INTERPHASE IN-SITU HYBRIDIZATION TO DISAGGREGATED AND INTACT TISSUE SPECIMENS OF PROSTATIC ADENOCARCINOMAS

A comparative study was performed of interphase in situ hybridization (ISH) to deparaffinized 4-mu m tissue sections and nuclear suspensions from eight prostatic adenocarcinomas, as well as one normal prostatic control. Whole nuclear suspensions were derived from the same tumor a reas to evaluate differences of ISH to truncated versus whole nuclei. DNA probes specific for the centromeres of chromosome 1, 7, 8, 10, and Y were used for detection of numerical chromosomal changes and aneupl oidy. In six adenocarcinomas chromosome aberrations (+7, +8, -8, -10, -Y) were seen. However, ISH to sections revealed focal aberrations (-1 0, -Y) in four cases that could not be distinguished in the suspension s. Chromosomal alterations occurring in larger tumor areas were also d etected in the nuclear suspensions. Chromosome copy number changes, es pecially gains, were better discriminated in the nuclear suspensions. The rate of ISH aneuploidy seen in nuclear suspensions corresponded wi th that observed in the tissue sections (P<0.01). Ploidy patterns as a ssessed by ISH to sections and nuclear sus pensions were in concordanc e with DNA flow cytometry (both P<0.001). We conclude that both sectio n and suspension ISH were able to accurately detect aneuploidy and num erical chromosomal abet-rations occurring in larger histological areas . However, section ISH was also capable of revealing (small) focal cyt ometric abnormalities, due to a precise analysis of only target cells. Focal abnormalities were not detected by suspension ISH, probably due to an admixture of non-aberrant tumor cells and stromal elements.