Eric Wickstrom - Academia.edu (original) (raw)

Papers by Eric Wickstrom

Bioconjugate Chemistry, 2018

Huntington's disease (HD) is an autosomal-dominant neurodegenerative genetic disorder caused by C... more Huntington's disease (HD) is an autosomal-dominant neurodegenerative genetic disorder caused by CAG repeat expansion in exon of the HTT gene. Expression of the mutant gene results in the production of a neurotoxic polyglutamine (polyQ)-expanded huntingtin (Htt) protein. Clinical trials of knockdown therapy of mutant polyglutamine-encoding HTT mRNA in Huntington's disease (HD) have begun. To measure HTT mRNA knockdown effectiveness in human cells, we utilized a fluorescent hybridization imaging agent specific to the region encompassing the human HTT mRNA initiation codon. We designed, synthesized, purified, and characterized Cal560-spacer-peptide nucleic acid (PNA)-spacer-IGF1 tetrapeptides. The human HTT PNA 12mer complement was CATGGCGGTCTC, while the rat htt equivalent 12mer contained the sequence CATGaCGGcCTC, with two bases differing from the human sequence. The cyclized IGF1 tetrapeptide fragment D(CSKC) that promotes IGF1 receptor-mediated endocytosis was bonded to the C-terminus. We tested the reliability of HTT mRNA imaging with Cal560-spacer-peptide nucleic acid (PNA)-spacer-IGF1 tetrapeptides in human embryonic kidney (HEK) 293T cells that express endogenous HTT and IGF1 receptor. By qPCR, we quantitated HTT mRNA in HEK293T cells with and without HTT mRNA knockdown by three different siRNAs. By confocal fluorescence imaging, we quantitated the accumulation of fluorescent HTT hybridization agent in the same cells. A rat homolog differing from the human sequence by two bases showed negligible fluorescence. qPCR indicated 86±5% knockdown of HTT mRNA by the most effective siRNA. Similarly, Cal560-HTT PNA-peptide fluorescence intensity indicated 69±6% reduction in HTT mRNA.. We concluded that the fluorescence hybridization method correlates with the established qPCR method for quantitating HTT mRNA knockdown by siRNA in HEK293T cells, with a Pearson correlation coefficient of 0.865 for all three siRNA sequences. These results will enable real time imaging and quantitation of HTT mRNA in animal models of HD.

Molecular imaging and biology : MIB : the official publication of the Academy of Molecular Imaging, Jan 25, 2018

In recent years, considerable progress has been made in the use of gallium-68 labeled receptor-sp... more In recent years, considerable progress has been made in the use of gallium-68 labeled receptor-specific peptides for imaging oncologic diseases. The objective was to examine the stability and pharmacokinetics of [Ga]NODAGA and DOTA-peptide conjugate targeting VPAC [combined for vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating peptide (PACAP)] receptors on tumor cells. A VPAC receptor-specific peptide was chosen as a model peptide and conjugated to NODAGA and DOTA via solid-phase synthesis. The conjugates were characterized by HPLC and MALDI-TOF. Following Ga-68 chelation, the radiochemical purity of Ga-68 labeled peptide conjugate was determined by radio-HPLC. The stability was tested against transmetallation using 100 nM Fe/Zn/Ca ionic solution and against transchelation using 200 μM DTPA solution. The ex vivo and in vivo stability of the Ga-68 labeled peptide conjugate was tested in mouse plasma and urine. Receptor specificity was determined ex vivo b...

Nucleosides and Nucleotides, 1997

ABSTRACT Prophylactic therapy with 5′-dCACGTTGAGGGGCAT phosphorothioate, (2.5 nmol/hr) strongly i... more ABSTRACT Prophylactic therapy with 5′-dCACGTTGAGGGGCAT phosphorothioate, (2.5 nmol/hr) strongly inhibited tumorigenesis in Eμ-myc transgenic mice, and ablated spleen cell MYC antigen. However, the anti-c-myc DNA also stimulated proliferation of spleen cells in vitro, though much less so than a positive CG motif control, 5′-dGCATGACGTTGAGCT.

Public reporting burden for this collection of information is estimated to average 1 hour per res... more Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number.

BJU International, 2017

To validate a hypothesis that prostate cancer can be detected non-invasively by a simple and reli... more To validate a hypothesis that prostate cancer can be detected non-invasively by a simple and reliable assay by targeting genomic VPAC receptors expressed on malignant prostate cancer cells shed in voided urine. Conclusion These preliminary data are highly encouraging and warrant further evaluation of the assay to serve as a simple and reliable tool to detect prostate cancer noninvasively.

