NONTUMORIGENIC SV40T IMMORTALIZED HUMAN BUCCAL EPITHELIAL-CELLS SHOW ANEUPLOIDY AND GENETIC INSTABILITY

Cytogenetic and DNA flow cytometric analysis was carried out on four S V40T-transfected human buccal epithelial cells lines. One of these was immortalized and showed a non-tumorigenic phenotype when rested in at hymic nude mice. DNA flow cytometric ploidy values correlated well wit h cytogenetic ploidy values as calculated from chromosome length or DN A content, whereas the chromosome counts correlated poorly with the fl ow cytometric results, Gross ploidy changes were seen at early passage s, while the immortalized cell line had a stabilized DNA content in th e near diploid range. However, this cell line showed ongoing random ch romosomal changes with the appearance of new marker chromosomes balanc ing chromosome losses. The chromosome losses were mainly found in the groups 12-16 and 18-23 and the gains in the group 1-6. This reflects, together with the stabilization of the DNA content, a nonrandom compon ent in the overall random chromosomal changes. In conclusion, aneuploi dy and genetic instability found in the immortalized cell line were no t linked to malignant growth in nude mice.