EXTRACTION OF RNA FROM SINGLE FROZEN-SECTIONS

The sensitivity of the reverse transcriptase-polymerase chain reaction (RT-PCR) makes it ideally suited for the detection of changes in gene expression. Unfortunately, traditional methods for RNA isolation requ ire time-consuming procedures that are not appropriate for small sampl es, such as individual frozen sections. This report describes a new te chnique that permits the rapid extraction of RNA from individual froze n histological sections. RNA is extracted by incubating a frozen secti on in an RT-PCR compatible buffer solution containing RNase inhibitor and dithiothreitol. RNA isolated from frozen sections is stable at roo m temperature for up to 3 h under the conditions described. Alternativ ely, extracts can be frozen for later use. When maintained in a dry st ate at room temperature, RNA in sections remained stable for 2 weeks. Histological, immunohistochemical, or in situ analyses can be carried out with sections that are immediately adjacent to those used for extr acting RNA. The simplicity and economy of this procedure may foster th e development of prognostic screens that can be performed in parallel with traditional histopathological analysis. (C) 1998 John Wiley & Son s, Ltd.