Gene Expression Analysis Comparing Two RNA Isolation Methods from Recent and Older Archived Formalin-Fixed, Paraffin-Embedded Tissue (FFPET) Samples

Formalin-fixed, paraffin-embedded (FFPE) tissue samples are widely available for retrospective studies. However the quantity and the quality of the isolated RNA can limit downstream applications. In addition to tissue fixation, subsequent storage time of the tissue blocks is one of the main factors that can influence the quality and quantity of the isolated nucleic acids, as long-term storage can result in lower yield. In this application note from Roche a comparative study using two commercially available kits for RNA isolation from FFPE tissue using older archived and recent tissue samples is presented. For testing the downstream applicability of the isolated samples, gene expression of three recently identified colorectal cancer-specific discriminatory transcripts was determined using real-time PCR.