Simultaneous mapping of human papillomavirus integration sites and molecular karyotyping in short-term cultures of cervical carcinomas by using 49-color combined binary ratio labeling fluorescence in situ hybridization

Abstract

Infection with high-risk type human papillomavirus (HPV) is a necessary causal factor in the pathogenesis of cervical carcinoma. In most invasive cervical cancers, HPV is integrated in the host cell genome, and additional genetic aberrations are observed among which are chromosomal aberrations. To analyze in detail such often complex chromosomal changes and simultaneously map HPV integration sites, we extended the multiplicity of the combined binary ratio labeling fluorescence in situ hybridization (COBRA-FISH) technique to 49 by inclusion of a large Stokes' shift fluorochrome as the third binary label. The technique allows mapping of the integrated HPV genome in the context of p- and q-arm COBRA-FISH, with a sensitivity of one copy of the HPV genome as tested for HPV 16 in SiHa cells. We investigated the molecular karyotypes and integration patterns of HPV types 16 and 18 in metaphase spreads from short-term cultures of primary cervical carcinomas (n=5). Of the tested cervical carcinomas, two contained integrated HPV at 8q24, one of which in addition harbored the integrated virus near a translocation breakpoint. Two carcinomas had integrated HPV at 17q21∼23 in a morphologically normal chromosome 17. One carcinoma contained HPV at 1q42 in a morphologically normal chromosome 1. Our data illustrate the efficacy of 49-color COBRA-FISH to resolve complex karyotypes and simultaneously map specific sequences in metaphases obtained from short-term solid tumor cultures.