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Needle in a Haystack: the search for immunogenic epitopes for TPD52

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Breast cancer is the leading cause of cancer-related deaths of women in the united states. Traditionally, Breast cancer is predominantly treated by a combination of surgery, chemotherapy, and radiation therapy. However, due to the significant negative side effects associated with

Breast cancer is the leading cause of cancer-related deaths of women in the united states. Traditionally, Breast cancer is predominantly treated by a combination of surgery, chemotherapy, and radiation therapy. However, due to the significant negative side effects associated with these traditional treatments, there has been substantial efforts to develop alternative therapies to treat cancer. One such alternative therapy is a peptide-based therapeutic cancer vaccine. Therapeutic cancer vaccines enhance an individual's immune response to a specific tumor. They are capable of doing this through artificial activation of tumor specific CTLs (Cytotoxic T Lymphocytes). However, in order to artificially activate tumor specific CTLs, a patient must be treated with immunogenic epitopes derived from their specific cancer type. We have identified that the tumor associated antigen, TPD52, is an ideal target for a therapeutic cancer vaccine. This designation was due to the overexpression of TPD52 in a variety of different cancer types. In order to start the development of a therapeutic cancer vaccine for TPD52-related cancers, we have devised a two-step strategy. First, we plan to create a list of potential TPD52 epitopes by using epitope binding and processing prediction tools. Second, we plan to attempt to experimentally identify MHC class I TPD52 epitopes in vitro. We identified 942 potential 9 and 10 amino acid epitopes for the HLAs A1, A2, A3, A11, A24, B07, B27, B35, B44. These epitopes were predicted by using a combination of 3 binding prediction tools and 2 processing prediction tools. From these 942 potential epitopes, we selected the top 50 epitopes ranked by a combination of binding and processing scores. Due to the promiscuity of some predicted epitopes for multiple HLAs, we ordered 38 synthetic epitopes from the list of the top 50 epitope. We also performed a frequency analysis of the TPD52 protein sequence and identified 3 high volume regions of high epitope production. After the epitope predictions were completed, we proceeded to attempt to experimentally detected presented TPD52 epitopes. First, we successful transduced parental K562 cells with TPD52. After transduction, we started the optimization process for the immunoprecipitation protocol. The optimization of the immunoprecipitation protocol proved to be more difficult than originally believed and was the main reason that we were unable to progress past the transduction of the parental cells. However, we believe that we have identified the issues and will be able to complete the experiment in the coming months.

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2016-05

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Creating an artificial antigen presenting cell system for HPV16 proteins

Description

Background: High risk types of human papillomavirus (HPV) are known to cause cancer, including cervical (99%) and oropharyngeal cancer (70%). HPV type 16 is the most common subtype. Three antigens that are critical for integration or tumor progression are E2,

Background: High risk types of human papillomavirus (HPV) are known to cause cancer, including cervical (99%) and oropharyngeal cancer (70%). HPV type 16 is the most common subtype. Three antigens that are critical for integration or tumor progression are E2, E6 and E7. In this study, we developed a systematic approach to identify naturally-processed HPV16-derived HLA class I epitopes for immunotherapy development. Methods: K562 cells, which lack HLA expression, were transduced with each HPV16 antigen using lentivirus and supertransfected with HLA-A2 by nucleofection. Stable cell lines expressing each antigen were selected for and maintained throughout the investigation. In order to establish a Gateway-compatible vector for robust transient gene expression, a Gateway recombination expression cloning cassette was inserted into the commercial Lonza pMAX GFP backbone, which has been experimentally shown to display high transfection expression efficiency. GFP was cloned into the vector and plain K562 cells were transfected with the plasmid by nucleofection. Results: Expression of K562-A2 was tested at various time points by flow cytometry and A2 expression was confirmed. Protein expression was shown for the transduced K562 E7 by Western blot analysis. High transfection efficiency of the pMAX_GFP_Dest vector (up to 97% GFP+ cells) was obtained 48 hours post transfection, comparable to the commercial GFP-plasmid. Conclusion: We have established a rapid system for target viral antigen co-expression with single HLA molecules for analysis of antigen presentation. Using HPV as a model system, our goal is to identify specific antigenic peptide sequences to develop immunotherapeutic treatments for HPV-associated cancers.

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2016-05

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PDZ-binding kinase promotes adrenocortical carcinoma cell proliferation and tumorigenesis

Description

Adrenocortical carcinoma (ACC) is a rare and deadly disease that affects 0.5-2 people per million per year in the US. Currently, the first line clinical management includes surgical resection, followed by treatment with the chemotherapeutic agent mitotane. These interventions, however,

