Integration of human papillomavirus sequences in cervical tumor cell lines

The establishment of three cell lines from keratinizing and nonkeratinizing cervical carcinomas was previously reported. These cell lines were analyzed for growth properties in vitro and in vivo. Metaphases prepared from tissue culture of these cell lines were cytogenetically characterized using GTG-banding and fluorescent in situ hybridization (FISH) using chromosome-specific alpha-satellite probes. Although the karyotypes of most cells were extremely complex, nonrandom karyotypic abnormalities could be identified. Molecular data had suggested that TC140, derived from a keratinizing cervical tumor, may contain HPV 16 in the episomal state, while TC146, derived from a nonkeratinizing large-cell cervical carcinoma, contained HPV 16 in the integrated state. Therefore, a fluorescent in situ hybridization study was undertaken using biotinylated HPV 16 DNA as a probe on order to confirm and to corroborate the original molecular study, as FISH is the most direct approach for mapping cellular and viral sequences in mammalian chromosomes. The results previously reported in abstract demonstrated the presence of positive hybridization signals on the long arms of the apparent homologs of a human D-group chromosome in cell line TC146. The results of recently completed experiments clearly indicated that while the predominant state of viral existence in the TC140 cell line was apparently episomal, consistent viral integration was found in the TC146 cell line. Furthermore, where viral sequences of HPV 16 integration were observed in cells of TC146, integration was apparently nonrandom. Fluorescent in situ hybridization using various chromosome-specific alpha-satellite and HPV 16 probes clearly indicated that viral integration occurred nonrandomly and at a specific site on chromosome 13. By chromosome morphometry, the viral integration site was localized to 13q14, also the mapped locus of the retinoblastoma (Rb) tumor suppressor gene.