Early genetic events in HPV immortalised keratinocytes

Cancer of the uterine cervix (CaCx) is the second most common cancer in wom en worldwide. More than 99% of all cervical cancers contain high-risk human papillomaviruses (HPVs), with type 16 predominating. HPV infection alone i s not sufficient for neoplastic progression; the HPV-infected cell must und ergo additional genetic changes. Cytogenetic analysis of CaCx has been limi ted due to difficulties in obtaining good-quality banded chromosome prepara tions. Oncogenic HPVs immortalise primary genital keratinocytes in vitro, a nd evidence suggests that the molecular genetic and cytogenetic abnormaliti es observed in HPV immortalised cells reflect the in vivo changes. Therefor e, these lines represent suitable models for HPV-induced carcinogenesis. We have used both spectral karyotyping (SKY) and multiplex-FISH (M-FISH) anal ysis to identify karyotypic changes in HPV-16 immortalised keratinocyte cel l lines and established CaCx lines. SKY and M-FISH identified chromosomal a bnormalities in all cell lines examined, with a translocation of chromosome 10 or i(10q) occurring in 9 of the 12 cell lines investigated. Further stu dies with chromosome 10 band-specific probes identified the translocation e vent as involving 10q with the breakpoint at 10p 11.2 in some cell lines or 10q 11.2 in others. The pericentric region of chromosome 10 is known to co ntain duplicated sequences flanking the centromeric satellites. The duplica ted sequences contain many zinc finger transcription factor encoding genes and disruption of these in HPV immortalised cell lines may alter the transc ription with consequences for both cellular and viral gene expression. (C) 2001 Wiley-Liss, Inc.