THE RELATIONSHIP BETWEEN NUMERICAL ABERRATIONS OF CHROMOSOME-17 AND NUCLEAR-DNA CONTENT IN COLORECTAL-CARCINOMA DETECTED BY FLUORESCENT IN-SITU HYBRIDIZATION (FISH) AND CYTOFLUOROMETRY USING AUTO-SCANNING STAGE

Recently, interphase cytogenetics using fluorescent in situ hybridizat ion (FISH) was performed on various kinds of solid tumor, and their in herent karyotypic heterogeneities were revealed. Concerning this heter ogeneity, we evaluated both the exhibiting number of chromosome 17 and nuclear DNA content on an identical nucleus by means of computer-cont rolled auto-scanning stage in order to demonstrate the alteration in n umber of chromosome 17 among cytofluorometrically distinct subpopulati ons. We investigated 8 lesions of surgically resected colorectal carci nomas, which were classified as aneuploid in quantitative DNA analysis and also exhibited an increase of 17-aneusomy nuclei. We used paraffi n-embedded archival blocks. First, we prepared isolated cell specimens , and memorized the position of the cells on a glass slide using compu ter-controlled auto-scanning stage. Next, the specimens were stained w ith propidium iodide, and the fluorescent intensity was evaluated as n uclear DNA content in the order of cell position data. And lastly, FIS H was performed with (peril centromere-specific DNA probes for chromos ome 17, and we enumerated the number of signals in a nucleus also acco rding to cell position data. Then, we compared the distribution of num ber of chromosome 17 among cytofluorometrically distinct subpopulation s. Three of 8 lesions showed a single G0+G1 peak, and the rest exhibit ed plural G0+G1 peaks in DNA profile. And 4 of 5 lesions, which showed plural G0+G1 peaks, presented a peak at the DNA value of (near) 2c. W e could detect an alteration in the distribution of number of chromoso me 17 between diploid peak and aneuploid peaks in 4 of 4 lesions which presented a peak at the DNA value of (near) 2c. However, we could not find a difference in the distribution of number of chromosome 17 betw een G0+G1 peak and G2+M peak. These observations indicate that the dis tribution of number of chromosome 17 reflects an endoreduplication of genome content, yet, it does not alter in accordance with the phase of cell cycle. It is necessary to evaluate nuclear DNA content simultane ously in order to assess an essential cytogenetic change.