Global MicroRNA Expression of Sarcomas. A Study of Formalin Fixed Paraffin Embedded Tissues Using NanoString MiRNA Assay PlatForm
Vikram Shettigar, Hansjuerg Alder, Joel Mayerson, Thomas Scharschmidt, William Kraybill, Denis Guttridge, Obiajulu H Iwenofu. OSUMC, Columbus, OH
Background: Sarcomas are malignant heterogenous tumors of mesenchymal derivation. The pathogenesis of many of the different histologic sub-types remains poorly understood. microRNAs (miRNAs) are endogenous non-coding single stranded RNA's of 18-25 nucleotides in length that act as expression modulators of genes involved in fundamental cell processes and its dysregulation have been implicated in cancers.
In this study we used a selective miRNA screening platform to study the comparative global miRNA expression signatures in a cohort of human sarcomas with the patients own normal tissues serving as controls from formalin fixed paraffin embedded tissue (FFPE) samples.
Design: FFPE blocks of 20 sarcomas from 4 histologic types were retrieved including: myxoid/round cell liposarcoma (n=4); well differentiated liposarcoma (WDLPS, n=4), dedifferentiated liposarcoma (n=4) and synovial sarcoma (SS, n=4). All the cases were re-reviewed and the diagnosis was further validated by additional molecular testing where appropriate. The areas of tumor and uninvolved (or normal appearing areas) were identified and marked. 19 adjacent normal tissues from the same patients were available and multiple 1.75mm cores were obtained from both tumor and the uninvolved normal tissues. Total RNA for NanoString nCounter Human miRNA expression analysis was isolated from FFPE human sarcomas (n=20) and subjacent normal tissue (n=19) using RecoverAll Total Nucleic Acid isolation Kit for FFPE tissues (Ambion, Inc) according to manufacturer protocol and analyzed using NanoString technology (NanoString, Seattle, Washington). The results were processed using SAM and cluster analysis module.
Results: Clustering analysis shows a distinct global difference in expression patterns between the normal and sarcoma tissues. The different sarcoma subtypes reveal expression signatures in an unsupervised hierarchical clustering analysis. Of note, more miRNAs were down-regulated than upregulated. MiR-143 showed significant down-regulation in WDLPS and SS while miR-145 showed down-regulation only in WDLPS.
Conclusions: Our data indicate distinctly different patterns of miRNA expression in normal and sarcoma samples regardless of histologic subtype. The unique expression miRNA signatures for different sarcoma subtypes may have diagnostic, prognostic or even therapeutic implications.
Category: Bone & Soft Tissue
Monday, March 19, 2012 1:00 PM
Poster Session II # 25, Monday Afternoon