Proteasome inhibitors bortezomib and carfilzomib are FDA-approved anticancer agents that have contributed to significant improvements in treatment outcomes. However, the eventual onset of acquired resistance continues to limit their clinical utility, yet a clear consensus regarding the underlying mechanisms has not been reached. Bortezomib and carfilzomib are known to target both the constitutive proteasome and the immunoproteasome, two conventional proteasome subtypes comprising distinctive sets of catalytic subunits. While it has become increasingly evident that additional, ‘intermediate’ proteasome subtypes, which harbor non-standard mixtures of constitutive proteasome and immunoproteasome catalytic subunits, represent a considerable proportion of the proteasome population in many cell types, less is known regarding their contribution to cellular responses to proteasome inhibitors. Importantly, previous studies in murine models have shown that individual proteasome subtypes differ in sensitivity to specific proteasome inhibitors. Furthermore, research efforts in our laboratory and others have revealed that proteasome catalytic subunit expression levels and activity profiles are altered when human cancer cells acquire resistance to proteasome inhibitors. We therefore hypothesized that changes in the relative abundances of individual proteasome subtypes contribute to the acquired resistance of cancer cells to bortezomib and carfilzomib. A major obstacle in testing our hypothesis was a lack of chemical probes suitable for use in identifying distinct proteasome subtypes. We addressed this by developing a series of bifunctional proteasome probes capable of crosslinking specific pairs of catalytic subunits colocalized within individual proteasome complexes and compatible with immunoblotting-based detection of the crosslinked subunit pairs. We confirmed the utility of these probes in discerning the identities of individual proteasome subtypes in a multiple myeloma cell line that abundantly expresses catalytic subunits of both the constitutive proteasome and immunoproteasome. Our findings indicate that constitutive proteasomes, immunoproteasomes, and intermediate proteasomes co-exist within these cells and support conclusions drawn from previous studies in other cell types. We also established non-small cell lung cancer cell line models of acquired bortezomib and carfilzomib resistance in which to test our hypothesis. Using immunoblotting and proteasome activity assays, we discovered that changes in the expression levels and activities of individual catalytic proteasome subunits were associated with the emergence of acquired resistance to bortezomib or carfilzomib. These changes were inhibitor-dependent and persisted after the selective pressure of the inhibitor was removed. Finally, results obtained using our bifunctional proteasome probes suggest that the altered abundance of an intermediate proteasome subtype is associated with acquired proteasome inhibitor resistance. Collectively, our results provide evidence linking changes proteasome composition with acquired proteasome inhibitor resistance and support the hypothesis that such changes are involved in resistance mechanisms to these inhibitors.

The emerging field of RNA nanotechnology necessitates creation of functional RNA nanoparticles, but has been limited by particle instability. Previously, it was found the three-way junction (3WJ) of the Phi29 DNA packaging motor pRNA was found to be ultra-stable and assemble in solution without the presence of metal ions. The three-way junction is composed of three short oligo RNA strands and proven to be thermodynamically stable. Here the assembly mechanism, thermodynamic and enzymatic stabilities, and kinetics are examined in order to understand the stability behind this unique motif. Thermodynamic and kinetics studies found that the pRNA 3WJ formed out of three components at a rapid rate creating a single-step three component collision with a lack of dimer intermediate formation while being governed by entropy, instead of the commonly seen enthalpy. Furthermore, the pRNA 3WJ proved to be stable at temperatures above 50 °C, concentrations below 100 pM, and produced a free energy of formation well below other studied RNA structures and motifs. With the high stability and folding efficiency of the pRNA 3WJ, it serves as an ideal platform for multi-branched RNA nanoparticles constructed through bottom-up techniques. RNA nanoparticles were constructed for the specific targeting of prostate cancer cells expressing Prostate Specific Membrane Antigen (PSMA) by receptor mediated endocytosis through the addition of an RNA aptamer; and the delivery of anti-miRNA sequences for gene regulation. The resulting nanoparticles remained stable while showing highly specific binding and entry in PSMA positive cells through cell surface receptor endocytosis. Furthermore, the entry of the nanoparticles allowed for the knockdown of against onco-miRNAs. Nanoparticles harboring antimiRNAs led to the upregulation of tumor suppressor genes, and signaling of apoptotic pathways. These findings display RNA nanotechnology can result in the production of stable nanoparticles and result in the specific treatment of cancers, specifically prostate cancer.

