Interphase cytogenetics in paraffin embedded sections from human testicular germ cell tumor xenografts and in corresponding cultured cells.

A protocol was developed that allows determination of chromosome aberrations in interphase nuclei from paraffin embedded human tissues. As a model system tissue sections from xenografts derived from three testicular germ cell tumors (two teratocarcinoma and one embryonal carcinoma), as well as sections from normal intestine and testicular tissues, were hybridized with a biotin-labeled DNA probe specific for 1q12. For comparison, isolated nuclei in suspension and metaphase spreads from in vitro cell lines derived from the respective xenografts were assayed. Our results show that interphase tumor cells with aberrant numbers of chromosome 1 can be reliably detected both in vitro and in vivo. Subclones with two and three labeled chromosomes, respectively, could be defined and quantitatively evaluated. Present and future possibilities to pinpoint specific chromosome aberrations directly in cells present in body fluids or in tumor tissues are discussed.