Sequential cytogenetic studies in an ovarian cancer cell line.

Cytogenetic analysis of a human ovarian carcinoma cell line JoN was performed at passages 6, 43, and 89. At passage 6 there were pseudodiploid and pseudotetraploid cells containing up to 22 markers. Pseudodiploid cells predominated. Significant differences were seen in the later analyses. At passages 43 and 89, cells had a modal number of 44 and 88 chromosomes with four new reciprocal translocations and loss of all unidentified markers. There was retention of one identified marker throughout plus one that gradually disappeared. Karyotypes at passages 43 and 89 were identical, suggesting stability of rearrangements. These changes indicate continuing chromosomal rearrangements in culture, not necessarily creating more complexity.