Metal-based engineered nanomaterials (ENMs) have potential to revolutionize diagnosis, drug delivery and manufactured products, leading to greater human ENM exposure. It is crucial to understand ENM pharmacokinetics and their association with biological barriers such as the blood-brain barrier (BBB). Physicochemical parameters such as size and surface modification of ENMs play an important role in ENM fate, including their brain association. Multifunctional ENMs showed advantages across the highly regulated BBB. There are limited reports on ENM distribution among the blood in the brain vasculature, the BBB, and brain parenchyma. In this study, ceria ENM was used to study the effect of size on its pharmacokinetics. Four sizes of ceria ENMs were studied. Five nm ceria showed a longer half-life in the blood and higher brain association compared with other sizes and 15 and 30 nm ceria had a higher blood cell association than 5 or 55 nm ceria. Because of the long circulation and high brain association of 5 nm ceria compared with other sizes, its distribution between the BBB and brain parenchyma was studied. The in situ brain perfusion technique showed 5 nm ceria (99%) on the luminal surface of the BBB rather than the brain parenchyma. For biomedical applications in the central nervous system (CNS), it is vital to develop stable and biocompatible ENMs and enhance their uptake by taking advantage of their unique properties. Cross-linked nanoassemblies entrapping iron oxide nanoparticles (CNA-IONPs) showed controlled particle size in biological conditions and less toxicity in comparison to Citrate-IONPs. CNA-IONPs considerably enhanced MRI T2 relaxivities and generated heat at mild hyperthermic temperatures (40 ~ 42°C) in the presence of alternating magnetic field (AMF). Numerous researchers showed mild whole body hyperthermia can increase BBB permeability for potential brain therapeutic application. Compared to conventional hyperthermia, AMF-induced hyperthermia increased BBB permeability with a shorter duration of hyperthermia and lower temperature, providing the potential to enhance IONP flux across the BBB with reduced toxicity. Overall, ENMs with optimized physicochemical properties can enhance their flux across the BBB into the brain with desirable pharmacokinetics, which provide great potential for diagnosis and therapy in the CNS.

Background: Staphylococcus aureus is an aerobic, Gram positive commensal organism that is capable of causing a wide spectrum of disease. This study contributes to previously published literature regarding daptomycin versus vancomycin use in S. aureus bacteremia (SAB). Methods: Adult patients admitted between 2010 and 2014, billed for ICD-9 code V09.0, 038.11, 038.12, 041.11, or 041.12, and received vancomycin and daptomycin were included in this retrospective analysis. Patients were stratified by time to change in antibiotics from vancomycin to daptomycin to the early switch (1-3 days), intermediate switch (4-7 days), or late switch (8 days or later) group. The primary outcome was treatment failure defined as 30-day recurrence, 60-day all-cause mortality, and 90-day all-cause readmission. Results: 193 patients were enrolled in the final cohort. The overall treatment failure rate was 18% with no differences between early switch, intermediate switch, and late switch (P=0.72) groups. Independent predictors of treatment success were length of stay (OR=1.035) and time to positive culture (OR=0.961). Conclusions: Results of this study did not demonstrate a difference in treatment failure based on time to switch from vancomycin to daptomycin. Future research should focus on optimizing use of vancomycin and daptomycin and medical management of SAB.