Adrenocortical carcinoma (ACC) is a rare and deadly disease that affects 0.5-2 people per million per year in the US. Currently, the first line clinical management includes surgical resection, followed by treatment with the chemotherapeutic agent mitotane. These interventions, however, have limited effectiveness, as the overall five-year survival rate of patients with ACC is less than 35%. Therefore, further scientific investigation underlying the molecular mechanisms and biomarkers of this disease is of high importance. The aim of this project was to identify potential biomarkers that may be used as prognosticators as well as candidate genes that might be targeted to develop new therapies for patients with ACC. An analysis of publicly-available datasets revealed PDZ-binding kinase (PBK) as being upregulated roughly 9-fold in ACC tissue compared to normal adrenal tissue. PBK has been implicated as an oncogene in several other systems, and its expression has been shown to negatively impact patient survival. Initial experiments have confirmed the upregulation of PBK in H295R cells, a human ACC cell line. We effectively silenced PBK (>95% reduction in protein content) in H295R cells using lentiviral shRNA constructs. Using high and low PBK expressing cells, we performed soft agar assays for colony formation, and found that the PBK-silenced cells produced two-fold fewer colonies than the vector control (p<0.05). This indicates that PBK likely plays a role in tumorigenicity. We further conducted functional studies for apoptosis and proliferation to elucidate the mechanism by which PBK increases tumorigenicity. Preliminary results from MTS assays showed that after 9 days, PBK-silenced cells proliferated significantly less than the vector control, so PBK likely increases proliferation. Together these data identify PBK as a kinase implicated in ACC tumorigenesis. Further in vitro and in vivo studies will be conducted to evaluate PBK as a potential therapeutic target in adrenocortical carcinoma.

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2016-12

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Structural characterization of potential cancer biomarker proteins

Description

Cancer claims hundreds of thousands of lives every year in US alone. Finding ways for early detection of cancer onset is crucial for better management and treatment of cancer. Thus, biomarkers especially protein biomarkers, being the functional units which reflect

Cancer claims hundreds of thousands of lives every year in US alone. Finding ways for early detection of cancer onset is crucial for better management and treatment of cancer. Thus, biomarkers especially protein biomarkers, being the functional units which reflect dynamic physiological changes, need to be discovered. Though important, there are only a few approved protein cancer biomarkers till date. To accelerate this process, fast, comprehensive and affordable assays are required which can be applied to large population studies. For this, these assays should be able to comprehensively characterize and explore the molecular diversity of nominally "single" proteins across populations. This information is usually unavailable with commonly used immunoassays such as ELISA (enzyme linked immunosorbent assay) which either ignore protein microheterogeneity, or are confounded by it. To this end, mass spectrometric immuno assays (MSIA) for three different human plasma proteins have been developed. These proteins viz. IGF-1, hemopexin and tetranectin have been found in reported literature to show correlations with many diseases along with several carcinomas. Developed assays were used to extract entire proteins from plasma samples and subsequently analyzed on mass spectrometric platforms. Matrix assisted laser desorption ionization (MALDI) and electrospray ionization (ESI) mass spectrometric techniques where used due to their availability and suitability for the analysis. This resulted in visibility of different structural forms of these proteins showing their structural micro-heterogeneity which is invisible to commonly used immunoassays. These assays are fast, comprehensive and can be applied in large sample studies to analyze proteins for biomarker discovery.

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Date Created
2012

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Small molecule inhibition of quiescin sulfhydryl oxidase 1 (QSOX1), a dynamic pro-tumorigenic regulator of the extracellular matrix

Description

Quiescin sulfhydryl oxidase 1 (QSOX1) is a highly conserved disulfide bond-generating enzyme that represents the ancient fusion of two major thiol-disulfide oxidoreductase gene families: thioredoxin and ERV. QSOX1 was first linked with cancer after being identified as overexpressed in pancreatic

Quiescin sulfhydryl oxidase 1 (QSOX1) is a highly conserved disulfide bond-generating enzyme that represents the ancient fusion of two major thiol-disulfide oxidoreductase gene families: thioredoxin and ERV. QSOX1 was first linked with cancer after being identified as overexpressed in pancreatic ductal adenocarcinoma (but not in adjacent normal ductal epithelia, infiltrating lymphocytes, or chronic pancreatitis). QSOX1 overexpression has been confirmed in a number of other histological tumor types, such as breast, lung, kidney, prostate, and others. Expression of QSOX1 supports a proliferative and invasive phenotype in tumor cells, and its enzymatic activity is critical for promoting an invasive phenotype. An in vivo tumor growth study utilizing the pancreatic tumor cell line MIAPaCa-2 containing a QSOX1-silencing shRNA construct revealed that QSOX1 expression supports a proliferative phenotype. These preliminary studies suggest that suppressing the enzymatic activity of QSOX1 could represent a novel therapeutic strategy to inhibit proliferation and invasion of malignant neoplasms.

The goal of this research was to identify and characterize biologically active small molecule inhibitors for QSOX1. Chemical inhibition of QSOX1 enzymatic activity was hypothesized to reduce growth and invasion of tumor cells. Recombinant QSOX1 was screened against libraries of small molecules using an enzymatic activity assay to identify potential QSOX1 inhibitors. Two lead QSOX1 inhibitors were confirmed, 2-phenyl-1, 2-benzisoselenazol-3-one (ebselen), and 3-methoxy-n-[4-(1 pyrrolidinyl)phenyl]benzamide. The biological activity of these compounds is consistent with QSOX1 knockdown in tumor cell lines, reducing growth and invasion in vitro. Treatment of tumor cells with these compounds also resulted in specific ECM defects, a phenotype associated with QSOX1 knockdown. Additionally, these compounds were shown to be active in pancreatic and renal cancer xenografts, reducing tumor growth with daily treatment. For ebselen, the molecular mechanism of inhibition was determined using a combination of biochemical and mass spectrometric techniques. The results obtained in these studies provide proof-of-principle that targeting QSOX1 enzymatic activity with chemical compounds represents a novel potential therapeutic avenue worthy of further investigation in cancer. Additionally, the utility of these small molecules as chemical probes will yield future insight into the general biology of QSOX1, including the identification of novel substrates of QSOX1.

