Cytogenetic analysis of rat cells, transformed by human papillomavirus genes

Chromosomal analysis of immortalized rat embryo fibroblasts (IE5) and transformed by HPV18 E6+E7 genes (A4E5) or HPV16 E7 alone (trB4; trF8; trC2) variants have been done. Transformed cell lines represented heterogeneous cell populations containing neardiploid subpopulations with 41-44 chromosomes and also heterogeneous polyploid cells in contrast to immortal cells IE5 that contained normal number of chromosomes-42. In transformed cells the abnormalities of interphase nuclei (giant-, micro-, apoptotic nuclei) were observed which could reflect genomic instability of polyploid cells. Several chromosomal alterations were revealed in immortal IE5 cells, but only reciprocal translocation t(8; 10) (q22q12.3) was stable and kept in cells transformed by HPV18 E6+E7 genes or HPV16 E7 alone. We can conclude that genomic instability and clonal expansion of the cells with specific chromosomal alterations contribute to HPV-mediated transformation.