β1i is a major catalytic subunit of the immunoproteasome, an alternative form of the constitutive proteasome, and its upregulation has been demonstrated in a variety of disease states including cancer. Our lab has developed a small molecule inhibitor of β1i, dubbed UK-101. While UK-101 causes apoptosis in cancer cell lines, it was not clear whether this apoptotic effect was directly mediated by its irreversible inhibition of β1i. Since off-target effects are major roadblocks for the development of new and effective pharmaceuticals, target validation studies in this system would assist in the further progression of β1i inhibitors towards preclinical trials. Our hypothesis was that the expression and catalytic activity of β1i is important for the growth and proliferation of the PC-3 prostate cancer cell line, therefore the apoptotic effect seen upon treatment of PC-3 cells with UK-101 was due solely to its covalent inhibition of β1i. To test this hypothesis, a number of complementary approaches were used. The expression of β1i in PC-3 cells was increased by the treatment of these cells with interferon-gamma or tumor necrosis factor-alpha, natural inducers of the immunoproteasome. The expression of β1i in PC-3 cells was decreased using small interfering RNA or short hairpin RNA, in a transient or stable manner, respectively. All of these cells were then treated with UK-101. The efficacy of UK-101 decreased in the interferon-gamma treated cells but did not change in any other the other cell lines, suggesting that UK-101 was not specific for β1i. This was confirmed using a molecular probe of the proteasome and demonstrated that UK-101 bound to other proteasome catalytic subunits. Additional experiments were performed to determine the effect of β1i on the proliferation of PC-3 cells. Simply removing the β1i using small interfering RNA reduces the viability of these cells. Other studies demonstrated that a mutation of β1i which inhibited its catalytic activity reduced the viability of cells when compared to those containing the wild type protein. Overall, our data indicate that β1i is a potential therapeutic target in prostate cancer. Further medicinal chemistry efforts will be required develop UK-101 into a truly selective proteasome inhibitor.

Lipid-based drug delivery systems (LBDDSs) are becoming an increasingly popular approach to improve the oral absorption of poorly-water soluble drugs. Several possible mechanisms have been proposed to explain the means by which LBDDSs act in vivo to enhance absorption. The goal of the current dissertation is to provide a better understanding of one proposed mechanism; the capability of lipoidal components in LBDDS formulations to create and maintain a drug in a supersaturated state under simulated GI conditions. Moreover, molecular details of equilibrium solubilization of a drug in a series of model lipid assemblies were examined. The results of these studies will aid formulators in choosing the optimal LBDDS to improve oral absorption of poorly water-soluble drugs. Time-dependent solubilization behavior of progesterone, 17β-estradiol and nifedipine in a simple model LBDDS composed of Polysorbate 80 was assessed employing the in vitro dynamic lipolysis model. The results illustrated the extent to which the supersaturated state was dependent on the extent of lipolysis of Polysorbate 80 and the initial drug concentration. Area-under-the curve-supersaturation was proposed as a means of quantifying the time-dependent extent of supersaturation in LBDDSs in simulated intestinal conditions. Concurrently, a series of model mixed micellar solutions, composed of Polysorbate 80 and oleic acid, were prepared to represent the lipid assemblies produced during the lipolysis experiments. The ability of these aggregates to solubilize progesterone, 17β-estradiol and nifedipine were evaluated and the aggregate/water partition coefficients were determined. The Treinor model was found to successfully fit the partition coefficients of the drugs in a range of mixed micelles. The equilibrium solubility of drugs in the mixed micelles was calculated and compared to that found under lipolytic conditions. The best agreement between calculated and experimental conditions was observed for nifedipine. These studies have established a foundation for the evaluation of time-dependent extent of supersaturation with more complex LBDDS formulations exposed to lipolytic conditions.

This dissertation work investigated the effect of acute and repeated in vivo administration of lobeline on dopamine transporter (DAT) and vesicular monoamine transporter (VMAT2) function. The effects of lobeline were then compared to the effects of acute and repeated in vivo administration of methylphenidate and amphetamine to determine if lobeline produced similar effects compared to these Attention Deficit Hyperactivity Disorder (ADHD) medications. These medications are considered the first line of pharmacotherapy for ADHD, although there is a growing concern associated with their potential for abuse and other side effects. This merits the need for novel ADHD treatments that have a safer side effect profile. If lobeline alters DAT and VMAT2 function in the same way as methylphenidate or amphetamine, further investigation may be necessary to evaluate lobeline as a potential treatment for ADHD. Kinetic analysis of [3H]dopamine (DA) was utilized to determine the effect on DAT and VMAT2 function in rat striatum. Results from the DAT experiments, revealed that lobeline as well as amphetamine had no effect on DAT function. However, methylphenidate increased DAT function after acute and 7-day treatment. None of the drug treatment regimens altered Km. To determine if the methylphenidateinduced increase in DAT function was due to DAT trafficking, biotinylation and Western blot analyses were performed. Acute administration of methylphenidate did not alter surface DAT, however repeated administration of methylphenidate for 7 days decreased intracellular DAT, suggesting that methylphenidate redistributes DAT in a time-dependent manner. Similar results were found in the VMAT2 experiments. Lobeline and amphetamine had no effect on VMAT2 function after acute or repeated administration. Amphetamine decreased the Km after repeated administration for 7 days. Methylphenidate increased VMAT2 function after acute and repeated administration for 7 days. The overall results of these experiments suggest that methylphenidate interacts with DAT and VMAT2 in a different manner than amphetamine and lobeline. In addition, since lobeline and amphetamine had no effect on DAT and VMAT2 function, further investigation is warranted to elucidate the underlying mechanisms of the therapeutic actions of these agents. This additional information will aid in the development of novel treatments for ADHD.