ACS Omega, 2017

Infections are a devastating complication of titanium alloy orthopedic implants. Current therapie... more Infections are a devastating complication of titanium alloy orthopedic implants. Current therapies include antibiotic-impregnated bone cement and antibiotic-containing coatings. Daptomycin (DAP) (1) is a novel peptide antibiotic that penetrates the cell membranes of Gram-positive bacteria. Few DAP-resistant strains have appeared so far. We hypothesized that when DAP covalently bonded via a flexible, hydrophilic spacer it could prevent bacterial colonization of titanium alloy surfaces. We designed and synthesized a series of DAP conjugates for bonding to the surface of Ti6Al4V foils through tetra(ethylene glycol) spacers via thioether linkages. The stability and antimicrobial activity of the attached conjugates were evaluated using Staphylococcus aureus ATCC 25923. Colonization of the Ti6Al4V foils was inhibited by 72% at 8 h and 54% at 24 h. The strategy described in this report provides a new, more facile way to prepare bactericidal Ti6Al4V implants.

ChemInform, 2003

Biochemistry Biochemistry Z 0250 Oncogene mRNA Imaging with 99m Tc-Chelator-PNA-Peptides.-[synthe... more Biochemistry Biochemistry Z 0250 Oncogene mRNA Imaging with 99m Tc-Chelator-PNA-Peptides.-[synthesis of title peptides and their uptake and hybridization to mRNA; 115 refs.].

Antisense Research and Development, 1991

A series of phosphodiester and phosphorothioate antisense oligodeoxynucleotides were synthesized ... more A series of phosphodiester and phosphorothioate antisense oligodeoxynucleotides were synthesized against the human transferrin receptor (TfR). The phosphorothioate analogs exhibited marked biologic efficacy in culture, as assessed by inhibition of surface TfR content and HL-60 cell growth, whereas their unmodified phosphodiester counterparts were ineffective. Phosphorothioate oligodeoxynucleotides were more resistant to hydrolysis by serum and cellular nucleases and were more readily taken up by cells than phosphodiesters, thus providing a partial explanation for the differences in biologic activity. A length effect was observed, with antisense 30-mers exhibiting greater TfR inhibitory activity than 17-mers. The degree of receptor inhibition observed, however, was not sequence dependent, suggesting that the phosphorothioate oligodeoxynucleotides may have pleiotropic activities in eukaryotic cells in addition to inhibiting gene expression by classic antisense complementary binding to mRNA.

Goals: Oncogene stratification of suspicious masses to guide treatment and extend survival Positi... more Goals: Oncogene stratification of suspicious masses to guide treatment and extend survival Position emission tomography (PET) imaging of particular oncogene mRNAs mRNA PET as quick surrogate for therapeutic efficacy, or lack thereof Magnetic resonance hybridization imaging with Gd-dendrimer-PNA-peptides Presentation: 1 hour and 4 minute

Society of Nuclear Medicine Annual Meeting Abstracts, May 1, 2007

Society of Nuclear Medicine Annual Meeting Abstracts, May 1, 2011

Society of Nuclear Medicine Annual Meeting Abstracts, May 1, 2012

Clinical Cancer Research, Oct 1, 2008

A7 Most pancreas cancer patients die within a year because they are diagnosed at an advanced incu... more A7 Most pancreas cancer patients die within a year because they are diagnosed at an advanced incurable stage. However, even before an enlarged mass can be seen by MRI or CT, early stage pancreatic intraepithelial neoplasia (PanIN-1) pancreas cells contain high levels of mRNAs copied from hyperactive cancer genes such as KRAS and HER2. However, PanIN-1 does not always progress. Later stage PanIN-3 pancreas cells, which do progress to frank cancer, contain high levels of mRNAs overproduced by activated CCND1 or BRCA2 oncogenes. Specific detection of PanIN-3 would enable resection of ductal pancreas cancer at a survivable stage. We hypothesized that developing pancreas cancer can be imaged externally in live cells and animals by near infrared hybridization fluorescence (NIRF) imaging of overexpressed cancer gene mRNAs basepaired to molecular beacons. We designed a 12 base peptide nucleic acid (PNA) without a hairpin stem. We hypothesized that twin NIR664 fluorophores at the N and C termini could stack upon each other, mutually quenching their fluorescence, unless the PNA were hybridized to a complementary RNA. No quencher chromophore or hairpin stem is required in this case, unlike typical molecular beacons. Incubation of human AsPC1 KRAS G12D+ pancreas cancer cells with NIR664-KRAS G12D PNA-NIR664 for 24 h incubation, followed by 24 h of efflux, yielded bright NIRF images in the AsPC1 cells. Base mismatch, peptide mismatch, and cell mismatch control experiments are necessary before proceeding to animal experiments. This work was supported in part by NCI contract N01 CO27175 and NCI grant U54 CA105008.