Elevated Microsatellite Alterations at Selected Tetranucleotides (EMAST) Is Not Attributed to MSH3 Loss in Stage I-III Colon cancer: An Automated, Digitalized Assessment by Immunohistochemistry of Whole Slides and Hot Spots

INTRODUCTION: EMAST is a poorly understood form of microsatellite instability (MSI) in colorectal cancer (CRC) for which loss of MSH3 has been proposed as the underlying mechanism, based on experimental studies. We aimed to evaluate whether MSH3 loss is associated with EMAST in CRC. METHODS: A conse...

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Main Authors: Martin M Watson, Dordi Lea, Hanne R. Hagland, Kjetil Søreide
Format: Article
Language:English
Published: Elsevier 2019-12-01
Series:Translational Oncology
Online Access:http://www.sciencedirect.com/science/article/pii/S1936523319303146
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spelling doaj-4c422d1e12764fdf9b4e3338454219922020-11-25T01:26:51ZengElsevierTranslational Oncology1936-52332019-12-01121215831588Elevated Microsatellite Alterations at Selected Tetranucleotides (EMAST) Is Not Attributed to MSH3 Loss in Stage I-III Colon cancer: An Automated, Digitalized Assessment by Immunohistochemistry of Whole Slides and Hot SpotsMartin M Watson0Dordi Lea1Hanne R. Hagland2Kjetil Søreide3Gastrointestinal Translational Research Unit, Laboratory for Molecular Medicine, Stavanger University Hospital, Gerd Ragna Bloch Thorsens Gate 8, 4011, Stavanger, Norway; Department of Gastrointestinal Surgery, Stavanger University Hospital, Gerd Ragna Bloch Thorsens Gate 8, 4011, Stavanger, Norway; Department of Clinical Medicine, University of Bergen, Bergen, Norway; Address all correspondence to: Martin M Watson; Department of Gastrointestinal Surgery, Stavanger University Hospital, Gerd Ragna Bloch Thorsens gate 8, 4011, Stavanger, Norway.Gastrointestinal Translational Research Unit, Laboratory for Molecular Medicine, Stavanger University Hospital, Gerd Ragna Bloch Thorsens Gate 8, 4011, Stavanger, Norway; Department of Clinical Medicine, University of Bergen, Bergen, Norway; Department of Pathology, Stavanger University Hospital, Gerd Ragna Bloch Thorsens Gate 8, 4011, Stavanger, NorwayGastrointestinal Translational Research Unit, Laboratory for Molecular Medicine, Stavanger University Hospital, Gerd Ragna Bloch Thorsens Gate 8, 4011, Stavanger, Norway; Department of Chemistry, Bioscience and Environmental Engineering, University of Stavanger, NorwayGastrointestinal Translational Research Unit, Laboratory for Molecular Medicine, Stavanger University Hospital, Gerd Ragna Bloch Thorsens Gate 8, 4011, Stavanger, Norway; Department of Gastrointestinal Surgery, Stavanger University Hospital, Gerd Ragna Bloch Thorsens Gate 8, 4011, Stavanger, Norway; Department of Clinical Medicine, University of Bergen, Bergen, NorwayINTRODUCTION: EMAST is a poorly understood form of microsatellite instability (MSI) in colorectal cancer (CRC) for which loss of MSH3 has been proposed as the underlying mechanism, based on experimental studies. We aimed to evaluate whether MSH3 loss is associated with EMAST in CRC. METHODS: A consecutive cohort of patients with stage I-III CRC. Digital image analysis using heatmap-derived hot spots investigated MSH3 expression by immunohistochemistry. Fragment analysis of multiplex PCR was used to assess MSI and EMAST, and results cross-examined with MSH3 protein expression. RESULTS: Of 152 patients, EMAST was found in 50 (33%) and exclusively in the colon. Most EMAST-positive cancers had instability at all 5 markers, and EMAST overlapped with MSI-H in 42/50 cases (84%). The most frequently altered tetranucleotide markers were D8S321 (38.2% of tumors) and D20S82 (34.4%). Subjective evaluation of MSH3 expression by IHC in tumor found ≤10% negative tumor cells in all samples, most being ≤5% negative. Digital analysis improved the detection but showed a similar spread of MSH3 loss (range 0.1–15.7%, mean 2.2%). Hotspot MSH3 negativity ranged between 0.1 to 95.0%, (mean 8.6%) with significant correlation with the whole slide analysis (Spearman's rho = 0.677 P < .001). Loss of MSH3 expression did not correlate with EMAST. CONCLUSIONS: In a well-defined cohort of patients with CRC, loss of MSH3 was not associated with EMAST. Further investigation into the mechanisms leading to EMAST in CRC is needed.http://www.sciencedirect.com/science/article/pii/S1936523319303146
