ALLELIC LOSS DETECTED ON CHROMOSOME-8, CHROMOSOME-10, AND CHROMOSOME-17 BY FLUORESCENCE IN-SITU HYBRIDIZATION USING SINGLE-COPY P1 PROBES ON ISOLATED-NUCLEI FROM PARAFFIN-EMBEDDED PROSTATE TUMORS

We have implemented a reliable new technique for preparing isolated pr ostate cancer nuclei from paraffin-embedded tissue sections followed b y analysis with single-copy fluorescence in situ hybridization (FISH). Our initial validation is described by comparison of our data with fr esh prostate tumor tissue and loss of heterozygosity (LOH) studies, We also describe evaluation of 36 previously unstudied prostate cancer p atients, Fifteen archival samples were selected from patients who unde rwent radical prostatectomy in which direct FISH and LOH data were ava ilable. Isolated nuclei were prepared and allelic loss was detected on 17q using a single-copy DNA (P1 phage) probe by FISH. A high (80%) co ncordance was found when comparing isolated nuclei data with 17q resul ts from fresh preparations and LOH studies. We also examined loss at s ites on 8p, 10q, and 17q in samples from 36 patients for whom clinical information was available, Loss was found at any of the three loci in 32/36 (89%) of the specimens with specific loss in 53% of the cases a t the 8p locus, 33% at the 10q locus, and 61% at the 17q locus. Studie s indicate that, as well as providing potential clinical information, isolated nuclei preparations are as reliable as fresh tissue for singl e-copy FISH studies.