Abstract 157: Variability of microRNA measurements in breast ductal carcinomas

Abstract

Abstract MicroRNAs (miRNAs) are a newly identified class of molecules involved in the post transcriptional regulation of genetic information. Multiple approaches have been developed to measure miRNAs including the measurement of miRNAs in paraffin embedded tissue. There have been few reported studies of the reproducibility of miRNA measurements, especially in paraffin embedded tissues, and how such measurements might vary due to tissue heterogeneity and/or analytical variability. We used microdissected paraffin embedded samples of ductal carcinoma of the breast enriched to a tumor nuclear cellularity of at least 80% to determine the reproducibility of analysis of miRNAs extracted from paraffin sections. From each of 3 microdissected paraffin embedded tissues, six 10μ paraffin sections were cut and combined as one specimen and the following six 10μ sections were combined as a second specimen from the same case. While the sections were adjacent, this would incorporate variation due to tissue heterogeneity over 0.12mm of the specimen that was analyzed. All six specimens were blinded and 1500 miRNAs including miRNAs from mice, rats and plants as controls were analyzed by High Throughput Genomics (HTG) considering each of these 6 specimens as an independent specimen. Even with tissue heterogeneity, the correlations of the values of miRNA of the three pairs of specimens were 0.96, 0.90 and 0.83; the 12 correlations between specimens of different cases did not excel 0.9 and only 2 exceeded 0.8. Results of combining alternative paraffin sections into 2 specimens from these same cases and laser capture microdissection specimens are pending to separate differences due to variation in tissue from analytical variables. Of note, the 22 most upregulated miRNAs (X20 to X30 basal levels) in these breast ductal carcinomas include the following: Let 7b, Let 7f, 1225-3P, 1228, 1237, 1280, 1281, 1308, 16, 1826, 191, 200c, 23a, 27a, 574-5p, 638, 663b, 720, 768-3P, 768-5P, 886-5P, and 92a. These studies are continuing and laser capture microdissection results will be incorporated in the study. Supported in part by the Breast SPORE at UAB (CA089019-09) and a grant from the Susan G Komen foundation (BCTR0600484). Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 157. doi:10.1158/1538-7445.AM2011-157