Methamphetamine abuse is a serious public health concern affecting millions of people worldwide, and there are currently no viable pharmacotherapies to treat methamphetamine abuse. Methamphetamine increases extracellular dopamine (DA) concentrations through an interaction with the DA transporter (DAT) and the vesicular monoamine transporter-2 (VMAT2), leading to reward and abuse. While numerous studies have focused on DAT as a target for the discovery of pharmacotherapies to treat psychostimulant abuse, these efforts have been met with limited success. Taking into account the fact that methamphetamine interacts with VMAT2 to increase DA extracellular concentrations; the focus of the current work was to develop novel compounds that interact with VMAT2 to inhibit the effects of methamphetamine. Lobeline, the principal alkaloid found in Lobelia inflata, inhibits VMAT2 binding and function. Inhibition of VMAT2 was hypothesized to be responsible for the observed lobeline-induced inhibition of methamphetamine-evoked DA release in striatal slices and decrease in methamphetamine self-administration in rats. Lobeline has recently completed Phase Ib clinical trials demonstrating safety in methamphetamine abusers. Lobeline is also a potent inhibitor of nicotinic acetylcholine receptors (nAChRs), limiting selectivity for VMAT2. Chemical defunctionalization of the lobeline molecule afforded analogs, meso-transdiene (MTD) and lobelane, which exhibited decreased affinity for nAChRs. MTD, an unsaturated analog of lobeline, exhibited similar affinity for VMAT2 and increased affinity for DAT compared to lobeline. Conformationally-restricted MTD analogs exhibited decreased affinity for DAT compared to MTD, while retaining affinity at VMAT2. One analog, UKMH-106 exhibited high affinity and selectivity for VMAT2 and inhibited METH-evoked DA release from striatal slices. Unfortunately, the MTD analogs exhibited poor water solubility which limited further investigation of these promising analogs. Importantly lobelane, a saturated analog of lobeline, exhibited increased affinity and selectivity for VMAT2 compared to lobeline. To improve water solubility, a N-1,2-dihydroxypropyl (diol) moiety was incorporated into the lobelane molecule. GZ-793A, an N-1,2-diol analog, potently and competitively inhibited VMAT2 function, exhibiting over 50-fold selectivity for VMAT2 over DAT, serotonin transporters and nAChRs. GZ-793A released DA from preloaded synaptic vesicles, fitting a two-site model with the high-affinity site inhibited by tetrabenazine and reserpine (classical VMAT2 inhibitors), suggesting a VMAT2-mediated mechanism of release. Further, low concentrations of GZ-793A that selectively interact with high-affinity sites on VMAT2 to evoke DA release, inhibit methamphetamine-evoked DA release from synaptic vesicles. Results showed that increasing concentrations of GZ-793A produced a rightward shift in the METH concentration response; however, the Schild regression revealed a slope different from unity, consistent with surmountable allosteric inhibition. In addition, GZ-793A specifically inhibited methamphetamine-evoked DA release in striatal slices and methamphetamine self-administration in rats. To examine the possibility that GZ-793A produced DA depletion, the effect of a behaviorally active dose of GZ-793A on DA content in striatal tissue and striatal vesicles was determined. GZ-793A administration did not alter DA content in striatal tissue or vesicles and pretreatment with GZ-793A prior to methamphetamine administration did not exacerbate the DA depleting effects of methamphetamine. Importantly, GZ-793A was shown to protect against methamphetamine-induced striatal DA depletions. Thus, GZ-793A represents an exciting new lead in the development of pharmacotherapies to treat methamphetamine abuse.

