Isolation of RNA, DNA and proteins from formalin-fixed paraffin-embedded tissue specimens

Abstract

Methods are disclosed for rapid, reliable and simple isolation of RNA, DNA and proteins from formalin-fixed paraffin-embedded tissue samples. RNA purified in this manner can be used to monitor gene expression levels. The tissue sample can be a tumor or other pathological tissue.

What is claimed is:  
     
         1 . A method for recovering DNA, RNA or proteins from a formalin-fixed paraffin-embedded biological tissue sample comprising: 
 deparaffinizing the sample;    heating the sample in a chaotropic solution comprising an effective concentration of a guanidinium compound to a temperature in the range of about 50 to about 100° C. for a time period of about 5 to about 120 minutes; and    recovering said RNA, DNA or protein from said chaotropic solution.    
     
     
         2 . The method of  claim 1  further comprising rehydrating the deparaffinized sample before heating.  
     
     
         3 . The method of  claim 2  further comprising homogenizing said sample before heating.  
     
     
         4 . The method of  claim 3  for recovering RNA from a biological tissue sample wherein said RNA is recovered by extraction from said chaotropic solution with a water insoluble organic solvent.  
     
     
         5 . The method of  claim 4  wherein said water insoluble organic solvent comprises chloroform.  
     
     
         6 . The method of  claim 5  further comprising purifying said RNA.  
     
     
         7 . The method of  claim 6  wherein said RNA is purified by ethanol precipitation.  
     
     
         8 . The method of  claim 1  for recovering RNA wherein said time period is from about 10 to about 60 minutes.  
     
     
         9 . The method of  claim 8  wherein said time period is from about 30 to about 60 minutes.  
     
     
         10 . The method of  claim 1  for recovering RNA wherein said guanidinium compound is guanidinium hydrochloride.  
     
     
         11 . The method of  claim 1  for recovering RNA wherein said guanidinium compound is guanidinium isothiocyanate.  
     
     
         12 . The method of  claim 11  wherein the concentration of said guanidinium isothiocyanate in the chaotropic solution is about 2 to about 5M.  
     
     
         13 . The method of  claim 11  wherein said chaotropic solution has a pH of about 3-6.  
     
     
         14 . The method of  claim 1  for recovering RNA wherein said chaotropic solution further comprises a reducing agent.  
     
     
         15 . The method of  claim 14  wherein said reducing agent is β-mercaptoethanol.  
     
     
         16 . The method of  claim 14  wherein said reducing agent is dithiothreitol.  
     
     
         17 . The method of  claim 1  wherein said RNA is used to determine the level of expression of a gene.