201. A ten markers panel provides a more accurate and complete microsatellite instability analysis in mismatch repair-deficient colorectal tumors
- Author
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Claudia Mescoli, Emanuele Damiano Luca Urso, Donato Nitti, Luca Morandi, Silvia Pizzini, Salvatore Pucciarelli, Marco Agostini, Roberta Bertorelle, Maria Vittoria Enzo, Silvia Mason, Chiara Bedin, Mario Lise, Agostini, M, Enzo, Mv, Morandi, L, Bedin, C, Pizzini, S, Mason, S, Bertorelle, R, Urso, E, Mescoli, C, Lise, M, Pucciarelli, S, and Nitti, D.
- Subjects
congenital, hereditary, and neonatal diseases and abnormalities ,Cancer Research ,Colorectal cancer ,DNA Mutational Analysis ,mononuclotide repeats ,Biology ,MLH1 ,DNA Mismatch Repair ,Polymerase Chain Reaction ,Multiplex polymerase chain reaction ,Biomarkers, Tumor ,medicine ,Genetics ,Humans ,neoplasms ,Adaptor Proteins, Signal Transducing ,Mononuclotide repeat ,Nuclear Proteins ,Microsatellite instability ,nutritional and metabolic diseases ,colorectal cancer ,General Medicine ,DNA Methylation ,medicine.disease ,Colorectal Neoplasms, Hereditary Nonpolyposis ,Immunohistochemistry ,digestive system diseases ,DNA-Binding Proteins ,MutS Homolog 2 Protein ,Oncology ,Cancer research ,Microsatellite ,DNA mismatch repair ,Microsatellite Instability Analysis ,MutL Protein Homolog 1 - Abstract
UNLABELLED Tumour microsatellite instability (MSI) is useful in identifying patients with hereditary non-polyposis colorectal cancer (HNPCC) with defective DNA mismatch repair (MMR) genes. A reference Bethesda panel has limitations resulting from the inclusion of dinucleotide markers, which are less sensitive and specific for detection of tumours with MMR deficiencies. We developed a multiplex PCR assay with additional four mononucleotide markers and one dinucleotide marker (NR-21, NR-24, BAT-40, TGF-BetaR and D18S58) for a rapid and proper classification of MSI-H, MSI-L and MSS colorectal cancers. Two tetranucleotide markers were added to identify sample mix-ups and/or contamination. RESULTS all the 44 cases test cases were in agreement with previous classification except for three cases: one case MSI-H-Bethesda unstable only for dinucleotides markers shifted to MSI-L category and two cases MSI-L-Bethesda unstable for mononucleotide markers shifted to MSI-H category. Immunohistochemistry analysis revealed that these two MSI-H cases did not expressed hMLH1 and they were found to be methylated at the MLH1 promoter, while the first one that shifted to MSI-L showed MMR protein expression. CONCLUSION a complete panel of ten markers including four dinucleotide and six mononucleotide microsatellites allows accurate evaluation of tumor MSI status.
- Published
- 2009