Translation of Effects of Retinoids and Rexinoids: Extraction and Quality Assessment of RNA from Formalin-Fixed Tissues.

Retinoids and rexinoids directly and selectively activate their nuclear receptors, resulting in changes in the transcript levels of their target genes. Consequently, quantitating mRNA levels transcribed from cognate target genes is the most accurate measure of retinoid action. These changes can serve as relevant endpoints in biomarker trials, as well as in vivo preclinical studies. In gene expression analyses of archival material such as formalin-fixed paraffin-embedded (FFPE) tissues, assessing the quality of the extracted RNA is essential for the validation of the studies. With next generation sequencing (NGS) becoming the method of choice for gene expression profiling, RNA quality has become a critical aspect of study feasibility. In this chapter, we describe a method to extract RNA and to assess the intactness of RNA samples extracted from paraffin-embedded tissues.