MicroRNA profiling analysis in a series of high-risk intestinal GISTs.

Abstract

10532 Background: Resected localized GISTs exhibit a wide range of biological behavior from low to high risk of recurrence. Risk categories (low, intermediate and high) are built from mitotic count, size and location. However, the molecular mechanism related to GIST relapse has not yet been fully clarified. The purpose of this study is to characterize miRNA expression profile in high risk GIST patients for both, recurred and not recurred, and detect those differentially expressed in these two subsets. Methods: Twelve cases of high risk intestinal GIST, 6 with relapse and 6 without relapse, were selected for this analysis. Sections were obtained for RNA extraction using the miRNeasy FFPE kit (Qiagen) and miRNA was hybridized to the GeneChip miRNA 3.0 Array (Affymetrix) including more than 1800 human miRNA. Normalization and statistical analysis were performed with Partek Genomic Suite 6.6 software by means of ANOVA test. Fold-change (FC) and p-values were applied to generate miRNA differentially expressed lists. Results: A subset of 85 miRNA were significantly deregulated (p<0.05; FC=1.5) when comparing both groups. Among them, the highest p-values and associated FC were: mir-4776 (FC= 1,95, p= 0,011;), mir-1973 (FC= 1,59, p= 0,014) mir-4649 (FC 1,74, p= 0,028) and mir-3605 (GC= 1,58, p=0,045). All of these were up-regulated in recurred patients. Interestingly, the two samples that correspond to the biggest tumors with relapse showed a significantly different expression profile that separated them from the rest of the samples. We have identified 44 miRNAs that discriminate these two samples from the rest and show a very high statistical significance. The most significantly up regulated miRNAs were miR-100 (FC= 90,87, p<0.0001), miR-30a (FC= 156,086, p<0.0001) and down regulated miR-1184 (FC= -24,94, p<0.0001) and miR-4529 (FC= -16,61, p<0.0001). These miRNAs are involved in cell cycle and cell proliferation. Conclusions: This is the first wide characterization of miRNA profile in high risk GIST. The highest differences in expression are related to not previously described miRNAs in GIST tumors. All of them are involved in cell cycle and cell proliferation, thus expecting to regulate many GISTs associated genes, related to the relapse event.