Correlation Between mRNA Detected by Microarrays and qRT-PCR and Protein Detected by Immunohistochemistry of Cyclins in Tumour Tissue from Colonic Adenocarcinomas

Abstract

There are several studies evaluating the prognostic value of overexpression of cyclin proteins, detected by im- munohistochemistry. Overexpression detected by microarray and real-time PCR techniques is now applied in analyzing the prognostic value of different genes on patient outcome. In this study we wanted to evaluate the correlation between these three methods for detection of cyclins (A2, B1, D1, D3, E and H) overexpression, as well as correlation between overexpression and gene amplification of the cyclin genes. We used both normal mucosa and tumour tissue obtained from 22 patients at the time of surgery. None of the cyclins were defined to be amplified at the gene level. qRT-PCR and cDNA microarray results are comparable, but no correlation between gene expression and protein expression, measured by im- munohistochemistry was observed. This may indicate that immunohistochemistry detects some other parameters than gene expression analysis measured by cDNA microarray and qRT-PCR. It is of interest to evaluate which of the three methods may give the most important information about patient prognosis.