Browsing by Subject "Pharmacology"

Now showing 1 - 5 of 5
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    Aptamers for in vivo applications
    (2008-05) Yan, Amy Chee, 1973-; Ellington, Andrew D.
    When aptamers emerged almost two decades ago, “selection-ologists” quickly realized the aptamer’s clinical potential - both as a diagnostic tool and as a therapeutic. Since that time, nearly hundreds of medically relevant targets have been successfully selected against. Moreover, many have proven efficacy in tissue culture and animal models. However, only one has successfully advanced to clinical use. Several key limitations in aptamer-based drugs may explain the dearth of aptamers in the pharmacy. Issues of expression level, delivery, and targeting will need to be addressed before aptamers can reach their full clinical potential. This work broaches on aspects of these limitations and leads into ways of transitioning the aptamer into clinical use.
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    Enzymatic depletion of L-Met using an engineered human enzyme as a novel therapeutic strategy for melanoma
    (2022-08-11) Wilder, Carly Strecker; DiGiovanni, John; Vasquez, Karen; Kidane, Dawit; Tiziani, Stefano; Georgiou, George
    Metastatic melanoma is an aggressive form of cancer responsible for the majority of skin cancer related deaths. While treatment for metastatic melanoma has improved in recent years with the introduction of targeted therapies and immunotherapies, the five year survival rate for stage IV melanoma remains only 15-20%. To address the need for alternative options for melanoma treatment, we have evaluated the use of an engineered human enzyme called methionine-ɣ-lyase (hMGL). Many cancers including melanoma, have a high requirement for L-methionine (L-Met) in comparison with non-cancerous cells. The hMGL enzyme exploits this metabolic vulnerability by degrading extracellular L-Met resulting in cancer cell starvation. The goal of this project was to assess the efficacy and identify mechanisms of action of the hMGL enzyme in melanoma models. In vitro and in vivo methods were used to evaluate the efficacy of L-Met depletion using hMGL on melanoma skin cancer. Four melanoma cancer cell lines were used, three were derived from human melanomas while one was a commonly utilized mouse melanoma line. Cell viability, cell cycle, and cell death parameters were evaluated first to establish that melanoma is sensitive to hMGL treatment. Global omics data sets including RNA-seq and metabolomics were generated from in vitro samples to give some insight into potential mechanisms of action to be investigated further. Since L-Met is involved in many cellular processes, it is not surprising that multiple mechanisms were found to be perturbed with hMGL treatment. Upregulation of the uncharged tRNA amino acid sensing pathway and an increase in DNA replication stress and ROS were observed with hMGL treatment. Drugs to be used in combination with hMGL were identified based on mechanistic relevance and screened in vitro. Treatment with hMGL inhibited tumor growth in both human xenograft and mouse allograft orthotopic melanoma models. The results of this study provide rationale for further mechanistic evaluation and clinical development of hMGL for the treatment of melanoma skin cancer.
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    The pharmacological effects of acute ethanol on catecholamines in the medial prefrontal cortex and dorsal striatum
    (2016-12) Vena, Ashley; Gonzales, Rueben Anthony; Dominguez, Juan; Harris, Adron; Duvauchelle, Christine; Morrisett, Richard
    The dorsal striatum and the medial prefrontal cortex are part of a neurocircuitry that is affected by acute and chronic drug use. In the present studies, we sought to characterize the pharmacological effects of ethanol on extracellular catecholamine concentrations in the dorsal striatum and medial prefrontal cortex. To this end, we utilized two different routes of administration to quantify ethanol’s actions. We performed in vivo microdialysis in adult, male Long Evans rats as they received single or repeated intravenous infusions of ethanol. Following infusion of a 1-g/kg dose of ethanol, we observed no significant effects on extracellular dopamine in either the dorsomedial or dorsolateral striatum, but in a separate group of animals, we observed significant stimulation of extracellular norepinephrine in the medial prefrontal cortex. However, following a cumulative intravenous dosing protocol, we observed a gradual ramping up of tonic dopamine activity in the dorsal striatal subregions, which was more robust in the dorsomedial striatum. Subsequently, we performed in vivo microdialysis in separate groups of rats during an operant self-administration session to quantify the time course of extracellular dopamine and norepinephrine in the medial prefrontal cortex. In the seven operant sessions prior to the microdialysis test session, each group of rats had been assigned to a separate treatment group: one that received a sweetened ethanol solution, one that received a sucrose solution, and a handling control group that did not receive any drinking solutions. In the ethanol-experienced animals, we report a reduction in basal dopamine and norepinephrine in the medial prefrontal cortex, relative to control groups. However, there were no significant differences in the temporal profile of extracellular norepinephrine across the three treatment groups. These studies demonstrate that limited voluntary ethanol consumption appears to be sufficient to alter tonic catecholamine signaling in the medial prefrontal cortex. Additionally, we conclude that central catecholamine signaling pathways are a target for ethanol.