Preferential loss of abnormal prostate carcinoma cells by collagenase treatment.

Effects of two different methods of tumor disaggregation on flow cytometric ploidy distribution and intact cell yield were investigated. Either mechanical disaggregation or collagenase digestion was applied to 35 prostate tumor specimens. Seven collagenase-treated samples failed to yield any intact cells, whereas with mechanical disaggregation in all cases a sufficient number of intact cells were obtained. No differences in the FCM ploidy distribution of tumors with a DNA diploid stemline were observed comparing both techniques. In DNA aneuploid tumors, however, collagenase treatment had an adverse effect on the abnormal cell populations. In 14/17 of such tumors, the abnormal cell populations were significantly reduced; in eight of these the percentage of DNA aneuploid cells declined even below the minimum percentage (10%) that was defined for DNA aneuploidy. Since collagenase is a widely used enzyme for tissue disaggregation, especially in tumor cytogenetics, the presented data will have consequences for the interpretation of results obtained by methods involving the use of this enzyme.