miRNA Extracted from FFPE Tissues Will Aid Cancer Prognosis

MicroRNAs (miRNAs) were extracted from formalin-fixed paraffin-embedded (FFPE) cancer tissues using a new, optimized protocol.

The new method for extracting miRNAs from FFPE tissues enabled scientists to identify 17 new and 53 known miRNAs from normal skin, melanoma, and sentinel lymph nodes. The miRNAs were well preserved in a 10-year-old specimen. Identification of novel miRNAs that differ in cancerous and healthy tissue, even from long-preserved tissue, will lead to better predictions of disease prognosis and treatment response.

Cancer tissues from patients are frequently stored by a method involving formalin fixation and paraffin embedding to retain morphological definition for identification. This method frequently prevents further molecular analysis of the tissue because of messenger RNA (mRNA) degradation. However, the tissues contain high numbers of microRNAs (miRNAs), which are short enough--approximately 22 nucleotides long--not to be broken down during the fixation process.

Dr. Soheil Dadras and colleagues from the Stanford University School of Medicine (Stanford, CA, USA) developed the new protocol for miRNA extraction. They reported the study in the September 2009 issue of the Journal of Molecular Diagnostics. The authors wrote that their "cloning strategy has the advantage of not only discovering novel and known miRNA sequence identity but also providing an estimate of relative expression level."

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Stanford University School of Medicine