Evaluation of tumor microsatellite instability using five quasimonomorphic mononucleotide repeats and pentaplex PCR

• Published in: Gastroenterology (New York, N.Y. 1943) Vol. 123; no. 6; p. 1804
• Main Authors: Suraweera, Nirosha, Duval, Alex, Reperant, Maryline, Vaury, Christelle, Furlan, Daniela, Leroy, Karen, Seruca, Raquel, Iacopetta, Barry, Hamelin, Richard
• Format: Journal Article
• Language: English
• Published: United States 01.12.2002
• Subjects: Africa - ethnology; African Continental Ancestry Group - genetics; Cell Line; DNA, Neoplasm - genetics; Endometrial Neoplasms - genetics; European Continental Ancestry Group - genetics; Female; Fluorescence; Gastrointestinal Neoplasms - genetics; Humans; Microsatellite Repeats; Paris - ethnology; Polymerase Chain Reaction - methods; Paris; Africa
• ISSN: 0016-5085
• DOI: 10.1053/gast.2002.37070

The microsatellite instability (MSI) phenotype is a characteristic of the hereditary nonpolyposis colorectal cancer syndrome as well as approximately 15% of sporadic colon and gastric tumors. It is a valuable diagnostic marker for the identification of hereditary nonpolyposis colorectal cancer cases and may be a molecular predictive marker for the identification of colon cancer patients who benefit from chemotherapy. To evaluate MSI, a reference panel was proposed at an international consensus meeting, comprised of 2 mononucleotide (BAT-25, BAT-26) and 3 dinucleotide repeats. Analysis of BAT-26 is sufficient for detecting the MSI phenotype in most, but not all, cases. Additional results with dinucleotide markers can sometimes lead to incorrect classification of MSI tumors. We describe here a single fluorescent multiplex system comprising 5 quasimonomorphic mononucleotide repeats for the detection of MSI tumors. None of 184 germline DNA samples, including 56 from African subjects, was found to contain allelic size variations in more than 2 of these markers. In contrast, all MSI tumors showed allelic size variations in 3 or more of the microsatellites. Using this assay, we confirmed (or reclassified in 6 cases) the MSI status of 124 colon and 50 gastric primary tumors and 16 colon cell lines. We propose that using a pentaplex polymerase chain reaction system allows accurate evaluation of tumor MSI status of DNA with 100% sensitivity and specificity without the need to match normal DNA. This assay is simpler to use than those involving dinucleotides and is more specific than using BAT-26 alone.