Abstract 1180: MicroRNAs and their target messenger RNAs associated with progression of breast cancer

• Published in: Cancer research (Chicago, Ill.) Ill.), 2010-04, Vol.70 (8_Supplement), p.1180-1180
• Main Authors: Schultz, Silke, Petat-Dutter, Karina, Walter, Michael, Poths, Sven, Vogel, Ulrich, Bonin, Michael, Sotlar, Karl, Neuburger, Christina, Wallwiener, Diethelm, Fehm, Tanja, Neubauer, Hans J.
• Format: Article
• Language: English
• ISSN: 0008-5472; 1538-7445
• DOI: 10.1158/1538-7445.AM10-1180

Background Based on own results using laser micro dissected cells of invasive ductal (IDC) and ductal in situ (DCIS) breast cancer of the same tumor combined with Affymetrix microarray technology 445 differentially transcribed candidate genes have been identified (Schütz et al., Cancer Research 2006, 66:5278-5286). In this project differential expression of miRNAs and mRNAs was investigated in the same DCIS/IDC breast cancers and pure DCIS fixed in formalin and embedded in paraffin (FFPE). Aims The aim was (1) to identify miRNAs and their target mRNAs to serve as progression markers between DCIS and IDC and (2) to find an miRNA/mRNA set to characterize aggressive DCIS with a high invasive potential. Material and Methods Bioinformatic analysis using support vector machine and principle component analyses was applied to extract a prognostic gene set from the set of differentially expressed genes and qRT-PCR validation was carried out on micro dissected FFPE epithelial cells. Additionally, Illumina microarray technology was applied for mRNA and miRNA expression analysis. For functional analysis transmigration assays were performed in combination with siRNA mediated knock down of target genes. Results We obtained a 9-gene progression set which is able to correctly classify DCIS and IDC in 23 out of 24 cases (95.8%). Eight of the 9 possible marker genes were correctly validated in FFPE tissues. Further, expression of these genes also varied between pure DCIS and DCIS areas of DCIS/IDC mixed tumors - expression validation is currently done with qRT-PCR. Nineteen miRNAs were differentially expressed between DCIS and IDC, of which 4 had already been described in tumors. These 4 miRNAs have binding sites on 5 of the 9 candidate genes. Microarray analysis of mRNA from FFPE tissues confirmed differential expression of LRRC15 which has been found to be functionally relevant for breast cancer cell invasion and of LRRC32. An siRNA mediated knock down of LRRC32 reduced invasive potential of MDA-MB-231 breast cancer cells in transmigration assays. Conclusions A small gene set of potential progression markers obtained by microarray analysis of native breast carcinomas was successfully validated on FFPE tissues. In addition, a set of targeting miRNAs was identified that might thus serve as prognostic markers. Further analyses are still ongoing. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association f