Label-free analysis of microsatellite instability in colorectal carcinoma by on-chip electrophoresis

Microsatellite instability (MSI) is caused by a failure of the DNA mismatch repair system and occurs frequently in various types of cancer. Since sporadic MSI are associated with approximately 10 to 15% of colorectal, gastric or endometrial carcinoma and impact clinical prognosis, MSI analysis is an important tool in clinical research and molecular diagnostics. Given that conventional techniques used for MSI detection e.g. polyacrylamide gel electrophoresis (PAGE) or capillary electrophoresis turned out to be laborious or expensive, this study aimed to develop a simple and efficient procedure of MSI detection. Forty cases were selected out of a panel of 150 patients with colon carcinoma. Of the forty cases selected, 26 cases had no MSI, while 14 cases had a positive MSI. Amplicons derived from areas of non-tumor (N) and tumor (T) were analyzed by microfluidic based on-chip electrophoresis on the Agilent 2100 bioanalyzer. The results presenting a pattern of five microsatellite loci were compared with the findings obtained by fluorochrome-associated PAGE technology. In all cases, label-free microfluidic separation of the PCR amplicons resulted in highly resolved, distinct patterns for each of the five microsatellite loci. Detection of MSI was demonstrated by microsatellite loci-associated, well defined deviations in the electropherogram profiles of tumor and non-tumor material, in agreement with the classification of the MSI cases performed by conventional technology (95% concordance rate). The presented data demonstrate that microfluidic chip technology is a simple, reliable and robust technology for MSI detection, which allows label-free analyses of microsatellite amplicons within 30 minutes. Label-free analysis of microsatellite instability in colorectal carcinoma by on-chip electrophoresis Stephan E. Baldus, Nora Barta, Sezer Lammers, Hans Peter Dienes, Rüdiger Salowsky*, and Margarete Odenthal Institute for Pathology, University Clinic Cologne, Germany and *Agilent Technologies Waldbronn, Germany