collection DOAJ
language English
format Article
sources DOAJ
author Martin M Watson
Dordi Lea
Hanne R. Hagland
Kjetil Søreide
spellingShingle Martin M Watson
Dordi Lea
Hanne R. Hagland
Kjetil Søreide
Elevated Microsatellite Alterations at Selected Tetranucleotides (EMAST) Is Not Attributed to MSH3 Loss in Stage I-III Colon cancer: An Automated, Digitalized Assessment by Immunohistochemistry of Whole Slides and Hot Spots
Translational Oncology
author_facet Martin M Watson
Dordi Lea
Hanne R. Hagland
Kjetil Søreide
author_sort Martin M Watson
title Elevated Microsatellite Alterations at Selected Tetranucleotides (EMAST) Is Not Attributed to MSH3 Loss in Stage I-III Colon cancer: An Automated, Digitalized Assessment by Immunohistochemistry of Whole Slides and Hot Spots
title_short Elevated Microsatellite Alterations at Selected Tetranucleotides (EMAST) Is Not Attributed to MSH3 Loss in Stage I-III Colon cancer: An Automated, Digitalized Assessment by Immunohistochemistry of Whole Slides and Hot Spots
title_full Elevated Microsatellite Alterations at Selected Tetranucleotides (EMAST) Is Not Attributed to MSH3 Loss in Stage I-III Colon cancer: An Automated, Digitalized Assessment by Immunohistochemistry of Whole Slides and Hot Spots
title_fullStr Elevated Microsatellite Alterations at Selected Tetranucleotides (EMAST) Is Not Attributed to MSH3 Loss in Stage I-III Colon cancer: An Automated, Digitalized Assessment by Immunohistochemistry of Whole Slides and Hot Spots
title_full_unstemmed Elevated Microsatellite Alterations at Selected Tetranucleotides (EMAST) Is Not Attributed to MSH3 Loss in Stage I-III Colon cancer: An Automated, Digitalized Assessment by Immunohistochemistry of Whole Slides and Hot Spots
title_sort elevated microsatellite alterations at selected tetranucleotides (emast) is not attributed to msh3 loss in stage i-iii colon cancer: an automated, digitalized assessment by immunohistochemistry of whole slides and hot spots
publisher Elsevier
series Translational Oncology
issn 1936-5233
publishDate 2019-12-01
description INTRODUCTION: EMAST is a poorly understood form of microsatellite instability (MSI) in colorectal cancer (CRC) for which loss of MSH3 has been proposed as the underlying mechanism, based on experimental studies. We aimed to evaluate whether MSH3 loss is associated with EMAST in CRC. METHODS: A consecutive cohort of patients with stage I-III CRC. Digital image analysis using heatmap-derived hot spots investigated MSH3 expression by immunohistochemistry. Fragment analysis of multiplex PCR was used to assess MSI and EMAST, and results cross-examined with MSH3 protein expression. RESULTS: Of 152 patients, EMAST was found in 50 (33%) and exclusively in the colon. Most EMAST-positive cancers had instability at all 5 markers, and EMAST overlapped with MSI-H in 42/50 cases (84%). The most frequently altered tetranucleotide markers were D8S321 (38.2% of tumors) and D20S82 (34.4%). Subjective evaluation of MSH3 expression by IHC in tumor found ≤10% negative tumor cells in all samples, most being ≤5% negative. Digital analysis improved the detection but showed a similar spread of MSH3 loss (range 0.1–15.7%, mean 2.2%). Hotspot MSH3 negativity ranged between 0.1 to 95.0%, (mean 8.6%) with significant correlation with the whole slide analysis (Spearman's rho = 0.677 P < .001). Loss of MSH3 expression did not correlate with EMAST. CONCLUSIONS: In a well-defined cohort of patients with CRC, loss of MSH3 was not associated with EMAST. Further investigation into the mechanisms leading to EMAST in CRC is needed.
url http://www.sciencedirect.com/science/article/pii/S1936523319303146
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