Microsatellite instability at AAAG repeat sequences in respiratory tract cancers

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• Microsatellite instability (MSI) is a known hallmark of various cancers.
• Tetranucleotide repeat microsatellites are frequently altered in cancer genomes.
• Understanding specific patterns of MSI can improve cancer detection and classification.

Purpose of the Study:

• To investigate the occurrence and characteristics of novel alleles at microsatellite sequences in non-small cell lung cancers (NSCLC).
• To identify specific microsatellite markers associated with instability in respiratory tract cancers.
• To define a novel type of microsatellite instability and assess its prevalence.

Main Methods:

• Surveyed 61 tetranucleotide repeat markers for novel alleles in 47 NSCLC samples.
• Identified markers with new alleles, indicative of microsatellite instability (MSI).
• Focused on markers with AAAG repeat sequences for further analysis in various cancer types.

Main Results:

• MSI was detected in 64% of NSCLC samples across 43% of markers.
• Eleven of twelve markers showing instability in multiple tumors contained an AAAG repeat sequence.
• This specific instability, termed EMAST, was prevalent in respiratory tract cancers (51% NSCLC, 56% head and neck) but less so in bladder (21%) and kidney (12%) cancers.

Conclusions:

• Approximately 50% of respiratory tract cancers exhibit microsatellite instability, primarily at AAAG sequences.
• This distinct instability pattern is termed EMAST (elevated microsatellite alterations at selected tetranucleotide repeats).
• EMAST markers show potential for the molecular detection of respiratory tract cancers.