Background: To test and introduce effective and less toxic breast cancer (BC) treatment strategies, animal models, including murine BC cell lines, are considered as perfect platforms. Strikingly, the knowledge on the genetic background of applied BC cell lines is often sparse though urgently necessary for their targeted and really justified application. Methods: In this study, we performed the first molecular cytogenetic characterization for three murine BC cell lines C-127I, EMT6/P and TA3 Hauschka. Besides fluorescence in situ hybridization-banding, array comparative genomic hybridization was also applied. Thus, overall, an in silico translation for the detected imbalances and chromosomal break events in the murine cell lines to the corresponding homologous imbalances in humans could be provided. The latter enabled a comparison of the murine cell line with human BC cytogenomics. Results: All three BC cell lines showed a rearranged karyotype at different stages of complexity, which can be interpreted carefully as reflectance of more or less advanced tumor stages. Conclusions: Accordingly, the C-127I cell line would represent the late stage BC while the cell lines EMT6/P and TA3 Hauschka would be models for the premalignant or early BC stage and an early or benign BC, respectively. With this cytogenomic information provided, these cell lines now can be applied really adequately in future research studies.

Background: The Neuro-2a cell line, derived from a murine neuroblastoma (NB), was established as early as 1969 and originates from a transplantable tumor that arose spontaneously in an A/Jax male mouse in 1940. Since then, it has been applied in over 10,000 studies and is used by the World Organization for Animal Health for the routine diagnosis of rabies. Surprisingly, however, Neuro-2a has never been genetically characterized in detail; this study fills that gap. Methods: The Neuro-2a cell line and two of its derivatives, Neuro-2a TR-alpha and Neuro-2a TR-beta, were analyzed for their chromosomal constitution using molecular cytogenetic approaches. Array comparative genomic hybridization was performed to characterize copy number alterations. Results: Neuro-2A has a hyper-tetraploid karyotype with 70 to 97 chromosomes per cell, and the karyotypes of its two examined derivatives were quite similar. Neither of them had a Y-chromosome. The complex karyotype of Neuro-2a includes mitotically stable dicentres, neocentrics, and complex rearrangements resembling chromothripsis events. Although no amplification of euchromatin or oncogenes was detected, there are five derivative chromosomes with the amplification of centromere-near heterochromatic material and 1–5 additional derivatives consisting only of such material. Conclusions: Since satellite DNA amplification has recently been found in advanced human tumors, this finding may be the corresponding equivalent in mice. An in silico translation of the obtained results into the human genome indicated that Neuro-2A is suitable as a model for advanced human NB.

After being established in 1967, the commercially available murine Leydig cell tumor line I-10 has been used in almost 50 published studies. I-10 has not been characterized, either at the chromosomal/ cytogenetic level or the genetic level, similar to many other murine tumor cell lines. In this study, we performed molecular karyotyping and multicolor banding-based molecular cytogenetics. A slightly hyperdiploid karyotype with 43 chromosomes was described. The main aberrations comprised several unbalanced translocations and three unusual rearrangements (two dicentric derivatives and one neocentric derivative). Nine regions showed copy number gains, and only five small chromosomal parts showed loss of copy numbers. A standardized translation of these imbalances in the human genome was performed, which showed a 63% overlap of the detected imbalances with testicular germ cell tumors, a 53% concordance with human spermatocytic seminomas and non-seminomas, and only a 36% overlap (approx.) of large copy number gains and losses were similar to the corresponding human Leydig cell tumors. However, no Y-chromosome was detected in this male-derived cell line. Overall, the I-10 cell line was found to be a testicular germ cell tumor model and cannot be treated as a model that is specific to human Leydig cell tumors. At best, it might be suited as a model for an early onset of Leydig cell tumors.