EMAST Type of Microsatellite Instability—A Distinct Entity or Blurred Overlap between Stable and MSI Tumors

Vuković Đerfi, Kristina; Salar, Anamarija; Čačev, Tamara; Kapitanović, Sanja (2023) EMAST Type of Microsatellite Instability—A Distinct Entity or Blurred Overlap between Stable and MSI Tumors. Genes, 14 (7). ISSN 2073-4425

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Abstract

Microsatellite instability (MSI) represents an accumulation of frameshifts in short tandem repeats, microsatellites, across the genome due to defective DNA mismatch repair (dMMR). MSI has been associated with distinct clinical, histological, and molecular features of tumors and has proven its prognostic and therapeutic value in different types of cancer. Recently, another type of microsatellite instability named elevated microsatellite alterations at selected tetranucleotide repeats (EMAST) has been reported across many different tumors. EMAST tumors have been associated with chronic inflammation, higher tumor stage, and poor prognosis. Nevertheless, the clinical significance of EMAST and its relation to MSI remains unclear. It has been proposed that EMAST arises as a result of isolated MSH3 dysfunction or as a secondary event in MSI tumors. Even though previous studies have associated EMAST with MSI-low phenotype in tumors, recent studies show a certain degree of overlap between EMAST and MSI-high tumors. However, even in stable tumors, (MSS) frameshifts in microsatellites can be detected as a purely stochastic event, raising the question of whether EMAST truly represents a distinct type of microsatellite instability. Moreover, a significant fraction of patients with MSI tumors do not respond to immunotherapy and it can be speculated that in these tumors, EMAST might act as a modifying factor.

Item Type:	Article
Uncontrolled Keywords:	microsatellite instability; MSI; elevated microsatellite alterations at selected tetranucleotide repeats; EMAST; mismatch repair; MMR; MSH3; cancer; immunotherapy
Subjects:	BIOMEDICINE AND HEALTHCARE > Basic Medical Sciences > Human Genetics, Genomics and Proteomics
Divisions:	Division of Molecular Medicine
Projects:	Project title Project leader Project code Project type Mikrosatelitna nestabilnost (MSI i EMAST) u molekularnom profiliranju sporadičnih karcinoma debelog crijeva-MSIandEMASTinCRC Sanja Kapitanović IP-2016-06-1430 HRZZ
Depositing User:	Josipa Karadžole
Date Deposited:	25 Mar 2026 10:18
URI:	http://fulir.irb.hr/id/eprint/11463
DOI:	10.3390/genes14071474

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