First Cytogenomic Characterization of the Murine Testicular Tumor Cell Line I-10

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.