocytes, while 30-40% in basal and suprabasal psoriatic keratinocytes. PTTG1 mRNA in psoriatic epidermis is about 5-fold more than that in normal one (P<0.01). PTTG1 is localized in cytoplasm in primary-cultured normal and psoriatic keratinocytes, and PTTG1 in HaCaT cells is distributed throughout the cytoplasm of metaphase cells. PTTG1 is seen at both G2 and M phases, and highest PTTG1 expression correlates with highest cyclin B1 expression and highest degree of nuclear pleomorphism at M phase. The positive rate of PTTG1 in SK, BCC, and SCC is about 10%, 20%, and more than 80%, respectively. PTTG1 siRNA, which knocks down the expression of PTTG1, reduced the invasive capacity of A431 cells. In conclusion, PTTG1 is a marker for proliferative skin diseases associated with cell cycle regulation and may aid in detection of aggressive cancers. ... Read more

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