Fibromyalgia syndrome (FMS) is a chronic pain condition with significant societal and personal burdens of illness. Chronic opioid therapy in the treatment of chronic nonmalignant pain has increased drastically over the past decade. This is a worrisome trend in general, but specifically, given the pathophysiologic characteristics seen in fibromyalgia syndrome patients, the use of this class of medication deserves special scrutiny. Although the theoretical case against this therapy choice is strong, little empirical evidence exists. In order to supplement this literature, retrospective analysis methods are utilized to examine the association of state-, provider-, and patient level characteristics with the prevalence of chronic opioid use in this disease state. Data gathered through this analysis is then used to develop a propensity index for the identification of an appropriate control group for fibromyalgia patients, a task that has proven difficult in the literature to date. Using propensity stratification and matching techniques analysis of the impact of fibromyalgia, chronic opioid use, and the interaction of these two variables are undertaken. Several key findings and updates to the understanding of chronic opioid use and fibromyalgia syndrome are reported. Wide geographic variation in chronic opioid utilization between states is seen. The role of diagnosing provider type in the rate of chronic opioid prescribing is significant and can be aggregated at various levels. Demographic characteristics, comorbid conditions, and concurrent medication use are all important associates of chronic opioid use in fibromyalgia syndrome. Additionally, chronic opioid use in fibromyalgia patients, independent of propensity to receive that therapy choice is a significant correlate with healthcare costs. A diagnosis of fibromyalgia is a statistically significant source of healthcare costs, though the clinical significance of its impact when compared to a closely matched control group is minimized. Despite the minimization of the role of this diagnosis the impact of the interaction of chronic opioid use with fibromyalgia, despite control for myriad regressors, is significant both statistically and clinically.

Thromboxane A2 receptor (TP) has been shown to play important roles in multiple aspects of cancer development including regulation of tumor growth, survival and metastasis. Molecular mechanisms of TP mediated cancer cell invasion remain to be identified. TP agonist, I-BOP, significantly elevated several matrix metalloproteinases (MMPs) including MMP-1, MMP-3, MMP-9 and MMP-10 in A549 human lung adenocarcinoma cells overexpressing TPα (A549-TPα) or TPβ (A549-TPβ). Signaling pathways of I-BOP-induced MMP-1 expression were examined in further detail as a model system for MMPs induction. Signaling molecules involved in I-BOP-induced MMP-1 expression were identified by using specific inhibitors including small interfering (si)-RNAs of signaling molecules and promoter reporter assay. The results indicate that I-BOP-induced MMP-1 expression is mediated by protein kinase C (PKC), extracellular signal-regulated kinase (ERK)-activator protein-1(AP-1) and ERK-CCAAT/enhancer-binding protein β (C/EBPβ) pathways. I-BOP-induced cellular invasiveness of A549-TPα cells was blocked by, GM6001, a general inhibitor of MMPs. Knockdown of MMP-1 and MMP-9 by their respective siRNA partially reduced I-BOP-stimulated A549-TPα cells invasion suggesting that other MMPs induced by I-BOP were also involved. Furthermore, secreted MMP-1 in conditioned media from I-BOP-treated A549-TPα cells (CM-I-BOP) autocrinely induced monocyte chemoattractant protein-1 (MCP-1) expression. The induction of MCP-1 by MMP-1 in A549 cells was via activation of protease-activated receptor 2 (PAR2) instead of commonly assumed PAR1. This conclusion was reached from the following findings: (1) expression of MCP-1 induced by trypsin, a PAR2 agonist, was inhibited by a PAR2 antagonist. (2) expression of MCP-1 induced by MMP-1 and by CM-I-BOP was blocked by a PAR2 antagonist but not by other PAR antagonists; (3) expression of MCP-1 induced by MMP-1 and by CM-I-BOP was attenuated significantly by pretreatment of cells with PAR2-siRNA. Finally, MCP-1 also can be induced by direct activation of TP in a SP1 involved mechanism. CM-I-BOP enhanced MCP-1-dependent migration of RAW 264.7 macrophages. Co-culture of A549 cells with RAW 264.7 macrophages induced expression of MMPs, VEGF and MCP-1 genes, and increased the invasive potential in A549 cells. My studies provide molecular mechanisms by which TP-mediated cancer cell invasion and suggest that TP is a potential anti-cancer drug target.