Alteration of STR profiles in ovarian carcinoma cells during primary culture

Cell authentication is a necessary procedure to avoid scientific data from cell culture experiments with cross-contamination or false classification. A genetic fingerprint pattern of a specimen by short tandem repeats (STR) is self-evident. Due to high amount of chromosomal rearrangements, known in epithelia ovary cancer cells and the instable STR pattern described in other tumour entities like leukaemia, this study explores the suitability of STR profiling for primary cultured epithelial ovary cancer cells.

STR profiles of epithelial ovary cancers of 16 patients were compared with corresponding blood and corresponding primary cell cultures. The primary cell cultures of epithelial ovary tumours were passaged up to 28 times. In between, cultures were cryo conserved and recultured again, two to five times per patient.

In two cases, the STR pattern of tumour lost alleles (1/16 and 3/16) in comparison of corresponding STR-pattern from blood. In comparison to blood, cell culture of a third case, lost four alleles (4/16) accompanied with morphologic changes after 14th passage. It is equal after cryo conservation of the seventh passage from the same patient. The only changes in STR profiles we recognized are losses of alleles. Remaining STR markers allow authentication.

Very likely, the allelic drop-outs beyond passage 14 assume complex genetic losses of heterozygosis resulting in changed growth behaviour of cells. All other STR-profiles of remaining 15 patients analysed in this study are stable over all passages and freeze-thaw processes. Thus, ovary cancer cell cultures in research should be authenticated by STR-profile in general.