Targeting Invasive Glioblastoma via the TROY-JAK1 Signaling Pathway

A Thesis submitted to The University of Arizona College of Medicine - Phoenix in partial fulfillment of the requirements for the Degree of Doctor of Medicine.Objective and Hypothesis: Glioblastoma multiforme, the most common and lethal primary brain neoplasm in adults, has been historically difficult to treat, as its invasion into contiguous brain tissue mitigates the benefit of surgical resection. Furthermore, its unique ability to evade apoptosis and selectively induce proliferation promotes chemotherapeutic resistance and explains the lack of substantial survival improvement despite decades of research. The orphan transmembrane receptor, TROY, has been shown to influence glioma cell migration and survival. While TROY downstream signaling presents a potential therapeutic target, the detailed pathway has yet to be fully elucidated. We identified the non-receptor tyrosine kinase, JAK1,as a candidate binding partner and hypothesized that JAK1 is a downstream mediator of TROY-induced glioma invasion, ultimately seeking to validate the potential therapeutic potential of this interaction. Methods: TROY-JAK1 binding was assessed by co-immunoprecipitation of JAK1 with immunoblotting for TROY. The mechanism of this JAK1-TROY interaction was assessed by western blottingfor phosphorylated JAK1 and STAT3 in wild type vs. TROY-overexpressing glioma cells. Finally, an in-vitro radial migration assay was performed under siRNA depletion of JAK1 to assess functional validation. Results: JAK1 was confirmedas a TROY binding partner by co-immunoprecipitation, with immunoblotting demonstrating that TROY-overexpression induces JAK1 phosphorylation. siRNA-mediated depletion of JAK1 also resulted in decreasedphosphorylated STAT3 level. Finally, a radial migration assay performed on wild-type and TROY-overexpressing T98G cells with and without JAK1 depletion demonstrated statistically significant reductions in migration rate in both JAK1-depleted groups compared to controls. Significance: This study identified and confirmed JAK1 as a downstream mediator of TROY signaling and demonstrated that JAK1 depletion results in mitigation of the pro-migratory effect of TROY overexpression. Thus, JAK1 provides a potential novel therapeutic target for disruption of glioblastoma TROY signaling in vivo andmay contribute to the development of more efficacious chemotherapeutic agents.This item is part of the College of Medicine - Phoenix Scholarly Projects 2013 collection. For more information, contact the Phoenix Biomedical Campus Library at [email protected]

IgG4-Seronegative Autoimmune Pancreatitis and Sclerosing Cholangitis

IgG4-related disease is a relatively novel clinical entity whose gastrointestinal manifestations include type 1 autoimmune pancreatitis (AIP) and IgG4-associated sclerosing cholangitis. The presence of elevated serum IgG4 is suggestive but not essential for the diagnosis of type 1 AIP and is a pervasive feature of the proposed diagnostic criteria. The differential diagnosis of type 1 AIP includes malignant conditions, emphasizing the importance of a deliberate, comprehensive evaluation. Management of patients with a suggestive clinical presentation, but without serum IgG4 elevation, is difficult. Here we present three cases of IgG4-seronegative AIP and sclerosing cholangitis that responded to empiric steroid therapy and discuss approach considerations. These cases demonstrate the value of meticulous application of existing diagnostic algorithms to achieve a clinical diagnosis and avoid surgical intervention

Factitious Disorder in Crohn's Disease: Recurrent Pancytopenia Caused by Surreptitious Ingestion of 6-Mercaptopurine

Factitious disorder is a rare psychiatric illness characterized by the willful and deceptive induction of illness for the purpose of assuming the sick role. It presents a substantial diagnostic challenge, as patients often go to great lengths to conceal their deception. Accordingly, its presence in the full spectrum of gastrointestinal diseases is likely underappreciated. While factitious gastrointestinal bleeding, abdominal pain and diarrhea are relatively common, factitious non-gastrointestinal symptoms in the setting of gastrointestinal illness have been infrequently reported. We present the case of a patient with Crohn's disease with recurrent pancytopenia attributed to the surreptitious ingestion of 6-mercaptopurine. In patients with possible access to immunomodulatory drugs, a high suspicion for and early identification of factitious disorder may improve patient outcomes and avoid invasive and costly diagnostic evaluations