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Date Created
2015

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Genome-driven targeted cancer therapy

Description

Cancer is a heterogeneous disease with discrete oncogenic mechanisms. P53 mutation is the most common oncogenic mutation in many cancers including breast cancer. This dissertation focuses on fundamental genetic alterations enforced by p53 mutation as an indirect target. p53 mutation

Cancer is a heterogeneous disease with discrete oncogenic mechanisms. P53 mutation is the most common oncogenic mutation in many cancers including breast cancer. This dissertation focuses on fundamental genetic alterations enforced by p53 mutation as an indirect target. p53 mutation upregulates the mevalonate pathway genes altering cholesterol biosynthesis and prenylation. Prenylation, a lipid modification, is required for small GTPases signaling cascades. Project 1 demonstrates that prenylation inhibition can specifically target cells harboring p53 mutation resulting in reduced tumor proliferation and migration. Mutating p53 is associated with Ras and RhoA activation and statin prevents this activity by inhibiting prenylation. Ras-related pathway genes were selected from the transcriptomic analysis for evaluating correlation to statin sensitivity. A gene signature of seventeen genes and TP53 genotype (referred to as MPR signature) is generated to predict response to statins. MPR signature is validated through two datasets of drug screening in cell lines. As advancements in targeted gene modification are rising, the CRISPR-Cas9 technology has emerged as a new cancer therapeutic strategy. One of the important risk factors in gene therapy is the immune recognition of the exogenous therapeutic tool, resulting in obstruction of treatment and possibly serious health consequences. Project 2 describes a method development that can potentially improve the safety and efficacy of gene-targeting proteins. A cohort of 155 healthy individuals was screened for pre-existing B cell and T cell immune response to the S. pyogenes Cas9 protein. We detected antibodies against Cas9 in more than 10% of the healthy population and identified two immunodominant T cell epitopes of this protein. A de-immunized Cas9 that maintains the wild-type functionality was engineered by mutating the identified T cell epitopes. The gene signature and method described here have the potential to improve strategies for genome-driven tumor targeting.

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Date Created
2017

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Small Molecule Inhibitors as Probes for Studying the Role of Quiescin Sulfhydryl Oxidase 1 in Tumor-Associated Extracellular Matrix

Description

Quiescin Sulfhydryl Oxidase 1 (QSOX1) generates disulfide bonds in its client substrates via oxidation of free thiols. Localized to the Golgi and secreted, QSOX1 helps to fold proteins into their active form. Early work with QSOX1 in cancer began with

Quiescin Sulfhydryl Oxidase 1 (QSOX1) generates disulfide bonds in its client substrates via oxidation of free thiols. Localized to the Golgi and secreted, QSOX1 helps to fold proteins into their active form. Early work with QSOX1 in cancer began with the identification of a peptide from the long form of QSOX1 in plasma from patients with pancreatic ductal adenocarcinoma. Subsequent work confirmed the overexpression of QSOX1 in numerous cancers in addition to pancreatic, including those originating in the breast, lung, brain, and kidney. For my work, I decided to answer the question, “How does inhibition of QSOX1 effect the cancer phenotype?” To answer this I sought to fulfill the following goals A) determine the overexpression parameters of QSOX1 in cancer, B) identify QSOX1 small molecule inhibitors and their effect on the cancer phenotype, and C) determine potential biological effects of QSOX1 in cancer. Antibodies raised against rQSOX1 or a peptide from QSOX1-L were used to probe cancer cells of various origins for QSOX1 expression. High-throughput screening was utilized to identify 3-methoxy-n-[4(1pyrrolidinyl)phenyl]benzamide (SBI-183) as a lead inhibitor of QSOX1 enzymatic activity. Characterization of SBI-183 activity on various tumor cell lines revealed inhibition of viability and invasion in vitro, and inhibition of growth, invasion, and metastasis in vivo, a phenotype that was consistent with QSOX1 shKnockdown cells. Subsequent work identified 3,4,5-trimethoxy-N-[4-(1-pyrrolidinyl)phenyl]benzamide (SPX-009) as an SBI-183 analog with stronger inhibition of QSOX1 enzymatic activity, resulting in a more potent reduction in tumor invasion in vitro. Additional work with QSOX1 shKnockdown and Knockout (KO) cell lines confirmed current literature that QSOX1 is biologically active in modulation of the ECM. These results provide evidence for the master regulatory role of QSOX1 in cancer, making it an attractive chemotherapeutic target. Additionally, the small molecules identified here may prove to be useful probes in further elucidation of QSOX1 tumor biology and biomarker discovery.

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Date Created
2020