Applicability of next generation sequencing technology in microsatellite instability testing.

Area of Science:

• Oncology
• Genetics
• Molecular Diagnostics

Background:

• Microsatellite instability (MSI) is a critical biomarker in colorectal cancer (CRC).
• MSI status influences treatment decisions, chemotherapy response, and patient prognosis.
• Current MSI testing methods have limitations.

Purpose of the Study:

• To introduce and validate a next-generation sequencing (NGS) approach for MSI testing in colorectal cancer.
• To evaluate the efficacy of deep resequencing focused on microsatellite loci.
• To compare NGS-based MSI detection with traditional methods.

Main Methods:

• Utilized the MiSeq platform for deep resequencing of specific microsatellite regions.
• Analyzed two series of colorectal tumor samples (44 and 6 samples) with varying controls.
• Focused on five MSI loci (BAT25, BAT26, BAT34c4, D18S55, D5S346) and two mononucleotide loci (BAT25, BAT26).

Main Results:

• Successfully classified tumors into MSI-High, MSI-Low, and microsatellite stable (MSS) categories.
• Identified 17 MSI-High, 1 MSI-Low, and 26 MSS tumors in the first series.
• Identified 3 MSI-High and 3 MSS tumors in the second series.
• Achieved concordant MSI status determination compared to traditional multiplex PCR methods despite minor marker variations.

Conclusions:

• The described NGS deep resequencing method provides a reliable and accurate approach for MSI testing in colorectal cancer.
• This novel method demonstrates comparable performance to established techniques.
• The NGS approach holds potential for improved risk stratification and treatment guidance in CRC patients.