Publications by authors named "Stephen McCune"

3 Publications

  • Page 1 of 1

Oct4-Mediated Inhibition of Lsd1 Activity Promotes the Active and Primed State of Pluripotency Enhancers.

Cell Rep 2020 02;30(5):1478-1490.e6

Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA; Purdue University Center for Cancer Research, Purdue University, West Lafayette, IN 47907, USA. Electronic address:

An aberrant increase in pluripotency gene (PpG) expression due to enhancer reactivation could induce stemness and enhance the tumorigenicity of cancer stem cells. Silencing of PpG enhancers (PpGe) during embryonic stem cell differentiation involves Lsd1-mediated H3K4me1 demethylation and DNA methylation. Here, we observed retention of H3K4me1 and DNA hypomethylation at PpGe associated with a partial repression of PpGs in F9 embryonal carcinoma cells (ECCs) post-differentiation. H3K4me1 demethylation in F9 ECCs could not be rescued by Lsd1 overexpression. Given our observation that H3K4me1 demethylation is accompanied by strong Oct4 repression in P19 ECCs, we tested if Oct4 interaction with Lsd1 affects its catalytic activity. Our data show a dose-dependent inhibition of Lsd1 activity by Oct4 and retention of H3K4me1 at PpGe in Oct4-overexpressing P19 ECCs. These data suggest that Lsd1-Oct4 interaction in cancer stem cells could establish a "primed" enhancer state that is susceptible to reactivation, leading to aberrant PpG expression.
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February 2020

Evaluation of Contamination Risk by the cobas e 602 Serology Module Before Viral Load Testing on the cobas 6800 System.

Sex Transm Dis 2020 05;47(5S Suppl 1):S32-S34

Medical and Scientific Affairs, Roche Molecular Systems, Pleasanton, CA.

Background: Diagnosis of HCV, HBV, and HIV involves antibody screening followed by confirmation and/or treatment decision using nucleic acid tests. However, minimal data exist evaluating the risk of nucleic acid cross-contamination on serology devices upstream of molecular testing despite the potential clinical and laboratory workflow advantages of single specimen vial testing for both procedures.

Methods: We conducted a checkerboard study investigating the potential risk of HCV, HBV, and HIV nucleic acid cross-contamination on 480 negative specimens by a serology screening instrument that uses disposable tips for sample transfer, rather than a fixed needle, before molecular testing.

Results: Nucleic acid contamination was observed in 0 of 480 negative specimens when processed with alternating high-titer HCV, HBV, or HIV specimens on the serology platform.

Conclusions: This study suggests that specimens analyzed by a serology instrument using disposable tips for sample transfer may be suitable for direct primary specimen reflex testing by a sensitive nucleic acid confirmatory test.
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May 2020

Assay Integrity of a PCR Influenza Point-of-Care Test Remains Following Artificial System Contamination.

J Appl Lab Med 2019 11 1;4(3):422-426. Epub 2019 Jul 1.

Roche Diagnostics Corporation, Indianapolis, IN.

Background: Healthcare providers who have access to tests at the point of care (POC) are increasingly requesting the same performance from the POC test as they expect from the laboratory. With the introduction of the cobas Liat instrument, highly sensitive molecular diagnostic testing can be performed closer to the patient in CLIA-waived, POC settings. As more sensitive tests become available, there is concern regarding contamination of instrumentation owing to improper handling, mistakes made when processing, or environmental contamination. Recent concerns were raised when a nurse performed environmental surveillance for flu A/B by inserting a dry swab into the cobas Liat instrument and then ran it as a sample on the instrument, generating a positive result. This finding stimulated questions about the possibility of system contamination contributing to false-positive results, ultimately leading to the possibility of providing incorrect treatment to patients.

Methods: To assess the likelihood of system contamination contributing to the generation of false-positive results, in this study we contaminated a cobas Liat System with flu A/B-positive control material. The system contamination was then assessed by swabbing exposed surfaces. Following confirmed system contamination, negative control samples were processed to determine whether system contamination had an impact on the expected negative results.

Results: Instrument contamination was confirmed, and no detectable flu A/B signal was observed for any of the negative control tubes run immediately following confirmation of system contamination.

Conclusion: Environmental contamination of the Liat instrument does not have an impact on the integrity of the result.
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November 2019