Viral integration sites in human papilloma virus-33-immortalized cervical keratinocyte cell lines

Abstract

The viral organization of HPV-33 was determined by Southern blotting in 2 HPV-33-immortalized cervical cell lines (CK11 and CK12) and compared to our previous results obtained on 10 other already characterized HPV-33-immortalized cell lines (CK1 to CK10). As observed in CK1 to CK10, the viral DNA was found integrated in the cellular genome of CK11 and CK12. However, in CK11 and CK12, the integrated viral genome was deleted and mostly limited to the URR and the E6-E7 ORFs, stressing the importance of those sequences in the immortalization process. Furthermore, CKll and CK12 showed a unique and identical integration site, as observed in CK1 to CK10, which also harbored HPV-33 integrated at a unique and identical site (which was however different from the one evidenced in CK11 and CK12). Indeed, in situ hybridizations on chromosomes allowed the precise localization of the viral DNA on chromosome 13q33-34 in CK1 to CK10 whereas it was mapped to chromosome 9p13 in CK11 and CK12. We discuss the possibility that integration of HPV-33 at those two particular sites has conferred some growth advantages to the cells and could have thus played a crucial role in the immortalization.

Single copy heterozygote integration of HPV 33 in chromosomal band 5p14 is found in an epithelial cell clone with selective growth advantage

“…The most probable scenario regarding the physical state of HPV 33 in the UT-DEC-1 cell line is an early integration, followed by a selective enrichment of the cells containing integrated form. A positive selection for the cells containing integrated HPV is supported by the observation that HPV 16 and HPV 18 integrated into the cellular genome provided a growth advantage to these cells (7,37,66,67). The results of the mixing experiment with 'episomal' and 'integrated' cells supported such selective growth advantage for the latter UT-DEC-1 cells.…”

“…HPV 33 integration has been studied previously using the immortalized cervical keratinocyte cell lines CK1 to CK12 (65,66). It should be noted that HPV 33 integrated at a single and identical site in CK1 to CK10 (subclones of the transfected cells), which was also evident in the HPV 33-carrying UT-DEC-1 cell line.…”

Cloning and Characterization of a Novel β Integrin-Related cDNA Coding for the Protein TIED (“Ten β Integrin EGF-like Repeat Domains”) That Maps to Chromosome Band 13q33: A Divergent Stand-Alone Integrin Stalk Structure

“…Other genes that have been mapped to chromosome band 13q33 include the pro alpha 1 and 2 (IV) collagen genes (Boyd et al, 1988), the DNA ligase IV gene (Wei et al, 1995), and the gene for xeroderma pigmentosum complementation group G (XPG) (Samec et al, 1994). In terms of disease association, band 13q33 is a site for integration by human papilloma virus-33 (Gilles et al, 1996); it is amplified in oral squamous cell carcinomas (Matsumura, 1995) and is commonly deleted in ovarian cancer (Yang-Feng et al, 1992).…”

Integrated HPV genomes tend to integrate in gene desert areas in the CaSki, HeLa, and SiHa cervical cancer cell lines

“…The integration of the HPV genome into the human genome might be one of the important mechanisms that induced related cancers [5,9] and is also the strategy used by many other species of virus for carcinogenesis [3,7,33,34,38]. The integration sites in genomes targeted by viruses have been extensively explored [13,16,26]. In some cases, viruses do not exhibit strong biases to integrate into fragile sites or cancer related sites in human chromosomes [21,23,24,32].…”