Comparison of microarray platforms for measuring differential microRNA expression (Exiqon data)

Microarray technology applied to miRNA profiling is a promising tool in many research fields. At present, only few studies have addressed intra- and inter-platform reproducibility by using tissues/cell-lines of different origin to maximize differences in miRNA content. Although the approach might provide an useful system to address technical issues since, for sure, a huge modulation can be evaluated, it does not reflect the common experimental practice in laboratory. As a matter of fact, from all these studies it is not know how concordant can be expected the results obtained by different platforms starting from biological meaningful specimens. We investigated the issue of inter-platform reproducibility using four miRNA microarray platforms and nine paired tumor/normal colon tissues. The tumor and the normal counter-part samples were prospectively collected from 9 patients who underwent surgical resection at the INT-MI. Neoplastic samples were obtained from the central area of the neoplasia, avoiding to select necrotic material or transition zones with healthy mucosa. Samples of colonic healthy mucosa were resected at least 20 centimeters far from the neoplasia and distant from the surgical resection margins. Tissue samples were stored in liquid nitrogen until RNA extraction. Total RNA was extracted from 10–20 mg of tumor samples and from 30–40 mg of normal samples. Nine paired tumor/normal colon tissues on Exiqon miRCURY LNA microRNA Array